q:
Using 3D printing I'd like to create a text oversized keycap that uses several strong LEDs to make the text light as red or green, depending on status.  It's quite similar to what are called annunciators on aircraft:

I'd like to create an MX keycap with this ability and size with the backlighting changing from green to red to indicate something is on or off. I understand including the MX connector in the center, but how would I print a black panel and leave the text transparent, or at least transluscent?

[A]
There are a few possible ways you could go about this:
If you have a multi-material printer, you may be able to print with both a transparent or translucent material for the internal structure of the print and an opaque material for the external parts of the print. PET(G) may be suitable for this purpose but is harder to print compared to standard PLA.
You can print the entire print in a translucent material, mask off the lettering at the front and spray paint the rest of the print.
You can create a multi-part print, where one outer 'shell' is printed in opaque filament, and another piece in translucent material, which will mate together after printing.
You can deboss the lettering of your print, and with the letters face down to the bed, print the first layers in an opaque material, and then swap filaments to a translucent material for the rest of the print, spray painting the upper parts of the print to match a uniform color, while leaving the bottom untouched.
There are several advantages and disadvantages to each method:
Requires that you have a (typically) expensive upgrade installed onto your machine, but would be the most straightforward way to go about this.
Requires precise masking of your letters to make them come out looking nice, but will give you sharper, more defined edges on the lettering.
Will require you to design for tolerances for the two parts, or add glue in the post-processing steps, But could be produced en masse with two printers, one for each material.
Can be a bit fiddly, and will possibly result in an undesired look, with the lettering being debossed into the part, But would be less complex than the other options.
Pick whichever method you wish, or try all of them to see which gives you the best results.


q:
Ok I’m so new at Blender. Half the time it’s knowing what question you have to ask to get the answer you need...

I want to make a 3D printable warrior type action figure but I only have one very detailed frontal view. Can I input that image into somewhere and it gives me a 3D model to start from? Like will it generate a 360 view? I have no idea where to start.

[A]
In short, no. A 2D image has insufficient information to determine a 3D form.
If you want to do this yourself, what you could do is start with the 2D outline in a program like Blender (as 0scar mentioned in a comment), extrude it to make a thin "cardboard cutout", then begin shaping it into three dimensions from there. Imagine it like cutting a slab of Play-doh with a cookie cutter matching your 2D outline, then using the picture and your imagination as a guide to form it into 3D. I'm not sure whether something like that makes any more sense than just starting from scratch modeling it.
Alternatively, nowadays there
might
be some "AI" models to produce a reasonable guess at what 3D structure you want, with the knowledge that it's supposed to be a person, for a 2D image you provide. I'm not sure if there's anything yet of usable quality, but it's something you could look for.

s: huggingface

c: devops

d: intermediate


q:
I'm getting zits or blobs in lithophanes while printing on my Ender 3 and 10S Pro. I tried a suggestion: change resolution in mesh fixes of Cura to 0.5 (from 0.05 default). That removed the zits.

But now there are white patches as shown in the image. I reduced the resolution to 0.2 but to no avail.

Anyone else encountered this problem?


q:
I have an FDM printer, I printed ABS for years.

Since SLA printers became really cheap lately and are able to print finer details, are there resins out there as strong as ABS/PLA?

[A]
I'm an owner of both an FDM printer and a resin one:
I've long searched a resin capable of printing durable objects even in tiny details but with poor luck.  I've tried ABS-Like resins, and they provide a slightly better resistance than regular resin but do not expect great improvements; I've tryed the siraya tech Blue V2 that is for sure much more durable but eventually would fail on the smaller details...
In the end i think I'll try the flexible resins like the Liquicreate flexible X or the Siraya tech Tenacious because those (similarly to TPU in FDM) can better absorb energy from impacts and having a smaller young's modulus can help when under load.


q:
Wouldn't it be better to mount lead screws with the motor on top and the bottom end unconstrained? Compared to the conventional way (motor on the bottom) the lead screw would be under constant tension rather than compression and any misalignment would always be "pulled straight" and in this way minimize z-wobble.

Here is a image for clarification:

With the motor on top the load of the bed will help to move the lead screw in line with the mount. In the opposite case the load tends to further increase any misalignment.

[A]
The motor is mounted in a fixed position no matter if it's on top or bottom.
You can imagine the lead screw as a rod hanging down and supporting the bed in the Z direction only, because all of the XY rigidity comes from the Liner rails the bed is attached to it works just as well if the stiff rod is under compression instead of hanging from the rod.
Any forces that might "pull it straight" are the same forces that can cause Z wobble so you would not want to even try to use the misalignment to straighten a bent lead screw.
The only thing this that really changes with this orientation is if the lead screw is under tension or compression. Even a relatively thin lead screw can easy counter the forces of gravity and the forces is the same in both directions. Its easy and cheap to make a smooth rod or rail straight but not so easy to make a threaded one straight.


q:
How safe do you think it is to run an SLA 3D printer in the bedroom? I am planning to run Mi Air Purifier 3H/C while the printer is running, I am also thinking about adding this inside the actual printer (Elegoo Mini Air Purifier with carbon filter).

Is this safe or still too risky?


q:
I've been using a resin printer for some time now, and am looking for a filament printer to compliment it. It will mostly be used to print scenery or bases to match 3-6" models printer on the resin printer.

I'm aiming for an entry level printer, or possible a mid level one on black Friday sale if I can find one.

Should I limit myself to looking for one with a heated bed or auto-bed leveling, or should I mark these down as being bonus features that are nice to have but which are not essential for the kind of printing that I will be doing?

I will probably be using basic budget filament to print items under 6". Probably no more than 2 prints a week.

[A]
Most "auto-leveling" is not leveling but compensation for a non-flat or non-level bed surface. It's helpful to beginners who don't understand bed leveling or evaluating bed surface flatness and replacing a bad bad, for the sake of being able to get started without prints failing to adhere, but it will necessarily give you moderate to severe accuracy problems in the first cm or so of your print unless you manually level the bed right too. (This is as opposed to real three-point, three-motor leveling systems, which
do
really level and are great, but won't be found on entry-level printers.) Decide whether you want to spend money on that accordingly.
Personally, I find heated bed unnecessary unless you'll be printing ABS, ASA, or maybe PETG (it's hard but not impossible to print PETG without it). Heating the bed kinda makes PLA print worse (at least there are tradeoffs; it does help adhesion though), and flexible materials never need heat. However, pretty much all popular printers nowadays offer a heated bed anyway, so I don't think you'd be saving anything by going without it, and you're likely enough to want it at some point that you should just get it.


q:
My OctPrint and Monoprice Maker Select IIIP (A Wanhao i3 Duplicator Plus clone) were working fine, but suddenly today the hot end won't heat up anymore. I tried disconnecting the OctoPrint USB and resetting the printer power, and it still couldn't heat up the extruder, such as through the filament menu.

But then it got weird.

I left it off for a few hours and turned it on to see if it was getting 12 V to the hot end, and it was heating up again!  So I plugged in the OctopPrint and we're back to square one, the extruder has just been cooling down. I know the thermistor is working, because it's accurately following the temp, such as following the cooldown after the heating stopped working again.

Is it possibly I have a dead hot end and for some reason it temporarily started to work again?  Maybe an intermittent short?

I guess the next step is to open up the base and look at the connector to the motherboard, and or measure for 12 V

[A]
This has nothing to do with OctoPrint itself, the cause is related to the printer itself, not the print server running the printer.
This is a pretty commonly seen issue (usually seen at heated beds), this is caused by faulty wires/cables or connectors. This usually happens after a vast period of usage. You should (periodically) check the cables and connectors. You could even test if the heater cartridge works by connecting it directly to the power supply.
Considering the limited amount of costs involved to replace the heater cartridge, it is preferred to replace the heater with a similar specification heater element (voltage and power).


q:
I have an STL (Raspberry Pi 4 casing) that automatically places itself like below on the bed surface:

Would it be a better and more efficient print if I place it like this:

At first, I thought this is no-brainer, the bigger surface should be the bottom layer. However, the horizontal print might result a more efficient head movement.

[A]
The second placement is a better choice from an overall standpoint. In the vertical placement, adhesion is going to be more critical, although Prusa printers have good bonding for PLA and ABS, from my direct experience.
The other aspect of more importance is that the holes are going to be distorted in the vertical arrangement. The cut-outs in the smaller portion will also "droop" unless otherwise supported. If supported, you'll have greater post-processing labor and unsightly surfaces.
The design is quite well done, as the corners have radii which allows for smoother carriage travel, rather than abrupt stops with direction changes at each end.
Importing the model and having the result appear as in the first image means that the designing software swaps the z-axis and the y-axis, which is relatively common.


q:
I am printing Benchies at high speed, I successfully printed one at 300 mm/s. If I set the speed to 400 mm/s, the Y axis begins shifting around. This is usually accompanied by a banging sound.

In addition, the extruder motor occasionally clicks. When it clicks, the filament shoots back out a little bit.

Print settings:

Infill: 100 %

Hotend: 200 °C

Bed: 60 °C

Material: PLA

Infill: Lines

Walls: 2

Top/bottom layers: 2

Speed: 400 mm/s

Jerk: 400 mm/s

Acceleration: 1000000

I am running custom Marlin-based firmware on the stock mainboard.

The printer shakes my desk when printing like this.

