text:
First layer looks weird and print fails
Update below
Printed 650 of these tokens, no problem. Then all of a sudden I can't get them to stick and the first layer looks wavy and weird.

After a few tokens it knocks one loose and the whole print fails.
Did try to recalibrate the z-height. Should it be even closer? The test pattern for first layer height looks good.
Removed the nozzle to inspect if it's damaged but it looks fine to me...

Any help is much appreciated.
Update - Dec 29th 2019
With the new nozzle and recalibration I managed to get one more print to stick as in my answer below. Then back to not sticking.
I did order a textured plate from Prusa. Recalibrated the XYZ. That did not help.
I have played around with the first layer calibration.
In the video below the setting of -0.900 is fixed the whole time.
The lines look good and healthy but then lifts on the right side of the bed.
Video of first layer calibration
I then moved the nozzle even closer and REALLY smash it into the bed @ -1.050
It still lifts on the right side and a little bit in the corners. The first purge plastic that is output to the bottom left usually does not stick at all.
Untouched with nozzle closer
Things I have done:

Recalibrated the XY & Z axis from scratch.
Did two cold pulls of the filament (link) to make sure the extruder is not clogged. The pulled filament looked nice and clean.
Switched to new textured bed sheet
Switched to a new 0.4mm nozzle (E3D V6)
Tried different filaments (only PLA though)
Lubricated moving parts
Checked heat bed to make sure screws are tight and the bed sits snuggly

Two ideas now:
Can it be the mesh leveling that is acting up? How do I check that?
The heat bed feels differently warm in different places. Is the heat bed constructed with different zones where one can fail and the rest keep working? Do not have access to a heat camera to check.
Any suggestions would be much appreciated!
EDIT:
Thanks @Paulster2! It's good to find this community!
I've been using several different PLA filaments since this started happening. Before, they all stuck to the printing bed like champions, now none of them do. Pictured is som generic white, but getting the same result with Prusament PLA. Nozzle 215°C, Bed 60°C. As I wrote above, I did check the nozzle and it LOOKS fine. It's very small though and I have ordered new nozzles. If no one has any other suggestions I will post more when I have tried the new nozzle.
Also thanks to @Greenonline for correcting spelling and layout. Cheers!

Welcome to 3dPrinting.SE! You don't mention what filament you're using, nor what the bed/nozzle temps are. What printer are you using? Have you checked the nozzle to see if it needs to be replaced? After 650 tokens, this could actually be an issue of the nozzle being worn out .. just some thoughts.

This has become a messy question, you should try to restructure it so that it is a more clear question with things you tried (more logical, chronological). SE is not a regular forum, typing out edits and updates, instead you should rephrase the question, that way it more likely attracts better answers. Hope that helps you to get the answer you need.

215 seems kind of hot. What's the bed temp? This looks a bit like the plastic isn't setting up fast enough as you put down adjacent lines, so running a bit cooler might help.

A new day, a new nozzle, an old result!

EDIT
The success was a one off. The problem remains!
Heat on the heated bed seems to differ a lot in different areas. Just using my hands to feel it since I have no IR-camera.

Thanks for posting your results with the new nozzle! Hope you hang around and vote! Good luck printing!

A problem I encountered a similar problem with adhesion because the nozzle was pressing straight into the bed. This made the filament squeeze out the side resulting in near zero adhesion. Check that the print bed is levelled and the nozzle isn’t obstructed by anything.

Yes, this looks like nozzle is too close to the bed.

Wait, you have your Z-height at a negative 1 mm+ offset for the first layer? After a build plate leveling? I'm surprised your extruder isn't gouging long trenches in your plate surface. Then again, this is a Prusa, they are actually capable of negative offsets from their "zero" unlike many other printers where "zero" is when the microswitch engages at the bottom of the lead screw travel.
From the description of your problem, and what you're printing, my diagnosis is improper bed prep, possibly coupled with some alignment issues. Prusas, unfortunately, fall out of adjustment almost constantly; in addition to usual bed alignment requirements, the dual lead rods have to be kept in perfect alignment at all times, which among other things means you have to be really careful manhandling the printer to get things off the build plate. Your first video shows a pretty decent extrusion line at first, with problems occurring as you get close to the front right corner, which tells me that corner is a bit low, and maybe the gantry or the entire right side of the plate is backed off too far.
Your second video has the extruder way too close. Even if you're printing a 0.15 mm or 0.1 mm layer height, that is far too thin a layer.
The bed prep, however, is likely the bigger issue. You're compensating for the layer not sticking by moving the extruder closer. That's a possible solution, but you've exhausted that as an option; your extruder's right down on the plate in that first print picture and it's still not sticking. That means the plate is dirty, which if you just spent several minutes prying tokens off the build surface, is only to be expected.
Plate surface preparation is something you need to at least look at between every single print. Some prep methods are more durable than others; I've printed dozens of prints on a single layer of kapton tape (which is good, because getting a wrinkle-free, bubble-free layer of kapton down on a non-removable print bed in an enclosed printer design like the MakerBot 2X is a real chore), meanwhile hairspray or blue painter's tape, while easy to apply, might have to be reapplied after every print.
Exactly what you do depends on the build surface and the material you're printing, but the absolute minimum you should be doing, if you print directly on your build surface with zero bed adhesive, is to clean and degrease the bed every time. A little isopropyl alcohol (rubbing alcohol) or denatured alcohol ("methylated spirits" for those speaking the King's English) is usually the thing to use, with a paper towel or microfiber cloth and a little elbow grease to really cut any grease layer on that surface.
It may well be that with this Prusa, you will have to give the plate a wipedown with denatured alcohol and then re-check the bed's calibration between every single print. Such is the nature of these RepRap-style printers, developed specifically to make 3D printing more affordable at which they succeed admirably; the tradeoff is the \$300 printers take a bit more futzing with, while the \$3000 printers are designed specifically to minimize hands-on work. But even on a \$6000 industrial printer, you have to prep the bed for each print.

Okay so I am not an expert but I think I can help.

First off, your nozzle is too close to your bed. Take it up, I guess, to like between -0.75 to -0.6 mm. Play around there.
For not sticking part, see whether it sticks with higher bed and nozzle temperature. Higher temperature like for Nozzle: 220-250 °C and for Bed: 65-80 °C. (Yes its too extreme for PLA filaments but we are observing what happens).
And I couldn't make out from the video, is your print fan on? If so, switch it off.
I would advice to test print with a cube of dimension 200x200x0.2 mm. In your PrusaSlicer, set the Bottom Fill Pattern to be "Concentric" and your First layer height to be 0.2 mm. (I got this idea from a forum but I cannot recall its name)
And as mentioned by @KeithS, keeping your bed clean is important. With isopropyl alcohol and cotton balls wipe the surface. (Though don't this too many times. I have heard that the bed looses its adhesion if done so. After a couple of prints wipe with isopropyl alcohol and before every print wipe just with a kitchen towel).
If your bed is clean, then use glue sticks (note note all glue sticks work) on the print surface right before a print. Don't worry you can take it off after the print.


text:
Does CuraEngine get some advantage slicing cylinders to move the head back to the center twice on each layer?
To date I have used RepG and Repetier with CuraEngine to do my slicing.  In various instances when printing a layer of a cylinder it will start in the middle and head out toward either side.  Then it moves the nozzle back to the center and prints toward the other side.
Knowledge of TSP suggests the print would go a lot quicker if the travel operation back to the middle were omitted.  Here is an example.
By that I mean that to fill the layer of a cylinder from one edge, across the middle to the edge on the right.
My question is why is this done?   What advantage does printing it in two passes have over printing it in one pass?

