q:
Is it possible with the accuracy of current 3D printers to print a sound trace?

On a vinyl record the grooves in the record are an encoded sound. Is something like this doable with 3D printers?

If Vinyl-like isn't possible, could a sound be printed at desktop scale? I mean printing the waves out that if you ran your finger along it it would reproduce the encoded sound? Examples would be Rumble Strips, the Musical Roads or highway rumble strips.

[A]
Sound Encoding basics
Sound is a compression wave, and any depiction of it has to be an encoding of it. You can encode it so you can recreate the sound using a contraption that oscillates in the right way to compress air again in the right pattern, but you can't just "print it out" like you can scale up a lightwave from the nanometer scale to a visible one as a representation.
Let's take a simple example: a 440 Hz tune is generally considered to be the A
4
, aka
concert pitch a
or A440.
It could be encoded in a various ways. The probably oldest is to encode it as a note in violin notation, which then could be reproduced by anyone using a properly tuned instrument. The actual result depends on the instrument used as much as on the skill of the player. Each instrument thus might decode this encoded note differently, based on the physical setup of the instrument. Each instrument
automatically
creates the appropriate overtones.
In Midi, it is encoded as
```
Note 69
```
and any machine that can decode a midi file could use this instruction, paired with an instrument to use, to create the A
4
that is set for it. In Midi, the mere instruction of Note 69 does cut out skill, but how it sounds and feels comes from the instrument setup - which contains information about what overtones are to be created when playing this note.
For a physicist, the pure sound is encoded as just the notion of
```
440 Hz
```
and some amplitude to balance how loud it is. With those instructions, he'd be able to set up a device that has these creates a 440 Hz tune. To generate the sound and feel of an instrument, the encoding for a physicist would need to contain all the overtones that are to swing with this one sound.
History of sound recording
Let's look at the very first way of recording sound: The Phonautograph of 1857 used a piece of paper or a sheet of glass blackened and then a membrane move a needle. When the plate would be moved, the needle left a written path. The encoding was done via 2 factors: the setup of the stylus (mainly how long is the arm) and the speed of the movement of the plate. Changing either changed the encoding. A longer arm would record a larger amplitude (making fainter sounds recordable) while faster movement would alter the timescale recorded, allowing to look at short instances and better compare them.
These vibration-pattern records could be used to measure and compare sounds but not be used to recreate the sound, as lines on paper nor scratches in soot are a good way to keep a reading needle in boundaries. it took till 2000 and the use of scanners as well as digital processing to recreate these recorded sounds.
The solution to recreate sounds was found by the Edison Laps in 1877 with the phonograph, which used a piece of thick tinfoil to record the motion pattern of the membrane. Again, then encoding was done via the arm setup and the speed at which the tinfoil clad cylinder moved (or rather rotated). It would till the 1880s develop to a wax cylinder, which was easier to inscribe and reproduce from. One such machine was used by Carl Orff.
The first Gramophone came in 1889, mainly altering the shape of the recording medium from cylinders to the well-known shape of vinyl records but made from hard plastics and shellac. Around 1901, a 12-inch gramophone disk held only a 4 minutes track, speaking volumes about the problems of encoding the complex patterns of sound onto a disk. At the same time, an Edison Amberol Cylinder held 4 minutes 30 seconds but would spin at 160 rpm. Soon after, celluloid would become the recording medium of its time, and the disk the de-facto "standard" as it was much better storable.
In 1925 finally, a real standard was developed to record at around
$78^{+0.26}_{-0.08}$
rpm, which lead to only a 0.34 rpm difference between areas of 60 or 50 Hz mains voltage (though they needed different encoder rings), making records interchangeable between both machine types. All these recordings were encoded naturally: the vibrations of the membrane in the recording tool would be 1:1 transmitted to the vibrating stylus that would then do the encoding in such a way that a machine would reproduce what the recording one "heard" quite accurately.
When Vinyl came to the playing field as a recording medium at the end of world war II, so came a swap in the reading needle type: instead of a needle that would agitate a membrane directily, sapphire needles that would agitate an electrical pickup which in turn would activate a speaker. But while the recording technology advanced, the track length of a 12-inch disk was still limited to about 4 minutes at 78 rpm. It would only reach more than this in the last years of its use by applying LP technologies to pack the track tighter in the 1950s, achieving 17 minutes.
1948 came the LP, what we know as a classic vinyl record. At its introduction it could cram 23 minutes onto one side, making this possible by only using 33.5 rpm as the recording speed and thinner, much tighter coiled groves, increasing the information density by a factor of 5.75 for a 12-inch disk. 7-inch 45 rpm "singles" came out 4 years later. Within 10 years, the 33.5 and 45 rpm encoded variants had almost completely replaced the 78 rpm market.
Vinyl
As the history of analogous recordings shows, encoding a sound signal is rather easy in theory, hard in practice. A typical 12-inch
LP Vinyl record
of 20 minutes is a grove that is  427 meters long and coiled up 667 times. That means a single groove is between 0.04 and 0.08 mm wide - with an equally thin wall between. That means, that to achieve a printed phonograph record, you'd have to print accurately down to 40 microns to get an
empty
track. However, we also need to add the signal atop. And here comes the real problem:
An empty track has some 22 µm deviations, which the needle will usually not pick up at all. Dust, which creates the crackling at times, is in the same area (1-100 µm). The actual sound signal is encoded to have features as small as 75 nanometers. That is 3 magnitudes lower than the mere geometry of the grove, and equally much lower than any printer - including SLS - can achieve today, as 50 µm is often considered a lower limit in 2019.
To show how much tiny defects would ruin the sound quality, look at
this rapid cast
of a vinyl record. The resolution of the negative and the subsequently cast record is good enough to recognize the music, but the resin cast did contain so many gas bubbles that the noise level of the copy is very high.
Bonus: Unlike on cylinders the encoding of the signal on disks changes from the start to the end! The vinyl spins at a constant rate, but the radius from the center changes, leading in the speed on any part of the grove to be different as
$|v|=|\omega \vec r \sin(\theta)|$
, where omega is the speed in rad per second, theta is the angle of the reeding, so in this case, the sinus term becomes 1 and vanishes. This factor has to be taken into account for encoding so the pitch of the record doesn't change if the record is not created naturally by inscribing the signal onto a spinning disk.
Other encoding
Rumble Strips
However, it is quite easy to create a structure that creates sounds based on interaction with another body. Highway Sound Strips create sounds as the car tire bumps up and down, turning the car and tires into resonance bodies while the street "beats" upon it. In the case of a large percussion instrument like a car, we are talking centimeter scale.
Peg-Cylinder
A very simple method would be to go back to encoding and check out the note notation but limiting the length of notes to one unit. Encoding music this way results in pegs or ridges on a cylinder, which then can be used to actuate a mechanism to decode the music and create sounds like in a music box. In a music box of this kind, the demand for accuracy is about 3 to 5 magnitudes lower than in vinyl records: we speak about a tenth of a millimeter to centimeter scale.
Such a
Musical box
or
noisemaker
can be easily printed and is pretty much a rumble strip coiled around a cylinder. The length of the sample is determined by the resolution, playback speed and diameter of the cylinder while the complexity is determined by the rows of pegs of it: a noisemaker is pretty much a 1-note, high speed, music box. Typically, one rotation stores about 25 to 30 seconds. Typical examples would be the first part of
Für Elise
,  or the
Marble Machine
(Between second 30 and 35 the encoding wheel rotates 1 fifth). Some barrel organs also use the peg method, like one can
see here
. With some trickery, one cylinder could be used to encode multiple parts that play one after another once a rotation is done by and silencing some parts of the machine depending on an extra encoder, like
this 3-part
Für Elise
music box.
Hole-Plate(-strip)
A different method would be to encode the music as holes in a continuous strip and use air as a decoding method. If the air then gets directed into pipes, we have a street organ. Typically, one would use a paper strip as the encoded message, but it could be printed just as well, especially if one uses a setup that uses plates hinged to one another instead of a rolled-up paper as in
this example
. With such a way to stash away the extra length, the upper limit for music length rises from a couple of seconds to several minutes easily even with such a "bad" encoding.


q:
I am printing using an Ender3 Pro with eSUN PLA+ 215/45 and I am getting this issue on two corners, the other two corners look fine.

Any idea on what can be causing this?

The bad corners

The good corners

[A]
Looks like it treated those corners a bit differently in the slice routine.  Normally something like this different treatment would be too slight to matter, but (probably due to the slight overhang?) it appears to have caused some layers to not adhere to the bottom ones and get pulled along to a different shape (red line in image).  (Be sure to check some general layer adhesion/overhang topics too.)
I'd try increasing the infill there (and using honeycomb style infill) or even using a cad software to hollow the interior to essentially a desired infill before slicing if the current infill is important elsewhere.
Moving slower, Increasing the temperature a bit, and/or extruding more material per line and layer if the layer adhesion is due to the slight overhang (although it looks pretty small).

s: huggingface

c: devops

d: intermediate


q:
I'm using Cura to slice my prints. I've noticed that when printing the bottom layer (and also the top layer, if it's flat), it first prints three walls, then fills in the middle by moving back and forth in straight lines.

I've noticed that for my parts, the walls look much nicer than the zig-zag pattern in the middle, and it also seems that the zig-zag part detaches from the bed quite easily, whereas the walls don't.

My parts would look much better, and possibly also stick better to the bed, if I set the number of walls to 100 or so, so that the parts would be entirely filled in with walls. But then the parts would be completely solid, which isn't what I want. So what I want to achieve is that the bottom layer (and if possible also the top layer) are printed as if the part was composed entirely of walls, but the other layers are printed with three walls as normal. Is this possible in Cura?

[A]
I found the answer myself just after posting - I'm posting it because it might be helpful to other Cura novices.
There is a setting for this, it's just that it's not shown by default. In print settings, you have to click on the three lines next to the search box, and select "Show All Settings". Then you can find a setting called "Top/Bottom Pattern". Setting this to "concentric" does what I described.
Actually this setting affects not just the top and bottom layers, but all layers that are part of the top and bottom shell. This seems like a good thing, but if you really want to affect
just
the bottom layer, there's a setting "Bottom Pattern Initial Layer" that does this. There is also a setting under "Experimental" called "Top Surface Skin Pattern" that I think does the same for just the top layer.
In addition to "Concentric" there is also a "Zig Zag" option that's quite similar to the default "Lines" mode.
You can also change the visibility of settings in the preferences menu, to make these settings show up by default.


q:
I have made some prints with the Ultimaker 2+ and Ultimaker 2 Extended+. The prints are in PLA. For slicing, I use Cura and I check the support checkbox (haven't gone to advanced settings to adjust support yet). I can clearly see that there is a little space between the support and the print. The supports often look like long pillars and such.

