q:
3D Printers (those who print, not the machine, dummy)!

I haven't been printing in a while, so when I returned to my Monoprice Select Mini VII, of course it had been sprung out of whack. Some of my first prints would not even come out of the extruder until I realized I had some pretty bad (and worse, unnoticed!) heat creep going on. After fixing that issue, it became apparent that many more persisted.

My question for you all is this: In general, what problems should be addressed first when looking at a complete disaster of a print?

I'm not going to specify any singular problem, but I am interested in seeing the "order of operations" for general problem solving when multiple issues exist. For example, "Fix bed height before anything else; this is a common problem that produces multiple others." Hopefully, this can help others with multiple printing issues, too.

[A]
for sure the answer could be dissertation or even a book because there is no simple way to address "all" issues - it's just to wide area
but as the simple troubleshooting i would list it this way
is your printer alive so is it
working at all (check power, cables)
communicate with the world (check app, drivers, cables)
moving HE and heating HB (check jams, end-points, belts, screws)
is it extruding (check heating, temperature, HE jams, filament path)
if all above is "yes" then
is your printer making printouts and are those printouts
starts and continues (check heating HB, HB adhesion, leveling, cooling)
finished at all (check all above again, stepsticks temerature)
keeping the shape (check screws and nuts, couplings, stiffness, stability, temperatures)
if all above is "yes" then in general you are half way ;)
common issues - printout is
bent or skewed (check geometry, stiffnes, leveling, belts, vibrations, stepsticks temerature)
wrapped or overextruded (check temperature, extruding, printout angles)
underextruded (check filament flow, filament path, stepsticks temerature)
stringy (check temperatures, app settings)
that is the main path i think. all above is more or less applicable to all DIY printers and all prusa clones and all clones of clones ;)
it can go wrong and fork in all possible moments as there is so many aspects to screw...


q:
I have a Tevo Tornado that I've outfitted with an official BL-Touch auto level sensor. I can see the bed probing run, and I can see the Z axis slowly adjust during x/y moves, so it's doing something. However, you can see that there appears to be a systematic tilt:

Any ideas what could be causing this? The bed, gantry and print head is tight, no wobble. Here's my start code:

G28 ; home all axes
G29
G1 Z5 F5000 ; lift nozzle

I have mesh leveling enabled with a 5x5 grid and correct probe offsets. The bed itself is on PETG printed standoffs instead of springs to eliminate any jitter.

[A]
The problem with the Tevo Tornado design is that the design is as such that the Z-axis is powered by a single stepper (under the assumption that you have not added a second Z stepper).
This means that the level relies on the rigidity of the X-axis assembly, more specific the play on the guide wheels. Apparently the BL-Touch level determination suffers (the up and down movement while probing) from this design as can be seen from the tilt around the Y-axis direction. This effect causing the tilted level plane is called
hysteresis
. Now that the Z-axis moves up and down you experience much more problems than using a mechanical switch. The effect is more pronounced when the mass of the hot end carriage is furthest from the Z-axis lead screw.
Note that an extra stepper can also cause tilted level when the second stepper does not move in sync (e.g. missing steps). In such designs, a single stepper (geared) belt driven 2 lead screw has better performance in that respect.

s: huggingface

c: devops

d: intermediate


q:
I have been looking at getting some painters tape to use on the glass plate for better print adhesion, and everything I read suggests the blue painters tape, such as this:

However, this white tape is considerably cheaper:

This looks like normal masking tape to me.

Is masking tape ok, or is the blue painter's tape preferable? If the latter, then why is that so? What is so special about the blue tape? Is it a different material?

[A]
Of course, I don't know what kind of tapes you have. My experience with blue tapes is, that they seem in general softer and "nicer" than white tapes. Their structure appears denser and they seem to have longer "furs" while the white ones are "dryer" and "sharper"
This surface makes the blue tapes I sourced more suitable as the molten filament catches more furs.
Here are magnified photos of my comparable tapes. Unfortunately, my microscope is pretty lame but at least we can take a look on closeups:
This comparison shows the lower density of my white tape better:
to complete the picture here goes angle photos which reveals some more details
above shows that this white tape is made out of flat plastic fiber as they shine when illuminated from different angles
this could lead to another question
is such tape melted in any way in contact with extruded filament?
worth to analyse...


q: I’m designing a part that will need to be autoclaved—it will be under steam at 121°C for about 15 min per job and I will want it to be able to go through the autoclave repeatedly. I ran a test PLA part through the autoclave and it warped noticeably; based on their glass transition temperatures, ABS (105ºC) and PETG (80ºC) would probably also not hold up. For a consumer-grade FDM printer, what filament materials that could be used for parts that could be autoclaved?

[A]
It might seem that common 3D printer materials such as PLA and ABS should be capable of being autoclaved—unfortunately. However, although their melting temperatures are higher than autoclave temperature (typically 121ºC), their glass transition temperatures are below that limit so they can warp or undergo creep deformation.
Sterilization of numerous plastics is described
here
, with PLA, ABS, and PET all being described as "poor" for autoclaving. For each "good" material on that list, I looked for filament by Googling and consulting material guides from
Prusa
and
Matter Hackers
.
Polypropylene (PP) or acetal (POM, also known as Delrin) are the best choices. Filament is available for PEEK, PEI (ULTEM), FEP, PPSU, and PPS but these filaments are expensive (>$100/kg) and require high extruder temperatures (>300ºC).
In contrast, PP is about $50/kg and uses an extruder temperature of 254ºC; POM is similarly priced and uses an extruder temperature of 210ºC. Nylon (depending on the exact type) and HT-PLA may also be worth considering.
"High temperature" filaments are not worthwhile for this application. Again, they're expensive and, more significantly, do not work well with consumer-grade 3D printers. For example, the upper limit for a Prusa i3 MK3s is about 280ºC—the thermistor only is good up to that temperature. Higher temperatures would require swapping out sensors and modifying firmware and building an enclosure.
It's been done
. Printers designed for high-temperature filaments easily cost
thousands of dollars
.
This question was previously asked on
Reddit
a few times
but this analysis is more comprehensive.


q: Can I use three-phase stepper motors with pololu style stepper drivers? If not, what kind of drivers support three-phase motors?

[A]
3D printers typically use bipolar two-phase stepper motors, and it is possible that Pololu-style carriers for stepper-motor drivers only support such motors.
Certainly, drivers for three-phase stepper motors exist, for example, the Trinamic TMC5062, but I cannot find any Pololu-style carriers for this chip. Even if a Pololu-style carrier can be sourced, it is not certain that existing 3D-printer firmware can be configured to control it.
If you are thinking about re-purposing some three-phase motors, I would advise that you purchase standard bipolar motors, instead. Bipolar two-phase motors suitable for 3D printing are not that expensive.
Trinamic TMC5062


q:
I've been playing around with PETG for the first time, and everything seemingly worked right just from the start - clean prints, no stringing, no bed adhesion problems, no warping or dimensional accuracy problems, etc. As expected it prints a lot like PLA, and as expected, it's less brittle/stands up much better to crushing/impact, except that it's really brittle when it comes to inter-layer adhesion. Vertical cylinders that were fairly strong in PLA just snap with no effort as PETG.

My particular PETG filament is Sunlu, with recommended print temperature 230-250 °C. I started out with 235 and am now using 250, which does somewhat better. I've used layer heights 0.125 - 0.2 mm.

Are these kind of results normal? Is there anything I should be doing to get better adhesion between layers?

[A]
What you describe is usually the result of using a too high of a part cooling fan rotational speed. Like ABS, PETG doesn't require much cooling (if needed at all that is). If you do cool too much, layers and perimeters do not bond optimally (you can get string cheese like printed parts on failure).
Why should you use cooling for PETG?
Cooling helps cool the deposited filament on small cross sectional parts. If un-cooled, the printed part picks up too much heat and will deform or sag out.
In such cases, reduce cooling to 40 % to start with (another option is to print more parts or increase minimal layer time). Note that there are so many print cooling fan constructions, some more effective than others, so you need to tune the print cooling fan speed to your setup. E.g. for an Ultimaker 3E I get good results at 50 % fan speed, for other self-build printers with effective part cooling solutions, 40 % works best (printed several kilometers of 2.85 mm PETG). First few layers don't need any cooling at all.


q:
After a few months of printing with my Prusa Mk3 (with plans to get a second one soon), I have been wondering about making my third printer a home-built one was a larger print bed than the Mk3. One thing I wondered about is perfectly expressed in the title question.

Are there practical reasons to not use a stepper motor with lead screw for the X and or Y axes?

I am certainly happy with the GT2 belts used in my current printer, but I wonder if the design might be simpler with lead-screws on all three axes.

[A]
Cost would be the primary reason.  You can engineer a belt driven system that will be equally accurate, faster, and with longer travel for a lower cost.
Lead screws are comparatively expensive. The cost differential dramatically increases with length of travel and speed with equivalent accuracy.
Lead screws do have a significant advantage of being able to carry a much heavier load while maintaining rigidity which is important for something like a CNC mill but isn't as relevant for 3D printing.
This is on the assumption when you say:
Are there practical reasons to
not
use a stepper motor with lead screw for the X and or Y axes?
you meant that you are still planning on using stepper motors but considering a lead screw vs. belts.


q:
I have two Tronxy 2.0 V5 Marlin boards that reboot whenever heat is applied to the bed. The bed has been swapped (because I thought that was the problem) for a new shiny one. The thermistors, too, of course.  The same boards (both) work when the beds remain unheated (setpoint = 0 °C).

Any ideas what might be causing this, or what I might do to figure it out?

Note: I really have no idea which Tronxy board this is;  the "2.0" is stenciled on the board, so that's all I can figure out. I shamefully admit I tagged it with Tronxy x1 to see if I could generate any interest, and because a "Tronxy" tag is not available.

[A]
It sounds like a power-related problem. Always use an external MOSFET to drive a heated bed, and consider investing in a decent power supply. Inevitably, the Tronxy PSU will be barely adequate.
Edit: I've just noticed the
tronxy-x1
tag. Be aware that the stock (60 Watt) PSU for the Tronxy X1 cannot power a heated bed (the printer does not have one). Trying to do so will overload the PSU and cause an immediate reset.


q:
I've got some curious marks on my heatbed.

It appears to be from my black Sunlu PLA+ (I can just feel it if I scrape my finger nail over it) but I can't scrape it off with the metal spatula.

When I try and print over it the filament won't stick.