[A]
TL;DR: Don't do that.
Detailed answer: You need motion limit parameters that actually make physical sense, and firmware capable of executing a motion plan according to them. Your jerk and acceleration settings absolutely don't. Marlin's whole implementation of jerk is wacky (note: modern Marlin versions don't even use it but an alternative they call "junction deviation" instead) and likely to cause problems above very low values; I never was able to take it above 25 or so on Marlin without layer shifts. Acceleration is dependent on the stepper motor torque and the mass you'll be accelerating. For the Y axis, that's the bed, and it has enough mass you won't accelerate it above 12000 mm/s² or so, much less the requested 1 km/s² plus near-infinite acceleration from the extreme near-instantaneous 400 mm/s velocity change ("jerk").
The speed of 400 mm/s is achievable if you don't do it instantaneously. Stepper motors begin to rapidly lose torque beyond a certain speed due to limits on how fast the magnetic field can build up and be reversed, which has to happen for each step.
This calculator
can compute the limits if you know the properties of your motor. For the Ender 3 Y axis motor, the limit is around 425 mm/s or so if I'm remembering right.
For actual print speed, though, the hotend and extruder cannot keep up with anything nearly that high. 150 mm/s is about the limit with that hotend, and it might even be lower with a stock extruder. Fortunately, Benchy is mostly acceleration-bound, not top-speed-bound, so if you can get your acceleration profile right, you can still print quite fast.
Now the next limit you'll hit is Marlin. Marlin is... not good at high speeds and accelerations. Often the layer shifts you hit with Marlin aren't even physical limits but Marlin bugs. If you want to go fast, you need Klipper, not only because it lacks these step timing bugs, but because you need its Input Shaper feature to keep the high acceleration from tearing your printer apart (literally, vibrating all the screws out!).


q:
I have used PLA and PLA+ so far and I know that it can use ABS and PETG but I'm curious what other materials could I in theory use with my Ender 3?

It is a stock configuration, for the time being at least until after Christmas, and my grandfather and I have designed an enclosure to build together.

[A]
Consider
Wood PLA
.  It is similar to PLA but more abrasive, and with different happy-temperatures.
Especially useful if you want to paint your output, or if you have woodworking skills/tools then prints can be (somewhat) worked and incorporated into larger projects.
Imagine printing detailed
scallions
or
crenellations
or
gargoyles
for a spooky dollhouse - the main walls would use an inordinate amount of filament whereas sheet-wood is cheaper.


q: I've changed SD cards, printed from USB connection, upgraded/reloaded firmware and attempted using different software packages.  Nothing has worked yet.  When connected via USB, I get a "disconnected" error after a few minutes into the print.  Also, the LED lights now either don't work at all or will randomly go out after a few minutes - usually indicating that the print failure is imminent.  I've had the printer for about 4 years without issues.  I don't want to replace the motherboard only to find out it's the power source or vice versa.  Help?

[A]
I recently had this problem and narrowed it down to the part cooling fan (on the side of the extruder head).  I diagnosed the problem by noticing that the printer would reboot shortly after the second layer started, only on PLA prints.  Of course, the part cooling fan is not usually started until after the first layer.  It was shorted and when the printer got to the second layer it would overload the power supply and cause a reboot.  Took a while to determine this, but it is worth looking at if somebody else is having this problem.
I would guess that any shorted fan, even the extruder fans, might cause a similar issue, however, I don't know this for sure.


q: Suppose I have the X, Y, and Z coordinates (either in a list or a function z = f(x,y)) that defines a shape as the one provided and I want to 3D print it with a solid bottom, is there an easy way to do this? If not, how can a functionally well-defined shape be put into a 3D modeling software like FreeCAD?

[A]
For stuff like this, OpenSCAD is your friend. There are several different approaches you could take:
Generate an image file with grayscale color representing the height of the function on an XY grid, and use the
```
surface
```
feature to import it as a heightmap.
Write the function as a mathematical expression in OpenSCAD language, and write a module to generate a
```
polyhedron
```
by iterating over a sufficiently fine coordiante grid, sampling the function, and producing points and triangles.
Use a library someone else has already written for this purpose. I'm not aware of specific ones but pretty sure there are quite a few.


q:
I have been printing toy cars for about a month now and my Ender 3 has stopped extruding plastic even when I insert filament, it has been about a day since it stopped working. Is there any tips for getting it working again?

I tried manual feeding which worked.

[A]
You need to figure out what is not working
Is the hotend getting hot?   If not, melted filament won't come out.
Is the nozzle clogged?   In your toolkit was a bit of thin wire for poking into the nozzle - try that and see what happens.
You may need to heat the hotend, extract the filament, wait for it to cool, remove the bowden tube and push the wire up from below, if the obstruction is too big to come through the 0.4mm nozzle.
Is the extruder pushing/feeding filament?  Undo the bowden tube at the top, tell the control panel to extrude and observe if plastic moves.  An Ender3 V2 has the round handle on top, you should see it slowly revolving.
If you can see the gears turning and the filament is not coming through, try snipping that piece off and inserting a fresh end.  Also clean inside the pushing gears of the extruder, could be simple plastic detris laying about.
Are you having reel problems?  Can you tug on the filament and have the reel turn? If not, it might be binding on the roll, or knotted/tangled.


q:
When I pluck the belts of my CoreXY printer, I feel significantly different tension between the two idlers on the back and the tension on the sides, between the gear on the stepper shaft and the idler on the back.

Is this normal? If not, what could be the cause?

For reference, I'm using this support for the idlers:

[A]
If you are referring to the tension in a single belt, but ar different positions, the tension is everywhere the same. It is one belt, the force/tension is the same in the belt. If the length of the belt is shorter because of a carriage to idler, the plucked sound may differ but the tension is the same.
If you are referring to different belts, e.g. the top versus the bottom belt, for CoreXY machines, the tension in the two separate belts should be equal to allow equal force pulling the carriage. If uneven, this may lead to incorrect/skew prints or binding of linear bearings (from experience). A typical layout of the mechanism is shown below. Note that there are several solutions for placing the belts; they can be in the same plane (where the belts cross in the back, as depicted below) or have the belt each in their own plane (as in the HyperCube Evolution design as depicted in the image of the question).
Drawing published by Ilan E. Moyer, taken from
http://corexy.com
.
For both options, incorrect belt tension causes for different forces onto the the printhead carriage and result in a torque on the carriage (either in X-Y or in X-Z). E.g. a tight blue belt with a less tight red belt cause a resulting counter-clockwise torque on the carriage in the image below:
I use
a tool (gauge)
to determine the tension to compare both belts and make sure the tension in both is the same:
Many CoreXY designs can adjust the tension of the belts at the carriage by screws. Some designs feature the stepper in the back and an adjustable pulley in the front.


q:
I bought an Ender 3 V2 printer and printed successfully with PLA and PLA+. Ender 3 V2 is rated at <= 250 °C but when I set temperature above 200 °C to print to PLA+, I get an error message "Nozzle is too lowperature" and the printer freezes (the term lowperature is actual and not a typo error).

I tried to raise the temperature gradually. I started at 200 °C and have gone to 205 °C and a little bit more. I started printing and I might get this message again or might not. Also, the temperature seems to change or lower while printing. It is not stable.

Any suggestions as to what causes this unstable behavior?

Following the above behavior, I was able to raise the temperature to 213 °C and I was printing for 10 minutes or so, then I got the message "thermal runaway".

I managed to capture the event here

[A]
This sounds like a bad thermistor. Try replacing the head thermistor, see if this fixes it.
As for the strange error message, it looks like the word Temperature is being drawn on the wrong line, and then "is too low" writes over it.
See the way the word lines up below:
```
```
nozzle temperature
is too lowperature
```
```


q:
For some reason, my larger prints, or rather the ones that I create, have this "dotted" line in them. And, that line usually splits into two pieces.

I use Ultimaker Cura for a slicer, I use Blender for modeling, and I have an Ender 3 Pro

Let me know if anyone knows the reason for this as it's preventing me from making things on my own.

Picture:

Here's my Cura file, if anyone needs it

[A]
At first glance, this looks like it could be missing layers.
There are five possible causes for missing layers.
Something is off mechanically.
Check to see if anything has slipped, shifted, moved, or popped out.
Misalignment
Check to see that all three axes are properly aligned and haven't shifted. If there is any resistance, something is misaligned, bent, or a problem with the bearings.
Bad Bearings
If a bearing is the culprit, it will make some noise. The bearing will also exhibit some uneven motion in the print head.
Lack of Lubrication
Check to see if any of the axes are binding in any way. A little, and just a little, bit of sewing machine oil can be the solution.
Under-Extrusion
This is a whole different set of problems that requires a new question to get an answer.
For more detailed information, see All3DP.com's article "
3D Printing Troubleshooting All Common Problems
"


q:
Can you convert a 3D printer to a laser engraver?

If so is there a specific thing I have to buy?

[A]
Yes, one can convert a 3D printer into a Laser Engraver, and it isn't even all that problematic.
You'd need to acquire a laser diode. These are usually not available with a lot of power - certainly not the hundreds of Watts that come from a proper CO2 laser - but depending on your printer, it might be pretty much a bolt-on addon.
The conversion isn't
too
invasive, and takes much less time than building a printer from a set.
All3D
converted an Ender-3 to have a laser within less than an hour. In their step-by-step guide, they wired it into the 5V part cooling fan port of their printer. Whatever laser diode you choose, the setup will be similar, as long as your diode works with 5 Volt power.
Once installed on the physical side, you will need to prepare your prints with a different "Slicer" that uses the commands for the fan speed as powers for the laser:
```
M106 S
```
sets the power to S, where S is a number from 0 to 255 ; Without an S value, it turns on to the last setting (if turned off via
```
M107
```
)
```
M107
```
turns off the laser.
One such slicer would be
Creality Workshop
, which would work with any Marlin-run printer, as long as you use the fan as the diode's power source.


q: Is it possible to 3D print a QR code? or to engrave it using a 3D printer? I tried to convert it to individual boxes but that takes too long and is very inaccurate. Is there a better way?