Could you add some pictures of what you mean? How does it print the infill, what do you mean with start in the middle, moves back and prints to the other side? If you print a cylinder it will deposit the walls first and then proceed to the infill.

0scar.  The example link will take you to a short video demonstrating the symptom.

I have seen this behavior a lot in CuraEngine slices. Mostly older versions of the slicer. Not sure if they actually improved it.
You could see this a lot in long and complicated forms. I also don't like this. Not only for unnecessary moves, but also for imperfections due the start in the middle. Sometimes you can tell where the filling started and which segments were printed separately.
I think it comes down to several issues here:
1.) Starting from the middle saves a move at the beginning of the fill. It probably starts the fill where is stopped printing the perimeter. If the change you want would be implemented, a move after the fill printing would become necessary to start at the right position. So therefore the benefit of faster printing might be gone already.
2.) For the sclicer implementation it is hard to do. The algorithm that computes the print moves for the fill just knows the start point (end position of last perimeter line) and the points that define the area. It does not know if the area is round or square or shaped like a "C" or like a "Y". Usually the slicers have a preferred direction that changes with every layer. This way the fill lines of different layers cross each other and that probably increases stability.
I have seen slices where the fill started several times in "C" shaped prints.
Also if you think about the "Y" shape. If you start at the bottom then you can print horizontal lines and fill the form until you reach the split. Now you have to decide which arm to print fist. And then you have to do the other arm separately.
As you can see a perfect way to fill all possible shapes in one go is impossible.
And defining an algorithm that can fill any shape with only knowing the outline is already hard. I assume the solution has to do with splitting a form into segments and to then fill each segment after the other. Even your example form has probably more sections than only the two obvious ones.
What could be done would be to "optimize" the sequence used to fill the segments. Basically adding a computing step that checks if by introducing a move to the best starting point the fill of the segments could be done in one move.
Again that is probably rather hard to do, but CuraEngine and other slicers are open source, so if you or somebody else would like to invest some time to get this feature that would be great!

I like your answer.  There is a lot to think about in it.  In the simple case of a circle one might argue that it is a simplification to start in the middle again as it is a smaller distance than traversing the chord that takes you 90 degrees away from the endpoint to start the next layer.    And you need to think about printing the outer shell.   "Oh my aching head"

It doesn’t really have much of effect in the actual print. I’m pretty sure the setting can be modified either in the GUI or through gcode. Usually it’s just the standard process when filling in a flat surface. There could be some minor benefits that are quality related. But my main assumption would be for ironing if you have that setting enabled. It would allow it to smooth it better starting from the middle.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Convert ball-stick model to STL from the command line
I regularly have 3D models that consist of a Boolean union of balls and cylinders (molecule models, star maps, mathematical designs), that I then want to convert to a STL model for printing at Shapeways. But I don't know how to easily do that! I already have the model as a series of floating point numbers (four for each ball, and seven for each cylinder), so I don't want to have to go into a graphical interface to click/drag points. Instead I want to convert my lists of floating point numbers to STL from the command line.
I thought this would be a trivial thing, but I cannot find what is the best tool for this. All I need, I think, is a pointer to what tools are most appropriate (although more detailed help will be appreciated :-)) I thought that "gmsh" might be good for this, but it is not immediately clear to me how to use it for that.
I would like the software for this to be "free", in the sense that it does not cost money. Also, I am not a Windows user, so I would like to be able to run this under Linux or macOS.

Being naive, I asked this on the graphics design stackexchange, and was told to take it here.

Maybe probably perhaps OpenSCAD could use those points of yours.

That was the answer on the graphics design stackexchange: https://graphicdesign.stackexchange.com/questions/131653/convert-ball-stick-model-to-stl-from-the-command-line

I appreciate the upvote on the GD SE. If you find it acceptable, please click the check mark on that SE. Kevin Reid provided a good answer here and should also receive an upvote and an acceptance. I see no need to post my previously created answer here, especially as you've linked to it via the comment.

I would suggest using OpenSCAD for this. OpenSCAD does not natively support reading data files that aren't 3D/2D models or images, but you can write a simple program to generate OpenSCAD code.
I would suggest first writing an OpenSCAD file that implements your chosen type of "ball" and "stick", perhaps like:
module ball(x, y, z) {
    translate([x, y, z])
        sphere(d=10, $fn=60);
}
module stick(x, y, z, length, rx, ry, rz) {
    translate([x, y, z])
    rotate([rx, ry, rz])
        cylinder(d=5, length=length, $fn=60, center=true);
}

Then, take your data file — let's suppose it's a CSV —
ball,0,0,0
ball,100,0,0
stick,50,0,0,100,0,90,0

and convert it into OpenSCAD by adding the appropriate syntax (this could even be done using a basic find-and-replace tool):
import <ball-and-stick-definitions.scad>
ball(0,0,0);
ball(100,0,0);
stick(50,0,0,100,0,90,0);

Then, producing the STL is just a matter of running the openscad command on your generated OpenSCAD source code.
If your stick parameters are not Euler angles but "start point" and "end point" you'll have to add the "rotate to point at…" math yourself, but that is within OpenSCAD's capabilities as it has vector math operations and multmatrix, or trigonometry if you prefer to generate Euler angles; you don't need to do that math at the file-conversion stage.

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text:
overlaying epoxy resin on PLA
I've been experimenting with FDM 3D printers and PLA for about a year now.
I'm at the point where I'd like to produce something considerably stronger than PLA, and was wondering if there is a faux-pas list, or general instructions on how to coat PLA with epoxy resin, or even fibreglass/carbon fibre and resin to add strength and a surface to sand and paint.
I would have assumed that I'd need to coat the PLA object using a brush and epoxy resin, but I've also seen blogs where the epoxy mix has been heated enough to become liquid and then the PLA object was submerged in it.
Obviously the fibre coating would most likely have to take place manually by adding sheets, unless I decide to go for shredded fibres (which probably won't provide the strength I'm interested in).
Has anyone tried it, or have a guide on how to do this?

Have you considered printing in a different, stronger material rather than coating it? Know that there are also fibre reinforced nylon filaments available. So, is the question still directed to a coating or stronger print?

@0scar I have, unfortunately my current setup doesn't allow me to do so. Furthermore this question isn't only about strength, but also about the finish the object will have. For example, coating it with epoxy would allow me to treat it differently (spraying, painting, even electroplate it). I've seen carbon filaments which are prohibitively expensive and still won't reach the strength of a CF reinforced object.