Any suggestions as to what it is and how you get rid of it?

[A]
Edit: As Trish noted, apparently Prusa printers don't ship with Buildtak stickers like the other printers I've used, so this is probably a bad idea in your specific case. For others reading this, only do the sanding shenanigans with buildtak or other stickers that you can easily replace and don't mind wearing down over time.
Used to happen to me printing PETG on Buildtak. I ended up using a medium grit sanding sponge to remove the PLA layer. Related, you might want to grab some 1k grit sandpaper for the same reason, it does a great job of freshening up your build surface once builds stop sticking well.


q:
I now own the Prusa3D MMU2.  The benefits, costs, and experience others have had is well documented.  I am interested in rebuilding my large, home-designed delta machine to be multi-material, and don't want to overlook strategies I haven't considered.

My original implementation used an E3D Kraken as the hot-end, and handled the inevitable delta tilt by adding two additional degrees of freedom to the head to lower the selected nozzle to the bed.  I've been through three generations of mechanisms, and I think the third will work.

But, I feel that I am not seeing obvious and better alternatives.

So, the question:  Through what methods and mechanisms can a multi-material (different polymers, different temperatures) FDM printer operate, and are there available designs or examples of best practices for those methods?

[A]
One of the easiest ways that I've seen, which I'm a fan of, is simply putting Y splitters on your Bowden tube and having multiple feeds to a single hot end. The main benefit is that you only need a single hot end, so you don't have to worry about extruder offset or alignment or anything like that, but you do have to worry about material blending somewhat. Basically you end up needing to build a "purge tower" next to your printed items that you use to transition from one material to another.
There's the Diamond hotend setup that basically moves the connections into the hotend itself, which reduces the size of your purge tower but increases the risk of burning if you're trying to print with materials with vastly different printing temps, like PLA and PETG.
You could also have swappable hotends but that requires you to be there to manually swap the print head twice per layer. Don't recommend.
Unfortunately there's only so many solutions to the multi material problem, either you put multiple materials through a single hotend, or you have multiple hotends. I'm a fan of the single hotend approach personally, especially on deltas where weight and space are at a premium and alignment becomes problematic.


q: I read that PTFE starts to deteriorate past 260 °C. Does that mean heating to 250 °C is no problem at all, or will that destroy the PTFE material over time to?

[A]
Degradation starts at 260 °C and shifts towards full blown decomposition towards 350 °C. 250 °C is technically fine, but you should keep in mind that you've got little to no wiggle room for error at that temperature. Your thermistor and board may not be accurate enough to guarantee you'll never overshoot that temperature, and the way 3D printers often handle temperature adjustment exacerbates that risk. You
can
print at 250 °C, just be aware you've got basically no margin for error.


q:
I need to cool some liquid (250 °C) while it’s flowing through a tube which has to be able to bend and flex.
My idea is to make a flexible tube with a second tube spiraling around it through which coolant will flow.

I’d like to 3D print this tube if possible so I wonder if there is some printable filament that:

doesn’t melt at 250 °C

is flexible enough that it can print some tube that can bend (bending radius of 30 cm)

optimally also has good heat conductivity

Is there any 3D printer filament available that has these properties?

[A]
3D printing nerd showed a couple of filaments that fits this in his latest video "Printers at RAPID + TCT 2019":
Firstly a
Nylon 6 high temperature filament
:
Another part of the video shows another flexible print, created on a four axis 3D printer, using
TPU filament
:


q:
Given a 3D boolean array representing voxels, how can it be converted to a 3D-printer-ready file?

The end-goal I would like to achieve is to print the 3D shape that the numpy array represents (True coding for fill this voxel, False for leave it empty).

For example, the array

[
    [
        [T, T, T],
        [T, F, T],
        [T, T, T]
    ],
    [
        [T, F, T],
        [F, F, F],
        [T, F, T]
    ],
    [
        [T, T, T],
        [T, F, T],
        [T, T, T]
    ]
]

would encode a level-1 Menger sponge.

[A]
I agree with the use of OpenSCAD, but since it is difficult to program in OpenSCAD, I would use
SolidPython
, which is a front end for OpenSCAD with the full programming capability of Python.
In the alternative, you could use any programming language to decode your arrays and generate the OpenSCAD code for the little network of cubes (or voxels).
The final possibility is to generate an STL file directly.  I've helped someone do this, but we found the rules to be a little non-intuitive.  We used mesh tools to check out results, both by looking for error messages, and by displaying the result to see if it looked as we intended it to look.


q:
When I print with a 0.4  mm nozzle I have no problem with stringing at all but because I need a more detailed print I must use a 0.25 mm nozzle.

I use Ultimaker Cura and an Anycubic i3 Mega.

What i tried so far:

Enable/Disable Z hop

Tried different retraction distance and speed.

Tried with lower temperature

Different wall thickness

If you have any suggestion please let me know.

[A]
First, you should change the
nozzle diameter
setting, not just the line width setting, in Cura. Both are involved in determining extrusion. Line width can be less than or greater than nozzle size, but setting it much larger or smaller is not going to work well.
I suspect your main problem, though, is print speed. The area of the 0.25 mm nozzle orifice is only 39% of the area of an 0.4 mm nozzle orifice, bounding the material extrusion rate
at best
at 39% of what you could get with the larger nozzle (in practice it will be even lower due to complex fluid dynamics, probably much lower), but at the same linear print speed with narrower lines, you'll be extruding (or trying to extrude) 62.5% as much material per unit time. Now, if that much material can't actually make it out of the nozzle, pressure builds up between the extruder gear and the nozzle, and stringing is the result.
So, try lowering the print speed.
A lot
at first. If that solves the problem, gradually increase it until you find the limit. Increasing retraction and temperature may help you push it a little further. See my question and self-answer on stringing with flexible filaments, which might give you some ideas on other things to try:
Avoiding stringing with flexible filament


q:
What grease to use on linear rails to make them stick as little as possible? I've tried so far:

WD40 (let’s not start a discussion about that please),

silicon spray and

some bearing grease called ‘motorex’,

but with all of them the rails stick quite much and don’t slide as easily as I’d hope.

Can someone recommend some good grease for linear rails (specifically the hiwin type, 12-15mm)?

[A]
Don't use grease
, it is better to use a
light oil
to lubricate the rods.  A light oil will help flush out any dust and filament debris, grease will trap it.
I've used both light machine oil (like used for sewing machines) and PTFE based spray (Teflon). Grease is thick and will collect and trap dust and particles more easily than light machine oil.
Even high-end consumer printers use light machine oil, e.g. the Ultimaker 3 Extended I got came with a bottle of light machine oil for the linear guide rails. Their advice is to regularly add a drop of oil on each shaft once in a while (how frequent depends on how much your printer prints).


q:
I just updated my Maker Select Plus from the stock (I believe RepRap-based) firmware to Advi3pp, which is Marlin based. The printer starts up and everything seems okay, but I haven't actually tried a print yet and there was a message during the upgrade about deleting incompatible settings.

What do I need to do to recalibrate the printer following the firmware upgrade?

[A]
If it is Marlin based or RepRap based, many parameters are stored in EEPROM memory. A G-code command
M502: Read parameters from "configuration.h"
would reset all parameters that can be changed to their default value as defined in your configuration file. Don't forget to follow the
```
M502
```
command with a
```
M500
```
command to store the loaded parameters to EEPROM. This would overwrite all previous settings.
From the linked source,
```
M502
```
:
This command resets all tunable parameters to their default values, as set in the firmware. This doesn't reset any parameters stored in the EEPROM, so it must be followed with M500 if you want to do that.
You can send these commands over a terminal interface to the printer using applications such as Pronterface, OctoPrint, Repetier-Host, and probably many more, or store the commands in a G-code file (e.g. a text file with a
```
.g
```
extension) and print the file using an SD card.


q:
How can I print an embossed image in a concaved shape?

Like a big saucer. I will use this an a mold for a project.

So far I've found lots of software with huge spread of features. It's sort of overwhelming. There is lots of ways to create images into 3D printable objects but to add the extra step and concaving that image is harder to find out.

How would you do it? I'm open to suggestions.

I'm new to 3D printing and would really appreciate the help.

[A]
What you describe, sounds like you want to create a lithophane; a pattern etched or engraved on a thin translucent base material (in your case a bowl) that can only be seen clearly when backlit with a light source behind it. Apparently you want to use it for another purpose.
Special software and or scripts that transform the image to the base material exist. An example is e.g.
this sphere which becomes a globe when lit from the inside
. Recommending a tool for creating such bowl is a little
out of scope
as these types of questions become outdated very quickly as technology changes or tools cease to exist. With the provided information you should be able to find software that is able to provide what you want to do.


q:
I am searching for a Linux software to control the 3000 mW laser engraver depicted below. It's a common model you'd find on AliExpress, Banggood, etc. under different brand names.

I have already tried nejePrint, LaserWeb, and EzGraver, but they don't work. Any ideas?

[A]
A program that lists as functional with Linux is
Lightburn
. It's new to the laser engraving world and supports GRBL type controllers as well as Ruida brand and possibly a few others. If you can determine your controller, you're a step ahead of the game.
Directly from their site:
LightBurn
LightBurn is layout, editing, and control software for your laser
  cutter. With LightBurn you can:
Import artwork in a variety of common vector graphic and image formats (including AI, PDF, SVG, DXF, PLT, PNG, JPG, GIF, BMP)
Arrange, edit, and even create new vector shapes within the editor, with powerful features like offsetting, boolean operations, welding,
  and node editing
Apply settings like power, speed, number of passes, cut order, brightness & contrast, dithering mode, and much more
Send the result directly to your laser cutter
LightBurn is a native application written for Windows, Mac OS, and
  Linux.
I'm a satisfied Lightburn user, not a company representative.


q:
Recently on one of her videos a YouTuber stated that prints from large format printers are more brittle than if you were to print them in parts and glue them together. This seems to contradict the testimonials from the customers of a large format printer, who say that they get good prints from those printers (which print have a print area of a meter square).

Would a print form a larger format printer be more brittle than a print made of smaller pieces super glued together?

(with all other aspects being equal e.g. the nozzle, the temps, the material and the shape of the object).

The YouTube didn't cite any source information to back up her claim.

[A]
If you break up a large piece into multiple smaller pieces and properly glue them together, you basically add stiffeners (as a result of printing walls). This could lead to a more stiff model; this might have been confused by calling large prints more brittle opposed to constructed models.
If printing is conducted at similar conditions on large printers, there shouldn't be a reason why the model becomes more brittle unless the conditions aren't the same. But that would be true for printing at small printers too, e.g. if one print was printed in a draft.


q:
I want to print a flowerpots, for advanced watering system.