[A]
From the excellent Thingiverse link,
Customizable QR Keyring or Tag
by
OutwardB
- which was provided in the (now deleted)
link-only answer
:
Create the QR code
Go to
QRCode Monkey
Only change the Content settings
DO NOT change the color, logo or design settings
Click
Create QR Code
Click
Download PNG
and wait for the file to download
Convert to SVG
Go to
PNG to SVG Converter
and convert the PNG image you just downloaded to a .SVG file
Customise in OpenSCAD
You will need
```
QR_Code_Customizer_V01_2.scad
```
from the
files
repository on Thingverse
Download OpenSCAD from here and install it -
https://openscad.org/downloads.html
Put the downloaded SVG file in the same folder as the .SCAD file from this page
Double-click the .SCAD file to open it
Click
Window
, then untick
Hide Customizer
Optional
: Click
Window
, then tick
Hide Editor
Enter the SVG file name in the basic settings tab (or rename the file to qr-code.svg before opening OpenSCAD)
Customize the settings. After changing a setting, you may need to click outside the text box to apply the change
Click
Design
>
Render
and wait for the design to render
Click
File
>
Export
>
Export to STL
Save the file
Notes
Raised
and
Cut-Out
types are for changing filament at layer height
Multi-color
and
Code
are to be used together for inlay/multi-color printers
You can also set
Base Height
or
Code Height
to 0 and export each part on it's own
If you want to print a
double sided tag
, you can set
Base Height
to 0 and export the second side. Then just flip this over in
the slicer
The text options are a okay for basic text, but if you want to use another program to add some, you can add extra height to the
top/bottom of the card under
Extra Size Setting
Advanced Notes
There is some logic in the script that stop you from making the size too small if you have Line Size set, you can set Line Size to 0
or half your line size value if you really want to override this.
You can change the Customize Design settings before generating the QR Code (on
QRCode Monkey
), but you'll need to set Line Size to 0
and there are no promises that it'll print well
If you want to use a different site to create the QR code, resize the image to 1147x1147 pixels before converting it to an SVG. Or if
the QR code in the image doesn't have a border, resize it to 1000x1000
px.
If you want to use a different source for the SVG file, there are instructions for working out the size in the code
(
```
QR_Code_Customizer_V01_2.scad
```
) at line 215. You'll need to
export it as a STL and measure it outside of OpenSCAD, then enter the
values into the script.
The linked to Thingiverse page also has some extra steps for adding an icon:
Add an icon
You can import another SVG file as a logo or use logo fonts.
The below example uses an
wifi SVG file
from IconMonstr
Download the wifi SVG file
Place it in the same folder as the .SCAD file
In the customizer:
Add some extra space to the top or bottom of the card under
Extra Size Settings
Go to SVG Logo Settings
Tick
enable svg logo
Enter the filename under
svg logo name
Set the
svg y nudge
position and
svg logo scale


q:
If you are printing an object that has a base (A statue or trophy, for example), and presuming that you have already optimized every other setting: which shape of base would give you the best and most consistent bed adhesion when using PLA on the widest range of printers (For example, if you're putting it up on a site for anybody to download)?

For example:

A square base that is thin at the edges and thick in the middle, and slopes upwards in the center, like a pyramid.

A circular base that is thin at the edges and thick in the middle, like a dome

A flat thick square.

A flat thick circle

Is a shape with corners better, or a shape with no corners like a disc or a fried egg?

Do sloping sides make a difference, or general thickness?


q:
I'm struggling to find the name of a connector I just broke, so I can order a new one.

It's a six pin nylon terminal, that plugs into a set of header pins on a stepper motor.

What do I search for to find these?! Also, how would I go about finding something like this in the future? I seem to struggle to find connectors.

[A]
In an attempt to salvage my (sadly) previously incorrect answer (at the bottom),
and
to add to
anttix's superlative answer
, here is a quote from
Stepper cable for MKS Boards pinout
, which clearly shows the difference - locking and non-locking, and pitch difference (note the thickness of the plastic between each individual pin socket) - in the two plugs:
This pinout information will help you to use our 1 meter stepper
cables correctly. Cable was made to be compatible with 6-pin JST
connectors on NEMA 17 stepper on one side and 4-pin JST connector on
other side. These cables are compatible with MKS BASE and MKS Gen
boards that we sell in our store.
For compatibility with Anet board you will need to swap 2 wires - RED
and BLUE on the 4 pin board side connector.
Whilst they aren't labeled
PH
and
XH
, it is pretty safe to assume that:
For the control board, the
4 pin
female connector
on the
left
is the
XH
, and;
For the stepper motor, the
6 pin
female connector
on the
right
is
PH
.
The
mattmillan.com
link in anttix's answer, whilst informative, unfortunately doesn't show both sides of the 4 or 6 pin connector.
For the sake of completeness, but at the risk of going
off-topic
, the connector to the printer controller board is often a DuPont, and not a JST,
particularly in
, but not limited to, Arduino (Atmel/AVR based) boards.
From the same website, this page
Stepper cable for RAMPS pinout
, shows the DuPont connector to the control board and the JST-PH-6P connector to the stepper motor (I've not fixed the typos in the quoted text):
This pinout information will help you to use our 1 meter stepper
cables correctly. Cable was made to be compatible with 6-pin JST
connectors on NEMA 17 stepper on one side and RAMPS board connector
(also called dupont connector) on other side. Main feature of RAMPS
stepper header and this cable is that you can reverse stepper
direction by turning connector on RAMPS 180 degree.
This cable is aslo compatible with CNC V3 shields for Arduino UNO and
other electronic boards for 3D Printers and CNC control. Please
observe the following piut diagram to make sure that your particular
electronic board is compatible.
Note
: I'm not promoting this particular website, it just so happens that they have the best comparison photos.
Maybe
It is most likely
not
... JST XH 2.54 6 pin female
and the reverse side, showing the locking, with the male PCB connector


q: Is there such thing as a 3D printer with a very large diameter nozzle, that can make low fidelity, large and fast prints? I'm picturing a soft serve ice-cream machine on a gantry, with a hopper.  You feed it shredded plastic, and it prints bricks, or boards.

[A]
You can certainly get large nozzles, but the material for extrusion still needs to be consistent.  So any chunked plastic would have to be melted and that will produce an erratic flow at the extruder.
By reforming your shredded plastic into a consistent string of filament, then the printer has a steady supply of material to use.  There are already filament extruders for the small shop, but they're still expensive for the home user.  The main problems are getting consistent thickness of filament, and minimising contaminants.  Also colours tend to be lost and muddied.  These might be economical if you have a print farm and are consuming a spool a day on average.
On a large scale, there are "3d printers" that can place a special quick-drying concrete and produce small buildings as homes in a matter of days.  However they're fed a special mixture of smooth cement and accelerators to set the concrete ready for the next layer.


q:
Will a 3D scanner capture internal details within an enclosure?

I'm contemplating buying a 3D scanner, but they're pretty expensive so I'm looking for advice on whether they will actually be useful for the projects I have in mind. So with the picture below as an example, could I expect to generate a usable STL file by scanning this?


q: I thought I am not bad at Google, but simply I am unable to find a G-code for doing circular motion for nozzle cleaning. It is possible to write a simple circular motion in G-code?

[A]
To draw a circle, you need to approximate the circle as a sufficient number of line segments. This requires computing or using a table of sine and cosine values for each angle step. Then you just emit a sequence of
```
G1
```
commands.
Some printer firmware also supports arc drawing commands you could use instead in principle, but support is not widespread, and the quality of the results varies enough that I would not recommend trying to do it this way.


q:
I'm trying to print large objects (around 1 meter squared) with polycarbonate pellets. The problem is sometimes the print cracks. It is not due to delamination as it is a shear crack across multiple layers. I know the ideal scenario is to have a heated enclosure but I cannot do that due to the size. Any suggestions?

I am using a robotic arm (KUKA KR360) with a custom extruder. That is why I can't build the enclosure. As for the temperature, they are 230 to 260 °C. Nozzle is 10 mm.

I like the idea of directed heat. I might try that.

[A]
Printing polycarbonate requires a high end 3D printer that is suitable for the task.
From
Simplify3d support
we learn that:
... requires very high temperatures for printing and will
exhibit layer separation if printed at too low of a temperature or with excessive cooling enabled
. Polycarbonate is frequently
best printed on a machine that has an enclosed build volume
and is capable of handling high bed and extruder temperatures.
High temperatures and enclosed build volume are key to print polycarbonate without cracking or delamination.
Any suggestions?
Note that NASA has successfully printed ULTEM (even higher temperatures needed)
using open source hardware
. They have used infrared lamps directed at the build plate, this may be an option if a full enclosure is not possible. Also people seem to get good results with draft shields for printing ABS on non enclosed printers. Key is that a constant elevated temperature is created near the print, whether that works for such a large size remains to be seen. Best solution would be enclosing the printer.


q:
I want to put in a date and serial number that would be difficult to erase or change. Is it better to print in the number or engrave it in with a laser engraver.

Material will be anti-bacterial PLA.

It will be on free masks donated to schools, I want to make sure we can identify them when they show up at the market or in shops.

[A]
It's plastic. Nothing is difficult to remove, but it could be difficult to remove without damaging the functionality of visual quality of the part. If you want to be really devious, you could embed the serial number in an inaccessible cavity
inside the print
that's not visible without breaking it open.
However, I wonder if it would make more sense to drop this. If you're worried about students (?) or educators (?) stealing and reselling these items, does having a way to trace and punish them really benefit anyone? Even before you consider the harms from doing so, isn't the effort spent tracing (and even the effort automating generation of STLs with each serial number and slicing each one to print individually, rather than using a single gcode job) greater than the value of the item you're worried about losing?


q:
A 3D printer needs to be homed (homing) before the print starts.

What is homing?

What is the purpose of homing?

Is it necessary?

[A]
What is homing?
From the
tag wiki
homing
we can read:
The process of determining the location of a 3D printer nozzle in
three dimension using a reference point (home location) is referred to
as "homing". Homing should occur before every print and involves
bringing the X, Y and Z-Axis motors to pre-defined limit locations
(usually these are endstops). Pre-recorded homing data offset values
determine the position of the build plate origin with respect to the
endstop locations.
What is the purpose of homing?
So, homing is defining the printer coordinate system location with respect to a reference location we call "home". Why? The controller board or steppers have no memory for storing their position and could have been manually moved. Once the axes have "seen" there reference location, the printer will remember to refer all movements in respect to this point (this may include offset values to get to the origin of the printer (see
How to center my prints on the build platform? (Re-calibrate homing offset)
). Note, if a problem occurs where e.g. the nozzle hits the bed or print object, the nozzle may be out of sync with the reference point. Such an anomaly is e.g. layer shifting which occurs on open-loop stepper movement (servo steppers have feedback to prevent this from happening, but these are more expensive). The purpose of homing is to set a reference so that your sliced objects can be printed at the correct location within the printer print volume. If correctly configured, and no problems like layer shifting occur, the benefit is that proper homing prevent the machine to print within the limits of the printer.
Is it necessary?
Strictly speaking, no, it is not necessary. But if you do not automatically set a reference for each axis, you would need to manually provide a position to start from. This can work just as well, but the use of end stops automate the procedure so that it is very easy for the printer operator. Some (of the cheaper) CNC machines do not have end stops, the operator needs to be aware to position the tool head of the CNC machine at the proper starting position.


q:
When choosing which filament to use for a particular print does the color of the filament have any impact on it's performance, or is it purely a cosmetic choice?