Fair enough, let's see what post processing answer this generates! Welcome to 3DPrinting.SE! :-)

resin tag does not apply, as that is for SLA/DLP/... Resin Printers

It would be interesting to see a resin that could hold the shape of a PLA  print in high temps. Maybe a two part resin, mixed together, painted on at room temp, that would harden and hold PLA's shape up to like 250 C. PLA is just so easy to print

@KMmmm We call that concrete! ;-)

I've bought some epoxy resin, clear and fast curing. I'll try using it on a phone holder, a Moebius artwork and maybe a ring. For the phone holder I want to coat it with epoxy, then add carbon fibre 0.5mm sheet around it and then add another layer of epoxy. For the artwork I just want to encase it/embed it. The ring is meant to have a piece of pebble stuck on top, so the epoxy would need to adhere to PLA, else it will fall off. I'll keep this post updated and if I have time I'll post it on YouTube.

@KMmmm Plaster or Gypsum. I am experimenting with a lost-mold item to be cast in aluminium atm...

I have used Styrol based Polyester resins on prints and they created the usual stench as well as a surefire bond and it is easily useable with unstructured fiberglass, as that fiberglass has usually a binder that will react with the styrol and bond the mat.
Epoxy resins also bond nicely to PLA and don't have the styrol smell, but they are not bonding that nicely to normal fiberglass, you want to use them with fiberglass weave.
Either resin is a quite viscous fluid. When you cast a flat surface, it will try to smooth out to a good degree under gravity. When coating a curved surface, you should make sure to align it in way that the lowest point is either the top of the dome or the lower edge, so it settles equally. You can aid in this process by providing heat as this will lower viscosity. An airstream will also aid as it presses onto the surface helping to smooth out unevenness.


text:
What UART port to use for RPi GPIO pins on an SKR v1.3 board
I have a Bigtreetech SKR v1.3, and I'm trying to connect a Raspberry Pi to the board using the RPi's GPIO pins as opposed to using a USB connection because space is limited within the case of CR10S Pro.
I watched this youtube video where he explains using the Z min and Z max endstops to connect to a RPi via the GPIO pins on a Raspberry Pi, and I've watched the video several times, but havent been able to get OctoPrint to connect to the SKR v1.3 board.
There is a dedicated UART serial port on the board other than the USB port but I'm using that for the Bigtreetech tft35 v2 display so that is not an option for connecting OctoPrint to the board.
There are 5 inputs on the board for stepper drives and the TMC2208 stepper drivers that I have installed operate over UART so I'm not opposed to using the extra stepper driver port on the board to communicate with the Pi if that is an option, but figuring out how to use the Z min plus the Z max pins to connect the Pi would be ideal.
board graphic pins

If you followed the video verbatim then the pins file will be wrong, because he's changing the pins based on an MKS Gen 1.4 and not the SKR 1.3. All pins on the SKR will look similar to P2_04, which is the pin for the 2nd hotend terminal.

Indeed, MKS boards are based on RAMPS (so "pins_RAMPS.h" are edited on video) and AVR-based. SKR is ARM-based (LPC1768), and use different pin symbols. (The voltage difference agains Pi is the same, though.) The video (@2:40s) presents how to free pins D18 (TX1) and D19 (RX1) and enable communication over this by setting #define SERIAL_PORT 1. But do you know how to resolve the question of @ipatch? I could only find instructions for connecting to SKR via TFT. If any pins could be successfully configured for OctoPrint connection?


text:
Clearance between moving parts
I am using a Prusa printer to print parts for prototyping. The project I am currently working on needs parts to be able to slide against each other and they need to be printed together. A bit like these gears, where the whole construction needs to be printed in one go and the gears need to be free to move afterwards. What clearance should one use between such moving/sliding parts to make it snug but not unmovable?

Maybe this answer answers your question?

Each printer will have different "print in place" tolerances, but you can find such a model with which to determine the numbers you seek.
One such item is on Thingiverse:

Thanks, I'll try one print to see what clearance I need.


text:
Removing Supports Inside Cone
I'm new to 3D printing. I've made some projects before just fine, but this project is giving me problems.
I 3D printed a trumpet mouthpiece, and the printer made supports inside the mouthpiece funnel. I can easily remove the exterior supports, but I don't know how to get to the supports inside. Does anyone know how I would do that?

Here is the link to the model

Btw nice bannana in fhe background

That model didn’t need supports. Most of the time you can break the connections with the supports to the model by inserting a knife or flat object into the cavity. In this case you could use a probe to loosen the joins then wedge it out. If that doesn’t work you can use needle nose pliers to remove prices.
Your best and cleanest option would be to reprint the mouthpiece without supports at all. Print it so that the wide section(the section touching your mouth) is on the buildplate.

the item needs to be turned 90° though: stand on the mouth area.

It just needs to be oriented so that the wide opening is flat the surface. A trumpet mouthpiece is symmetrical at all vertical angles.

...which is a 90° turn around either the X or Y axis because of the shown orientation.

Ok I’m not good at axies

They always confuse me. ;)

X and Y are those that span up the bed. In case of that item: One of the two will not change the item at all (you rotate around your symmetry axis), the other will put it into the wanted orientation.

"Don't use supports"<-- that is the best part of this answer. Sadly, this doesn't work.  If you print vertically, you end up with an extremely fragile piece -it'll snap between layers.  The OP properly printed horizontally, and possibly by using a very "thin" layer height he can get by without supports.  That's the only way to succeed.

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

I see what you mean. I'm reprinting it with the mouth-part facing down. Thanks!

@VictorResnov - I think you'll be a lot happier with the print results reprinting as Fred suggests. The print lines will work/look a lot better than how it is now.

"Don't use supports"<-- that is the best  answer.
Warning
Sadly, if you print vertically, you end up with an extremely fragile piece -it'll snap between layers.  The OP properly printed horizontally for strength, and possibly by using a very "thin" layer height he can get by without supports.  That's the only way to succeed.
I guess I should state that this answer assumes you want to use the print in a trumpet.  If it's purely for decoration, then definitely print vertically.


text:
Ender 3 displaying wrong temperatures for hotend and bed
I've had issues with my hot end and decided to replace the whole assembly with this.  After the replacement, my printer started reading about 135/185 °C for the hot end and bed are both at room temperature. It also gives the "Heating Failed" error message. Printer halted when I tried to heat it.
Things I've tried:

Checked the wiring, the thermistors are reading about 110k and 10k at end of the wires.
Tried updating the firmware with a few different thermistor settings. Only the static (dummy) ones worked (reading a static value of 25/100 °C)
Tried with old thermistor and reading stayed at 135/185 °C.

I'm suspecting something wrong with the motherboard but was hoping I could figure out what's wrong before going ahead and buying a new board. Would appreciate any thoughts/suggestions.
In troubleshooting the issue, I tried disconnecting one/both of the thermistors at a time and the reading stayed unchanged. Now thinking I might've somehow broken the board when I was disassembling it.
Upon receiving a new motherboard, that fixed the bed temperature reading. The hot end is now reading -14 °C with the thermistor plugged/unplugged. Took the resistances on the old and new hot end thermistors and couldn't get reading from either. So turned out both the stock motherboard and my hot end thermistors were not working. Ordered new thermistors and that should fix the problem.

Welcome to 3dPrinting.SE! You checked the thermistors themselves, but did you check the wiring at the main board for proper connection?

@Pᴀᴜʟsᴛᴇʀ2 Yes just checked them again and they are properly connected. But I noticed as I disconnect one and both thermistors, the reading didn't change at all. Does that suggest faulty/broken board?