Plants are going to be eaten.

What is the most suitable material, when we consider the fact, that we do not want to just make forms and do clay flowerpots(which may seem most healthier), but having them directly printed.

What are the temperatures that makes plastics emit dangerous components in surrounding water, and what are those components?

Is there some "totally safe" material out there? I was thinking of PLA or PETG, because I've already heard that ABS is not safe for edibles.


q:
I'd like some advice regarding defects on my print :

Here some details :

Printer CR-10 S, nozzle 0.4

Material PLA

Bed 60, Hotend 215, 50 mm/s speed

SLiced with cura 4.1, 5 walls (i can provide more detail of the profile if needed)

Layer height 0.1

modeled on fusion 360

The surface where the defect sits is actually tilted 45 degres

Thanks !


q: I am working with Ender 3 Pro and in menu it has an option to cooldown. Is there any need to cooldown 3D printer before shutdown or can I just shutdown without cooldown?

[A]
Depending on what material you print it it most likely a good idea to let the hotend cool down before shutting off the printer (fan).
For example if you shut down the printer right after you print a PLA part, at 190 - 220 degrees Celsius, your hot end will still be that hot and will suffer heat creep without the fan running. The next time you fire up your printer the hotend will be jammed and you will need to clear it before starting a print.
This is obviously situation dependent but in most cases you should let your hot end get below the TG (glass transition temperature) of the material before turning off the printer.


q:
A fillet is like a rounded corner but on the inside of the corner.

Does it make a difference (structurally) to use fillets on a 3d printed part?

[A]
If your part needs structural support, then the word is:
absolutely
. Fillets provide the added support when you need it. If your part has a meeting line which is sharp - 90° (or perpendicular), there is a natural
stress riser
in your design. This is a weak spot where a crack can form. If strength is needed and the fillet won't interfere with the design, it's definitely something you should include with your part.


q:
In regards to a part that I'm having printed remotely (by two processes:- stereolithography and laser sintering), I've been advised by the 3d printing company that 'the triangulation of the file is rather rough'.

In this particular instance, it probably doesn't matter, but for the future, are there any tips to improving 'triangulation' when generating forms in AutoCAD?

Note, AutoCAD's FACETRES variable is set to 10.

[A]
The phrase "triangulation of the file is rather rough" is somewhat vague, but one can interpret it to mean that the surface is what is considered "low poly" in the 3D modeling world.
From
Thingiverse
, this low poly fox shows an intentionally reduced poly surface. I'm not suggesting that your models appear this distorted, but it may give a hint to what the service is referencing.
Consider to load your model into a program such as Meshmixer, which will show you the triangles in 'W'ireframe mode. If there are few triangles over a surface, you can get the aforementioned effect.
Meshmixer also allows you to increase the mesh count, possibly improving the surface and satisfying the requirements of the printing service.


q:
This video brought to my attention the 8 mm lead of the Ender 3's Z axis screw, which seems like an exceedingly bad choice from a standpoint of accuracy with respect to common grid alignments in the Z direction. In particular, with the stepper having 200 full steps per rotation, the 8 mm lead consumes all the powers of two out of 200, leaving 25 full steps per mm - and 25ths of a mm are not a typical unit that layer heights/feature heights are going to be in. It seems like a 5 mm lead would be ideal, giving you 40 steps per mm, evenly divisible by 3 powers of 2 and one power of 5, for exact tenths and exact eights.

Is there a motivation behind the choice of 8 mm lead? Is this common for other printers, and are there printers that use a 5 mm lead, or 5 mm replacements that work well?

[A]
I've not seen trapezoid lead screws with 5 mm lead, you can get 5 mm lead ball screws though.
On one printer I use 4 mm lead screws to get native 0.02 mm resolution (so 5 full steps for 0.1 mm, 10 for 0.2 mm, etc.). I also geared down 8 mm lead screws with a 2:1 ratio (e.g. to use a single Z-stepper driving a belt that drives 2 lead screws), works fine.


q:
I am printing a small cylinder, but when the object is finished, it's smaller than the measures I used when create the model.

I used thincerkad to make a simple model, the measures are:

width: 90 mm

height: 2 mm

After the print was done, the actual dimensions were:

width: 70 mm

height: 2 mm

Pictures

First attempt

The smaller object that's in the drawn circle was the first one printed, the dimensions I used were:

width: 110 mm

height: 2 mm

Then I printed it again, and the result was:

[A]
Are you using the stock firmware of your printer? Sounds like to me that you have 16 tooth pulleys and your firmware is set to 20 tooth i.e. 80 steps per mm
The calculation behind the steps per mm is
$\frac{\text{Steps per Revolution} \times Microsteps}{Teeth \times Pitch}$
. The reason for this is that one revolution of the pulley will move the belt the number of teeth times the pitch of the belt. Now take the total number of steps, Steps per Revolution times microsteps, and divide by the distance moved giving the steps per mm.
In
$\underline{most}$
hobby 3D printers you have:
1.8 degrees steppers which equals
$\frac{360}{1.8}=200$
steps per revolution , Less common is 0.9 degrees steppers
$\frac{360}{0.9}=400$
GT2 is the most common belts now which have a pitch of 2mm
The two most common pulleys are 16 tooth and 20 tooth,
Depending on what stepper drivers and or configuration you have
A4988
$\to$
16 microsteps
DRV8825
$\to$
32 microsteps
Trinamic
$\to$
16-256 mircosteps
In your situation I believe you have a 1.8 degree stepper with 16 microsteps, a gt2 belt, and a 16 tooth pulley. Which means your XY steps per mm should be
$\frac{200 \times 16}{16 \times 2} = 100$
. While your firmware is expecting 20 tooth pulleys, yielding
$\frac{200 \times 16}{20 \times 2} = 80$
. This would result in your prints being
$\frac{100-80}{100} = 20\%$
smaller, which explains your results with the circles.
Generalizing, the steppers, microsteps, and pitch don't matter. To go between 16 tooth pulleys to 20 tooth, multiply by
$0.8=\frac{16}{20}$
. From 20 tooth to 16 tooth, multiply by
$1.25=\frac{20}{16}$
.


q:
I'm not talking about making something that's outright disproportionate of course. I've been working in Blender and I've use Absolute grid Snap to snap my vertices to the grid. The problem is that it (didn't seem) to always work perfectly for centimeters, and seemed to work better for meters.
(edit: I've learned what the problem was and it was simply the placement of the vertices in side view, being at  slightly different elevations. I'm going to emphasize that the difference was very slight. It was just enough to show up in the measurements. When I switched from front view to side view I was able to adjust the elevation to the grid and that fixed the problem.)

[A]
It depends on what you're working on. If you're producing mechanical/functional parts (even if that just means having to connect to one another or to some non-printed part), 3 mm (0.3 cm) error is almost surely going to prevent them from working. Even 0.3 mm error might be a problem.
If you're doing standalone prints that don't have to interface with anything else, e.g. art, non-articulated figurines, etc., then it becomes just a question of what's visually acceptable, and that's a matter both of scale and of the detail level you want. For typical tabletop-RPG scale, for example, most of the acutal visual features are going to be smaller than 3 mm, so that much error is not going to work out. It might work for large busts, though.
In any case, I would recommend trying to solve the underlying problem. Either change your grid snap, or work at a larger scale and just scale down the final model.


q:
I've always been wondering about the actual accuracy of 3D printing devices. When looking for the perfect machine to buy, I looked at the speed, price, filaments supported etc, but also accuracy. I once asked somebody who could give me some advice on what to look at.

One of the things I was told about was that many printers don't necessarily have that crazy precision of 0.05 mm (50 micron). Another person told me something different - he said most of those printers actually were capable of putting out 50 micron layer height. How is it really?

Another thing is that the official slicers for those machines also claim that this precision is real, for instance the PrusaSlicer v2.0.

There are many high-end, very expensive machines and even they sometimes claim their resolution is worse than 50 microns.

[A]
One of the things I was told about was that many printers don't necessarily have that crazy precision of 0.05 mm (50 micron). Another person told me something different - he said most of those printers actually were capable of putting out 50 micron layer height. How is it really?
Both things you've read are completely correct.
Most printers are capable of 50 micron layer heights. However, layer height does not equal "accuracy" or "precision". The layer height specification is a useless marketing term that you should ignore; layer height is to 3D printers what dynamic contrast is to monitors.
All FDM printers are inherently quite bad at producing parts with tight tolerances. The filament extrusion process introduces lots of variables that are hard to control: the diameter of the filament may vary, there is a delay between feeding filament into to the extruder and it coming out, and the gooey filament that comes out of the extruder behaves in unpredictable ways.
Nobody has figured out how to quantify "accuracy" for 3D printers in a way that correlates with the quality of the finished parts. It is impossible to tell which printer produces "better" or more accurate parts from the specification sheet of a printer.


q: In 3D printing firmware and slicers, jerk settings are expressed in units if mm/s. This is contrary the physical definition of jerk, which is in units of mm/s³, being the second derivative of speed with respect to time (or the third derivative of position). What is the reason for this discrepancy and how does one interpret jerk in this contect?

[A]
The jerk setting in 3D printing G-code and firmware represents a concept similar to, but distinct from, the physical definition of jerk. Rather, it's a [limit on] instantaneous change of speed.
Mathematically, one way to make sense of this is to think that, rather than being the second derivative of speed with respect to time, this "jerk" is the entire remainder of the first-order expansion of speed with respect to time - it corresponds to the second-order term
and all higher order terms
. Such terms cannot be combined just as coefficients, since they all have different units corresponding to different powers of time; rather, they can be combined only
with their corresponding powers of time
, in which case the resulting unit is mm/s.


q:
ABS is a very strong material, but it also has some downsides. One of them, which is the necessity of having a printer with enclosure, completely discouraged me from using it, as it would be a waste of money. This is quite sad, because I cannot make prints that will be able to withstand a large load of tension without breaking.

Is there any way to print ABS without any enclosure? Maybe there are several types of this material and some are easier to print?