For example, are there any side-by-side comparisons available that demonstrate that differences do\don't exist between different color filaments from the same company\range, such as a particular filament needing a hotter bed because the pigment changes it's properties?

[A]
Yes in some cases it does.
It is widely known in communities which are pickier about properties that white filament requires a percentage of pigments much higher than other colours, therefore white filaments are typically weaker (or significantly weaker) than most other colours.
Another exception is black: ABS is not UV resistant, but if you use black ABS, the UV will not penetrate and, unless the surface is continuously scraped away, the UV resistance of black ABS is better than other colours.
I remember some mentions in the Voron discord chats that red (at least from some manufacturers) is better than some other colours from the same manufacturer, but I don't remember the details. You can
join
the chat yourself and search (before asking!) in the #filament chat.
I remember reading that pure ("natural") filaments are however not always better than filaments with colours added, but I cannot remember the source. It could be that some little amount of extra additives (the colour pigments) offer the polymer something to "grab", so better than nothing. My guess, but I have no support for it.


q:
My new Ender 5 Plus' Bowden tube keeps popping out of its socket on the extruder mid-print, I've tried several times and it keeps doing it even though it's locked into place securely at the start every time. Is this a known issue? And how do I resolve it?

I just got it so I doubt it's the coupler, I replaced it with a spare as my first solution, I did notice that it got almost stringy plastic around it whenever it gets popped out.... could that be indicative of what the problem is?

[A]
The coupler for the Bowden tube is probably worn out or the tube end has been scraped so that the coupler can't grab it or you have left out the clamp on the coupler.
The coupler has a sleeve that when pressed down releases the Bowden tube.  There is a C-shaped clip that should go between the top lip of the sleeve and the body of the coupler that prevents the sleeve from moving and should help hold the tube more firmly.  Make sure this is installed.
If the tube outside is visibly worn with scrape marks (this is rare), it might help to cut a few cm off the end so that a fresh section is gripped by the coupler.  Be sure to cut the end flush so that there is no gap between the heat break and the Bowden tube or you will have other problems.
Alternately (and this is more likely), the coupler itself is worn out, possibly with bent or broken-off teeth.  If this is the case, you will need to replace the coupler.


q:
Most people, articles, videos, etc. refer to printing speed by linear speed (mm/s), but a lot of YouTubers prefer to talk about volumetric flow (mm3/s) (mm cubed per second).  I suspect that at some point in the past year or three, some of the more engineer-y types switched to this new measurement standard, but I'm not entirely sure what happened.  What is the practical difference between using linear speed vs flow rate to determine print speed?

For a follow-up, how can you go about changing your print speed as a flow rate in a slicer?  It's easy to find the linear speed, but I have not found the flow rate speed.  I use Cura and will start using Prusa Slic3r soon.

[A]
Flow rate adds a dimension to the regularly used printing speed. Note that maximum volumetric flow is determined by the hotend (unless your extruder is under dimensioned or highly geared) as it cannot supply more molten filament than it can melt in a certain time.
So, instead of specifying the print speed, you should include the amount of material it can process. Volumetric flow includes nozzle diameter, layer thickness and hotend type.
E.g. a 60 mm/s of a 0.4 mm nozzle at a 0.2 mm  layer height has a very different volumetric flow (4.8 mm³/s) from a 60 mm/s 0.8 mm nozzle at a 0.4 mm  layer height (19.2 mm³/s). The latter may require a different hotend to get that flow, but usually it is advised to print slower with a larger nozzle.
Most practical is to use the linear printing speed. This is the value you find in the slicers. But, for a given hotend design it is good to keep the maximum volumetric flow into account to determine whether you are within the specifications of the hotend when you change certain printing/slicing parameters.


q:
It seems there are some missing lines on the outer wall on the Z-axis with my prints. I'm not able to pinpoint the problem. Does anyone have ideas about what might be wrong with my setup/settings?

Example:

Here are some settings that I think are relevant:

Printer: Ender 3 v1

Filament: Das Filament

Slicer: Cura

Hotend temp: 215 °C

Layer height: 0.2 mm

Wall speed: 30 mm/s

Travel speed: 200 mm/s

Retraction distance: 6.5 mm

Combing mode: not in skin (Max comb: 30)

Cheers

[A]
According to
'The-EG' comment
in this GitHub issue,
Add Creality Ender 2 Pro config #633
, you can often determine the stepper drivers by one of a few ways:
Listen to the sound. The 'TMC22**' will sound much quieter
Look for a marking in Sharpie on the SD Card reader
```
```
C = HR4998
E = A4988
A = TMC2208
B = TMC2209
H = TMC2225
```
```
Remove the heat sync
https://github.com/MarlinFirmware/Configurations/pull/633#issuecomment-995480295
After removing the heat sync, it appears that the Chip is actually a
```
MS35775
```


q:
Recently, my Ender 3D Pro has been unable to print any large models successfully with PLA as the filament starts to expand inside the Teflon tube, causing a clog after about an hour of printing. I am starting to suspect that the problem is heat creep.

This occurs with the two brands of PLA filament that I use (3D Fila and Voolt 3D).

The hotend that I am using is the one that comes with the printer, I don't know what it is made out of.

I have tried many things to patch this problem:

Try to unclog it with the needle

Replace nozzle (three times)

Check if the Teflon tube is touching the nozzle

Increase temperature from 200 to 220 °C

Increase temperature from 200 to 215 °C

If the problem is indeed heat creep, I have plans to control the heat sink temperature with a Peltier and an extra thermometer. Any other ideas are appreciated.

[A]
This sounds like heat creep may be the problem. For preventing heat creep to occur you should do the opposite, print at lower temperature, tweak retraction length and increase cooling of the cold end.
A Peltier element is not very effective cooler, use a bigger fan, or a fan with a higher flow rate. Note that the Peltier element required a large cooling body and a fan as well, so this adds a lot of weight to and limits space of the hotend. You should not go there, it has been tried before.


q:
I have a Prusa MK2.5 which runs at 12 V, the Prusa MK3 runs at 24 V.

I noticed that on Prusa's webpage, they list the stepper motors as being compatible with both the MK2 and the MK3 even though they run at different voltages.

My question is: are stepper motors typically tuned for specific voltages (like most fans are), or are these stepper motors compatible with both 12 and 24 V systems?

[A]
Without having the exact model number of the motor to check the data sheet, this can't be answered.  Glancing at the link you supplied, I didn't see either a data sheet or a model number I could use to get a data sheet.
Typically stepper motors overheat when they are run at too high of a voltage.  However, the advertised voltage for the motor could be the lowest voltage at which it works.
For a real answer, you'd have to look at the manufacturer's datasheet for the motor, which should include minimum and maximum voltages and graphs showing current vs. voltage vs. force graphs, and possibly duty cycle graphs.
Also, in some cases, if you run a motor at a higher voltage than it is rated for, it may produce back EMF that is larger than the motor controller is prepared for, and it could burn out the controller.  However, if the controller is designed for 24v, this is less likely of a problem.
Note also that there are conversion kits, where you place a small board between the controller and the motor that fixes the voltage for the motor.


q:
I'd like to print a cylinder, 50 mm diameter, 200 mm long, with 1.5 mm diameter holes tightly fit like this:

The holes go all the way through from top to bottom.

I am using a Prusa i3 MK3S. With 0.1 mm detail and 20 % infill, printing one cylinder is going to take 5 days and 5 hours. I need at least five cylinders.

Is the above setting appropriate for this job?

Is there any way I can reduce the printing time?

[A]
That's a hell of a print!
You are printing a model that has a highly complex structure there, with about 650ish holes, assuming there is space for about 2 perimeters between each hole.
Taking my standard 0.3 mm layer height and 0.4 mm nozzle using a 0.45 mm wide line, I sliced a 10mm high slice of the model for a first estimate of the expected print time - and came out with 2:21 hours. That means the expected print time with 0.3 mm layer height is in the area of 47 hours - or just about 2 days.
As a result, 5 days and 5 hours are in the order I'd expect from a 0.1 mm layer height print for the same nozzle, in fact, your settings seem to have a faster print speed than I do work with.
In general,  don't think this model is good for FDM Printing at all, due to many non-fully formed lines inside the model (yellow) and the red perimeters being a very dense pattern.
Solutions?
print faster
You might get a faster speed with a high flow solution, for example, using a long melt zone (volcano-style) or an even higher flow core-heating 3DSolex nozzle. The latter originally only comes in 0.6 mm and up, also mandating fewer holes, but in late 2021 CHT Nozles in 0.4 mm came to the market. This could drop print time some, but it'd still be a several days print job.
reduced pattern
Besides increasing layer height to drop printing time by the same factor, reducing the number of holes and as a result, spacing them further apart not only can increase the print speed but also make the print form more reliable.
Another alternative would be to alter the pattern from a circle to a hexagonal pattern: by using hexagons, the resulting pattern does not contain thin walls and might print much faster - depending on hole size, you might experience a drop by a factor of 2!
Printed differently
Going from FDM printing to a system such as SLS might be faster and more reliable while SLA/DLP would make this print not only fast and reliable but also trivial - if one can get a 200 mm high SLA/DLP printer, all three models should be able to be printed in one go at the same time!


q:
the 3D Benchy is everywhere. It is one of the top test prints if you look away from a simple cube.

But what makes the Benchy a good test print at all? It does have almost no critical dimensions that would be measurable to see if the printer is calibrated correctly!