I got my printer fixed and am posting steps I took for people with similar problems in the future.
Initial problem:
After I replaced my entire heating unit and reconnected the wires, my printer started to read about 135/185 °C for the nozzle and bed at room temperature. It gives the "Heating failed, printer halted, please reset" error when I tried to heat the hot end and bed.
Troubleshooting steps:

Checked the resistance of the thermistors. Both the hot end and bed were about 100k.
Reflashed Marlin with different thermistor settings. Only the static (dummy) ones worked (reading a static value of 25/100 °C). All the other settings were giving very high readings at room temperature.
Replaced the mainboard. This fixed the bed reading but hot end was still not working. Checked the hot end thermistor again at this point and couldn't get any values, which suggests the thermistor wire was broken somewhere.
Replaced the hot end thermistor and that fixed all the issues.

So what I think happened was that I messed up the board when I was reconnecting the heating unit. Then at some point after I first measured the thermistor resistance, the hot end thermistor broke. Replaced the thermistor and that solved the issue.

For future readers,
On a second-hand 3D printer with unknown firmware, I compiled the Marlin 2.1.1 firmware for the Creality 4.2.7 board with the default configurations for the BOARD_CREALITY_V427 board, and at room temperature, the hotend reads about 121 °C.
I then measured the hotend thermistor by disconnecting the JST cable and got 9.1 kΩ with the room temperature of about 30 °C. This tells me the thermistor is a 10 kΩ NTC type.
The default configuration for Marlin is 100 kΩ NTC.
So, if you have a 10 kΩ hotend thermistor, either recompile the Marlin firmware for a 10 kΩ NTC thermistor (more trouble than it is worth if you do not know the temperature curve data), or get a new thermistor specifically listed in Configuration.h, for example:
 *  Analog Thermistors - 4.7 kΩ pullup - Normal
 *  -------
 *     1 : 100 kΩ  EPCOS - Best choice for EPCOS thermistors
 *   331 : 100 kΩ  Same as #1, but 3.3V scaled for MEGA
 *   332 : 100 kΩ  Same as #1, but 3.3V scaled for DUE
 *     2 : 200 kΩ  ATC Semitec 204GT-2
 *   202 : 200 kΩ  Copymaster 3D
 *     3 : ??? Ω   Mendel-parts thermistor
 *     4 : 10 kΩ   Generic Thermistor !! DO NOT use for a hotend - it gives bad resolution at high temp. !!
 *     5 : 100 kΩ  ATC Semitec 104GT-2/104NT-4-R025H42G - Used in ParCan, J-Head, and E3D, SliceEngineering 300 °C
 *   501 : 100 kΩ  Zonestar - Tronxy X3A
 *   502 : 100 kΩ  Zonestar - used by hot bed in Zonestar Průša P802M
 *   503 : 100 kΩ  Zonestar (Z8XM2) Heated Bed thermistor
 *   504 : 100 kΩ  Zonestar P802QR2 (Part# QWG-104F-B3950) Hotend Thermistor
 *   505 : 100 kΩ  Zonestar P802QR2 (Part# QWG-104F-3950) Bed Thermistor
...


text:
How to use second hotend for bed heating?
The heated bed output on my printer recently stopped working. I have an output for a second hotend. How can I reprogram this output as a heated bed output? The board is a Geeetech GT2560 rev A+.

Have you tried using the other heater output in the G-Code? Like E3 or something? What is the label of the other heater that you're talking about? Is it the extruder heater or a secondary bed heater? Do you have a pic of the output you're talking about? Can we see it? Do you have an environment for compiling the firmware? Do you know what firmware it is using?

Although it appears to be a RAMPS compatible board as described in this now deleted answer, it is not using a RAMPS pin configuration.

To fix this in the firmware, this requires an upload of newly configured firmware to the board. See e.g. question: "How to upload firmware to reprap printer?". For Marlin firmware (which is also loaded at the factory) You need to assign the correct board number or constant name (amongst several other things) in the Configuration.h file. Note that this is "clearly" described by the manufacturer here.
From factory, a version of 1.1.X is loaded note that version 1.1.9 is the last of the 1.x branch, the default is now version 2.x.
From the manufacturer of your board you find that:
#define MOTHERBOARD 7

needs to be set. Note that using number is old, nowadays you would use a constant. For board number 7 this is the constant defined as BOARD_ULTIMAKER. Note that in version 2.x this number is now 1117, so the preferred usage is the constant name BOARD_ULTIMAKER!
Specifically for your board, the Configuration.h file should contain:

#ifndef MOTHERBOARD
  #define MOTHERBOARD BOARD_ULTIMAKER
#endif

The pin arrangement used by this board is found in pins_ULTIMAKER.h.
In this pin file you need to swap the pin numbers that identify the bed and the second extruder (E1) thermistor pin. In this file change:

//
// Heaters / Fans
//
#define HEATER_0_PIN        2
#define HEATER_1_PIN        3
#define HEATER_BED_PIN      4

to:

//
// Heaters / Fans
//
#define HEATER_0_PIN        2
#define HEATER_1_PIN        4 // or -1
#define HEATER_BED_PIN      3

Note that it could be that the E1 heater output may not be designed to take the high current load the bed requires (depends on the traces on the board and the used MOSFET; with respect to the MOSFET, the manufacturer states that:

3 55Amp MOSFET (with LED indicator, the actual output is restricted by the PCB board and the connector), all 3 MOSFET are equipped with heat sink to ensure sufficient heat dissipation and stable operation

, implying that the MOSFETs are identical). It is therefore advised to use an external MOSFET module. This will keep the high currents away from your printer board. Such a module looks like:

You need to wire the second extruder heater leads to the white cable, the power and the bed leads use screw terminals and are clearly labeled.

Don't forget you have to walk them through how to install the compiler, get the source from git hub et al.

@user77232 No that is not necessary, there are already questions on that front. I'll link them.

Oops, I only read that the board "integrated 2560 and RAMPS" - didn't know they weren't competent enough to route it similarly.
Marlin 2.0 has just been released out of bugfix though.

@towe +1 for the 2.x statement! I have updated the answer, many thanks!

If you want to use Extruder heater and thermistor 2 as a hotbed driver, then you will need to get an external mosfet, since I doubt that the extruder heater mosfet will be able to handle the required current. Then in your slicer, just remap the bed from BED to E2


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How can I convert STL files into PDF drawings?
Does anyone know of an easy and free way to convert my STL models to a PDF drawing for CAD and metal CNC machining?
I've created some great designs that are all STL files and want to somehow send them to a CNC/milling machine to make my designs in metal parts.

if all else fails  "PrintScreen"  :-)

What does your milling machine take for input?  E.g. convert the STL to an OBJ file and that may be all you need.

The normal process is to start with a CAD file, and then generate a dimension drawing for manual machining, or an STL file.

@CarlWitthoft yeah that’s pretty much what I did a and was manually adding dimensions to a screenshot...I was thinking there must be an easier way and I think the guy who suggested Onshape takes the cake with his suggestion.

I've had good results with using the free web-based program known as Onshape which allows you to import/create 3D models. One of the features built into Onshape is a drawing tab. You can select the views desired or use a standard layout, as well as add dimensions to the individual drawing views.