[A]
There is no requirement for an enclosure when printing ABS. Like many things in FDM, there are improvements to be made, but there is a scale of what is possible.
A heated bed is much more necessary (for similar reasons, the thermal expansion is significant and without a heated bed you have very high risk of warping).
An enclosure is important for high quality, large ABS prints. Otherwise, a warm location which is free of drafts will be fine, particularly for parts which are only a few cm high.
If you're not using an enclosure, the part cooling fan should probably
not
be used to print ABS. You should also be aware that ABS tends to generate more noticeable fumes than PLA (although this varies with product, and how sensitive you are).


q:
My anet A8 stepper drivers get very hot after some time printing, so I decided to install a 5V fan to cool them down. I had the idea to get a 12V to 5V regulator to connect a 5V fan, but then i found this image:

(source: lokspace.eu)

It looks like the Anet A8 has an ICSP and Serial header that can deliver 5 or 3.3 V directly from the board. Is this correct? If it is, how many amps can i get from this pin? Can I connect a 5V fan directly here?

Thanks and sorry for my bad English.

[A]
5 V and 3.3 V are both
logic "highs"
in computing and measured against GND. If the fan simply has to know the on stance and nothing more, then you could run a fan with the logic 5 V (and probably 3.3 V for about 50% spin speed).


q:
I've done calibration test with "Concentric circle test" (https://www.thingiverse.com/thing:11895) and at specific points there are little bumped points on the print. Also Thingiverse page of the test mentions about these.

How can I solve this problem?

My printer is Creality Ender 3 Pro, I use Esun PLA+ with 210 celcius extruder and 60 celcius bed temperature.

Here is the printed object, both are same print, just took photo on different base.


q:
How should I describe this part which looks like a small gear so that I can research replacements?

This came with my FLSUN 3D printer, which may be based on a Prusa design.

[A]
It is an "aluminum timing  pulley"
https://www.google.com/search?psb=1&tbm=shop&q=aluminum%20timing%20pulley&ved=0CAMQr4sDKAFqFwoTCMis1KHmiuMCFRoMswAdMqUElxAB
https://www.ebay.com/i/152446519860?chn=ps&var=453435947176


q:
I've upgraded my stepper drivers.

I'm looking to understand why my stepper motors made noise in the first place.

[A]
To make a stepper perform a step, block signals are send to energize the coils to position the rotor. Such a block signal causes abrupt motion and triggers harmonic frequencies. This is audible as stepper noise. If the block signal is smoothed, the motion is more fluent and less noise will be observed. A similar effect is achieved using micro-stepping.
It could be that the new stepper drivers use more/less microsteps
1)
or a smoothed/block
1)
signal opposed to the previous drivers, hence less/more
1)
noise.
1)
The question does not state if the noise is reduced or increased, but noise reduction is most probable


q:
Developing an electronic product for which I'll need an enclosure. It's about 50x30x20mm and should survive higher temperatures (50-60 degrees). Because of the low volume (under 500 required per year), I'd like to go for an enclosure option that doesn't require a huge upfront cost. So ended up at 3d printing.  As the product will retail for around 500$, the surface finish needs to be up to a higher quality than the standard pla prints that I've seen. From my own research (3d printing noob), the best material for this would be ABS. Maybe with some manual polishing at the end. Then I'd either buy a 3d printer and do it myself or find a company to do it.

What am I missing? :)

Anything I'm missing? Thanks a lot.

[A]
ABS should be able to handle the the temperatures you describe. ABS will have a similar finish to PLA when it first comes off the printer, but you can refine and smooth your results via an acetone vapor treatment. This only takes a few minutes per piece, and can cost as little as a $1 bottle of fingernail polish remover, a used coffee can, a bit of wire, and some paper towels.
What you're missing is the hobby-level 3D printers ($1000 and below) can be
extremely
finicky. You're not gonna get the kind of quality you need the first print out of the gate. Or the second. Probably not the third or fourth, either. And then you'll find every now and then something isn't quite right any more, and you'll need to troubleshoot why.
You certainly can make this work... just be prepared for what you're getting into.


q: When I print parts in ABS, acetone vapour smoothing is a good technique to get a smooth finish. Is there an equivalent solvent or process for parts printed in ASA? Ideally I'm looking for something as easy to obtain as acetone, and not so awful a chemical that I wouldn't want to work with it, but I'd still be curious to learn about less friendly solvents.

[A]
ASA
is Acrylonitrile styrene acrylate. According to Wikipedia:
ASA can be solvent-welded, using e.g. cyclohexane, 1,2-dichloroethane, methylene chloride, or 2-butanone. Such solvents can also join ASA with ABS and SAN. Solutions of ASA in these solvents can also be used as adhesives.
Staff, PDL (1997). Handbook of Plastics Joining: A Practical Guide. Elsevier Science. p. 515.
Solvent-welding means that the material is at least somewhat easily soluble in these fluids (they dissolve the material at the interface and as they evaporate, the former interface layers bond as if molded or welded), and the fact that the material can become an adhesive means that it is somewhat good soluble in these.
The least dangerous (and thus most advised from my side) of these 4 is 2-butanone, the others are listed as carcinogenic, and in the case of 1,2-dichloroethane, also toxic.
If these solvents can be used as a smoother similar to acetone with ABS would need testing, but a short exposition to their vapors should suffice to test this.
Addendum:
These four solvents also are able to solve Acrylonitrile butadiene styrene (
ABS
), which is a quite similar plastic in regards to its contents (butadiene instead of acrylate).
The acrylate rubber differs from the butadiene based rubber by absence of double bonds, which gives the material about ten times the weathering resistance and resistance to ultraviolet radiation of ABS, higher long-term heat resistance, and better chemical resistance.
Wikipedia
Acetone might prove to be also a possible option, but results might differ from those on ABS.


q:
How can I write G-code for a triangle without sharp tips?

I want to generate the corners manually, rather than using a slicer to generate them, just to know how it is done.

[A]
Marlin has
```
G2
```
(clockwise arc) and
```
G3
```
(counterclockwise arc) commands that could be used to do this.
You can find detailed documentation for the command here.
Basically, you can use
G2 R1 X5 Y5
to draw a (clockwise) arc from the current position to
$(X,Y)=(5,5)$
with a radius of
$1$
.
So, your rounded triangle could be drawn with 3 straight line moves and 3 arc moves. Figuring out the exact coordinates for each move would be a quite challenging geometry exercise, as you'd need to know where the straight line portion of each side ends and the rounded portion starts.


q:
Is there a specific name for that problem? What causes this, and is there a way how to solve it?

Printed with PLA, 2 mm nozzle diameter, 0.2 mm layer height, 20-60 mm/s, 200 °C extruder, 60 °C bed.

[A]
I have experienced this problem.  This picture is one that I could have taken.
It has always been because I was putting too much plastic into the available space.
This has been caused two things: overextrusion -- squirting out too much plastic for the intended layer height, and the bed being too "high" so that the gap between the nozzle and the bed is too thin.
In both cases, too much plastic is trying to be placed in too small a volume.  The plastic has to go somewhere, and ripples follow.  Because the nozzle rubs against the adjacent lines which have already been deposited, an up-bump pushes up the nozzle on the line beside the bump, and a coherent pattern of ripples can form.
The "bump up" is a real effect from the elasticity of the Z-axis, including all the resulting strains of twisting and lifting the nozzle.


q:
I have started printing about a month ago on an Ender 5 (using mostly PLA but recently also PETG) and it seems it's about time to give the print bed a more thorough cleaning than what I usually do after most prints. I'm using the flexible magnetic mat that came with the printer which has a slightly rough surface, but all of the cleaning suggestions I found so far either did not mention the bed material or were specifically for glass beds.

Can/should I use stuff like acetone or rubbing alcohol on this? Or should I stick to warm soap water?
I have had some fairly decent results with spectacle cleaning tissues but that will only remove grease, not filament residue.

Also, I am occasionally having some first layer adhesion issues (especially with the PETG or when printing things with a circular base) and I was wondering whether common suggestions like glue sticks or hairspray to prepare the bed for printing  can also be applied to the flex mat?

[A]
I have the WhamBam system which uses a PEX layer over flex steel (which sticks to a magnetic sheet on the printer bed). To clean old material off, I use a "brass sponge" intended for cleaning soldering iron tips to remove the old plastic, then give it a wipe with a paper towel with some isopropyl alchohol (I have 99.99 anhydrous on hand as I use that for cleaning printed circuit boards as well).
The brass sponge is fairly soft, does a good job of grabbing the old plastic without tearing up the PEX layer.


q:
If a customer sends me a non-commercial 3D model to print, am I allowed to charge money for the 3D printing process? I understand I cannot charge anything for the model nor offer it as a part of my business.

I cannot download the model myself, print and sell it, but if the customer downloads it and sends it to me for me to print it, is it a violation of the license or not?

[A]
In more practical terms, you could design the part so that the corners are rounded (also known as fillets). This will help keep the print head moving and would prevent the sudden stop and start effect that causes "jerking". Further 8 bit controllers tend to get saturated when reading large amounts of g-code from the sd card or the serial port. Upgrading to a 32 bit controller will prevent that kind of jerking.
Both of these methods pale in comparison to just speeding up the print. Upgrading the hardware to be faster (various methods exist) would yield more of a reduced time than trying to optimize the g-code (in my humble opinion). Delta printers have the potential to be the fastest type of FDM printer, assuming that you could get the filament to melt fast enough.


q:
Am just wondering if any conclusions can be drawn from this:

Three corners are solid, but not the one in the centre of the plate.

The bed was levelled before printing (and checked afterwards also). Even though the photo may appear to show a slant or lower corner (where the print is coming off), there is not. The bed is level, relative to the extruder, at room temperature.

The temperature of the bed is about 70 °C. I get inconsistent readings (with laser thermometer) but to the finger it feels about the same everywhere.

It's a glass bed, presumably with some coating. Is it degraded? Local temperature variation? Any ideas anyone?

[A]
From here:
https://io3dprint.com/review-anycubic-i3-mega-ultrabase/
Ultrabase Bed
  The Anycubic i3 Mega Ultrabase is the latest version in the Anycubic i3 family. As hinted in the name, the main upgrade from the previous version is the Ultrabase bed. This is a textured coating on the Borosilicate glass bed that means you don’t need to apply any glue or tape to the bed to make your prints stick to it.
Ultrabase is similar to the popular BuildTak beds except unlike BuildTak it doesn’t wear off and the most significant benefit is that parts are exceptionally easy to remove once the bed has cooled.
The Ultrabase surface has a Moh’s hardness of over 7. This means you can safely use metal scrapers and blades to clean it without risk of it scratching!
Perhaps it was just not cleaned sufficiently from a prior print.


q: How to successfully pause 3D printing and turn off the printer and the next day, continue to print the model?