My question then is: "What is the best technique for removing the support?". Is it to use a knife, pliers or perhaps PLA-water? Is it possible to use PLA-water to remove support when printed with Ulitmaker 2+ or is that just the Ultimaker 3? What type of technique would give a good looking print?

Ultimaker 3 has support filament that's water-soluble. Is there something similar for Ultimaker 2+?

[A]
PLA and ABS are hard plastics. They are not water-soluble. If you print with these materials, just snap printed support materials off and clean the interface layer with a knife and sanding.
To remove the support, it is best to use strong tweezers or a pair of pliers to grip and then apply some force. Generally, I use needle pliers, but occasionally I also use snippets to cut up the support towers into more manageable chunks and keep the printed part safer. It can help to remove it in pieces and score the breaking lines.
As PLA is brittle, I prefer to break away from the object and not pull.


q:
I have a Printrboard rev. D which includes Allegro A4982 drivers. I would like to replace them, but it appears that newer TMC drivers all require several pins for proper operation.

How can I upgrade the drivers in the Printrboard rev. D?

[A]
You can't. In fact, pretty much all boards with directly soldered drivers are not upgradable.
I'd recommend to buy a proper, contemporary, customizable board like the SKR 1.3 for TMCs.
The Fysetc F6 would also work, but uses "custom" connectors and is still AVR based.


q:
So while doing some research I stumbled upon a wiki page on reprap from a few years back where the user was creating a glass nozzle to replace the brass and PTFE assembly.1

Does anyone know the theory behind this? Glass is a great insulator so I could see how that would be beneficial for the heat break part but I can't see how it is appropriate for the nozzle as this is normally brass which is a good conductor.

Surely the glass takes much more energy to heat up?

On a side note I've seen similar projects using ceramic instead.

[A]
Ceramic I can understand - very strong, great thermal range capability.  Glass not so much - you'd need some seriously careful annealing at least.
In either case the material is much harder than brass, or even steel, so you could presumably use tougher tools to unclog, etc. as needed.  If you're using materials loaded with wood or metallic particles, the glass/ceramic tip will be less likely to degrade than brass.
BTW, glass being a thermal insulator means it may take
longer
to heat up, but the
energy
required is probably less . The specific heat of glass is on the order of .84 J/gm-K . Compare with brass at  0.38 , but keep in mind the rate at which brass will shed heat into the air vs. glass.  In either case the energy is tiny compared with the thermal mass of the hotend assembly.


q: I recently got a Creality Ender-3, and tried printing a few things for some tests. I’ve printed a cube and just printed a cylindrical tube today, and I notice each time, it adds this random line on the left and a sort of outline around the actual print. Neither of these were there in my Cura file, but they’re always printed and I’m not sure why?

[A]
The outline around the actual print is called
Skirts
. and the random line on the left is called
intro line
it's not necessary you need both Skirt and intro line. The intro line can disable from custom starting gcode settings
A skirt is an outline that surrounds your part but does not touch the part.
The skirt is extruded on the print bed before starting to print your model. Skirts serve a useful purpose because they help
prime your extruder and establish a smooth flow of filament
.  Observing the skirt also allows you to
detect and adjust any leveling or adhesion issues
before the actual model begins printing.
You can easily edit/disable(not recommended) those settings in Cura (or in any slicing software)
In you Cura navigate to
Build Plate Adhesion
settings
Skirt line count:
The number of skirt lines printed around the model.
Skirt distance:
The distance between the model and the skirt.
Skirt minimum length:
The total length of the skirt. This will
override the skirt line count when the minimum length is not reached
yet.


q:
According to the instructions I have read, you use the same output on the printers mainboard to control a 110 V heated bed with a solid state relay, as you do to power the 12/24 V heated bed that comes with the printer.

The relay's datasheet states that its max input current is 25 mA, obviously a 12/24 V heated bed would draw a lot more than that.

How does Marlin know that the heated bed pins are controlling a relay now instead of a bed directly, and therefore should limit their current output?

In other words: I am worried that if I just drop in the relay, it will burn up since the board still thinks it needs to supply high current to the bed.

[A]
There are two current parameters which you are looking at in your instructions for the solid state relay. The first one (the 25mA) is for the
control
circuit. This is how much amperage the device itself will draw when in operation. The second is for the
load
circuit. This is the max amperage which can pass through the device.
Your
instruction sheet
shows the device having the ability to work at 10A, 15A, 20A, 25A, or 40A. These are different ratings for the same style of device. When you purchase the device, you'd need to specify which amperage rating you'd want your device to be at. They use the same spec sheet for all five flavors, because they are basically the same thing with the one exception, which is the amp rating.


q: I am trying to increase the flow rate on my Ender 3 from 100 to 108 % but every time I start a new print it reverts back to the old 100 % flow rate. I have clicked through the settings and pressed the "store settings" button but it still reverts back at the start of every print. I don't want to do this in my slicer settings as I run 18 Ender 3's so I want to be able to use the same G-code for each.

[A]
Changing the
flow rate
during a print can
not
be saved. There simply is no way. It is usually meant to be a fix with filament inconsistencies or to look for the right extrusion factor for a new filament batch.
Slicer
The only way to consistently increase the flow rate would be  to alter the
```
flow rate
```
in your slicer to what you have found to work best for each machine, probably using separate profiles. This will up the rate for every subsequently sliced print. Note though that this 108 % increased extrusion is converted extrusion factors that are simply numerical and 1.08 times the normal in the g-code. These numerical values will be taken as 100 % by the printer - and since it requires extra work to slice the gode for different profiles it is not the optimal solution.
As you elaborated though, this is not a doable thing, so let's look further.
Source hunt & Workaround
Since only one printer is showing underextrusion while the others do not, it is time to check the hard- and firmware:
underextrusion can be caused by a defective extruder assembly or a damaged or blocked nozzle.
if a machine has consistent underextrusion, its steps/mm in the firmware might be off. This could be altered and stored in the EEPROM. Since this could be a machine unique setting, here would be your point of attack to increase the extrusion of just one machine while using the identical G-code to all other machines.
Note that the standard firmware of the Ender-3 in 2019 did not contain Thermal Runaway Protection (
What is Thermal Runaway Protection?
) and should be upgraded because of this anyway. You have to flash a bootloader too, so in the process of doing the upgradeability and safety-upgrade to all the machines, you could store the altered steps/mm to each machine individually so they get consistent output.


q:
I understand the principle of why a heater block is used. Helping to reduce temperature variation as the filament is extruded using the heat capacity of the block.

But I’m wondering why it takes the form it does? I imagine it is cuboid in shape just for convenience as it’s easy to machine?

From a surface area to volume ratio a cuboid appears to be one of the worst shapes to use.

Note:
I am currently doing a project which requires me to increase the tool clearance of the nozzle of a 3D printer. Hence why I am exploring alternative print head configurations and heater block design trying to minimise the profile of the print head as much as possible.


q:
I just order myself an Ender 3 Pro which will come by the end of the week.
Before it arrives I want to be ready to flash a bootloader onto it.

I was wondering what other options there are to flashing except using an Arduino?

I have a bunch of ESP8266/ESP32 and a USB to TTL. Would it be possible to use these somehow instead of an Arduino to flash a bootloader to the Ender 3?
Or should I just go buy an Arduino?

[A]
What you need to is called a ICSP or ISP:
in-circuit serial programmer or in-system programmer
, which excludes the USB to TTL device you own.
I've never used an ESP8266 as ICSP but it seems there are
some resources out there
reporting it is possible.
If you want to go the easiest way probably you want to buy an Arduino and follow the tons of tutorials out there, if you are looking to save some money then you might get around buying an ICSP like the very well known USBASP (just Google for that).


q:
I know that M73 P19 means "Set completion progress to 19%", and I suspect that M73 R42 means "Set remaining time to 42 minutes", but what is M73 Q17 S43? I can't find description of such syntax.

The command is seen in .gcode files produced by PrusaSlicer.

[A]
The tooltip for "Supports remaining times" under
```
Printer Settings -> General -> Firmware
```
in PrusaSlicer quotes:
```
```
Emit M73 P[percent printed] R[remaining time in minutes] at 1 minute intervals
into the G-code to let the firmware show accurate remaining time.
As of now only the Prusa i3 MK3 firmware recognizes M73.
Also the i3 MK3 firmware supports M73 Qxx Sxx for the silent mode.
```
```
Therefore:
P = Percentage printed, normal mode
R = Remaining time, normal mode
Q = Percentage printed, silent mode
S = Remaining time, silent mode


q:
Is there a classification of method of control most (FDM) 3D printers fall under?

From a 1986robotics textbookref I was reading they defined three classes of control:

1) Pick and place

2) Point to point

3) Continuous path

However, both point to point and continuous path control are stated as requiring servo motors.

I know that the majority of 3D printers are actuated with stepper motors as opposed to servo. Does the continuous path classification still apply? Or is there another classification?

ref - Todd, D.J.(Ed.):Fundamentals of Robot Technology: An Introduction to Industrial Robots, Teleoperators and Robot Vehicles - Kogan Page 1986

[A]
The question is if robots classification terminology the textbook sketches applies to 3D printing?
Servos (closed loop) are used in robots to guarantee position (you don't want to accumulate an error after repetitive movement), most 3D printers use open loop steppers that are instructed on a point to point basis through G-code instructions, implying that the use of servos is not a "requirement" for point to point control.
It
is
a requirement if you want to be absolutely sure that the position is reached. In 3D printing where the loads are generally low, this requirement is frequently dropped. But, there are printers that use servo control.
Note that many CNC machines (operating at much higher loads than a 3D printer) even don't use servo's but (open loop) steppers, these are generally larger and more powerful (more torque).


q:
How can I correctly clean the lacquer from bed printer?