This image above was of a model created in and exported from Tinkercad. No dimensions have been added in this example, but it's available as part of the software. Being browser based, the program will work for any platform.
In order to make this answer more accurate, I attempted to duplicate the results shown in the drawing.
I've discovered that I used Fusion 360 to import the STL. The next step involved turning off history feature, then converting the STL to BREP. Once in BREP form, the no-longer-STL file can be exported as .step, which is accepted by Onshape.
Fusion 360 is a free-to-hobbyists program, but does not run in a browser. There may be other programs which will convert STL to .step and there may even be a browser converter-specific site to accomplish this.
I recognize that this is a convoluted solution, but it's not particularly burdensome, overall.

Wow thank you for this info! I had no idea onshape existed!

Is this a free program that will also work on Mac?

added edit, browser based means any platform.

how do you export a file like the one shown with the dimensions? I'm signed up with Onshape but am a total newbie and not sure how to use it yet

says "failed to create line rendering of topology"

I noticed that the drawing feature works just fine when I create a part using Onshape but my imported STL file just isn't working. I've tried DXF and other formats and it doesn't;t want to budge

I'm confident that I used Tinkercad to create the image in the post. That would mean that I exported it to a file format compatible to Onshape. It's been so long ago, I don't have a clear answer, although DXF is a poor choice. Look for .STP or .step or similar.

tried STP and it said that file has no importable geometry

new edit, intermediate step involved previously forgotten.


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Filament change (M600) causes color mixing despite excessive purge
I have an Anet A6, where I uploaded Marlin 1.1.9, because the manual filament change on the stock firmware was really bad (90 % of the times it clogged the hotend). I've tweaked it a bit, and I'd say it works fine, but I have a problem with my filaments.
I'm printing in ABS. I want to make a 3 mm black plate, with an orange text/image on top of it. I've been playing with a test print and I can't seem to fix one thing. I swap the filaments and purge the nozzle, but no matter how much I purge, the orange filament keeps getting dark form some remnants of the black one.
Here's a sample of the original orange filament and different attempts with filament swap during print.

The orange has a recommended print temp. of 240-255 °C while for the black one its 230-250 °C. I've tried purging the hotend at different temperatures (240 °C, 250 °C) and I've been purging ridiculous amounts (like 1 meter). At the point where the filament looked clean I've resumed the print and it still came out dark. The continuous purging didn't clean everything and the extrusions and retractions during printing probably scooped out more of the black filament.
Have you ever encountered such a problem? Any tips of effective purging?
For the record: Other mods to the printer include frames to make the body more rigid, tensioners, and similar - nothing of importance. I did however change the hotend to an E3D V6 look-alike with a silicon shroud and nozzles to match, but this was waaaay back. I've never had problems with either of these filaments when printing single-colored things.

I experienced the same with black and yellow PLA. Probably too much filament gets stuck in the heat break/nozzle. You need to purge more maybe. What heat break are you using? I expect the all metal ones to be more affected than the Teflon tube lined ones.

Out of curiosity, does the orange look how you would expect when printed by itself?  It's possible that the hetaing/extruding process is changing the color of the filament somewhat.

If your hotend is clogging then you have problems with the filament in use; this has nothing to do with purge method.   I agree with @Tal that you may be running way too hot and "cooking" the orange color.

Instead of purging through the nozzle, it might be a good idea to use a cold pull to remove a considerable chunk of the materia..

This is my second spool of this orange filament and never had problems. Its definitely not burning in the nozzle. I never managed to do a cold pull - it always moves the hot end carriage, so i'd loose alignment, not to mentioned that i once broke the original Anet heat break this way. They're terrible anyway. Now I have a cheap replacement heat break, but it still has a ptfe lining. The strange thing is that I do purge a lot until the extruded filament is clean. After i resume printing it gets dark again, as if the hot end has the old filament deeply clogged.

How many layers thick, and what layer thickness, is the orange part? Pigment is unlikely to be fully opaque until at least a few.

3mm with 0.2mm layers, so 15 layers. The weird thing is that it starts clean(ish) and gets darker as it goes up. I'll try experimenting with purge speed maybe it'll make a difference. Currently it's 3mm/s. At 5mm/s the filament slips. Maybe it i try a slow purge like 0.5mm/s it'll catch more of the old dirty filament.


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Question about the MK8 Extruder
I am trying to make a 3D printer (Prusa i3 model). I was testing all steppers and all steppers are working, however the Mk8 extruder (direct drive) is not working and I don’t know why. Can someone help me?

Mk8 just says "iteration 8", but at this time that is usually shorthand for the "Makerbot MK8" Hotend/extruder design. The Prusa i3 Mk3 swapped to the previous Makerbot Mk8 for an e3D v6 hotend some years ago.

What firmware are you using?
Chances are, you've forgot to disable the rather useless "cold extrusion prevention" if you're using Marlin.

Usually, the extruder movement is protected to only move when the hot end is above a certain temperature (typically 170 °C). Please update the question by [edit] to explain what you exactly did, as it stands now,the question is nominated for closure unless more information is added.

It’s either because you haven’t connected it properly or you have not  mounted it the correct way. This could lead to the damaging of the part and failure to work again.
Check your connections with the stepper motors and hotend power wires. Make sure the connectors are in fine condition and cords are not frayed. Ensure all power is completely off and mains cable is unplugged.


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Usable build volume of a Makerbot Replicator Plus?
I've got a class with access to a few Replicator+s. Makerbot's official site gives a build volume of 11.6 x 7.6 x 6.5 ". (LxWxH)
Out of curiosity (I'm not intending to print it), I created a 11.6 x 7.6 x 6.5 inch rectangular prism and placed it in the build plate in the Makerbot software. It didn't like that, so I scaled it back to 11.5 x 7.5 x 6.4 inches to fit inside the build volume.
It accepted that, and I could click the generate preview button, but then it got stuck 50% of the way through generating the preview and toolpath. I'm guessing that the extruder can't actually reach all of the build volume and so it can't generate a toolpath to create this monstrosity. Does anyone know the actual volume that it can reach and actually utilize?

Exactly what software are you using to slice?  From your description, it appears the gcode was successfully generated, but the software choked when trying to draw teh preview image. That could be due to lack of local RAM or problems with memory leaks in the software.  This happens when the number of layers and the complexity of the layers gets large.
Try just creating a plain rectangular solid and set a large layer height.  Let us know what happens with that.

Software: Makerbot requires using their own software, so not too much info on what it's doing is given - all proprietary.

ok cool it works now


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Reprogramming Makerbot Extruder Controller 3.6 with Arduino toolchain?
Long story, but I inherited a friend's old experimental Replicator project (version 1, balsa frame), which included a bunch of Makerbot EC3 extruder controllers.
After scrounging around the net for old documentation, I found a few threads suggesting these things can be reprogrammed. I'm on a budget, and the ability to control high-current applications straight from an Arduino interface would be pretty neat. Once firmware exists, there's a procedure to flash it, but I'm interested in something a little more straightforward. Someone in the forums said that these can be programmed from the Arduino IDE (as the boards are Arduino derivatives), but I haven't found any official documentation on the subject.
(1) Does anyone know if it's possible to reprogram these straight from the Arduino IDE?
(2) Is there a known conversion between board pins and extruder controller pins?
Links I found:
[1] https://github.com/makerbot/G3Firmware
[2] http://makerbot.wikidot.com/ec36-firmware-installation
[3] https://www.reprap.me/makerbot-extruder.html
[4] http://web.archive.org/web/20110905083750/http://wiki.makerbot.com/thingomatic-doc:extruder-controller-3-6
[5] http://makerbot.wikidot.com/forum/t-367035/flashing-extruder-controller-3-6

Welcome to 3dPrinting.SE!