[A]
1) Cut the model up in several parts and print one each day. Remove each part every day and in the end, glue them all together.
2) Cut the model up in several parts and each day, add a G-code to the file to be printed so it lowers the heat-bed and thus starts to print on top of yesterdays print. This cannot be used when the printer is auto-calibrating as the printer-head would crash into the already printed part. It would probably be tricky.
3) Pause the printer in the evening, then resume next day (don't forget to lower temperatures and rise them again tomorrow).


q: So after a long print the walls in the print begin to weaken and it appears they might not be printed at all.  In the upside down picture you can see the weakness where the two pieces are separated.  I'm wondering if perhaps reducing my speed and changing the extrusion size from .35 to .45 which is larger than the extruder itself.  Thanks for any help and suggestions!

[A] What you refer to as weak walls in fact are under-extruded walls. This can be caused by multiple sources, but, since the print recovers this most probably is caused by filament that is entangled on the spool (this causes more friction for the extruder and as such less flow, so under-extrusion; like as if the filament is being pulled back). Any other source that may induce extra friction is equally valid. E.g. kink in filament when using a Bowden configuration (long time extra friction in tube) or friction on the spool itself (I once had severe under-extrusion as the spindle of the spool caught a plastic bag which got wrapped around).


q:
I am trying to slice a model that is half a mm less than max width, but not successful.

What am I missing? Is there some minimum value less than maximum allowed, or something?

Edit: after changing the width to 220 in machine settings, slicing works. This is a dangerous thing to do, as it could damage the printer.

[A]
Take a look at this post:
https://community.ultimaker.com/topic/15588-cura-23-not-using-full-print-area/
. As the raft/skirt/brim will fall outside of the build volume, Cura is not able to slice it. Look at the the answer by @ahouben. He suggests that if you want to use the maximum build volume :
adhesion type = brim
brim line count = 0
travel avoid distance = 0
horizontal expansion = 0
support horizontal expansion = 0 (if support is enabled)
draft shield disabled
ooze shield disabled
infill wipe distance = 0
Note that in most cases brim with brim line count=0 will get you most of the way there
Try this and see if it makes a difference.


q: I read that G-code commands can be sent through a console/terminal over USB. What is a console/terminal and how do you use that?

[A]
There are several programs that could serve as a console to connect to a printer, put let's start somewhere: the USB connection.
Step 1: Connection with USB
When connecting the printer via USB for the first time, we will get a notification that some unknown item is connected. If we use windows we can learn what device it decided we now have via the
```
device manager
```
(
```
Windows Key
```
then typing in
```
manager
```
and
```
Enter
```
). It should be a COM Port as this picture shows.
In this case, we have connected to
```
COM4
```
. To change the COM port, we can do so via a
```
Rightclick
```
->
```
properties
```
, then the
```
connection settings
```
and
```
advanced
```
. In the new window, we can change the COM port number to anything from 1 to 256, but it is recommended to keep the number somewhat low.
Make sure you run the printer's power supply
and
the connection via USB, as you can't use motor control commands if you have the power supply for the printer off.
Step 2: Using the COM-port
Now, we need a program that can use the COM port to connect to the printer. There are, as said, several out there. One such is
Repetier Host
, which comes with slicer and a good graphical interface. Another is
Ultimaker Cura
, which has the same capacities but lacks logging of all the commands exchanged. Because many are familiar with it as a slicer, I will look at it first. As a third option, I will take a look at
Pronterface
.
CAVEAT: Only
one
program that actively uses the COM port can be properly run at the same time, as the first program accessing the port will claim all uses for the COM port till it is shut down - any program or even other instances of the same program trying to access the port after that will have no control of the port.
Ultimaker Cura
After launching Ultimaker Cura, choose your printer. many printers are available as presets by now, so just import the printer you use or make a custom profile. At the moment the latest version of Cura is 4.1.0, and will look like this:
After switching to
```
Monitor
```
, it will automatically connect to the Printer via the COM port, in my case 4.
Once more we test the connection via Home
and then use the Send G-Code prompt, confirming lines via
```
Enter
```
.
Repetier Host
After running Repetier Host the first time, you need to configure your printer.
```
Ctrl
```
+
```
P
```
opens the config window for the printer. We need to know the Baud Rate of our printer, so I looked up the documentation of my Ender3, which told me 115200 is the right setting. Most printers seem to run on this setting. The other tabs decide the speeds, extruder number and limits and the bed shape. The rest isn't needed for this. My settings for the Ender3 are these:
Ok, we made our settings and saved via
```
OK
```
.
Now, we press the Connect button on the left side of the menu:
It should change to the blue Disconnect button and display other parts of the print now, showing that we have connected. Note that at the bottom of the screen a log is filled with all the commands and exchanges.
On the right side, we now can choose the Tab
```
Manual Control
```
Before sending any commands, it is a good idea to press the Home
button. This also serves as an extra test to see if the printer is connected correctly. Now we can use the Prompt G-Code to send our commands. The commands will be put into the log below.
Pronterface
This is the first time that I used
Pronterface
. The first thing to do after downloading the Printrun package and running the Pronterface application is to press
```
Port
```
, then set the right Baudrate (115200 seems to work for many machines) and press
```
connect
```
.
The GUI will saturate and the right log will show lots of things tested in connection. Note that in the lower right of the GUI, there is a temperature curve log, which can be very handy for troubleshooting, as it shows the change over a little time.
Below the log, we find the input for commands, and if we send a command, we get a log entry of it:


q: I have a model that contains a cavity, into which I want to insert a piece of metal, so I can use a magnet to stick to the print. How can I introduce a pause into the G-code without manipulating it manually in Ultimaker Cura?

[A]
Ultimaker Cura contains "Extensions"; in version 4.1.0, the process is as follows:
Extensions -> Post Processing -> Modify G-code
Add a Script -> Pause at height
Choose the one that matches your firmware!
Choose the
```
Pause height
```
to match the height the insertion should take place. Usually, this is to be the layer just before the roof is to be printed to keep the inserted objects from protruding from their cavities.
Choose a park position well outside of the print. X 10 Y 10 is usually a good position for this.
Add a little retraction if you want.
In printing, you have to wait till the cavity is formed, insert the item quickly and press the control button to resume. The shorter the pause, the better the next layer will hold to the already printed.
Also, keep in mind to make the cavity a little larger than the insert, both in XY and Z, to compensate for the plastic shrinking a little and to allow the nozzle to pass well over the inserted item.


q: I'm making a hybrid 3D printer and circuit etching (CNC milling) machine that can both 3D print and etch prototype circuit boards. I'll be using Marlin firmware with an Arduino Mega & RepRap 1.4 board. It will have a 3D printer head and a milling head side by side. I'd like to have it be able to read both .gbr (for circuit etching) and .gcode (for 3D printing) files. How should I configure Marlin to read both types?

[A]
You can use both .gcode and .gbr files one one machine. We do it where I work.
However, when we make prototype circuit boards, we don't print them; we acquire circuit board blanks, and then we either:
Use a diode laser to burn off the top layer of garolite for isolation traces, then do a chemical dip to remove that copper, then another laser burn to expose pads for surface mount components; or
Use a spindle tool to remove the top layer of garolite where needed for pads, as well as mill through the copper layer for isolation traces.
We have not found a printable material that has the conductivity we want in a circuit board.
Source: I work for
Hyrel 3D
Note: we don't use Marlin on Arduino, we use in-house firmware on STM32F429 boards.


q:
When making a cylinder, sometimes I need to only take a pie slice. I'm currently using this neat trick to make pie slices for angles under 90 degrees. However, I have need of a few angles over 90 but under 180 degrees. Is there a way to generalize/extend this to work for these bigger angles?

module pie_slice(r=3.0,a=30) {
   intersection() {
    circle(r=r);
    square(r);
    rotate(a-90) square(r);
  }
}

pie_slice(r=10,a=15);

[A]
My current workaround is to use
```
union
```
instead of intersection. Unfortunately, that means I have to use an
```
if
```
clause which makes the code have two paths instead of one clean approach. Also, unlike the above method, this does not result in a clean cylindrical shape but must instead by combined with a proper cylinder to get the final pie slice
```
```
size = length + 2;
    if (angle_deg <= 90) {
      translate([0,0,-1])
      intersection() {
        cube(size);
        rotate(angle_deg-90) cube(size);
      }
    } else if (angle_deg <= 180) {
      translate([0,0,-1])
      union() {
        cube(size);
        rotate(angle_deg-90) cube(size);
      }
    } else {
      echo(str("FAILURE - Angle cannot exceed 180"));
    }
```
```


q:
I'm printing on an Ender 5 with the default flex/magnetic build surface.
I read that PLA and PETG may sometimes be printed without any bed heating at all and also that bed heating is the main contributor to the power consumption of a printer.

As I do see that bed heating definitely helps with the first layer adhesion I did not want to turn it off completely, but I did start experimenting with turning off bed heating after all solid bottom layers have printed (using the ChangeAtZ script in Cura) and so far I haven't seen any negative effects, especially no warping (I am usually printing with a brim or raft; I think that might also help in that regard).

Am I missing something? Why is anyone keeping the bed heated for an entire print?

[A]
All the valid points of bed shrinking and dislocating your parts when cooling from the other answer aside there is also the added complexities both in testing reliability of such a thing that may or may not be applicable to all materials.
The added complexity to the slicers to figure out when it is safe to turn off the bed which I would imagine depends on part footprint. I also sometimes print several parts sequentially in the same job so then it would need to know that and time the bed heating correctly or pause and wait for bed between parts.
I would also categorize printer power use as trivial (order of three 60W lightbulbs), but considering millions of machines worldwide economics of scale does kick in.


q:
My local library has a 3D printer (Lulzbot Mini) for patrons to use. The prints are limited to 4 hours and if I go after work I really only have two hours before the Library closes. The software at the Library will give an estimated time, but I would like to be able to estimate the time before I get there.

Currently I have been creating my designs in TinkerCad and then I export the STL file. From the STL file I can find online estimators that will tell me how much material but nothing that says how long it will take to print.

Is there a way of calculating the estimated printing time from a STL file for a given printer?