I have used some ethylic alcohol (ethanol) to help cleaning

But what is the best way to do it?

[A]
The Ender 3 does not come with a lacquered surface at all.The bed should have a rough build surface that is a clone of the BuildTak build surface. It is
intended
to be rough and satin-gloss in its native state. I do not remember if there was a thin protective plastic foil on my Ender-3 bed on delivery, but if there was, it should have been removed during assembly.
A BuildTak surface can be easily cleaned with isopropyl or ethyl alcohol of grease and fingerprints. The odd discoloration at the edges seems to be a layer of grease and dust, which can be easily cleaned away by soaking it in Isopropyl alcohol and then wiped with a microfiber cloth.
If the bed surface is destroyed by chipping holes into it, sanding it or otherwise ruining it (like melting plastic rap into it), you will need to replace it. Replacement surfaces come about 5 bucks on Amazon. Doing this, you might find
How to clean up my buildpate for a new build surface?
helpful.


q:
I switched my Anet A8 over to a Bowden and it's printing great. Moving that weight off has enabled me to almost double the speed and resonance problems have vanished.

My question is regarding after the print is done should I add a retraction code and back the filament out of the v6 or is it okay to leave it in there?

My concern is that if I leave it in there, will it cause a clog or anything when I warm up the printer tomorrow to print something else? If that's not a something I should be concerned about let me know.

[A]
It's okay to leave the filament in the hot end, as long as you let it cool down with the hot end cooling fan running.
From comment:
That's not an issue, you can simply leave it in the hot end. The only "end of print" clogs usually occur when leaving the hot end hot for a while - allowing the filament to drip out - and then retract the filament without feeding it against the nozzle once more. That creates a plug that's larger than the filament diameter that might get stuck in the bowden tube


q:
From the M502 documentation page can be read that M502:

Reset all configurable settings to their factory defaults.

Please note that this phrasing from the manual has been used in the question title!

To also reset settings in EEPROM, follow with M500.

Note that:

This command can be used even if EEPROM_SETTINGS is disabled.

The question is what is the definition of "all configurable settings"?

Are these the settings that are displayed with M503, or are there hidden settings?

[A]
What Marlin does when
```
M502
```
is called is defined in the
```
configuration_store.cpp
```
file.
It resets:
Max acceleration
Steps per mm
Max feedrate / speed
Min segment time
Acceleration (Normal, Retract, Travel)
Min feedrate
Min travel feedrate
Jerk settings
Junction deviation
Home and SCARA offsets
Hot end offsets
Filament runout sensor distance
Tool change parameters (Swap length, extra prime, prime speed, retract speed, Park
positions, Z raise)
Backlash correction distances and smoothing parameters
Extensible UI
Magnetic parking extruder settings
ABL (fade height, stored points, nozzle offset, servo angles
Delta calibration data (Height, Endstop offset, radius, rod length, segments per
second, calibration radius, trim angle)
Dual / triple endstop adjustments
Preheat parameters
PID parameters
self-defined thermistors
LCD contrast
Power loss recovery
Firmware retraction
Filament diameter (for volumetric extrusion)
Endstops (if disabled)
Stepper drivers
Linear advance parameters
Motor currents (digipot)
CNC coordinate system (if selected)
Skew correction parameters
Advance pause filament change lengths


q:
I'm new to 3D printing. I've made some projects before just fine, but this project is giving me problems.

I 3D printed a trumpet mouthpiece, and the printer made supports inside the mouthpiece funnel. I can easily remove the exterior supports, but I don't know how to get to the supports inside. Does anyone know how I would do that?

Here is the link to the model

[A]
Based on the photo provided, there's a strong possibility that you can print that model without internal supports. The angle of the walls falls within the limits of just about any FDM/FFF printer. An exception to this would be if you had a structure internal to the cone of the mouth piece which needed support.
ERROR: I neglected to note that your print is created "laying down" rather than vertically. This certainly complicates the printing/support problem. I typically print cylinders without internal support, although it does result in a small amount of droopies within the cylinder. Those are easily cleared away as required and much more easily than a full support forest.
Is it impractical for you to consider to cut the model in half, print both segments, remove the supports more easily, then glue them together?


q: I'm designing a mount for a cylindrical speaker to attach to my bicycle. It will mount on the bottle cages. I've printed a few iterations with various infill settings (using PLA) and the weak point is always the bolts holding the entire mount to the bike. They can't handle the compression needed to secure it properly. I had thought about using an imbedded metal part to distribute the load, but it's not easily replicable and I want to make the design public and fairly accessible to others with the same speaker. I currently have PETG and ABS, would one of those perform better or should I order a specialty high strength polymer?

[A] Try heating op your PLA while mounting it. The PLA wil temporarily weaken and will become a bit moldable. PETG is a bit more brittle than PLA is my experience so I'd say stick to PLA. Otherwise you might try Arnitel ECO. I can try to find an amazon purchase link for you if you want. Anyway, it is more rubber like and stays flexible, it will never crack but depending on your design it might become a bit more wobbly. If you share a picture of your design or an STL i might be able to help you a bit better.


q: I want to make a project involving many small dots indents and I would like to know how I can calculate the smallest dot hole the Prusa i3 MK3S can extrude around on a layer using PLA. In other words, if I printer a mesh with circle shaped holes, how would I know the minimum diameter of the holes. Is it simply the same as the layer resolution (0.35 mm), filament size (1.75 mm), or is it something else?

[A]
That depends on the ability how fast you get filament to stick to the build plate and whether the filament is loaded in the extruder. It also matters which size of nozzle you are using. The filament diameter has no influence other than smaller filament width (e.g. 1.75 mm) requires more length to extrude with respect to thicker filament (e.g 2.85 or 3.0 mm), and is therefore more precise to lay down (on the other side is the deviation on the filament diameter, i.e. manufacturing tolerance, larger than for thicker filament...).
If it does not stick you need more length, also, if the filament is not preloaded enough, the nozzle chamber needs to be filled first. Note that the printing of several small circles is a challenge, see e.g.
"How do I get circles on small interior holes to adhere to the bed?"
.


q: I am printing minis and other very detailes stuff and I find that 0.04 mm layer height gives the best looking (smoothest) result. However it takes a long time, so I am looking for ways to speed it up. Is there any slicer which offers different layer heights for the outer perimiter? So you can print your model at 0.12 mm or so, but the outer layer gets printer first 3 times at 0.04 mm?

[A]
In Ultimaker Cura, unless you print a single perimeter outline and add extra wall infill support you are not going to have different outer perimeter layer heights.
However, Cura is able to reduce the printing time, E.g. you can have fine layers for the wall (all perimeters), and coarse layers for the infill. The option is called
"Infill Layer Thickness"
:
Infill layer thickness
Since the layer height of the infill is not important for visual quality, you can use thicker layers on the infill to reduce the print time. When adjusting this setting, always make sure that it is a multiple of the layer height, otherwise Ultimaker Cura will round it up to a multiple of the layer height. This means that you can, for example, print with an infill thickness of 0.2 mm while the layer height is 0.1 mm. The printer will first print the walls for two layers, and then it will print one thicker infill layer.
Note that this is not a standard option, you need to put Cura in the "Custom" mode and filter/search for the option using the search bar. Below you'll find the upper right corner of the Cura Graphical User Interface where I searched for the option:
Note that there are 2 options, one for regular infill of your product and one for infill of the support structures.
An other department at work is working together with a start-up university company to 3D print PEEK molds (from pellets) using 2 nozzles/extruders (to create resin injection parts), one has a large nozzle, the other has a fine nozzle. They use their own developed slicer software to use the fine nozzle for the outer contours and the coarse nozzle for infill and support. It could be that they developed this because it was not available in commercial slicers. For the 2 most common free slicers, Cura and Slic3r, there is no option to have just the outer perimeter of different height than the inner perimeters. If you think of it, it is also pretty difficult to execute, you either get:
(which does not improve the quality of the product, it will make the outside more coarse) or you'll get gaps:
Note that both upper images do not include infill, only 1 outer and 3 inner perimeters. The image below is probably what is possible with Cura, so all perimeters the same; green is infill now:


q:
Here is the context

I've got an old car for which I have a small plastic piece who is broken. As it's an old car and a very specific piece, I can't find it anymore. So I was thinking about 3D printing it.

My problem is this piece is on the carburetor, so close to the engine. This means, it can heat a lot, close to 90-100 °C.

My question

Do the pieces created with the common 3D printing techniques melt at 100 °C? If yes, what kind of other 3D printing technique can I use?

Here is the piece I want to recreate (sorry for the bad quality), the scale is in cm.

[A]
Depending on the exact mechanical load and material used to print, you might get away with 100 °C.
Next to the melting temperature required to print the material (which will always be substantially higher than the maximum useable temperature!), you probably also want to have a look at the glass temperature of your specific material. Around that temperature your material becomes soft (rubber like) and can deform permanently when cooling down again. Chances exist that under a considerable mechanical load, the part will deform at even lower temperatures.
Maybe it would help to post a picture or describe the exact component you're trying to replicate. It might help in finding an alternative solution. (E.g. carving out of say PEEK to say anything.)


q:
I'm printing with a Prusa MK3, with the following settings:

3 perimeters

50 % infill

infill overlap: 50 %

The filament is Polyalchemy emerald green (PLA). Nozzle temperature: 210 °C.

On a simple part (it's a keychain), the shell detaches if I apply a bit of force on a zone of the part that is "fragile". See picture. You might not be able to see it, but only the 2 external perimeters detach from the rest of the part. I used to print this part on another printer, and I never observed this problem.

Any idea on how to solve this problem? It seems the 3 external perimeters didn't fuse properly.

[A]
I am looking at your picture, and I realize that it is not only that the perimeter is detaching from the infill, but also that the perimeter is breaking.
Once the perimeter breaks, the weaker connection with the infill will surely break, too.
You could try:
Using more than two perimeter layers.  Go big. Try five.
Add a fillet where the ring attaches so that the force is not focused on a point.
Choose an infill percentage and pattern that maximizes the contact between the perimeter and the body.
Change the angle on the bed at which the keychain is printed so that the infill maximally connects with the breaking point.  That might make the ring be 45 degrees off the X and Y axes.


q:
I’ve just brought my printer back out after a month and it’s first print created a solid block of resin about 1.5 cm deep and the full width and length of the print bed. What could cause this?