[A]
the 3D Benchy isn't a specific calibration test
With the Benchy you don't see if your printer is calibrated in any axis, but it is a general use-case test for a model that can show you many of the issues you might face in a normal print. For all intents and purposes, it is more a general Benchmark item than a specific calibration test like a cube, stringing test, or temperature tower, where you go through iterations of a profile to dial in settings and printer properties.
the 3D Benchy is a Benchmark for printer and settings
Most of the printing issues that can be seen on a Benchy are related to the print settings, though some are also related to the physical properties.
Overhangs
The bow of the Benchy has a shape that is very conducive to seeing how much the printer can handle overhangs due to proper cooling and settings.
The arches in the sides of the cabin, as well as the back window, have a rather challenging overhang pattern (the extension needs to be larger and larger), and the front of the Benchy has a short bridge, which shows if cooling is happening properly.
The upper edge of the hull also is a little overhang, which shows how well small oversteps can be printed.
Small Diameter
The funnel of the Benchy is of sufficient small crossection, that with bad settings it can result in printing layers upon one another too fast, which can result in bulging, misinformation, or totally blobing that area.
Sharp corners
The front and back corners are rather sharp and can show the effects of ringing on the area next to them due to bad acceleration settings


q:
It seems that a Bowden extruder is the most used in all cheap 3D printers by far compared to Direct Drive that is very rare under 500 USD machines. But I haven't understood the reason, since in terms of hardware a direct drive doesn't seem to have any impact on price more than Bowden (correct me if I'm wrong).

Why?

[A]
As I understand it, there's really no good reason for this except "momentum". At some point in the not too distant past, a Bowden extruder was seen as an "upgrade" over direct drive, which required a bulky toolhead that was seen as limiting speeds.
(This perception was at best accurate only for delta and CoreXY machines at the time even, I think. As it turned out, Bowden doesn't let you print faster, at least not at any quality, because the nonlinear/hysteresis effects of the Bowden tube on the actual amount of material extruded can't fully be compensated with linear advance/pressure advance once you reach moderately high speeds. You can overcome this with the
Nitram Bowden
but good luck finding a cheap 3D printer manufacturer willing to put in that kind of custom part!)
Anyway, all the cheap printer manufacturers jumped on Bowden as a feature, and they're slow to develop any new designs rather than just making incremental improvements and production cost optimizations to existing ones.
Since then, direct drive designs have improved greatly, and the mass of the good ones has gotten so low that it's hardly a consideration anymore except on the most extreme agility-seeking printers (designs attempting 50k-300k acceleration). Everything should be direct drive, especially since it makes things so much easier for beginners (no difficult-to-load tube, broken filament in tube, loose fittings messing up retraction, etc.)
Teaching Tech has a video, oddly named
Why direct drive is not automatically better than bowden tube
, where he basically concludes that it is actually better, and goes over some of the history I've touched on.


q:
In Cura Slicer, is it possible to change the direction that the filament is laid down when making the top layer?

For example, in the above picture the filiment is laid down at about 45 degrees to the X\Y axis. Can I make it 90 degrees?

[A]
Yes with a few tricks:
You could turn the item by 45°, then all layers are turned to follow the local X and Y-axis of the body itself, but not the global X and Y of the printer - there'll be a 45° conversion between the items local coordinates and the printers global ones.
Or you could choose a different upper layer pattern, for example concentric, for the upper and lowermost layer.
If you want to define a specific zig-zag direction, you need to go advanced mode, click the gear and enable "Top/Bottom Line Direction". This now allows altering the direction by setting an angle different from 45°/135°. The setting however is ignored if you don't use Lines or ZigZag


q:
Faulty endstop caused the printer (a traditional cartesian FDM) to try to move over the maximum axis limit at top, the noise has been atrocious, I don't see damages (apparently) but I'm wondering if this could have damaged something or the motors aren't strong enough to do any serious physical damage to mechanics of movement.

Could you clarify this?

[A]
It's highly unlikely this crash caused any physical or electrical damage to your printer. Printers are designed to be able to withstand an occasional crash as typically, no Axis Maximum endstops are installed. The 'atrocious' noise you describe hearing is the sound of the stepper motor having lost (or, in this case, repeatedly losing) steps. If you are worried, I would check that the X/Y Gantries are still in-tram and that the printer can still home itself without any problems.
If this was a Z-Max runout (ie, printer tried to move too high), I would also check that the Z carriage is still on the Z axis Leadscrews before attempting to home, because if the Z carriage is not on one or both of the leadscrews, It is possible for the machine to engage them at different heights, throwing the X gantry out of tram or worse if only one leadscrew manages to re-engage.


q:
I am currently printing PLA infused with 80% copper powder. So far I mainly used it because it looks and feels really nice and post-processing is almost limitless, however recently I have thought that metal-like filaments might actually be a good idea for gears (in case I don't want to use polycarbonate or carbon fiber PLA).

I have been researching about the material properties of copper-infused PLA and found a few studies about the "strength", however, those seem to have exclusively focussed on how much weight can be suspended on a hook where it showed pretty good results. The only other info I found was an unsourced "it is more brittle", however the objects I printed so far do not feel more brittle.

Does anyone have any experience with spur gears printed from copper-infused PLA? Are there any advantages over regular PLA? Any downsides (I could imagine higher abrasiveness is not really helpful)?

[A]
At a guess, copper really isn't that strong so you're likely to see minimal improvements, if any.
The PLA carrier plastic is still PLA, with a low melting point.
The copper won't "fuse" with the PLA, it will still be flakes of metal embedded in a tiny pocket inside of a plastic structure.
However this is all speculation, and your best option for an answer is to print some gears and methodically test them against plain PLA, and perhaps a metal gear if you can.  Try and use identical setups/bearings/pressures and times.
Perhaps a high torque and a high-speed test, in both lubricated and unlubed, for PLA, copper-PLA, and a straight metal gear? That would be 12 tests in all and clear out all questions.


q:
I have a bit of an odd request. I am studying the vulnerability of 3D printers and would like to know if there is a way to disable the limit switches on, for example, an Ender 3 in the G-code.

Ideally, the exploit would be used by plugging in the malicious code via SD card into the 3D printer. I have found ways to change the nozzle temp and things like that, however, nothing on the limit switches.

If I were the manufacturer, I wouldn't implement the function, so if it's not possible it will not be a surprise. If that's the case, what would be some other options for tearing this thing up?

[A]
Ethics and justification:
If you have physical access to the device you could just... physically damage the device. Running arbitrary G-code is just more complicated
Most printer farms have a strict no outside G-code policy for good reason. Because direct physical access to the printer does not provide any security.
This is also a problem for CNC Mills and other equipment. The firmware is not there to protect you. If you ask the system to put the spindle into XYZ_POS, the device's job is to deliver your 300 dollar end mill into the part as expediently and directly as you have told it. It does not hold your hand.
As a result, it's probably best that
no one
run pre-compiled G-code. You should use an STL and generate your own G-code. Not only does it allow you to properly tune the print for your specific printer, but it prevents nasties from breaking your printer.
Do not test this on a system you do not own. You will face civil and criminal liability for any damages as a result of performing this on printers that are not your own. Additionally, I would question the value of your research provided that physical access to a device automatically makes it vulnerable; let alone running arbitrary code from an untrusted source.
To help your research: Most "secure" facilities prevent even touching a machine with external code. All code has to be generated on trusted and isolated machines by trusted persons. There is no guarantee that the "trusted" person can't manufacture a job that will crash their 300,000 dollar CNC mill and cause damage - but there are serious repercussions for doing so.
It's extremely difficult to "tear up" a printer by turning off the endstops.
You can disable physical endstops with a simple command
```
M121
```
.
However, this only does so much.
With
```
M121
```
, the printer is only really vulnerable before it has been
home
d. Most printers will
auto home
when starting a print, or refuse to print until they are
homed
. If issuing
```
M121
```
then arbitrarily trying to ram it past an endstop, it will continue until it counts steps to the
software endstop value
```
[XYZ]_MIN_POS
```
to
```
[XYZ]_MAX_POS
```
.
Older printers didn't have software endstops and would keep going until they were stopped or turned off. But this wouldn't
explicitly
cause damage as physical limitations would prevent it. Outside of old designs that do not physically limit the Z position - and crashing the nozzle into the printer.
Nowadays - the printer would crash into the axis limit and then stop because it would hit the software endstop (and funnily enough, be homed as a result - I have done this as an experiment on my own printers)
This would not damage the printer - just be annoying for a short time until it hits the software endstop.
You can however make it work like an older printer provided it does not have stall or crash sensing (like Prusas have by default) by issuing
```
M211 S0
```
.
This turns off the software endstops. And should allow it to continually try to reach the value programmed in the G-code. It should continue to count until it gets to XYZ_POS then finally stop.
Will this cause damage? Maybe. If the Z-axis is high and it can physically push its way into the printbed hard enough it can cause damage to the hotend. However, generally, most printers are designed (these days) that the Z-axis cannot go too far into the print bed and cause (too much) damage. Modified printers can be vulnerable if they modify the bed but do not physically limit the Z-axis from going down too far. Additionally, when the printer
autohomes
on print it usually will set zero to the endstop before the payload can be run, giving a home and only allowing excursion to the axis positives. When this happens, no damage can really occur outside of overheating the steppers/drivers and possibly damaging belts.
There are also some firmware protections to help protect the end-user (e.g. Prusa Crash Detection) - depending on the printer these may need to be circumvented as well.
How you can really tear up a printer? If you have physical access to it - you have total control over it. Simply being physically near it is enough for you to just throw it out a window. It's arbitrary to try to run any code. But if you're trying to research how a threat actor can mess up someone's printer?
Thomas Sandladerer made an excellent video on these vulnerabilities (specific to 3D printers) here:
In his video, he's speaking directly on the threat of running pre-formed G-code from public sources. (Something that you should not do - something that
no one
should do)
Conclusion:
In security, physical access to a system by an untrusted person or running untrusted code on a machine is not allowed.
For this vulnerability to be exploited, it requires a person to do things that they should not be doing - running generated G-code from an untrusted source. This includes from "friends" or even family.
I won't tell you how to "really tear up" a 3D printer as there are a plethora of horror stories out on the internet of printers catching fire let alone the threat of running some random code on your printer. How to do it is publicly available. You just have to figure it out yourself.
The lesson here is simple:
Just don't run pre-compiled G-code.


q:
I'm running a stock Ender 5 pro with the filament that came with it, and using Creality Slicer 4.8.2, but I'm only able to get reliable bed adhesion if I increase the bed temperature from 50 to 60 °C for the bottom layer and decrease the print head speed by about 75 % from the default profile for the Ender 5.