[A]
There is no way to estimate the print time of an STL file directly.
The print time is based on the number of instructions in the g-code file plus the time it takes to move the effector (the hot end) around the build area. The only way to compute that is to know what settings their slicer is using and then slice your stl the way they will; and this is assuming that you have the same slicer software. If you manage to do that, then the slicer software will give you an estimate.
Here is what you would need to do:
Get access to the same slicing software, and obtain a copy of
the profile that they use to slice with. The nozzle diameter, feed
rate, layer height, and infill settings will affect the print time.
Import your stl into the sofware and "slice it" There will usually be a large button that is used to generate the g-code. There are quite a few slicers that will output the print time into the text of the g-code. They may also show the print time on the UI during slicing.
alternatively: Email the stl to the staff at the library, and them to generate an estimate for you. They might just do it.
However, that estimate could be incorrect. It will depend on the printer itself. As an example: the time it takes to heat the bed and the hot end is never included in the time estimate the slicer gives.


q:
I'm making a Circuit etching machine (CNC) and I need a good DC motor and drill bit for the spindle.

My machine should be able to etch, drill, and cut:

Etching: take copper off the surface like chemicals or a laser would

Drilling: drill holes for THT (through-hole) components and possibly 2-sided boards

Cutting: cut out a piece of the board (cutting a big piece in half or cut a circle out of a big piece)

I'd like to have 1 drill bit work with all 3 functions if possible. Having to switch out different bits is OK but a single bit is prefered.

What sort of specifications should my spindle DC motor (rpm, voltage/amperage rating, ...) and drill bit (material, size, angle, ...) have?

[A]
There are several sources of PCB "etching" bits.  They tend to be single straight flutes and high angle, very pointy bits.
For the motor, high speed is good.  Look for 30k+ RPM.  The main thing to be concerned about is the amount of runout, or wobble in the tip.  With a tiny tip, you can't afford much runout at all.  It will broaden the gap you are cutting and put stress on the bit, probably snapping it.
The key to low runout is very careful alignment of the chuck that holds the tip with the shaft of the motor, and a collet chuck to hold the tool.
The power needs aren't high since the speed is high and the cuts are light.  I would think that a 250 watt motor should be way more than sufficient.
The question now asks for drilling and routing, which should work better with the high-speed spindle.  30k is better for the tiny drills than a much slower spindle.  These are hurt by run out.
Usually the drill bits are made of carbide.  For cutting, carbide router or file bits are used.  All drill-bits and router bits and copper cutting bits I have seen for sale have 1/8" or 3mm shank.


q:
I'm doing some research on what types of LCD displays can be used to filter and pass UV light for resin curing - specifically in the context of building a DIY 3D SLA printer.

The community commonly uses the Sharp LS055R1SX03 module. Looking through the datasheet, there doesn't seem to be any information pertaining to the characteristics of the device when passing UV wavelengths. Is there something special about this module that allows it to filter/pass UV wavelengths compared to other common LCD displays?

[A] I am not an expert by any stretch but I hope this helps, but these are regular old TFT LCD screens. You can even get 4K ones and use them for the same process. You can for example pick up 4K displays such as the H546UAN01.0 and do the same with them.


q:
I just got my first 3D printer (Creality Ender 3) on Friday, 2 days ago. It works great, but for some reason I'm getting a lot of stringing on my prints, especially the ones where the extruder head has to move a long distance between columns/posts, etc.

I'm using Hatchbox "True White" PLA, which has a recommended temperature range of 180-210 °C. I've tried printing at 200, 190, and 185 °C and didn't see much improvement. I've also made sure I've enabled the 'retract' setting in the slicer (4.5 mm) and verified the printer is retracting when it should.

I'm not sure what else I can try... any suggestions?

[A]
4.5 mm is a low retraction distance. Cura's default is 6.5 mm, and the Ender 3 profile provided with Cura sets it to 6 mm. The first thing you should try is increasing the retraction amount up to at least 6 mm. Also, make sure you actually enabled retraction. I saw one question here where a Cura user had enabled "Retract at layer change", which
does not
enable retraction (but of course it shows the options like retraction amount since you need to be able to select it for this too).
Your low nozzle temperature of 185 °C is also a problem. You'll have very low flow at that temperature, resulting in under-extrusion and pressure building up in the nozzle instead of extruding the material. That in turn will make it so, even after retracting, there's still material (and pressure) at the nozzle and it will keep oozing, unless you set a
really
high retraction amount (and even then problems will build up over time during the print, but you might get lucky and not see them). The only way to print PLA at 185 °C is really,
really
slowly.
In general, some people would also recommend trying a different filament, based on reports that some vendors' PLA oozes and strings badly, but I don't think that's an issue for you. I use Hatchbox filament on my Ender 3 all the time and never have a problem with stringing from it. And even if the filament is prone to stringing, you can almost surely avoid it with proper settings. Even very soft flex filaments can be printed on this printer without stringing as long as your retraction, temperature, and speed are tuned to avoid having pressure at the nozzle during travel moves.


q:
I have a Tevo Tornado Gold 24 V. I want to use this LJ12 A3-4-Z/BX Inductive NPN NO 4 mm with 6-36 V operation current as a Z probe. I do not want to fry my machine by putting in 24 V into the sensor input.

What do I have is a 12 V, single channel optocoupler isolation module.

I want to know if this 12 V optocoupler module can be used with a 24 V power supply, or do I need another module in order to prevent me frying my sensor.

If I do need another what would I need?

[A]
Not using a 12 V rated module
"on its own"
.
Using a 12 V/5 V optocoupler to try to connect 24 V to the 5 V circuit is running the optocoupler outside of its rating, meaning you will destroy it, either immediately or after a short time.
A properly rated one
To shield the 5 V against the maximal 24 V from the probe without extra parts, you will need to use a 24 V/5 V optocoupler.
Trickery with voltage dividers
With a 50 %
voltage divider
made from two properly rated resistors, you could limit the voltage to the optocoupler, which in turn would turn the 24 V signal into a 12 V signal, which would protect our optocoupler and the board beyond.


q: I'm trying to make a water insulated 1 cm3 (1 ml) transparent container and I bought some plexiglass, I cut and glued some pieces together but it looks really crappy and barely holds the water in. I was wondering, is there a transparent material (similar to plexiglass) that can order to 3D print the container out of it? Also, if 3D printing is not the best option, where can I order around a 100 pieces of 1 cm3 transparent water insulating containers with caps?

[A]
Yes. You'll probably want to use SLA or Polyjet printers with transparent resin. For example, here's
Shapeways' page on transparent SLA
and
their page on Polyjet
(which says you need to phone them for transparent Polyjet parts as their online order system can't handle it).
FDM printing with transparent materials doesn't usually result in parts that look like transparent injection-moulded parts, because the lines of material laid down by the printer are visible. There are
some techniques to make this better
, but a printing bureau is less likely to offer this kind of special handling.
In any case, you should discuss your requirements in more detail with suppliers, and they'll be able to advise whether they offer any manufacturing processes that meet your needs. In particular, if you need your containers to be food-safe, you should mention that at the start, as it'll rule out a lot of possible suppliers, machines, and materials.


q:
I have an Anet A8 and have a problem with my first layer. I printed nice prints but starting today the first layer is tearing in the middle:

Any idea how to fix this?

[A]
The great pics really help with the answerability of this question. From how catastrophic the failure is, and how it's clearly independent of any specialty needs for the particular print such as tiny bed-adhesion contacts, sharp overhangs, bridges, etc. this is definitely not a problem with temperature. Different people recommend different temperatures for PLA, but I find that 210°C works well for me, and if you go much lower you'll hit problems getting the needed extrusion rate for anything but slow print speeds.
I've seen nearly this exact phenomenon before, so I knew it was probably a matter of the bed being too high, blocking extrusion of the first layer and forcing what little material can escape out to the sides of the nozzle, then tearing into it when the next adjacent line is laid out.
If I didn't know that, though, I'd still start looking for a source of the problem that's related to extrusion rate. Something was clearly wrong with getting the right amount of material in the right space, which indicates to me that there's either too much material (overextrusion/wrong filament diameter selected) or too little space (bed to high).


q:
I'm looking to 3D print a structure that won't deform in high heat, up to about 220 °C. The filament itself can be 3D printed all the way up to about 380 °C.

PEI seems like it could be a viable option. I found some here. This PEI filament  specifies the glass transition temperature at 217 °C.

Would this filament work? Are there any other types of materials that would fulfill this engineering requirement?

[A]
Your expected operating temperature exceeds the glass transition temperature by 3 °C. This implies that the structure will become weak and can deform under load.
Note that you cannot simply print PEI on a normal machine, it requires a special high temperature capable printer with hot end temperatures up to 400 °C and heated bed over 120 °C up to 160 °C, furthermore it will need a heated chamber (up to about 80 °C) which requires special care to cooling and placement of electronics and motors.
Not having specified what kind of structure you require, you could look into steel.


q: A few minutes after finishing a print job, the filament is solidified in the nozzle and the nozzle-throat. When I start another print job a while later, the filament is not sufficiently melted and the nozzle is obstructed. Do I need to clean the nozzle after every print job ? or is there a practical method to overcome this difficulty ?

[A]
Your solution will not cool all sides effectively. Firstly don't use zip ties; get thermal tape.
(
https://www.amazon.com/Thermal-Interface-Products-Heat-Sink/dp/B00QSHPH8E/
Secondly, the heat will need to travel around the outside of the motor to get from the side that doesn't have the water block. Its expensive but you could use
Pyrolytic Graphite Sheets
to wrap around the outside of the motor, to get the heat to the water block faster.


q: When go to export a model using Fusion 360 or Meshmixer, I see that there are two options. Could the final model be affected by the format chosen at the time of saving?

[A]
I have experienced problems on occasion when using a binary exported Meshmixer model. The slicers used have been Simplify3D and Prusa Slicer 2.0 and possibly an earlier version. I've not attempted to resolve the problem other than to change that specific model to export to ASCII which then solves the problem. ASCII files will be larger but that's not a significant factor, in my opinion.
If you are using a program which fails to properly process a binary export, it's simple enough to overwrite the model in ASCII form.


q: Why don't 3D printer heads use ceramic inner walls? PTFE tubes melt with high enough temperatures and all metal ends risk jamming as heat makes its way up the head.

[A]
Because PTFE doesn't transmit heat very well? The whole idea when using a PTFE tube (and this is just my understanding ... which could be wrong), is for the tubing not to transmit heat, therefore allowing the filament to pass through it without melting or at the very least, collecting a lot of heat along the way (which helps prevent jams). PTFE does a pretty good job of standing up to heat while accomplishing the task at hand. Ceramic does an
excellent
job of standing up to heat. The problem is, it will pass the heat along to the filament, most likely melting it, thus causing it to deform and jam before it gets to the hot end. This would then become a maintenance nightmare.


q:
I've just built my son's A6 and have connected all cables apart from the last power cables. The mainboard says hotbed line and extruder line but the cable says heatbed.