My only thought so far is that the FEP film / vat bed is looking a little cloudy even after cleaning. I wondered if this could have caused the light to diffuse across the whole bed?

[A]
Is the laser (or whatever light source it uses) visible? The cloudy film sounds like a good candidate for light diffusion and thus solidifying the entire resin, but if there are visible components to the light source it may help narrow it down.
If it uses a projector ("LCD") solutions, it may also be that the display that filters the light to certain regions of the resin to selectively solidify the print may be at fault, but that's rather unlikely.
The first thing that, in my
opinion
, you should do is to check that the object you are printing does not have a corrupt model file. Assuming that you have spare, fresh resin (if your resin is old, that's actually the most likely issue...) and it wasn't too hard to pry out that block, you could try printing something else that worked in the past.
While it's doing that, you may be able to see where/how it is printing. If the beam diffuses or lights up the whole area, you can tell if it's a printer issue (the film sounds like a good first thing to try replacing in that case). On the other hand, if the resin is old, it's probably just getting oversensitive and your printer is fine.
The resin is very touchy with these things, and has a shelf life of a few weeks to a few months, and less if it's ever opened.


q:
I bought an Ender 3 two days ago and assembled it today. I think I did it properly, tested the movement of all axes which works for all axes. Then I performed the calibration as described in the manual. I used a piece of paper and adjusted the bed until it barely fits underneath the nozzle for all four corners. Afterwards, I wanted to print my first model so I selected the cat from the usb stick which came with printer. And now comes my problem. I let the printer run for 15 minutes. It moved and moved and moved but there was no filament on the bed. The nozzle and bed were heated properly. The one thing which I noticed was that the stepper which feeds the filament turns for like 30° and then flips back: to me it looks like the filament can not be fed in. After canceling the print the extruder moves back to the home position which is like 5 mm off the bed and then suddenly the filament flows out of the nozzle.

What part of the configuration I'm missing?

[A] I use Cura on my Anycubic Chiron which I encountered a similar problem with and I was able to resolve the issue by preheating the nozzle to a higher temp. I would test the nozzle and make sure it is feeding properly. What I mean by that is load the filament manually and make sure it comes out. Reason I say this is because the other issue you may be running into is either the nozzle is clogged or it may be too close to the bed for it to come out of the nozzle. This is all speculation but hopefully it helps.


q:
I printed a model and now I can't remove it.

I have been chiselling away with a putty knife and made little or no progress.  I even heated the bed up to 70 °C.  That really didn't seem to help.

Last time, I put it in vice, and tried to free it that way, but instead I broke the glass.

Suggestion?

[A]
It's useful to know what material you used for the print. Also, you've referenced the glass that broke in the vise, which implies a glass bed, but did you use any adhesive spray or other application?
Allowing for all of this unknown information, there may be a solution for your release. Our library makerspace has a small bottle of 50-50 water/denatured alcohol, although isopropyl alcohol should also work if your glass is not coated with a special film such as PEI. Heat up the surface of the glass to your usual temperature (50-60°C) and apply a few drops of the mixture to the edge of the print.
It will evaporate pretty quickly, but some of it will work under the glass/model interface. Apply a bit more while the glass is still warm. Continue to apply until the the evaporation is no longer accelerated.
Considering the difficulty you are experiencing, it may be necessary to repeat the heating sequence multiple times in order to get enough wicking of the liquid to effect a release.


q:
I've just built my first 3D printer. It uses a Bowden setup.

When I try to print the extruder starts fine, but after a few seconds the extruder motor start skipping and the nozzle is jammed.

I tried a cold pull, but it didn't help. I removed the PTFE tube and tried to push the filament with my hand, it works but at the start I need the push harder but after it flows fine. But if I reinstall the Bowden setup, it works fine for a few minutes, but after a few seconds it starts again.

Note I am using silver PLA at 200-205 °C. I tried to raise the temperature to 215 °C, but it also jammed, and the filament what after I pushed out was black (it is a new hotend and I never used black filament before), like it was burned (if it is possible).

[A]
It is useful to diagnose your problem if you provide more information, specifically what material you are using and what temperature you are using on your hot end.
Even without the above information, it is likely that the hot end temperature is too low. At a low setting, the filament in the nozzle will soften, perhaps even melt as deeply as needed to be extruded, but as new filament is provided by the extruder motor, it also cools the heater block.
By increasing the temperature, you're ensuring there is sufficient thermal energy to handle the incoming cold material.
It would be useful to increase your nozzle temperature by 5°C for each test. Despite matching your controller's temperature to the manufacturer's specification, you can not be certain that the temperature at the nozzle and heat block are what you have programmed.


q: I'm getting wavy lines on the first layer only in both the x and y direction identically.  The first layer is 0.4 mm with a 0.4 mm tip. The other layers are 0.2 mm.  I've tried changing the Z offset all the way from -1.2 to 0.5 mm.  I've tried changing the hot end leveling the heated bed.  None of these changes affected the wavy lines.  The waves have about a 1 mm period.  The printer is a German RipRap.  The material is ABS.  The heated bed is 110 °C.  I've tried the hot end at 220 °C and 240 °C.  So far, nothing has changed the waves.

[A]
The general recommendation for layer height is to go no thicker than 75% of the nozzle diameter. Your post states 0.4 mm layer height with a 0.4 nozzle, exceeding the recommendation.
If your first layer is dropped to 0.3 mm, you'll fall into the recommendation, but the thickness is a reference for ALL layers.


q: I have made a temperature ⨉ fan speed tower which needed 3x9-1 ChangeAtZ post processing scripts and it took me quite much time to configure them all (and check it twice). Is there a way to save this, so that I wouldn't need to make them all again if something went wrong and I needed to start over or if I wanted to do something similar again ?

[A]
The UK uses 230 V mains voltage. The 220 V designation is from the past, Europe is now using 230 V. You do not have to worry about the frequency.
You should place the switch to 220 V and plug the cord into the socket. The printer should start immediately booting (cycling) the printer firmware, the LCD should light up and the cold end cooling fan will spin (annoyingly).
If nothing happens, you need to check the Power Supply Unit (PSU) and all cables for proper connection (does the fan of the PSU spin if it has one, you should at least see a led light up). A multimeter is not expensive and generally very valuable to test if it outputs 12 V. That way you know the PSU is working or not, if it works the problem is at the main printer board.
As these PSU's are pretty cheap and faulty, you could well have received a broken one.
How to measure the voltage?
If you look at the connection terminals you will find labels above them. Measuring position 6 and 8 might be the incorrect ones, this depends on your PSU. If you have exactly the same PSU as from the linked video, measuring between 6 and 8 would be correct:
From the image above the connections from left to right (for other PSU units, the order may be different, I have units where the connection to the mains is on the right):
```
L
```
,
```
N
```
and
```
ground
```
are used for connection to the mains,
```
COM
```
(stands for common or 0 V) or sometimes denoted as
```
-V
```
is the output ground (negative, connection for the black wires) and
```
+V
```
is positive, connection for the red wires.
You need to measure the voltage difference over
```
COM
```
and
```
+V
```
, this should be the voltage of the power supply. Ideally you measure the voltage when the power supply is delivering a load (e.g. directly connected to a strip of LEDs or directly connected to the heated bed; some faulty PSU crash in under load, this can be seen by a lower voltage than the rated voltage).
If the PSU is correctly wired, your fuse is not broken, does not have a LED lighted and the voltage is zero the unit is defective.


q: I want to create two piece labels for storage containers. The main piece would be the “badge” which would have text cut out of it (e.g. “Paint”, “Electrical” etc.). The second piece would be a positive of the text which is would be in a different colour, and would fit inside the cut out on the badge. Because of the tolerance of 3D printers, I need to make the insert slightly smaller than the cut out. Initially, I thought I could just scale the insert but that would affect the letter spacing. Then I thought it would work if I could somehow taper the letters so they are slightly smaller at the top than the bottom. So my question is, how I do that. I did the original in OpenScad but I would try Fusion360 if that’s a better solution. Any and all suggestions are welcome. Thanks.

[A]
In OpenSCAD, apply the
```
offset
```
transformation to inset the letter outlines before extruding them. However you may find it works better to fill the sunken letter shapes with nail polish then remove the overflow with acetone; see my question & answer
https://3dprinting.stackexchange.com/a/10872/11157
.


q:
I've tried to apply a sharp blade (the one that came witht he printer) to scrape the model off like I usually do but this model seems overly robust. What method can I do to take this off safely?

See image

[A]
Unfortunately, you may have to destroy this part, or the build surface, just to get it off the plate. It looks really on there, and if you can't get under it even with a razor that further supports my gut instinct. It's happened to me before, just part of learning how to print with a particular material on a particular printer and build surface.
One thing to try before just hacking away at the part or replacing the build surface (which you may have to do anyway) would be to heat the plate back up to maybe 60-70*C, then hit the part with some freeze spray (or the poor man's version, turning a can of air duster upside-down). The rapid expansion-contraction may pop the part free. How effective this is depends on the plastic you used. PLA doesn't stretch and shrink much, but by the same token it's also very inflexible, so the stretching and shrinking it does do can stil pop the part off. This method's
really
effective for plastics like ABS that stretch/shrink a lot with heat. Remember to ventilate well; the principal component of these sprays is difluoroethane, which isn't great stuff to breathe in any significant concentration, and when spraying the liquid the resulting "steam" state of boiling liquid is much more flammable (so after the bed comes up to proper heat, I'd turn off the printer just in case).
EDIT: Per the comment to this answer, an alternate method would be to heat the plate even further, to about 80-90*C, which would heat the PLA beyond its glass transition temperature, softening it and reducing its adhesion. You would destroy the part, but parts can be reprinted, that's the beauty of owning a general-purpose computer-controlled additive plastic forming machine.
Your first layer including the brim looks a little close to the plate, which is part of the problem; you
really
squished that first layer down onto the bed. I would relevel the bed a bit further away, or (if you're happy with how actually level the bed is) set a Z-offset to increase first layer width. There's a very fine balance to be struck here; once you find it, printing (and removing said prints) becomes a lot easier.
In future, a build adhesive like Elmer's glue stick or hairspray (or a dedicated adhesive like 3DLAC or Bed Weld) also doubles as a release agent; the adhesive grabs the extruded plastic to keep it on the plate, but also prevents direct contact between two plastics and thus avoids any chemical bonding between the part and plate. Also consider upgrading to a flexible removable surface, like a magnetic BuildTak surface. Being able to take the bed off the printer and then flex the surface to help  pull a corner free (at which point you can slip a scraper in to lift the rest of it off) is a real boon to these types of situations.


q:
Are there any statistics regarding how many units each manufacturer has sold, e.g. in 2019?