OK, just found this link (for an older product) - will try and see if this version is similar.
http://www.geeetech.com/wiki/index.php/Extruder_Controller_2.2


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Printer extrudes too little filament at beginning and end of extrusion
I've bought a new type of filament (GreenTEC Pro Natural) for my Anycubic Mega i3 to print some food-safe cookie cutters. Now I have changed the print settings to an extruder temperature of 210 °C and a heated bed temperture of 60 °C and everything works well.
But when I look at the print, I see that too little filament is extruded at the beginning of an extrusion and at the end. So every time the nozzle is lifted to move without extruding, it takes too long for the filament to correctly start extruding again (see picture).

What can I do? Is there a setting to print slower at these points (I'm currently using Cura)? Maybe change retraction distance? Different extrusion temp? Before I used PLA from Anycubic and everything worked fine...

how much retraction are you using?

Welcome to 3DPrinting.SE! Essential to solving this is to know what the settings for the retraction, and re-retraction (loading) of filament are.

My first thought was a retraction issue as well.

I see some heavy excess material deposited on those combing moves. Maybe turn off combing too.

What is your slicers overlap perimeter/infill %?

Check your retraction settings.. It's either too far or one of your priming/wipe settings is off, some slicers call it priming or extra restart distance.
Your linear advance "k" might be set wrong if you're using linear advance.
I see a bit of under-extrusion on the between walls and center, your overlap % might a little short. Or you're printing too fast for the filament to melt and deposit.

I think there's a retraction issue(had the same issue). You need to change retraction and check whether there are any improvements. Some times different filament types need slight filament setting calibration.

One critical detail; if extrusion isn't starting smoothly after a retraction move, most slicers allow an "extra restart distance" or similar setting, which basically tells the extruder to advance the filament more than it retracted by this additional amount. @Lieselottelernt should increase this, probably by tenths of a millimeter, and test using some simple print shapes like leveling squares, until the jitters at the beginning of a print move after a travel move are smoothed out.

@keiths: That option is a hack that always, necessarily extrudes the wrong total amount of material. To fix the issue you need to stop it from getting extruded in the wrong place, not just extrude more to "compensate".

@KeithS the extra length on restart is controversial because it assumes a small amount of plastic is disappearing into thin air. It might be the overall extrusion amount is off, or linear advance is off. Could also be oozing out because travel is slow. The hard part about fixing ooze while traveling is the ooze will depend on how long the travel move is, how long the extruder is retracted, temperature (how oozey). One number often won’t cover that, with a variety of objects.

authors: سعيد الشمراني

authors: คุณชายชา จันทะมนต์


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Z-Axis raising and dropping substantially during print knocking print off
I've had my Creality Ender 3 Pro since October 2019. It was running like a dream until about a month ago. The Z-axis started knocking prints off the plate during printing. I've changed mats and worked on adhesion issues. I've switched to a glass plate and triple checked that it is level. I checked to see if it was binding but honestly I couldn't tell.
I'm at a loss of what to do to troubleshoot and fix the issue. Any suggestions?
It homes fine and manual controls work fine with no issues.

Welcome to 3dPrinting.SE!

Can you explain what you mean by the "Z axis knocking prints off"? What part actually collides or moves in a manner that's unexpected/erroneous?

can you check if your Potal (X-Axis) is orthogonal to the vertical bars? knocking it off is a known issiue.

Did you ever find out what happened? Please add an answer if you did!

did you get an answer to this? I'm having the same issue and the z axis keeps dropping during prints at regular intervals above a certain height, as if it can't hold itself up (all screws seem to be right, and there's no binding it just isn't holding itself at the right height)?

Can you send a link to a short video of the problem occuring? It might be because of multiple factors but we will be able to identify if there's a video of it.
Possible reasons:

Z axis nut might be too tight. This would cause the nut to bind with the leadscrew and so the motor will not be able to lift the z-axis further while printing.
Not enough retraction. This would cause filament to ooze from the nozzle during travel moves and this filament would collide with the printed object, causing it to be knocked off. A possible solution for this would be to enable Z-hop in the slider, have the hop distance set to at least 1.5x the layer height you are currently printing with.
Too small of a contact area. This usually happens more often for tall prints. A solution would be to increase brim in the slicer settings (at least 10~15 lines) to increase the adhesion of the print and the bed.
Dirty nozzle. Old prints filament may be stuck on the outer face of the nozzle and might be catching onto the printed part while printing.


text:
What is the difference between M420 S and M420 S1?
I have been reading through the Marlin website about ABL (Auto Bed Leveling)  and I see what appears to be conflicting information.
At https://marlinfw.org/docs/features/auto_bed_leveling.html it states that running G28 (Auto Home) will turn off ABL and that to reactivate it you need to insert the code M420 S1.
However at https://marlinfw.org/docs/gcode/G029-mbl.html it states:

G28 disables bed leveling. Follow with M420 S to turn leveling on, or
  use RESTORE_LEVELING_AFTER_G28 to automatically keep leveling on after
  G28

The latter is referring mostly to manual bed leveling, but in this section is referring to ABL.
So what is the difference between the S and the S1 options?

TL;DR
Short answer: "There is no difference!".

Long answer
G-code is parsed line by line. The parser in the firmware reads the command and the options (also called parameters) following it, comments are discarded.
Therefore, option S should be followed by a Boolean value 0 for False or 1 for True. Without a value it is undefined and should be reported as incorrect or treated as false (in my opinion). But, the developers have chosen differently. If a Boolean value is expected and the value is not given, the parameter is parsed as true. This has analogy with other software options or switches like e.g. used by Linux commands.
This means that for Marlin  the G-code M420 S is exactly the same as M420 S1.
I've checked this with another command (this is not depending on the G-code command as there is a single parser processiong the G-codes and the following parameters); M211 where M211 S is exactly the same as M211 S1.

authors: Александр Громов


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Bowden setup keeps jamming between PTFE tube and heatsink
I keep getting a jam where the PTFE tube meets the top of the v6 hot end. I have the PTFE tube all the away in but for some reason it gets a bulge at that spot and will stop printing. It happens with or without retraction. Any ideas?

I am thinking you mean the middle of the cold end instead of the hot end; above the top of the heat break. Could you add a sketch? Sometimes chamfering the tube helps!

Do you have cooling fan for the e3d heatsink ?

Can you show a picture of your setup?

Filament sometimes get stuck on the rim of the PTFE tubes inside the heat sink. Josef Prusa from Prusa Research has published a document on how you should chamfer the PTFE tubes for his printers:

Maybe chamfering your tubes works for you too.