The cables are two red which are crimped together and two black crimped together.

All of the videos online show a different mainboard and connections.
There are more connections than cables because the wires are crimped.

I can't get my head around which wires go where, any ideas?

[A]
The manual appears to be available here,
Installation Instruction_Anet A6 3D Printer - Elektor
However, according to
this comment
from
Hard copy of the build guide?
, there is a mistake in the PDF of the manual, with respect to the heatbed, and as such, it is better to follow the videos:
I find it is better to use the 3 videos:
3D Printer Instruction--Anet 3D Printer A6 Assembly Video 1
3D Printer Instruction--Anet 3D Printer A6 Assembly Video 2
Printer Instruction- A6 - Hot Bed Level Adjustment and Print Test
Only errors in the videos and i believe the instuction the Hetbed
fixing plate i have build diffrently , rotated by 180 degrees
vertical, since it is better for the belt and somewhere in the video
during fixating of the end-switch and the blower he interchanged the
screws.
However, looking at the manual, if it is to be believed, then be aware that
as well as
one connection for the extruder motor, there are two connectors
each
for
both
the extruder and the hotbed heaters:
One for the separate heating elements, of the extruder and hotbed respectively, and;
One for the thermistor sensor (both the extruder
and
the hotbed have separate thermistors).
This makes
five in total
for the extruder and the hotbed combined.
However, the power connections for the Extruder
motor
has four pins (in white at the top), whereas the heating elements for the hotbed and the extruder have two pins and are of a different shape (in green on the left). The sensor connections for both the extruder and the sensor have three pins (in white at the bottom), but it should be easy not to confuse them, so long as you follow the wires to check to which component they go to.
Additional points to be aware of
From
this comment
in the same thread:
I just built an A6 three weeks ago and with the videos it is really a
breeze to assemble the unit.
Just pay attention to the heat bed mounting plate as it is installed
bottoms up in the video. The bar connecting the outer two plates where
the heat bed is finally mounted should be below the plates, not above
as in the video.
Also, if you still have time, order some decent toothed belt, Igus
Drylin RJ4JP-01, and toothwheels for the Y and X belts and replace the
original pulleys, bearings, and belts before you even assemble the
unit. I just changed mine last week and it does make a hell of a
difference - with this little upgrades (cost me less than 30$ for
everything - at Amazon) you upgrade from an okay printer to a really
decent machine.
The belt:
https://www.amazon.com/Anycubic-Meters-Timing-Pulleys-Printer/dp/B0152ZNDLK
The pulleys:
https://www.amazon.com/Aluminum-Bearing-Timing-3D-printers/dp/B0188HW4Z0
The bearings:
https://www.amazon.com/Printer-Solid-Polymer-LM8UU-Bearing/dp/B06XPRCMJS
(actually, you need 8 pieces - not seven as in the images - 4 for the
Y-axis and 4 for the X-axis)
The above are not the actual articles I've bought because I am from
Europe where Amazon sells in different quantities.
If you want to go on the safe side, grab a second power supply and two
MOSFET boards to remove the high current from the mainboard:
PSU:
https://www.amazon.com/eTopxizu-Universal-Regulated-Switching-Computer/dp/B00D7CWSCG
(just as an example)
MOSFET:
https://www.amazon.com/Wangdd22-Printer-Expansion-Heatbed-Current/dp/B01MY50JL3
Power socket and switch:
https://www.amazon.com/URBEST-Module-Switch-Certification-Socket/dp/B00ME5YAPK
Last recommendation: get some 3mm borosilicate glass to lay (clip)
over the heatbed. This will make the prints stick better and also
provide a perfectly flat surface for the builds (still, you'll need to
do the levelling)
Glass:
https://www.amazon.com/Signstek-Printer-Tempered-Borosilicate-2132003mm/dp/B00QQ5Q3BI
When assembling the heatbed mount, pay lots of attention to the 16
screws. Tighten them one by one diagonally and move the bed around. If
the bed feels stuck, loosen the last screws and shift the mounts
around a bit. The lighter this mount moves, the better your prints
will be.
One thing that you must be aware: This printer is a great little unit,
but it needs love, dedication and plenty upgrades. Out of the box it
works okay, but with the upgrades it becomes a really good unit.


q:
You can see small gaps in the print which looks like under extrusion (see image below).
What is the reason for that?

I've tried smaller retracting distances. Temperature looks stable.

Print settings:

PETG from Extruder

245 °C Printing temperature

50 mm/s print speed

25 mm/s wall speed

30 mm/s retracting speed

1 mm retraction distance -> stringing...

Print cooling fan is enabled

Setup:

E3D Titan Aero

Duet Wifi

1,5 A Motor current for feeder motor

250 mm/s2 feeder max acceleration

Slicer:

Ultimaker Cura 4.0

[A]
Here's your problem:
1 mm retraction distance -> stringing...
If you have stringing, that means that material that was supposed to end up as part of printed lines instead ended up somewhere else, leaving less material (underextrusion) where it was actually wanted. This particular test piece may not exhibit stringing, but it's likely that it occurred interior to the piece, in the infill region. Contrary to widespread(?) opinion, stringing here is not harmless. It's just not visibly ugly. But it still messes up the surface quality, and even more importantly the strength, of your print.
You don't say if your printer has a bowden extruder or direct drive. If a Bowden, the 1 mm of retraction is virtually useless; a typical Bowden system has more than 1 mm just of
compression
between the extruder gear and the hotend, meaning that retracting by 1 mm does not pull the filament back out of the hotend at all, and doesn't even relieve all the pressure that's pushing melted material out. I would recommend an absolute minimum of 5 mm for Bowden type extruders, unless your printer firmware has linear advance (Marlin 1.1.9+ or comparable features in other firmware) in which case you might be able to reduce it some. For direct drive, I don't have experience, but 1 mm is still probably too low; 2.5 mm is the believable recommendation I've heard.
In addition to retraction, you can further reduce material loss to stringing/oozing in the infill region by turning on Ultimaker Cura's "Zig-zaggify infill" option, which helps avoid in generating travel without retraction over unprinted area within the infill zone (see e.g.
this issue
). Turning slicer setting "combing" to "off" is an even more extreme option here. Of course make sure retraction is really on (not "retract at layer change", which is a separate, mostly useless option) and make sure "retraction minimum travel" is set low (something like 150 % of the nozzle width or less) to prevent retraction from getting skipped on short travel moves.
I also just noticed you wrote:
I've tried smaller retracting distances...
This was probably based on erroneous advice. Reducing or eliminating retraction does not mitigate these sorts of problems; it creates them. The only reasons to reduce retraction distance are to fight problems with the extruder gear grinding down the filament after repeated retraction, and problems with jamming the path into the hotend due to pulling molten material back into the cool part where it then solidifies and jams. If you're not having such problems you should not reduce retraction. If you are having such problems, you should try to fix them in other ways that still let you keep the necessary amount of retraction not to have catastrophic print quality problems from material coming out in the wrong places.


q: Do we need mold release agent in 3D printing mold? If it is not used, what effect will it have on the product?

[A]
Welcome to the 3D Printing Stack Exchange site.
Used in Casting
A mold release agent is commonly used when a part is cast.  The release agent is placed on the inside of the mold before the liquid object is added.  As the object becomes solid, the release agent prevents the object from adhering to the mold.  As a result, the objects are easier to pop out of the mold, and in some processes, the mold can be reused.
3D Printing is Different
A mold release agent is used to allow the desired part to be separated from the mold.  In FDM (thin plastic extrusions bonding together into objects) 3D printing, the object is surrounded by air, except for the bottom where the object contacts the print bed.
Bed Adhesion
For most materials, getting the bottom of the object to stick firmly enough is the problem faced, rather than making it easy to remove.  In many cases, a compound is placed on the top of the bed to help the plastic stick to the bed.  It is a "mode adhesion agent" rather than a release agent.
For some combinations of materials, the bed material and the plastic have a particularly strong adhesion, such that it can be difficult to remove the object without damaging the bed surface.  Notably, this occurs with a PEI bed and PETG plastic.  In this and similar cases, the mold adhesion agents can be used on the bed.  This slightly separates the plastic from the bed material, and we can avoid bed damage.
Internal Adhesion
With multimaterial printers becoming more common, there are cases where two parts which might touch and stich during printing should be isolated during the printing process.  A second (or third) material can be used to isolate the parts.  If the isolation material is sufficiently different from the desired objects, it can be removed by a solvent.
This approach is limited to cases where the objects should be separated by at least one printer thickness of the soluble material.


q: I am a fresh graduate student in 3D metal printing. My undergraduate major is mechanical engineering. Later research will focus on the process of metal 3D printing. I hope that you can recommend some excellent 3D metal printing books for learning.

[A]
This is a free ebook that I have perused briefly which it looks interesting, and it is free (did I say that already?)
3D Printing of metals
Manoj Gupta
ISBN 978-3-03842-591-5 (Pbk);
ISBN 978-3-03842-592-2 (PDF)
Three other books that
might
be of interest are:
3D Printing with Metals for Design Engineers, Explained
Ann R. Thryft
Downloadable free ebook, but some sort of sign up is required
Additive Manufacturing of Metals: The Technology, Materials, Design and Production
,
Yang, L., Hsu, K., Baughman, B., Godfrey, D., Medina, F., Menon, M., Wiener, S.
ISBN 978-3-319-55128-9
Additive Manufacturing of Metals: From Fundamental Technology to Rocket Nozzles, Medical Implants, and Custom Jewelry (Springer Series in Materials Science)
Although, as the title contains a (rather obvious) mis-spelling, it does not bode well for the rest of the book.
John O. Milewski
ISBN-13: 978-3319582047
ISBN-10: 3319582046


q:
For the geometry I am making, I want to extrude each face individually along its normal.

This is a standard procedure in 3D modeling software like Blender; see Example 3 here.

Is this possible in OpenSCAD?