An article from 2016 claims Monoprice to have led the market back then - but all of the printers in that article have become obsolete since then.
Some manufacturers also claim theirs to be "one of the most popular" - but that likely doesn't translate to sales, at least for the more overpriced ones.

[A]
Getting this data is not easy.  Many companies that make 3D printers are either private companies that do not report results or are larger companies where 3D printers are one of many products they manufacture.  Some companies study this information through mining public sources and surveying users for their opinions and experience.  The result of some of these studies are available for a fee.
Occasionally, a trade publication will survey data sources and produce an article.  In other cases, a trade pub will publish an article generously offered by a commercial contributor.
It is always difficult to know what is true when abstracting information from obscured, noisy, and biased information sources.
Your question itself includes a bias.  You use a words that include a value judgement: "but that likely doesn't translate to sales, at least for the more overpriced ones."
The article you reference is not a deeply researched investigative piece.  It is simply some product details for the five printers in 2016 which sold the most on Amazon.com.  It doesn't include printers which were not sold on Amazon, so it leaves out any printers which use a different distribution channel.  Also, the article include an link, probably which generate revenue back to the magazine, to each of the five printers sold through Amazon.
To summarize, it is very difficult to aggregate this kind of information.  Those who try to do so like to be compensated.  A list of the top five devices on Amazon is a biased list.


q:
Say I wanted to print a plastic credit card like shape (like these), but with a QR code engraved. How could I do that for cheap? You can buy an "ID card printer" for $1,000-1,500 on Amazon, but that's way too much for printing one or two cards. Maybe down the road this would be a good option, but I kind of like the option of 3D printing the card from scratch, so the QR code bleeds halfway or all the way through the card, rather than just being printed on the surface. Is this possible for cheap? Maybe like this but not as fancy. Mainly (I'm new to all this) I am wondering what machine would accomplish this for low price yet good quality, and what other equipment I would need.

Basically, what printer is best for this type of task?

[A]
FDM printer?
If you want to print one, maybe you should outsource it (let it print the tag on both sides), even the most affordable printers are in the \$100 - \$150 price range. If you want a printer and use it also to create ID tags, you could go for an FDM printer. Considering your request of having the tag inside (and through) the ID-card you need a dual filament option (one or two nozzle arrangement). If the tag can sit on top you can print it with a filament change with a single filament single nozzle printer. But, don't expect to get crystal clear prints (see experience printing signs below)!
Alternatives
As an alternative, you could print a blank PLA ID-card and laser mark the tag onto both sides, see e.g.
this video
.
If it is a small batch you can also consider printing/lasering stickers and stick these onto blank ID cards.
From experience
I've done some signs with black letters on a white background for "on-lay", inlay and through arrangements using a more expensive (for home use) dual extruder 3D printer (Ultimaker 3 Extended about \$5000,-) with PETG, but the results were not very satisfying. Usually the black smears out on or in the white no matter tweaking the options. Considering the size of an ID-card, the amount of tag squares, this is even more likely to happen when you print at that small size (the signs I printed were sized similar to the "A5" paper standard).
From my experience I would say that a 3D printer may not be the best solution for your task.


q:
Which type of filament material(s) is safe to use as an in-wall box for regular, 120v wiring? For instance, an electrical outlet box.

In case it matters, location is the state of Washington, USA.

[A]
I haven't tested the commercial "blue boxes" used to hold 120/240 V electrical outlets, switches, and splices to see how they behave when heated.  As such, this argument is based on intuition, which is intrinsically flawed as a logic device.  Never-the-less, I think the no extruded molten plastic (FFF) 3D printing filament will work.
The purpose of the junction box is to contain an overheating connection or switch and prevent it from causing a fire in the wall.  Any FFF filament will have a melting point below the ignition point of wood, and would therefore flow away from the overheating point.  It seems that any thermoplastic with a "normal" melting point would have this problem.
You might look at UV polymerized printing resins, such as are used in the Stratasys Objet, Form Labs, and Prusa SL1.  These printing processes aren't constrained to use plastics that can be melted or heat softened.  Because the polymerization can involve more aggressive crosslinking (polymerization) that FFF materials, they have the potential to be good for a higher temperature.
As an example of a high-temperature, non-melting plastic which could perhaps have an analogue in SLS resin, polyester "casting compound" is cross linked by a methyl-ethyl-ketone-peroxide catalyst to form clear solid.  24 hours after the polymerization starts, the solid does not melt under the influence of a hot air gun.  I tried to melt it and it would not melt.  It slightly softened, but the plastic cup I had cast it in was dripping away -- but the polyester was not melting.
I looked through the Stratasys materials and Form Labs materials and did not see a much higher temperature material.


q: I got a new CR-10S 3D printer (I received it at Christmas). It has been printing just fine until yesterday, I was doing a print and it randomly paused, it did not restart on its own, I had to restart the print, then the item finished just fine.  I am printing today, a very small item, the printer now stopped 3 times.  How can I fix this, or do I need to return it?

[A]
It would be great if you can write what the printer says when it stops.
I suggest you try printing other small objects. If that also stops then the printer itself has a problem. But if the printer prints other objects without stopping, then the one you want to print has bad gcode files. You also need to make sure to keep it up-to-date Cura. It would also be great if you can update your printer firmware. But other than that, problems could be heat problem, power problem, and other stuff; it would be great again if you can write the problem that says on the printer as it stops...


q:
I could have sworn I read somewhere that when printing with TPU to make sure the part cooling fan is blowing. But I just did a quick Googling and couldn't find anything stating such on Matter Hackers or All3dp.

I currently don't have a part cooling fan attached (waiting for square nuts to come in). I've been able to get by printing PLA without the fan. I'm curious if this is going to be a major obstacle with TPU.

[A]
You'll probably be fine printing TPU with no fan. I just started printing with TPU, and did a lot of test prints to find out what settings work. Fan made little difference. With hotend at 230 °C, which I started out with, 0-20% fan was fine. I eventually increased temperature to 250 °C, which made extrusion more consistent and allowed me to reduce linear advance K-factor somewhat, and at that temperature having a bit more fan (I'm using 40% now) seems to help the material hold its shape, but it mainly made a difference at higher print speeds (over 35 mm/s) where the motion of the nozzle was "pulling on" the still-very-soft material just extruded. At 30 mm/s and below, fan still doesn't seem very important.
All of this is likely to vary somewhat with the properties of your machine. However I think it's safe to say you should be able to find a combination of print speed and temperature that make it possible to get by with no fan.
Follow-up:
Upon further experimentation with TPU, I would say you really
don't want any fan at all
, except possibly for bridges. I've found significant distortion to shape just from air pressure from the fan, and at higher speeds the fan makes the print brittle just like what happens with PETG. Layers of TPU really seem to want time to melt together to bond, and without a fan blowing on them they don't seem to lose their shape during that time.


q: Looking for something to smooth out a PLA print. Would Mod Podge be a good solution? Will it stick?

[A]
From what I've read about Mod Podge, it is an adhesive with a vinyl acetate base. As such it is similar to both PVA (used for wash-away support) and ordinary white glue. One of the more common references to the product refers to it not being water proof, although the outdoor version of the product presents as being water-resistant.
As part of the research for this answer, I found references to overly-thick coats becoming milky. This follows a reference to applying thin multiple coats and allowing proper cure time between coats. That proper cure time is listed as 28 days.
Another set of posts suggest to cure the MP more rapidly than 28 days, one can heat the item in an oven to 175°F (80°C) which should not cause the PLA to melt, but may allow for sagging of unsupported parts. Testing is recommended.
MP is an adhesive, is known to stick to non-porous surfaces and would be no more harmful than glue stick for a PLA (or ABS) model.
Durability is uncertain. If you intend to paint the item after sealing/smoothing, you'll gain durability and water resistance.


q: What is the thread pitch of the Ender 3's bed leveling screws? The diameter measures about 4mm. Are they M4 0.7 (coarse) pitch or 0.5 (fine) pitch? I'd like to develop rigorous formulas for the amount to turn the knobs by after measuring (or visually inspecting, since I can see an accurate 0.2 mm first layer decently well) leveling-test patterns in the corners rather than using a closed-loop tune-and-retry approach.

[A]
I don't know what the value is, but there are a few ways to find out. It is very hard to measure this with a caliper, but it can be done, mark the upper and bottom of e.g. 10 windings and measure this with a caliper. Alternatively measure how much the screw drops after 10 full turns.
There are special tools that give you the answer directly, they cost a few Euros/bucks but can be very handy; a thread gauge, just place the 0.5 mm and the 0.7 mm beside the screw and you will instantly see which is the correct one.
I bought mine at a typical Chinese vendor site.


q: I have an Ender 3 with a removeable build surface. The build surface backing has become warped - the center is at least 0.3 mm higher than the corners. I'm not sure what the material of this plate is - it's the part behind the BuildTak-clone surface that sits on the aluminum heat bed and is clipped to it. This makes it impossible to level the entire bed, and annoyingly tedious to level it enough just to use the center, since the paper method doesn't work at the corners. Can this be fixed, or do I need to source a replacement for it?


q:
Marlin has a Linear Advance calibration pattern generator, but I find it's hard to use because:

It only prints the initial layer on the bed, where bed irregularities interfere with accurate reading of it.

It doesn't do proper retraction and priming, so a mess of strings and underextruded initial segments/non-adhesion mess up the results.

It's hard to visually evaluate.

Getting a very wide range of K values involves multiple runs.

It's hard to clean up.

Is there a better procedure for calibration of K value for linear advance?


q:
I faced some problem with my 3D printer device. It seems the bed warms up without any problem, however, the hotend does not warm up!