Thank you everyone for your help. Sorry I took so long to respond. I didn't get a notification of your responses. I'd like to to try this chamfer of the ptfe tube but this seems like a difficult thing to pull off accurately with a tiny round tube. Do you think a pencil sharpener would work?

@Hellrazor You can find printed objects on Thingiverse, if you are still able to print small parts; e.g. this.


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Anycubic i3 Mega layer shifting
My Anycubic I3 Mega shifts every layer by a little distance making straight model lean to it's side by an angle.
For example, this white round blob should've been a straight up cylindrical shape, but it leans to the right for some reason.

Don't look at dirty table, it was clean at the start of printing.
When I was printing this model, I prepared it with Cura 3.2.1 slicer.
What could be causing this problem? How it could be fixed?
Update 1: I've tried lowering print speed from 50 to 25 mm/s in Ultimaker Cura 4.4.1. It didn't help. After another test print it seems like it's an X axis problem.

Update 2: Result after setting print speed to 10 mm/s and travel speed to 50 mm/s (same model, same ABS):

Even such slight change to print speed as 15 mm/s still produces layer shifting.

Hi and welcome to 3D Printing.SE! Are the belts tight?

@0scar Hi! Thank you. Don't know if the belts are tight enough but not overly. How to know if they are?

Do you have the same problem with a generic gcode file from Anycubic or with G-code produce by another slicer than the one you used? On mine, I use the Slic3r version by prusa (called PrusaSlicer as I had a Prusa printer before) and I just change (reduce) the speed (and some minor details like bed size) from Prusa i3 profile and it works correctly (no displacement between layer).

@NeronLeVelu I will investigate this possibility. Thanks.

@NeronLeVelu tried lowering print speed from 50 to 25 mm/s in Ultimaker Cura 4.4.1. Didn't help.

I've had seen similar issues where the gear on a stepper motor was loose and causing layer shifting but only when travelling (due to the acceleration between print speed and travel speed). I spent a long time tweaking belts before it occurred to me to check the gears.

The massive reduction for good results hints that something with the carriage mounting seems to be defect. Can you tighten the belt on the Bed?

@Trish will try it, but all the belts seem to be tight enough.


text:
How to solve this extrusion problem?
I was using this model at 100% infill to test extrusion:

The printer is an old Printrbot which I converted to Klipper, so I'm doing some tests to ensure correct parameters.
ABS filament 3 mm (not 2.85 mm, measured in multiple points), 230°C hot end (optimised with temperature tower), 100°C glass bed. The extruder was calibrated by extruding a known length of filament. The extrusion was checked by printing a single walled cube and was within tolerance of the caliper I used. I used no cooling fan (except, manually, for the first two layers on top of the support to ensure optimal bridges).I skip cooling with ABS to avoid warping, since the air around is colder (no enclosure).
The top surface comes out perfectly indicating a perfect extrusion multiplier, but the outermost perimeter doesn't bond with the second one, see photo:

Something I've never seen before is that the whole print is somehow thicker in a corner where the nozzle stops before raising, and the walls tend to expand with height, so in fact I may have an excessive extrusion, see photos:

After removal of support:

The settings for slicing are (from the gcode, abridged):
; generated by PrusaSlicer 2.2.0-alpha2+win64 on 2019-12-23 at 18:44:54 UTC
; external perimeters extrusion width = 0.45mm
; perimeters extrusion width = 0.45mm
; infill extrusion width = 0.45mm
; solid infill extrusion width = 0.45mm
; top infill extrusion width = 0.40mm
; support material extrusion width = 0.40mm
; first layer extrusion width = 0.30mm
...
; avoid_crossing_perimeters = 0
; bottom_solid_layers = 3
; external_perimeter_extrusion_width = 0
; external_perimeter_speed = 50%
; external_perimeters_first = 0
; extra_loading_move = -2
; extra_perimeters = 1
; extruder_clearance_height = 20
; extruder_clearance_radius = 20
; extrusion_multiplier = 1
; extrusion_width = 0
; fill_density = 100%
; fill_pattern = rectilinear
; first_layer_extrusion_width = 150%
; first_layer_height = 100%
; first_layer_speed = 30
; gap_fill_speed = 20
; infill_every_layers = 1
; infill_extrusion_width = 0
; infill_first = 0
; infill_only_where_needed = 0
; infill_overlap = 25%
; infill_speed = 80
; interface_shells = 0
; nozzle_diameter = 0.4
; only_retract_when_crossing_perimeters = 1
; ooze_prevention = 0
; perimeter_acceleration = 0
; perimeter_extruder = 1
; perimeter_extrusion_width = 0
; perimeter_speed = 60
; perimeters = 2
; retract_before_travel = 2
; retract_length = 0.5
; seam_position = aligned
; skirt_distance = 2
; skirt_height = 500
; skirts = 1
; small_perimeter_speed = 15
; top_fill_pattern = rectilinear
; top_infill_extrusion_width = 0
; top_solid_infill_speed = 15
; top_solid_layers = 3

How can I solve the problems of the perimeters and of the irregular shape?

The problem looks like a heat problem, not an extrusion problem. You don't mention what material you are using, what extruder/bed temps are, no fan usage (at least I don't think I missed it in there). You are spending all this time on extrusion, yet if you're overheating, you could be leading yourself down the wrong path.

The extrusion width and the extruder stepper were calibrated. I also used a temperature tower to choose the optimal temperature. No cooling fan because cooling causes warping in ABS and skipping the fan was the solution I found to avoid warping, together with a tall skirt around the part to shield it from colder air. I added some of the information to the question.

All I can tell you is the part looks melted, like there's way too much heat. Solve that and you've most likely solved the issues you're seeing.

note the following three extrusion width seem off: ; top infill extrusion width = 0.40mm
; support material extrusion width = 0.40mm
; first layer extrusion width = 0.30mm

@Trish I set PrusaSlicer to default ("0") and that's what I got. In fact, Slic3r suggests different values: https://manual.slic3r.org/advanced/flow-math

@Trish I checked and in fact Prusa Slicer modified the rules for automatic extrusion width calculation: https://github.com/prusa3d/PrusaSlicer/issues/3399


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Is there some 3D printing process that puts enamel layers on the 3D printed metal?
I would like to custom design and print a medal (sign of chivalry order). I know that I can make 3D design and 3D print it in metal, but are there 3D printing processes that put some layers of enamel in different colors? Possibly with gradual moves among the colors, something like roses in the Brazil Imperial Order of Roses https://en.wikipedia.org/wiki/Order_of_the_Rose#/media/File:Order_of_the_Rose.jpg ? Is it possible to 3D print structure like that?
As I am googling for such process, I have found that there is 3D ceramic printing process and that is very close to the enamel. There is also transparent color 3D printing attempts, so - feel that this may be possible. But I am new to this field and I would like to get some prima facie estimation of the possibility to print such order-like structure in (any) metal plus enamel/ceramic material.

Welcome to 3dPrinting.SE!

I'm voting to close this question as off-topic because this seems to be a "shopping" question.

I updated my question - I found and put a bit worse picture of the sample order but it is from the wikipedia and not from the open sale offer. Hope, that now the close vote can be removed.


text:
Print copy of real life object, starting with .mpo file or files
I want to make a 3D printed copy of a real object. I have access to a Nintendo 3DS which is capable of making 3D .mpo files. Is there a straight-forward method to convert these into a 3D printable model?