[A]
Extruding faces is only possible on 2D polygons. From a 3D object you cannot capture the face and extrude it. To extrude "faces" you would need to define the shape of the face and extend it in the third dimension of your choice. This way a 3D shape is created that could be concatenated (joined using e.g.
```
union
```
) to the original shape. For the extrusion, the function
```
linear_extrude
```
is available:
```
```
linear_extrude(height = fanwidth, center = true, convexity = 10, twist = -fanrot, slices = 20, scale = 1.0, $fn = 16) {...}
```
```


q:
I am having a few problems with my BLTouch. I have calibrated it several times using different methods and get the nozzle being 1.3 mm lower than the BLTouch pin so a Z offset of -1.3 mm. This works fine for auto homing, bed levelling and using code G1 Z0 to lower to where needed. However when using Cura to print the nozzle homes exactly as it should then drives the nozzle in to the bed as it starts or tries to start to print and not just a little bit either. Anyone have any ideas?

Start G-code is:

G28 ;Home
G29 ;Probe
G1 Z15.0 F6000 ;Move Platform down 15 mm
G92 E0
G1 F200 E3
G92 E0

[A]
You should be able to offset this with a
```
G54 Z-1.3
```
-
if your setup accepts these gcodes
.
If you do this, always add a
```
G53
```
to the very start and just before the
```
M30
```
to clear all offsets after job finish (or in the event of a cancel, at the start of the next job).
I'm not experienced with a wide variety of printers or firmware, but our repetier-based printers (and we use the same controls for our refurbished Fadal CNC machines) use G53-G59:
As explained in this tutorial from cnccookbook.com
:
Basic work offsets are very simple to specify: simply enter one of G54, G55, G56, G57, G58, or G59. [...] When you execute the work offset g-code, the XYZ offset will be added to all of your coordinates from that point forward.
As detailed on Wikipedia
:
G54-59
: Have largely replaced position register (G50 and G92). Each tuple of axis offsets relates program zero directly to machine zero. Standard is 6 tuples (G54 to G59), with optional extensibility to 48 more via G54.1 P1 to P48.
And on the gcode dictionary provided by Hyrel 3D
:
G54 through G59 - Set Offsets
G54, G55, G56, G57, G58, and G59 will each store and invoke offsets in the X, Y, and/or Z axes for all subsequent moves. Any values not invoked will remain with their previous value (0 unless earlier specified otherwise).
X is the offset in mm in the X axis.
Y is the offset in mm in the Y axis.
Z is the offset in mm in the Z axis.
Here is an example:
```
G54 X100 Y-50
```
This command is decoded and executed by the printer as follows:
G54 (set offsets)
- X100 (+100mm to all X coordinates)
- Y-50 (-50mm to all Y coordinates)
Note that this differs from an M6, where the offsets are only applied to a SINGLE tool position.
Disclaimer: I work for Hyrel 3D.


q:
I have ordered a dual hotend Chimera and it came with 2x 12 V heater elements (in my rush I forgot to order the one with 2x 24V).

Is it possible to run these 12 V heater elements in series?

I am planning on running this with an SRK 1.3 board.


q:
Thermal conductivity is how well a plastic conducts heat. Most plastics don't conduct heat very well at all, which is what allows them to be 3D printed. That being said, there are a lot of potential use cases for highly thermally conductive filament, assuming you could print them. A commonly discussed one is computer heatsinks. Similar heatsinks could also be used for stepper motors and extruders in 3d printing.

To get a good picture which plastics are useful in such an application (like mentioned in question: "Water-cooling stepper motor with aluminum block"), I need to know what is the thermal conductivity of the commonly used thermoplastics.

[A]
All values are in W/(m*K).
PLA: 0.13
HIPS: 0.20
ABS: 0.25
PETG: 0.29
PEEK: 0.25
PLA with copper: 0.25 (
see discussion
)
PETG with 40% graphite: 1.70 (ansiotropic)
TCPoly
: 15
Steel (not a 3dprintable plastic): 10 - 50


q: Often, the pre-generated G-code is enough for start and end. However, sometimes we want to have something different. In this case: how to generate an audible alert of something like 4 bleeps at the end of the print, after putting the printer into the end position and when the bed has reached a "safe" 30 °C?


q:
Which of these will heat a bed fastest?

A. 12 V, 10 A power supply

B. 24 V, 5 A power supply

C. Both A and B will be the same (only total watts matter)

D. Depends on the situation

I originally thought Amperage was what mattered until I realized I needed a 24 V power supply to even heat my Lulzbot mini bed by one degree.

I know voltage is used to determine insulation thickness on wires. But thin wires with high current in them also get hot. Is insulation thickness on wires only to prevent you from accidentally cutting through them and shocking yourself, or is it for heat reasons?

I'd like to power my heated bed with a 19.5 V, 5 A power supply. It's just an old laptop charger - I want to reduce strain on my circuit. It's a big bed and I have a few other laptop chargers lying around so I'd prefer to choose the best one.

[A]
It depends on whether you are re-using the bed or not, it is actually the resistance of the bed that determines this in conjunction with the voltage (the current you get for free).
Let's say that the heatbed resistance is 1.2 Ω (depending on the heated bed make and model the resistance is typically in between 0.9 - 1.5 Ω), this means that the power can be calculated using:
$$P = U \times I$$
$$U = I \times R$$
combining gives:
$$ P = I^2\times R = \frac{U^2}{R} $$
For 12 V (assumed default printer voltage) this means that the heatbed power equals about 120 Watt (at a current of 10 A). Running that same bed at 24 V means that the power is 480 Watt (at a current of 20 A). So yes, that will heat up fast, at the expense of an increased current, which is pretty high, and should not be attempted without extra resistance in the loop.
If you're using the laptop charger, the current draw equals about 16 A, which the adapter cannot deliver.
This means that you need to acquire a new heatbed that is able to handle a higher voltage out of the box (more resistance), or you need to put additional resistors in the loop, but beware of the currents. Note that heated beds for 12 V/24 V exist, the wiring is different depending on the voltage. Note that such beds heat up faster, it all depends on the resistance and the voltage, but running the 24 V circuit on 19.5 V (160 Watt bed) is definitely an improvement over the 120 Watt bed at 12 V but still requires about 8 A (only applicable to heatbed that can run 12 V/24 V through extra resistance connections).
Be careful with this and be sure what you are doing!


q:
I have mounted two radial fan on my printer as a part cooling solution.

As you can see, the fan has input on the left side and blows air down. Does a mirror construction exists? With outlet on the right.

I can even print my own casing, but I'm not sure if the fan will work, if I change the rotation direction.

I'm using this print cooling fan duct: https://www.thingiverse.com/thing:1850163

The fan on the right side has the opening facing the hotend, and there is not much space, so the impeller can catch on wiring etc. If the right fan had opening to the right, there would be no such problem.

[A]
https://www.alibaba.com/product-detail/120mm-Small-Squirrel-Cage-Exhaust-Plastic_653850349.html?spm=a2700.7724857.normalList.14.23834341IiKFAu&s=p
After quite a bit of searching the above link from Alibaba was all I could find. I suspect that they don't make them like that because of the direction of the rotation of the blades. Perhaps they are made so that the rotor can be swapped around if necessary.
(
https://i1.wp.com/www.homeintheearth.com/wp-content/uploads/2012/11/CentrifugalFanTypes.jpg
)
The different curving of the blades affects either the volume or the pressure of the airflow (or both).
Alternatively how about one that is more agnostic:
https://www.amazon.com/2Packs-Wathai-40x40x10mm-Brushless-Centrifugal/dp/B07RNZF97F/
Or just 3d print your own housing!


q:
I recently installed a SKR 1.3 Board with a 3DTouch-Probe on my Creality Ender 3 Pro.
The probe works, G29 does its magic, but:

If i issue a plain G28, the hotend first homes X and Y like before the Z-probe.
The probe is now next to, not above, the bed.
As the next step, the printer is supposed to home the Z-axis. The probe deploys and Z starts to lower until it smashes into the bed, because the probe misses the bed (if I don't stop it, that is).

I configured X/Y offsets for the probe, but they don't seem to be honored when performing the G28 code.

If I home X/Y "manually" with G28 X Y, move the hotend with like G1 X45 Y10, then home Z with G28 Z it works fine.

What did I miss? Is this intended behaviour & the user has to take care never to issue a plain G28?!

[A]
You need to enable the constant
```
Z_SAFE_HOMING
```
(like:
```
#define Z_SAFE_HOMING
```
) in your
printer configuration file
(if you're using Marlin firmware that is). This will move the nozzle to the middle of the plate prior to lowering the nozzle by default:
```
```
#if ENABLED(Z_SAFE_HOMING)
  #define Z_SAFE_HOMING_X_POINT ((X_BED_SIZE) / 2)    // X point for Z homing when homing all axes (G28).
  #define Z_SAFE_HOMING_Y_POINT ((Y_BED_SIZE) / 2)    // Y point for Z homing when homing all axes (G28).
#endif
```
```


q:
I want to make Polyurethane molds for concrete using 3D printed PLA or ABS master object. like this video:

 (this video is not about concrete of course!)

I'm not sure if it will stick to PLA or ABS master or not! if it does stick, whick wax material can solve this problem... Do I need to print my masters with another filament?

[A]
Temperature
As polyurethane cures (or hardens), it undergoes a chemical bonding reaction, linking the mono- and oligomer strings in the components into long polyurethane chains.
The chemical reaction is exothermic
, it creates heat.
So, we have a process that heats up the polyurethane mixture as it hardens, but how much? Well, it's hard to find numbers for it, but I suspect it can easily reach 30 to 40 °C, depending on the mixture (fast curing) it could easily go higher. To combat the effects of heat softening of the PLA/ABS model inside the mold, I strongly suggest printing with extra shells and extra infill. While most items can get away with 10 %, in this case, I suggest 20-30 %. ABS would be the superior choice above PLA as it starts to deform at a higher temperature. PLA can start to deform at around 60 °C, ABS only at about 80 °C.
The temperature of the PU curing depends on the speed of the curing process - it is safer for the masters to choose a slower curing mix as the heat is generated over a longer time and the maximum temperature is thus lower as a result (as excess heat is lost to the room)
Surface
To reduce the sticking to the surface from the material creeping into the gaps of the model, it has to be as smooth as possible and best also sealed. If you choose ABS, a quick acetone vapor bath would do the trick in this case. PLA should be lacquer sealed as it doesn't like to stick to most waxes.
Adding a mold release agent isn't necessarily needed, but could help in removing the masters from the mold.
Conclusion
ABS might be the better choice in this application. It is advisable to use extra-thick walls (3+), a lot of infill (20-30 %) and a vapor smoothed surface.