Could you please help me identify what the problem is?

[A]
I really hope the extruder doesn't warm up as this would be a problem with your stepper motor :)
I'm sure you mean the hotend doesn't heat up. This could be a number of things but i would start to double check the pinout in your code vs the pins on your mainboard and measure if it gives 12v/24v (depending on your PSU) output.
There's a lot more info required to properly help you.
What board are you using?
What OS are you using? Marlin or something else?
Share the relevant code of the OS for the hotend config/pinout
potentially share pictures of your wiring


q:
Lately I noticed that there is a new type of nozzles (called airbrush nozzles?!?) available; typically found on those online overseas vendor sites. The nozzles are advertised for usage in E3D hardware, but are not found amongst the E3D genuine nozzles.

These nozzles look like this:

What are the basic physics principles or what is the engineering relevance for application of airbrush nozzles? (Gimmick or actual product improvement?)

[A]
They are used for nonplaner 3d printing.
https://all3dp.com/4/nonplanar-3d-printing-gives-the-smoothest-top-layers/
The gist of it is, that You can achieve smoother, curvy top layers that are more true to form, buy using a nozzle like the one you mentioned. Also, they can be used to print multiple objects at the same time, where is faster to print 10 to 20 layers of one object then switch to the next object on the build plate, rather than having to print each layer of each object sequentially. This reduces build time, stringing, voids and the potential knocking off the part by the nozzle (as it moves to print the next object, since that object may have shrunk/expanded since the nozzle last visited it).


q:
In analogy to: What glues for bonding printed PLA to injection-molded plastic?, what are the best glues to use for PETG?

I mostly print in PETG and have occasional failed prints which I usually reprint. But what if I'd like to repair a print e.g. a split between layers or a part broken off?

Knowing that PETG is more "greasy" than PLA, what typical glues can you use to create a good bond; this question excludes using heat to (re-)bond.

[A]
From
forum
Bison plastic - works great for me, only it's not "quick dry" but it's very strong, not brittle, holds PETG and PLA very strongly.
  Buy paint stripper that is/contains methylene chloride (dichloromethane). It will solvent weld both PLA and PETG.
Or see
other forum
which recommends Eastman-910 (original brand of cyanoacrylate) or any equivalent, polyurethane glue, or even epoxy.


q:
All of a sudden I seem to be having a lot of issues with under extruding on my Ender 3. The bottom layer (of height 0.1 mm) prints perfectly fine. This is done at 15 mm/s speed. However, The moment the print moves to layer 2 and above (at the default speed of 60 mm/s), I start hearing a lot of clicking noise on the extruder.

So far I have tried the following

Replace nozzle to eliminate clogs

Cleaned the inside of the hot end assembly

Calibrated extruder steps/mm

Reduced the layer height from 0.3 mm to 0.2 mm

Reduced feed rate to as low at 50 %

Cleaned the filament feeder assembly and verified that it is able to push the filament properly (Extruding when the print is not happening works just fine with no clicking)

Even with all the above, the issue is still persisting. I am not what else could be causing this.

I am printing with PLA at 200 C

[A]
Not allowed to comment, so have to answer:
The temperature sensor is a thermally sensitive resistor. Unfortunately, the temperature is near the high limit of that sensor, and the manufacturing tolerances are very significant. That is why a temperature tower is important for each printer, as well as each filament. (I have 4 printers and each requires a different temperature for the same filament. My worst-case is out by 25 degrees! - it's the one I bought second-hand because the original purchaser couldn't get it to work. I could replace the NTC, but it is easier just to have settings to suit that printer.)
Filament does change over time. Lots of theories about why, but the practical response is to tune settings to suit the filament. The alternative is to modify the filament (eg drying, adding oil to surface, etc.), but even with really old filament, I've found adjusting settings (in the slicer, like Cura) to be the most generally workable solution.
Bottom line is to test, adjust settings and repeat until the system achieves the result you need. Treat most recommendations as serving suggestions, so use them as clues (but not rules) for the puzzles presented as 3D printing.


q:
The e3D volcano features an extended heater block of length 20 mm with the cartridge heater running parallel to the filament.

The purpose of this is to increase the speeds at which filament can be printed (of course the extruder and other factors may still be limiting factors).

My question is how capable would this heat block be of printing at slow speeds with a 0.4 mm nozzle?

Is printing still possible at lower speeds or is the filament heated too much that jams occur? Is the retraction performance okay?

[A]
Speaking from first hand experience running a Volcano hotend, mostly using a 0.6 mm nozzle, but I have used 0.4 mm as well. I can't really complain about any lower printing speed limit (low speeds are usually a solution to high speeds problems for me).
Just for completeness: I am using a DaVinci 1.1 Plus with custom firmware (modified Marlin) and an E3D Volcano hotend. No problems with the nozzle, clean prints! Note: I am using the Titan Aero as extruder but not using the included pancake motor! Went with the original motor of the DaVinci.
And as always: the parameters are key! Given a bit of tuning you can get amazing results! For PLA and ABS I can work without stringing. Although ABS seems to be prone to pitting (slight underextrusion at start of path). TPU and other flex are sometimes a bit of a challenge, but that's mainly due to my own lack of experience there.
The one important caveat here would be to also reduce the nozzle temperature. A possible theory here might be that the filament has more time and surface to heat up.
(Sometimes I go as much as 15 °C lower as compared to normal/high speeds! Usually lower speeds means small pieces for me and in term means a limit to the layer cooling time.)


q:
I'm new to 3D printing and have bought a resin printer.

Cleaning with Isopropol Alcohol seems to be the rage, however I think this is unaware of cost savings.  It appears methylated spirits is ok and is 25% the cost of Isopropol Alcohol.

I'm now down to wondering if I should buy methylated spirits or turpentine (I ruled out kerosene as too flammable)?
I'm leaning towards methylated spirits, however would like input.

Factors I'm curious about:

Cost: same for methylated spirits and turpentine.

Evaporation/solvency: ?

Flammability: ?

Poisonous levels: ?

Resin object cleaning effect: ?

Skin effects: ?

Smell: ?

I checked a few sources.

[A] I would personally stick to isopropanol. Be aware that 3D printing is a very expensive hobby, but health wise this is a better option. Methylated spirits can quickly become dangerous, and often can burn with a close to invisible flame, meaning that you may not even see if it is burning. Also, the fumes can quickly become dangerous, whereas after years of dealing with isopropanol I have noticed no ill effects. Cost should not be your primary concern, health of you and your printer should be.


q:
I'd like to prefix this question with the fact that I know virtually nothing about 3D printers, aside from the general principles of how they work.

I've recently seen that SLS printers have become more affordable, to the point where in a few years they might be a compelling investment. I'm mainly interested in 3D printing miniatures for painting, and as such this one:

For scale, the miniature is about 150 mm long. I'm mainly worried about smaller details, such as the faces of the Gunner or Driver. Will a consumer-grade SLS printer be able to print to such level of detail?

[A]
It's difficult to tell from your photo the level of detail required. A scale reference in the form of a metric ruler would be valuable. If, for example, the metallic eye on the gunner is 2 mm diameter, that would be 40 layers of 50 micron grains, allowing for substantial detail.
Consumer level SLS printers, such as the Sinterit Kit, use fifty micron nylon powder and is subject to some shrinking. This implies one can expect slightly smaller than fifty micron detail to appear.
One of our makerspace members purchased an SLS model from Shapeways. The surface is layer-free and one can see the individual granules under magnification. If you required a level of certainty of this detail, consider that you can create a model containing various levels of detail, then commission Shapeways to create it.
It's certain that they use a production level system, but one can inquire of Shapeways of the size of the powder that is used.


q:
For practicality sake, I need to print a design such that there will be weight hanging parellel to the layer lines. Is there an infill pattern that would be better than others at handling this?

I realize that all kinds of infill will still have the same layer boundaries. Just wondering if choosing any given infill might provide better results.

[A]
Yes, some infill patterns are better than others for preventing separation of layers. Basically (modulo some assumptions about uniformity of distribution of force), the shearing strength of the part in the Z direction at a particular layer is going to be proportional to the
surface area
of bonding between successive layers. So infill patterns that stack identical infill extrusions on top of each other at each layer should be expected to be much stronger than patterns where successive layers make only partial contact. In other words, "2D infill patterns" - grid, lines, triangles, tri-hexagon - should be a lot stronger than "3D infill patterns" - cubic, octet, gyroid, ... This matches my experience printing bolts oriented along the Z-axis - ones printed with gyroid snap easily unless other measures are taken to strengthen them, while ones printed with triangles are fairly strong (though nowhere near as strong as ones printed oriented in the XY plane.
If you have other reason to prefer a "3D infill pattern", its weakness can be mitigated mostly by increasing the infill line width, so that the lines of successive layers which don't entirely overlap still touch on more surface area. (Just increasing the infill line width also works to make "2D infill patterns" even stronger.) However, be aware that with high print speed typically used for infill, increasing infill line width can easily exceed the capability of your hotend, resulting in underextrusion, extruder skipping, and stringing all over the place.


q:
Is it possible to convert an image image to STL file format?

E.g. I don't need the coloring, I need the lines.

[A]
PNGs are 2-dimensional picture data files. STL however is a 3-dimensinal surface data files. The two are not inherently transformable into one another, as there simply is no 3rd dimension encoded in the PNG.
However, there are ways to generate a 3rd dimension from a color picture:
Lithophanes
take color information and use that as a degree of deviation from a base plane.
Using 3D design software that supports importing image data, one can trace the areas in 2D and
extrude
them to different heights or
emboss
the patterns into a block, even with different depths for each color.


q:
I am Attempting to print this, from Blender

But Cura decides to fill in the middle part of the model.

I exported and imported the model from an STL file.

If anyone can answer this, that would be greatly appreciated.

[A]
I would recommend using an actual CAD/CAM program, such as Autodesk Fusion 360, instead of using a 3d model program. Not only will this be able to directly export you finished model to Cura, and the models are made in a way that works with a 3d printing slicer, there will be more help around 3D printing for it.
Although it is slightly difficult to use to start with, as you become more proficient, it is a very powerful tool to have. . Fusion 360 is free for hobbyists or students. See this link for help activating:
https://www.autodesk.com/campaigns/fusion-360-for-hobbyists
.
Another option would be SolidWorks, although you do have to pay for this option, but it is much simpler to work with in my opinion.


q:
My problem is that I have used a 3D printing machine from the University and found out that the cover for the car was not smooth even after using sanding paper and painting it.