The machine is absolutely stock, and is fresh out of the box except for bed levelling.

I used the default bed leveling print and that came out well, so I'm reasonably certain that it's not a bed leveling issue. The problem seems to be with models that I've made myself in blender and exported as STL files.

In all cases the raft that was generated by the Creality software has printed out perfectly, but the print has only partially gone down when it came to the model itself.

[A]
Assuming Creality's stock firmware still doesn't have Linear Advance enabled, there's a fairly hard requirement to go slow on the first layer. This is because, as the toolhead accelerates up to higher speed without advancing the extruder extra to compensate for the backpressure in the filament-path/nozzle, you'll have an interval of underextrusion, giving less contact area for the extruded material to cling to the bed at the same time there's added force pulling it in a direction parallel to the bed surface. This becomes less critical to adhesion starting with the second layer, since the new material is bonding to itself rather than just trying to stick to a bed.
Having the bed hot will help it stick better and maybe even help reduce the pressure at the nozzle by reducing the heat loss, so it might work around the problem. But in general, you don't want to be in a situation where a few degrees of temperature difference are the cutoff between a failed print and a successful one.
Anyway, do all the usual stuff to improve bed adhesion, and especially make sure your bed height is as close to perfect as you can get it, if you want moderately fast printing to work. But don't be surprised if you need to upgrade to a version of Marlin with Linear Advance (or to Klipper) to get successful high-speed first layers.


q:
Is there a machine (for hobbyists) that will make filament based on the type of plastic I put in. I will sort the plastic before I will put it in the machine.

I have seen the filabot but this uses only plastic from previous prints not plastic types Polyethylene Terephthalate (PET or PETE) or High-Density Polyethylene (HDPE) (these are the #1 or #2 plastic types listed at plasticoceans.org).

To reiterate:

I am asking if there is a machine that can turn a plastic bottle into usable filament.

I want to know if there is a machine (currently on the market) that will make filament, based on the type of plastic I put in.

I will sort the plastic before I will put it in the machine... so,

sorted waste in ---> sorted filament out

[A]
The source of the plastic doesn't matter a lot.
What matters is the plastic's composition and chemistry and how well shredded it is.
Issues are:
Is it a thermoplast that can be remelted?
Is the working melt temperature range compatible with your printer and/or the filament forming machine?
Is the plastic chemically compatible with the components of the machines and the print platform you are using in the 3d printer? (If it isn't, it either will stick when it shouldn't or won't stick when it should.)
Is the plastic shredded enough for the filament reforming machine to use it?
Is the flexibility of the remelted plastic suitable for 3d printing, or does it need volatile plasticizers added to make it soft enough to handle as filament?
Other factors may also be a problem.  For example, PLA, TPU, and PETG are fairly temperature stable, but other plastics have high thermal expansion rates that can cause warping during 3d printing.  There are a few ways to compensate for that however.
If the plastic is contaminated with other plastics or non-soluble inks or labels, this must be removed first, or the results may be weak or not melt evenly or leave debris in the extrusion nozzle.
Not only must the plastic be chemically compatible, but also there are tuning parameters such as temperature profiles, cooling speed, and extrusion speed that have to be calibrated to the plastic to get good filament.
If all of these things are OK then it might be possible to use a machine to reform plastic from any source into filament.


q:
I have an ender 5, and I'm not certain that the bed is getting up to temperature. Or maybe I'm not understanding what it should be like when it gets up to temperature.

If I use an infrared thermometer, where should I aim it, and what should it be saying in comparison to what the screen on the printer says?

For example, if the screen says 50 degrees should the thermometer read 50 degrees, or should it read something different because that's an internal temperature or something not a surface temperature?

At the moment the bed seems "nicely warm" when the temperature on the display says that I should burn my hand if I touch it.

[A]
Sensor mounting
An Infrared Thermometer prefers a non-reflective surface to accurately read the temperature reliably - glass is reflective for Infrared light under many angles and can in the worst case result in measuring anything
but
what you want to measure. To that degree, a piece of paper tape (Painter's tape or Washi-tape works fine) can act as a mounted measuring point.
A contact temperature sensor can be mounted touching the plate in a location easily by putting it in contact using some tape.
Sensor positioning
However, do note that the temperature sensor of the printer is not mounted on the top of the build platform but at the heater element under it. This means two things:
There is a temperature differential between the heater (which would be quite hot but not scorching in an instant of touching it) under the aluminium bed, the top of the aluminium bed, and even more if correlated against the surface of your build platform.
On the other hand, to verify your sensor setting, you need to measure under the bed at the heating element or at the interface between the heater and the aluminium bed. For example, you could use a spot right next to the heater as your probing point. This is incidentally quite close to where the temperature sensor should be mounted anyway.
Bed temperature control
Depending on your setup, the temperature difference between heater and the build surface could be up to about 15 °C and I would deem that an acceptable number. In accounting for the wanted build surface temperature, one can adjust the set heater temperature accordingly, as shown in this experience I had:
On particularly a cold day in late 2021 the heating in the room was not gaining enough heating water from the central unit set to a lower setting than it ought to. As a result, the room was down from the usual temperature to a rather cold ca. 12 °C. On that day I had to increase the bed temperature by a couple of degrees to gain proper bed adhesion, but it fixed itself once I figured out to fix the setting on the central unit.


q:
I'm new to 3D printing, but my printer supports Linear Advance. I heard that it offers improvements in print quality. I used Marlin Linear Advance Pattern Generator to generate a print with horizontal lines at a variety of k-values.

Which K-Value would be best from my below image?

[A]
As a general answer to evaluate the effectiveness of the K-factor, when the K-factor Calibration Pattern generator output print is inconclusive (probably not in this case), printing a tower at various K-factor values might give you more insight, e.g. like:
To vary the K-factor with height, a similar procedure as in
How does one use a heat tower?
can be followed to insert a new K-factor with
G-code
```
M900
```
.


q:
I have an Ender 3 pro. In my country electricity outage is an issue, though it comes back pretty instantaneously, when I hit the resume button on the Ender 3 pro after heating the hot end and the bed when the hot end lifts the Y-axis or X-axis shifts a little bit, I do not understand why as when there is no power outage the prints are just flawless.

I have also tried tightening everything but feels like the motors are having their own fun tilting an extra step for no reason. I have thrown away many prints because of this problem as I work in robotics and prototyping is a necessary thing for me and so is the accuracy.

[A]
Not sure on your exact firmware, but it could be that it is using a
M413 power loss recovery
rather than a power loss interrupt pin. Possible you might be able to change this with your current firmware, but worst case you could install a new controller that does support this power loss interrupt pin.
Depending on the frequency and duration of your power outages it may be worth getting an uninterruptible power supply (UPS). With the heat bed off
this UPS
would run a full print easily. It would even handle a heat bed for shorter outages.
Where you work in robotics, you are probably electrically savvy enough to set your printer up on
direct DC battery power
, which would be cheaper than a UPS of equivalent energy storage. If you need help going that route just post over on electrical engineering stack exchange with the power supply info.


q:
I'm working on a project using 3D printed parts, everything is working very nicely except for one part that needs a 3 mm x 1.2 mm diameter rod. I can print with PLA/PLA+ but such a thin object doesn't seem viable for 3D printing. Is it still possible or am I better off using a 1.2 mm metal dowel?

The bigger part (5 mm x 7 mm diameter) near the back isn't an issue, it's the small rod that I can't seem to print correctly

[A]
It would be impossible to print this standing with the rod straight up, and even if you got it to print the part would be very weak due to the thin cross-section of the rod aligning with the layers.
The only way to print this part and get a usable result is to print it in the orientation shown in the picture, with the rod part being horizontal. Because the layers will now have a much larger cross-sectional area, this not only makes the print much stronger but also prevents issues with the plastic not cooling off sufficiently between layers. Though this will still be a tricky print, because now you'll need lots of support material.
Using a metal rod is probably the better option. Another option is printing the rod lying flat on the bed, and gluing it in place later. This would avoid the issue with support material.


q:
I want to use magnets to hold the lid of a box down tight enough to keep it relatively airtight (along with a rubber seal etc.), but I am not sure what strength of magnet to use, that will still allow it to be opened without causing damage either by having to be pried open or by crushing the print layers. I cannot seem to find any guide to how magnets are used for 3d printing at various strengths and I cannot afford to buy too many types that I am not then going to use.

Any help that you can provide will be greatly appreciated.

[A] I had a similar experience using magnets to hold two plates together. Currently also building a device (3d-printed) that clamps together with magnets. For both of these scenarios, I typically start by looking at what size and force you need. I would look into maybe 3 options of different magnets to start with. It could be in the range of 0.6 lbs, 4lbs and 6lbs. Do you know how much the "opening force" would be? As in what would keep it opening? If its substantial, I could see more the 6lbs but this is a very very very rough estimate that honestly would be best supported with trying a few ranges of magnets first. Try McMasterCarr if you're in the US. They have affordable sized magnets that I've worked with, ranging from different sizes, thicknesses and magnetic forces.


q: I picked up a roll of Overture matte black PLA, and the surface of both the filament and the printed object feel like paper. This made me wonder if it contains wood-based fibers like "wood PLA" does, and if so, whether it's abrasive and harmful to the nozzle. In the past I wouldn't have cared, but I'm using a CHT now and would like to avoid ruining it since it's expensive and I don't have spares sitting around.