What material would work best to print  the cover of the Cyber truck. I want it to be light and smooth.

I have to print it from any online companies that have this service here in Germany.

[A]
I have 3D printed models which were then sanded using progressively finer grades of sandpaper, terminating with wet sanding using micromesh to 12000 grit. The result was smooth and shining without any coating applied.
If your original results were not acceptable, the process may have been flawed and should be re-considered for technique.
For your purposes, as a body for a radio controlled vehicle, you'll want to consider something that can manage an impact reasonably well. ABS is going to be less expensive and provide some energy absorption but will have layer lines that require sanding and finishing. Layer thickness plays a substantial part in providing for good results and a smooth finish. I used 0.100 mm layers to get optimum smoothness.
You could request your model to be created in nylon using the SLS method, but the surface will be granular and would also require sanding to accomplish a smooth finish.
SLA or MSLA resin printed models will provide a very smooth surface, but the material is brittle and may crack during "on-road" use. You may find a printing service which offers to create using a more flexible resin, but you'd have to request that or confirm the selection when placing the order.


q:
I am thinking to use closed-loop stepper motors to prevent step loss and make the machine more accurate. What options (preferably low cost) are there for:

stepper motor + driver + encoder + microcontoller

Is building it from scratch worth it? E.g. Arduino Mega 2560 + RAMPS 1.4/1.5/1.6 + stepper motors (e.g. NEMA17) + drivers (e.g. A4988, DRV8825) + encoders (e.g. AS5047P, AS5047D, AS5048A, TLE5012B) + microcontrollers (e.g. STM32).

[A]
A number of options exist, but keep in mind that cost will be a limiting factor.
(Small sidenote: cost depends on persective, financial cost does not equal mental cost. The tradeoff between buy or make depends also on your willingness to persist when things don't work right away.)
Before you start:
make sure that your printer has enough space to accomodate bigger motors.
So, what options are there?
Change your current configuration. If you are losing steps, it could very well be that it can be fixed in firmware.
Pro: No budget and nothing to lose.
Con: No shiny closed loop system. (Is that bad though?) Possibly need to configure and compile your own firmware.
MacGyver / DIY solution based on low lever components
Pro: Probably as cheap as you'll get depending on how you choose your components. Might be an interesting learning experience, not to mention the satisfaction afterwards. This could be the smallest build size you'll see in all the options.
Con: You'll need a decent amount of engineering and debugging. Might be tricky to mount the encoders.
Same as 1, but now consider using of the shelf stepper motors
with integrated encoders
.
Pro: Most robust option on a budget in my opinion due to the single mechanical piece (motor + encoder).
Con: Integrated encoders have a considerable cost and are large compared to their vanila versions.
Go for
off the shelf motor+encoder and drivers
.
Pro: No need to worry about driver configurations too much. Just plug in the numbers or set the dip switches. Very conveinient solution. Pretty much plug and play.
Con: This will already be challenging on a budget. Making a wrong mix and match might lead to unpredictable results such as drives going in overcurrent. (Which, believe me, is very frustrating for your application!)
If we are allowed to consider servo motors:
ClearPath-SD series
(Or any alternative for that matter!)
I'm just including this for completeness.
Pro: Performance wise a clear winner on pretty much any relevant level.
Con: You'll need a big budget!
Bottomline
: You'll probably want to give the first option a go before spending money. Next stop, you might want to take the second option (you already did research on different specific low level components), and if you have time to spare I'd go with that as well. If you are also on a budget timewise, I'd definively suggest to take the third option with existing driver boards.
The other options are more cost heavy and become real options in produciton environments, where downtime is also costsing money.
As to the microcontroller, take whatever you have available. Just know that more computational power will allow you to output steps faster and will allow for smoother movements. Lot's to talk about there as well!


q: If I set my prints on the window sill (indoors) will the sunlight still be able to cure the resin? The problem with setting them outside is the wind knocking them over.

[A]
The glass will block most of the uv light; but not all. It will depend on the type of light that the resin is sensitive to; in order to determine if it will continue to cure behind a glass window in direct sunlight. Some resins also sensitive to blue light. You will need to look at the material data sheet for the resin to be able to know for sure. Be advised though, that the resin does not stop curing, and will continue to cure slowly over time, just sitting on the desk.
https://www.thoughtco.com/does-glass-block-uv-light-608316
From the link:
Glass that is transparent to visible light absorbs nearly all UVB. This is the wavelength range that can cause a sunburn, so it's true you can't get a sunburn through glass. However, UVA is much closer to the visible spectrum than UVB. About 75% of UVA passes through ordinary glass. UVA leads to skin damage and genetic mutations that can lead to cancer. Glass does not protect you from skin damage from the sun. It affects indoor plants too. Have you ever taken an indoor plant outside and burned its leaves? This happens because the plant was unaccustomed to the higher levels of UVA found outside, compared with inside a sunny window.


q:
I began build LCD printer and I want make some modifications.

What if I will place LCD below VAT? Will the display break when printing? what are the risks?
I seen a lot of printers and all of them use PP material for VAT bottom and attach with a lot of screws. I want make more simple VAT-LCD constructions and I think this construction transmis UV light better

[A]
Short answer
Usually
no.
Long answer
There are several big factors that limit how small things you can print. The bigger ones are pretty much:
Positional accuracy and settings (limited by steps/mm in X, Y, Z)
Nozzle diameter
Now, why don't you need to care about steps/mm on the extruder that muchin the grand scale compared to the positional accuracy? Well, we have 1.8° per step, from which, with the diameter of the gear, 11mm, we get 0,1778 mm of filament extrusion or 0.428 mm³ of extruded plastic per full 1.8° step - which clearly is unsuitable to printing at all. But with the 16 micro-steps the shorter movements are possible and a single micro-step extrusion is in the area you calculated - I got to 0,0267 mm³, possibly the result of different rounding between us. With an assumed effective gear diameter of 11mm (usually the effective gear diameter is a little smaller, thus the 93 steps) we come to about 89.9 steps per mm of filament, which corresponds to about 2.4 mm³ of extruded plastic, or about 30 mm of line (with your given parameters), bringing us to about 3 microsteps per millimeter of line on the tray. So far, your math checks out. But that usually shouldn't be too much a limiting factor. We know from your given settings, that the
Configuration.h
will look like this, putting the microsteps into the steps/mm:
```
```
/**
* Default Axis Steps Per Unit (steps/mm)
* Override with M92
*                                      X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
*/
#define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 400, 93 }
```
```
As you don't have a micro-stepping driver, this part in
Configuration_adv.h
is non-functional:
```
```
// Microstep setting (Only functional when stepper driver microstep pins are connected to MCU.
#define MICROSTEP_MODES {16,16,16,16,16} // [1,2,4,8,16]
```
```
With the proposed 0.4 mm/0.2 mm line, we are still somewhat on the good side, allowing us about 1/3rd of a millimeter as the shortest line printable as a single step extrusion. That's a consistent with printing a simple, circular dot being printable with these settings - 0.4 > 1/3.
But once you get to smaller nozzle diameters, the limitation gets more noticeable: at a 0.2 mm nozzle and 0.22 mm line at 0.1 mm height, that's a 0.022 mm² crosssection, so the 1-step extrusion is equivalent to a full millimeter of line! That's much more bothersome in theory.
However, I haven't been able to witness the inability of showing that limit of lacking extrusion yet on my TronXY-X1 with a 0.2 mm nozzle - the steps/mm in it are also about 90-100 last I set them. The TronXY uses a very similar (virtually identical) extruder setup as the Ender 3, and it achieved printed lines of about 0.3 mm length at 0.1 mm layer height somewhat reliable, but the retraction made huge issues, which might also mask the problem.
I believe that it needs these smaller nozzles to amplify the problems to make them noticeable. It also should become more noticeable if you'd use 2.85 mm or 3 mm filament.
Ways to improve resolution
However, if printing with smaller nozzles, it might be a good idea to think about how one could improve the accuracy of the extruder system.
The most-easy way would be to alter the extruder and swap the gear to one of a
smaller
effective diameter - That way a single step accounts to
less
extrusion, which means, in turn, a higher number of steps/mm, and thus allowing for shorter extrusions that can be still achieved.
Next one might think about getting a different motor/driver setup that might have either more microsteps or generally a smaller step size.
Quadrupling the effective (micros)steps/mm would allow us to print about a 0.25 mm line on the 0.22 mm nozzle I proposed, being pretty much a spot - if it wouldn't be partially masked in other issues as I experience.


q:
A question to those who have a 3D printer. Have you ever needed a spare throat or a heater block? Do they ever break?

I just bought some spare parts: heaters, thermistors, nozzles... However, I am not sure if buying throats and heater blocks make any sense.

[A]
Short answer
Yes
Long answer
Heater bocks
A heater block is destroyed if one of the following happens
Threads stripped
Bent or otherwise deformed
stripped grub screw
All of these can happen by handling the block with too much force when securing nozzles, thermosensors or heater cartridges.
Throats
Throats can be destroyed, especially e3D v6 throats with their neck down on the center can be simply turned and broken in two. Lined throats can be heated too much and the liner destroyed, which not always can be replaced, mandating a spare part. And you can strip the threads.
Another chance to damage the throat is by using very hard material nozzles - stainless steel comes to mind. Such a nozzle would not deform itself like brass when tightened against the throat and might lead to damage to the end of the throat if exchanged several times.
Conclusion
If you run several printers or change nozzles regularly for whatever reason, it is a very good idea to have at least a complete set of spare parts on hand to fix problems that might occur during work on the printer. I have a fully assembled spare hotend waiting for its day to shine in case my current one breaks...


q:
In my custom printer I have probe and nozzle at same height and configured Marlin this way:

#define NOZZLE_TO_PROBE_OFFSET { 43, -20, 0 }

On the bed I've a 2 mm glass. How I need to change the configuration? Do I need to act adding a positive Z offset? like this?

#define NOZZLE_TO_PROBE_OFFSET { 43, -20, 2 }

[A]
No.
You define the Z-Value of the Nozzle to Probe offset mainly to get avoidance of collisions, but it is checked nowhere in the firmware code at all. Usually, the probe is mounted a millimeter or so above the nozzle anyway: you mount it in such a fashion that it triggers when the nozzle has the correct distance to the bed.
If you alter the bed by altering the distance between the nozzle and the metal part of the bed, you might need to alter the physical position of the probe to get the printer to trigger at the correct height, but you don't necessarily need to add a Z-offset.
You might, however, want to include it in the slicer for the case you want to print items in a sequence, which forces most slicers to try to do an error-avoidance pattern.


q:
I'm using a 200x200 mm PCB Mk2B which connects to the MOSFET of the D8 pin on a RAMPS 1.4 shield. I used 12 V power source for heat bed so I connected positive to pin 1 and negative to both pin 2 & 3 of the bed. Heat bed worked properly. But the wires that connects power source to power supply pin on RAMPS were being heated badly. I think the problem is come from heat bed because when I unplugged heat bed, wires were cool down instantly.

Can someone helps me with this problem. I'm just a newbie in this area.

[A]
I have an
open bug report/feature request
for this. Apparently Cura doesn't do it because some of Ultimaker's printers have underpowered power supplies that will shut off if you try to do both at the same time. I've been carrying a patch (note this is against CuraEngine not the Cura GUI) that fixes this:
```
```
diff --git a/src/FffGcodeWriter.cpp b/src/FffGcodeWriter.cpp
index de3c771c..ced22017 100644
--- a/src/FffGcodeWriter.cpp
+++ b/src/FffGcodeWriter.cpp
@@ -500,7 +500,7 @@ void FffGcodeWriter::processInitialLayerTemperature(const SliceDataStorage& stor
                 const Temperature bed_temp = scene.current_mesh_group->settings.get<Temperature>("material_bed_temperature_layer_0");
                 if (bed_temp != 0)
                 {
-                    gcode.writeBedTemperatureCommand(bed_temp, scene.current_mesh_group->settings.get<bool>("material_bed_temp_wait"));
+                    gcode.writeBedTemperatureCommand(bed_temp, false);
                 }
             }
         }
@@ -547,6 +547,18 @@ void FffGcodeWriter::processInitialLayerTemperature(const SliceDataStorage& stor
                 }
             }
         }
+
+        if (scene.current_mesh_group->settings.get<bool>("material_bed_temp_prepend"))
+        {
+            if (scene.current_mesh_group->settings.get<bool>("machine_heated_bed"))
+            {
+                const Temperature bed_temp = scene.current_mesh_group->settings.get<Temperature>("material_bed_temperature_layer_0");
+                if (bed_temp != 0)
+                {
+                    gcode.writeBedTemperatureCommand(bed_temp, scene.current_mesh_group->settings.get<bool>("material_bed_temp_wait"));
+                }
+            }
+        }
     }
 }
```
```


q: Have people been using 3D printing to genuinely create a number of needed objects in their homes, and if so, what? Or is 3D printing better for special niche interests like art projects, home engineering projects, etc?

[A]
Both.
3D printing is especially useful for creating replacement parts for things for which it would otherwise be difficult, expensive, or impossible to obtain a conventionally manufactured one. You may have seen in the news recently the
story about 3D printing being used to replace hospital ventilator valves
that were not available in time to save patients who needed them, and that normally cost \$11000 from the manufacturer. But the same kind of thing applies to regular household items too. For example, I've replaced broken wheels on my child's toy cars, a broken windshield washer fluid coupling in my car, and various similar things. I'm also planning to replace broken plastic wheel bearings in my vacuum cleaner (the manufacturer's design was atrociously bad and I'll probably adapt it to use real bearings with a 3D printed adapter), a window switch in my car, and lots of other things I can't remember at the moment.
Of course you can do craft and hobby things too. I don't think this really calls for examples/evidence.


q:
I want to make an order with this configuration

Arduino MEGA 2650 R3

Ramps 1.6 Plus

2 TMC2130

2 Stepper motors 17hs3401

1 Fan

But I am not sure what voltage and current would be enough to make it work. The Ramps 1.6+ board has an input of 12V as you can see in the picture, but I have read that other people had to increase the voltage with a DC-DC converter.

So, would be 12V and 15A enough to make work that configuration?

[A]
The easiest way to know how powerful the PSU should be is to download from
https://github.com/rcarlyle/StepperSim
the Excel workbook which simulates the power absorbed by the stepper motor. Input the motor specifications, check in the graph the max speed at which you plan to run it, check the absorbed power, add 20% for the various losses. Once you know the absorbed power, you can multiply by the number of stepper motors and obtain the current required, add 20% not to stress the PSU too much.
In you case, this is the result
Your motor will never absorb more than 7 W, 14 W for the two motors, around 20 W considering losses in the motors and overcapacity of the PSU. This means that around 2 A PSU will be perfect for your setup.
Previous answer, which may not be completely correct but still provides a useful background knowledge:
The TMC drivers limit the current to the value you set, which is most of the time lower than the datasheet. In no case you will need more than 1.3 A * sqrt(2) * 2 motors = 3.6 A. In fact, you won't need this much either.
When there is no field in a coil, the driver applies full voltage, but the current is low (initially zero) so you don't hit the 1.3 A per coil.
The current increases (the higher the maximum voltage available to the driver, the faster it increases) and the driver (probably) keeps the full voltage until the preset current is reached. Just a moment before that, the current is almost there, but you still have full voltage from the power supply. This is the theoretical worst case, but it applies only for a very short amount of time.
As soon as the current reaches the preset, the driver "cuts the voltage" to keep  2.4 ohm * 1.3 A = 3.2 V (because V = R * I). This means that the power supply sees 3.2 A/12 V*1.3 A = 0.35 A.
When running, the motors almost never start from zero to max current: both coils are powered and when one increases, the other one decreases.
In fact, the microstepping makes the steppers act more or less like AC motors with two phases. This means that overall the current is the max current per phase multipled by sqrt(2). Also, when using microstepping one phase (coil) is not completely shut off, but two of them work at the same time (with different current levels). This means that in total one compensates the other, and the power supply only provides, more or less, 0.35 * 1.4 = 0.5 A per stepper. You have two, so it's 1 A total, therefore 2 A PSU considering the inefficiencies.
A very easy and complete explanation is provided
here
:
By controlling the duty cycle of the chopper, an average voltage and
  an average current equal to the nominal motor voltage and current are
  created.
...
As the current increases, a voltage develops across the
  sensing resistor, which is fed back to the comparator. At the
  predetermined level, defined by the voltage at the reference input,
  the comparator resets the flipflop, which turns off the output
  transistor. The current decreases until the clock oscillator triggers
  the flip-flops, which turns on the output transistor again, and the
  cycle is repeated
So you never have coming out of the PSU more than the preset current.
Supply current is not the same as the motor current in a copper drive
. It is the motor current multiplied by the dutycycle, at
  standstill typically Isupply = IM · ( VM ⁄ Vsupply )
...
Depending on
  how the H-bridge is switched during the turn-off period, the current
  will either recirculate through one transistor and one diode (path 2),
  giving the slow current decay, or recirculate back through the power
  supply (path 3). The advantage of
feeding the power back to the
  power supply
is the fast current decay and the ability to quickly
  reduce to a lower current level.


q:
I have the original Prusa i3m3 printer.  Prusa recommends cleaning the bed before each print with isopropanol (isopropyl alcohol), with only occasional cleaning with acetone.  The textured bed prohibits using acetone.

Given the SARS-COV-2 situation and COVID-19, isopropanol is impossible to find, and will not be in stock on shelves in the US for months.

What would you suggest as an alternative that might still be found on store shelves?

[A]
Ethanol
(Ethyl Alcohol) should work just fine as long as it's around 80% or more. It's very similar to isopropanol as a cleaning solvent. What you're basically doing is removing any stray grease from the bed with a solvent that evaporates quickly.
Methanol
would also probably work. It's very poisonous though, and shouldn't come into contact with your skin, so it requires a bit more careful handling. Methanol also has the benefit that it can't be used for hand sanitizer (since it's absorbed through the skin), so supplies shouldn't run out.
Look for alternative sources, for example, methanol is often sold as de-icing agent for pneumatic brakes on trucks. Just make sure it's pure alcohol without anything funky added.


q:
I work with Fusion360 for designing lots of things. Recently I learned how to work with parameters that I can easily modify all at once, allowing to pretty much make easily customizable pieces.

Now, Thingiverse wants customizer pieces in the shape of .SCAD files, and some people just can't work with Fusion360 (.F3D) or proper .STEP files that can be imported by most CAD programs.

I have no experience with OpenSCAD. Can I import my .STEP into openSCAD, retain my parameters and export it as a .SCAD, and if yes, how?

[A]
No, you cannot import STEP nor Fusion360 files in OpenSCAD.
OpenSCAD
currently supports
:
3D formats
STL (both ASCII and Binary)
OFF
AMF [Note: Requires version 2019.05]
3MF [Note: Requires version 2019.05]
2D formats
DXF
SVG [Note: Requires version 2019.05]
Other
CSG can be imported using
```
include<>
```
or loaded like an SCAD file, PNG can be imported using
```
surface()
```


q: I'm new to 3D Printing and recently purchased an Ender 3D PRO I'm having an issue with the filament guide tube getting pushed out of the nozzle on the feeding mechanism.  The assembly instructions don't include a whole lot of detail about installing this guide tube but there are blue clips that were included along with the spare nozzle.  There are no instructions on where to use these blue clips and I have a hunch this might be the problem.

[A]
The blue clips stick in the connector on the extruder end of the feed tube. They are to keep it from opening as the printer extrudes and retracts filament.
To install them, push them in between the white part of the fitting on the feed tube (not the hot end). You should only need one or two, and they are all of varying thicknesses. If you're not familiar with these fittings, I found a
YouTube video
on how to use them.


q: Recently my RAMPS power connector caught fire while heating the heated bed. I suspect this was a defect caused by the connector, and de-soldered/removed it as best I could. I'm  not an electrical engineer, so I'm looking for advice on whether It is possible to re-solder the power connectors directly onto the board, or I'm just risking another fire. Here are pictures of the top and bottom.