[A]
You may be experiencing the feel of paper, which is typically a matte surface, when feel testing the printed item, as both would be matte. A search for your focus found one purchaser of this product (via Amazon) has
left an answer addressing this question
. The answer is on the last page of Q/A and is accompanied by another answer suggesting the white filament is abrasive. One has to click "see 2 more answers" in order to locate the quoted answer.
His reply was that he has printed 8 spools and found no deterioration of his nozzle.
Not any more than any other PLA. I've gone through 8 rolls of this PLA so
far with no noticeable degradation of my nozzle. D. DAmico · September
30, 2021
My own suspicion is that the filament has a chemical additive to create the matte finish, rather than any particulate that might cause abrasion.


q:
On a PLA print where stringing has occurred, what is the best way to remove it during post processing?

Should I simply cut it with a hobby knife and sand the surface or are the better techniques to use?

[A]
Use a hobby knife with a chisel blade (straight edge perpendicular to handle, beveled on one side only).
Apply with beveled edge against workpiece. Raise the handle in small increments while stroking over the flaw until it is entirely removed.  This provides pretty good control to prevent gouging.
Avoid sanding.
This method also works well for removing "ribs" caused by gaps in painter tape applied to print bed.


q:
I'd like to force Klipper to perform power on (using M80) before homing. For this purpose I'm trying to override G28:

[gcode_macro G28]
rename_existing: G28_BASE
gcode:
  M80
  G28_BASE { rawparams }

But for some reason this does not work, I'm getting the following error:

G-Code macro rename of different types ('G28' vs 'G28_BASE')

Isn't G28 overridable? Is there any other way to achieve the desired behavior?

[A]
Because of the way parameters work differently (
```
Sx
```
vs
```
NAME=x
```
) for gcode style commands vs Klipper extended ones, the rename has to be to the "same type" of command.
```
G28_BASE
```
does not fit the pattern to be considered a "gcode style" one. Use
```
G9028
```
or
```
G28.1
```
or something instead and it should work.


q:
In every 3D print that I have seen, the bed should be leveled (manually or with some sensor-based system) on multiple points, pretty annoying because often when you reach the perfect distance on a point another point should be adjusted again repeating the procedure multiple time to have perfect leveling on all points.

I'm wondering why height isn't just fixed with the optimal leveling.

[A]
The point of "leveling" (tramming) the bed is to make it:
square with the coordinate system of the printer so that it lies in a plane perpendicular to the direction of Z travel, and
a known distance from the nozzle tip at one point (and thus, due to (1), all points) in the plane at any given Z value.
In theory, if the machine were all preassembled and sufficiently/perfectly rigid, this could be done once at the factory and never need leveling again. However, even if that were possible, there's at least one factor that will throw you off: you're going to want to swap/replace nozzles, and they will not all be exactly the same length - especially if you use different nozzle diameters, styles, materials, from different manufacturers, etc. This is why, even with an ABL system, unless it performs probing using the nozzle tip itself, you always have to calibrate out the offset between the probe and the nozzle tip.
In practice, many machines (especially affordable ones) require final assembly by the consumer, which necessitates calibration. They also have parts which can warp or wear and require adjustment - especially POM V-roller wheels - which will then throw off the squareness of the bed with the rest of the frame.
If you find you're having to re-level often, something is wrong with your printer. You may have play in the Z-axis/gantry - on Ender 3 style printers with only one side driven, the undriven side tends to wander up/down unless you get everything tensioned perfectly, and this manifests as apparent loss of leveling. You may have
adjustment wheels working themselves loose
(watch the end to see final findings) that mess up your leveling (I've had good luck mitigating that with
this add-on
). You may have an unreliable endstop switch (mine was acting up recently after years of use, and replacing it fixed the problem entirely).


q:
There are numerous topics found on first layers that do not adhere properly causing prints to fail or cause print quality defects.

The advice is often to properly level or tram the build surface. How does one tram the build surface?

[A]
Definition of leveling
Tramming, often referred to as "leveling" in the 3D printer world ("tramming" and "leveling" is used interchangeably, but "tramming" is the correct nomenclature), is the process of creating a 2D
plane
of the build surface that is parallel to the nozzle at the whole print area (usually the X-Y plane).
Why tramming?
In order to adhere the hot filament from the nozzle it is essential that the distance between the nozzle and the build surface is as constant as possible. Increase of the gap may cause the filament to not be squished enough and it may be dragged instead of deposited or create an insufficient bond to cause problems later in the print job when e.g. shrinkage of the object comes in play.
How to tram the surface?
To tram the build surface (a build surface comes in many shapes and forms, sheet of glass, bare aluminum plate, some sort of coated heated surface, etc.) most printers are equipped with at least three so-called "leveling screws". Why at least three? It takes a minimum of three screws to fixate a plane in space, more screws cause the bed to be over-defined or indeterminate, but with a flexible build surface it is quite common to have 4 screws although it is causing a
statically indeterminate system
. So, these screws need to be adjusted as such that the build surface if parallel to the nozzle.
First step is to home (
What is homing? What is the purpose of homing?
) the printer,
homing
from the
tag wiki
reads:
The process of determining the location of a 3D printer nozzle in
three dimensions using a reference point (home location) is referred to
as "homing". Homing should occur before every print and involves
bringing the X, Y and Z-Axis motors to pre-defined limit locations
(usually these are endstops). Pre-recorded homing data offset values
determine the position of the build plate origin with respect to the
endstop locations.
Once homed (with G-code
```
G28
```
or through the graphical user interface of the printer display) , the origin (0, 0, 0) of the printer is known, from this origin you can determine the level. Note that the X and Y is usually correct (if not, see
How to center my prints on the build platform? (Re-calibrate homing offset)
) the Z offset depends on the height of the Z endstop and the leveling screws. For a surface that uses a sensor as endstop (see e.g.
Automatic Bed Leveling (ABL) with a sensor (BLTouch, inductive, capacitive), how does it work?
) the offset is defined by G-code (
```
M851
```
) or through the user interface of the printer display. Note that automatic bed leveling (ABL) is not magic, you still need to provide a trammed bed that is as level as possible, the sensor merely scans the surface and adjusts for larger imperfections of the build surface. After homing, move the nozzle at a certain Z value to the corner of the origin, which is usually the front left) (0, 0, Z) or close to this corner (10, 10, Z), put a piece of paper (A4/Letter) on the build surface and lower the Z to 0 (or if you hit the build surface before you reach zero height, then lower the build surface) raise the build surface until you can feel the the paper drag slightly when pulled between the nozzle and build surface (alternatively you can use a feeler gauge, A4 paper is 0.08 to 0.11 mm thick, so a 0.1 mm gauge will do fine). To be sure that the carriage hasn't been moved by the tramming, issue a homing command and move to the corner to the right and repeat the process to crete a slight drag of the paper when pulled between the nozzle and build surface. Note that tramming this point may have influenced the first point. Now repeat the homing and moving (for corners back right and back left) to start over again at the front left corner and repeating the whole process at least one to two times. This iterative process will deliver a trammed bed, the bed should now be parallel to the nozzle.
Trammed, but filament not adhering...
Once trammed the build surface should be parallel to the nozzle, if the distance (usually paper thickness) is too far or too close, adhesion or first layer deposition may fail or cause surface defects like
ripples
. If not adhering the initial gap between the nozzle and the build surface (paper thickness) might be too big, making this smaller may help squish the filament more so that it adheres better to the build surface. Alternatively use an adhesive in between the build surface and the first layer, nowadays there are multiple dedicated sprays and liquids available, but some house hold product like wood glue, glue sticks and
hair sprays
could be used.
Build surface cannot or is difficult to tram
When the build surface isn't perfectly flat, tramming is a challenge, or doesn't provide a 2D plane at a fixed distance of the nozzle. In such cases, scanning the build surface and adjusting during printing might help to get the filament to adhere properly; this process is called automatic bed leveling or ABL (see
Automatic Bed Leveling (ABL) with a sensor (BLTouch, inductive, capacitive), how does it work?
). An alternative is UBL (see
What is ABL or UBL? Is this the same?
).
Tramming frequently?
The frequency of tramming depends on the quality and (mis)use of the printer to maintain the 2D plane parallel to the nozzle. For good quality printers the tramming is performed very seldom.


q:
I have an Ender 5 Pro with a flexible build plate (The factory default one).

There are multiple extremely thin tracks of melted PLA all over it. Too thin to easily peal off when cooled. Thin enough that you can run your finger over them and barely know that they are there.

What is the best way to clean them off other than simply brut forcing them with a scraper and risking damaging the surface.

Rubbing with IPA and a cloth isn't enough.

I have a plastic razor that's normally used for removing vinyl decal from vehicles without scratching the paint, would that be useful, or maybe just scrubbing for an hour with a nail brush?

[A]
TL;DR:
Print more PLA on top of them, and pull it off together.
Preparation
First, of course, clean it well with IPA. This will both ensure there's no oil or other material on top of the PLA that will prevent it from bonding well with new PLA, and start to work underneath it to get it loose.
Printing
Then, print! Do a 2- or 3-layer square covering the whole buildplate if you need to, or just smaller ones in the affected areas. They should bond to whatever is there and pull it up when you peel them off.
Prevention
To avoid this happening in the future,
fix your bed leveling
. The type of tracks that are nearly impossible to remove by themselves normally come from printing with the nozzle so low that the material is forced entirely between the texture irregularities of the build surface, with no significant layer on top, and this means your bed is at least a whole layer-height too high relative to the nozzle.


q:
Is it possible to 3D print multiple 0.1 mm high layers with a 0.4 mm diameter nozzle in FDM while ensuring fidelity to the set layer height? The raster width is set at 0.4 mm and I am not touching that. The part thickness is 3 mm, so 30 layers of 0.1 mm have to be deposited for the completion of the print job. My polymer is PLA.

If not, should I be using a 0.2 mm diameter nozzle for this purpose?

Can a 0.4 mm print nozzle print rasters with higher width (0.5 mm, 0.6 mm, etc.)?

[A]
The
general consensus for nozzle diameter versus layer height
is to limit the layer thickness to eighty percent of the nozzle diameter. For a 0.4 mm nozzle, one usually limits the layer to 0.3 mm. The printer on which the nozzle is installed will determine the minimum layer thickness, often a typical value of 0.10 mm. I have printed successfully to 0.10 mm layer thickness with a 0.40 mm nozzle.
The linked site says just about the same as above, but also provides useful information regarding appearance, speed, strength, etc.
With a "next size up" nozzle of 0.6 mm, you'd want to limit the layer height to 0.48 mm but you might get away with 0.50 mm layers as there is some wiggle woom.
For 0.8 mm nozzle, you can get your 0.60 mm layers as the max for that nozzle is 0.64 mm.
The article also references that one can print wider than nozzle dimensions by increasing the extrusion factor, which may go by other terms, depending on the slicer used.


q:
I'm working on a gadget a bit like a jewelry box. I want the lid on a hinge. Are 3d printed hinges robust enough for daily use long term? Perhaps with a metal pin?

I want to incorporate the hinge into the design but my thinking is that it would be a waste of time if the hinge will break as I'd need to reprint the whole gadget.

[A]
More detailed information would be valuable. A hinge the size of a soft drink can is going to be stronger than that of a pencil, generally speaking.
A substantial portion of determining the strength of a specific printed object relies on the layer orientation and of the material from which the object is printed.
Consider to examine others' creations on sites such as Thingiverse and PrusaPrinters to see how the result fare against your objectives. I've noted that the better designs will have substantial wall thickness to the barrel portion of the hinge. Additionally, if one can print the hinge with the cylinder axis oriented vertically, the layer lines will "encompass" the pivot. This provides the better strength characteristic of the layer.
The pin aspect is not as important when considering strength, although a 3D printed pin can be weak if printed vertically.


q:
I love the idea of the XYZ test cube to help diagnose my bad prints.   I’m able to find online very common print issues however am looking for a resource that is more extensive. Often I run into a situation where my issue is not covered.

Would be great if there was a resource that had pictures of numerous bad or less than ideal XYZ prints with cause and fix for each. I’m thinking of more than 50 examples.

Does anyone know of such a resource?

[A]
Make sure to set the scale properly for your use case!
In CAD, you define your measurement space in either Inch or in Millimeter units, and that is your grid. In blender, the native unit is the meter.
This can be easily converted in exporting (remember to set it to scale!), but it is best to just set the measurement scale to actually match what you design: if you want to design a 5 mm hole, set your scale to Millimeters and make sure you export in millimeters. If you want to design in meters (maybe you design a building), then work in meters, and set your export scale in the end so that 1 meter actually is represented as 1 meter - or rather as 1000 millimeters.
The STL in the end will not know the difference
: it all is defined in scales of
unitary units
, and it doesn't even know if it was originally designed in meters, inch or angström. The typical slicer expects the unit to be either millimeters or inch, so any scaling of the exported model that does not result in units equivalent to 1 mm or 24.5 mm is bad procedure - converting between these two types is just scaling the model by 2450%.
Make sure to design closed manifolds made up of triangles!
When working with blender, it is very easy to leave the item in a shape that contains multiple intersecting, non-manifold surfaces and areas of inverted surfaces. While
interecting shells
is not a problem (the slicers can handle those by unionizing the item), the intersection usually covers up the non-manifold areas, making them hard to spot.
As a result, before finalizing your project, I suggest follow this procedure:
In Blender, turn on the visual for the normals of surfaces. If an area does not look like a hedgehog after that, the normals in that area are reversed and you need to flip the surfaces there or re-mesh it.
Triangulate the surface using the triangulate modifier. This is to spot artifacts from conversion to STL early and be able to fix them: STL only knows triangles, while blender knows
bent
n-gons.
Add a new object. A cube with side length 1.
Do a test export to STL with scale 1, which also contains the 1-unit cube as an extra shell.
Import the model into a software such as meshmixer, that has a command to separate shells.
Separate the item to all shells. In Meshmixer this is in analyze, separate shells.
After separating the shells, measure your 1-unit cube. If it is not 1 mm, calculate your scaling factor. It should be a multiple of 10.
Next, you should check each shell for gaps or other errors. In meshmixer, the automatic analyze feature points to these areas with red, blue and magenta lines.
Fix the marked errors in blender, then return to the test export. This time use the proper scaling factor. Repeat until no errors remain.


q:
Using cyanoacrylate to glue PLA parts sometimes leaves a white residue or haze near the glue locations.  Is there an easy way to remove it?

I've tried water and alcohol swabs but after drying the haze remains.


q:
I own a spool of PETG and I have been having major print quality issues: layer offsets, chunks of 3d print strewn across the buildplate and other things. I traced these effects to a single culprit: rough layers. I don't know how to fix this. I haven't had this issue at all with all of my other PETG filament colors. And the buildplate height is just where it needs to be, so why is this happening?

Print settings

Layer height: 0.23 mm

Extruder: 235 °C

Bed: 80 °C

Retraction length: 6 mm

Retraction extra restart length: 0.3 mm

Z-Hop height: 0.25 mm

Base print speed: 45 mm/s

Extrusion ratio: 106%


q:
I am new at this and maybe my model is not the best, I adapted it for another one actually. Can you tell me why I can't get the holes printed? I already checked the faces and they are all in the correct orientation (I think)

What happens is that I start printing with the holes facing down and they are not printed at all. I never let it keep going for long but it seems to be completely filled inside.

You can check the file here.

[A]
The overall appearance is that the normals are "normal," that you have no reversed facets, but there are discontinuities within the model that Meshmixer and Netfabb show as failure points. Windows 10 3DBuilder also attempts a repair which fills in the holes.
The Meshmixer capture image shows red lines and points at the flaws in the model. Both above programs fill the faces, which works fine on the cylinder, but fills in the plane where the holes reside, as well as removes the internal holes/cylinders, preventing a simple plane cut repair.
Additional examination of the original model shows an internal cylinder formed axially on the end face red warning markers in the image above.
I used Rhino3D v6 to slip inside, select the cylinder and remove it. Because the cylinder is "inside" the overall model, there's no inside face and outside face, causing the software to glitch.
On the red line along the circumference of the cylinder, there's an internal disk/disc with an internal diameter to match the previously removed internal cylinder. As it also resides within the overall model, the same trouble applies: no true inside/outside surface for the software to comprehend.
Once these were removed, a problematic set of errors appeared. I'm working on that. Work completed. Windows 10 3DBuilder has a pretty amazing repair facility, once the deep stuff is cleaned away. The end result passes the Meshmixer Inspector test and I suspect will work for you. The cylinder appears to be 37 mm in diameter (about an inch and a half) which is rather tiny, but with the flaws repaired, will scale up just fine.
It loaded into Simplify3D slicer with no errors and appears will print nicely, although with support required along the beveled portion of the cylinder.


q:
What are the real overhang limits? I see a lot online about 45 %, then up to 60 %, but I'm routinely doing them at up to 90 % for "shortish" distances and 80%+ for several centimeters at a time. I haven't tried to see how far I can do it, since I don't have filament to waste on that sort of thing.

It's making me wonder how believable all the YouTube and website experts are. Same thing with stringing, they all talk about it on Ender 3's but this print has been going for 25 hours and has maybe two tiny strings.

This is the second time I've printed this same STL with no supports.

0.2 mm layer height

Ender 3 Pro

Generic PLA

[A]
It is very difficult to determine a definitive number/value for the overhang angle, this is very dependent on the temperature, speed, material, nr. of walls amount of cooling fan percentage and the effectivity of the fan duct and your object geometry. Probably more settings are applicable.
You could find out what the specific values for you printer and your settings are by printing an overhang test, e.g. like
this one
:
Such a test will give you definitive answers on the overhang angle for your specific slicer settings and machine capabilities.


q:
I want to print out a flat object without any support structure straight onto the build plate of my ender 5. It's going to be PLA and I need it to be thin enough to still be flexible.

I don't have a picture available, but imagine that I wanted to print out the Coke Cola and then wrap it around a bland soda can, so that the logo is raised up slightly?

Alternatively, what is the best layer height to use, and how many layers should I use?

[A]
With PLA you can just heat it to curve around the object. I've done this with up to 2mm. Real easy with 1mm.
I haven't tried thicker but assume it would work ok.
You'd have to glue it though to make it stick. My attempts were just to shape the prints, I didn't want them sticking so I shaped them around a glass bottle.
If you want it flexible in it's own right, then I suggest 2 * 0.2mm layers. I have a large 2 layer print in front of me that bends easily.
This can be rolled up into a tube, but as soon as you let go it will return to flat.
1 layer is even more flexible but tears along the lines with a bit of effort. So if you want it really flexible I suggest you print 1 layer at slightly lower than normal nozzle height to really get the lines melded together. Or a bit hotter than normal.


q:
Questions like this are usually not allowed but since the price of a brass nozzle in Switzerland is 15.90 and the average price of a nozzle from Alibaba or AliExpress is less than 0.10, and nozzles are something you exchange frequently the issue becomes of such magnitude that we need to have a simple answer to the very straightforward question:

Do nozzles from China offer the same quality and results?

[A]
Up until this year, I used the cheap nozzles - the original that came with my Ender 3, and both the ones that were supposedly by Creality and appeared identical to it, and similarly cheap ones off Amazon. I never had any problem with them that I attributed to nozzle quality, but I went through them fairly quickly since they were so cheap, just swapping one out if it got a lot of buildup that was hard to clean off rather than bothering to clean it well. I would say they are perfectly usable.
However, if you're already used to paying more for a nozzle, I would
strongly
recommend ditching plain nozzles and going with the Bondtech CHT. The performance and quality improvement from it is
drastic
. It gives more improvement to flow than going from a standard size block to a volcano size block (see
Stefan's tests on CNC Kitchen
), and a lot less backpressure, so you can get by with lower values for Pressure Advance/Linear Advance, which put less stress on the extruder and get more consistent extrusion. In terms of ratio of printing performance boost to price (not to mention ease of installation), it's probably the single best upgrade you can make to a printer. And while it's not a special durable material, it is coated, which makes it a little bit better than plain brass.