.mpo are stereoscopic photo files, as far as I could discern.

That is correct. The Nintendo 3DS has a 2 lens camera to take the stereographs.

I've come close to what I want with a normal camera and photogrammetry software, but have not perfected my skill in it.

Do you have access to a DSLR camera?

Even a smartphone can be used for photogrammetry -- especially the last couple generations of iPhone with their lidar feature.  There are a number of YouTube videos on doing your own 3D scanning, with the result that one made with a smartphone was about 95% as good as one made with a $20k dedicated 3D scanner.


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Cura's solution to replace corners->arcs to increase corner speed?
I realized that with current Marlin I cannot use Junction Deviation with Linear Advance, see [BUG] Rapid changes of acceleration break linear advance when using Junction Deviation #15473.
Yet, it is very much beneficial to not stop at the corners with high acceleration but rather do a small curve. Is it possible on a G-code level?
Is there a feature or plugin in Cura which replaces sharp corners with arcs to remove need for Junction Deviation in firmware?

Can you clarify whether you are actually having a problem matching the one described in the linked bug report, or just concerned that you might? I use junction deviation and linear advance, K=0.6 for regular PLA, K=3.8 for flex material, and did not observe this problem whatsoever with the former but might be encountering it with the latter.

Also, what junction deviation parameter are you using?

@R.. I am the reporter of that bug... With K=2 there issue is very serious. What board do you have? It is possible that it happens only on AVR... Anyways, it is beneficial to make corners a little less sharp.

@R.. I am using JD=0.022

I have an Ender 3, which is an AVR-based board (ATmega 128-whatever). JD=0.022 is rather low; I use JD=0.08 (computed with formula for converting from comparable classic jerk) which isn't to say you should increase it, just that it's not a problem with your value being excessive.

Is there a reason you're not using classic jerk? I switched to JD because classic jerk seems to be the source of nasty layer shifting bugs, but if your setup isn't affected by that, classic jerk might be a solution.

@R..GitHubSTOPHELPINGICE Surely I currently live on Classic Jerk, that's the only working solution for me at the moment. But I would still be interested to try to round the corners a little bit.

Junction deviation does not produce round corners. It just performs the math for the allowable instantaneous change in velocity components as if it were going around a rounded corner with the configured deviation. See http://blog.kyneticcnc.com/2018/10/computing-junction-deviation-for-marlin.html

And I just confirmed that I'm affected by this issue too, even with K=0.6. Uhg. Switching back to classic jerk and hoping I don't hit layer shifts again... If your bounty expires without an acceptable solution I'll run another out of my rep to follow up.

@R..GitHubSTOPHELPINGICE Yes, I understand that JD does not produce rounded corners. But I believe automatic rounded corners would be beneficial for all 3d printers (R=0.1-0.2mm)

Short of using the arc movement commands (G2/G3), I'm not sure it would be very helpful. Doing a rounded corner with radius 0.1-0.2 mm is going to involve some utterly tiny segments, which Marlin and other firmware don't really like - they make the planner math a lot more expensive and potentially produce compounding jerk, allowing the cornering to happen faster than it's supposed to. The G2/G3 approach may be promising, but I've actually had to omit support for them from my builds to fit Marlin in 128k. :-(

see post processing idea here https://github.com/FormerLurker/ArcWelderLib/issues/33

@VincentAlex ArcWelderLib is awesome, It does most of what I dreamed about. But still as far as I see it does not replace corners with arcs (i.e. it does not change geometry).

@BarsMonster true, I'm also looking for something similar, the easiest would be to do it in 3D model, but that doesnt include infills, bspline fitting from CNC world would give you this, but not written for 3D gcode: https://user-images.githubusercontent.com/4163396/106666173-27fc8c80-659f-11eb-9c45-c443cbf05163.jpg

@BarsMonster an idea, draw your 2D base in dwg, use a script that rounds the corners, extend it to 3D, and slice that, a lot easier than processing gcode.

Cura's solution can be found in the "Jerk Control" settings.
Short analogy; when driving, and a corner is coming up, you basically have two options to take the corner smoothly; you can take the corner with a wide turning radius, or you can slow down. Taking a neighborhood street corner at highway speeds just doesn't work even if there's nobody else on the road; you'll very likely overshoot the corner, if you're in a RWD car you'll likely lose the back end and fishtail (or worse), and the occupants of the car, yourself included, are going to be thrown around violently, to no-one's real advantage other than to say you took that turn at 70.
Back in 3D printing land, something similar applies; as the extruder approaches a sharp corner, it will be disadvantageous all around for the extruder to try to maintain 70mm/s around what's basically an instantaneous turn. Your jerk (stopping the moving axis) and acceleration (starting the non-moving axis) settings are going to exceed the physical capabilities of your steppers and drive belts, making the corner less accurate (and in the extreme, losing steps causing layer shifts), and if your belts are not perfectly tensioned, and really even if they are, you'll get "ringing" (the 3D equivalent of fishtailing as you straighten out after the apex of a turn while driving).
The first option, cutting the corner, is your corner-to-arc replacement; rather than try for an instantaneous turn, just soften that corner by enough that you're within what's possible for the stepper motors in terms of acceleration. This keeps the speed and surface quality high, but necessarily reduces the accuracy of the print to the model.
So instead, Cura encourages the second option; slow down before the turn. Enabling Jerk Control and tweaking the associated settings lets the Cura slicer reduce head speed gradually as the extruder approaches a sharp corner, thus reducing the torque required to stop motion in one axis and start it in another, to something the steppers can actually accomplish at a rate you'd call "instantaneous". This keeps the corners sharp and avoids ringing along straight lines after a corner, at the cost of a slower overall print speed (though not as much as reducing overall print speed to the speed at which the extruder will take corners).
Now, I realize that this is the opposite of "increasing corner speed"; jerk control exists to slow the extruder near corners. However, increasing corner speed is rarely what you actually want, for the reasons stated above. If you really want nicely-rounded corners, fillet them in CAD, and then the slicer will generate a sequence of arbitrarily short linear movements (true G2/G3/G5 curve interpolation from the purely polygonal STL geometry has been experimented with, but currently more trouble than it's worth) which limit the change of velocity of the extruder as it rounds the corner, instead of making the rounding an "artifact" of printer limitations. At fine enough detail levels of conversion to an STL, the results are indistinguishable from a true curve.

Please explain more about which slicer will generate G2 moves from an STL file composed completely of flat triangles.

@Davo Actually, both Slic3r and Simplify3D have experimented with exactly that. But, I will edit to clarify that what really happens is a sequence of polygonal lines of arbitrarily small length (based on a number of variables in both CAD and the slicer), where each move accomplishes the overall goal of limiting acceleration around the corner.

I think this answer completely misunderstands/misrepresents what "jerk control" in Cura is. It simply means that Cura will issue gcode commands to set the printer firmware's jerk limits, possibly with different values for different parts of the print (outer walls, inner walls, skin, infill, etc.), rather than leaving the firmware's default setting in place. It does not mean Cura does any alteration of the movement paths or speed to reduce the physical jerk experienced by the toolhead. It's the printer's firmware that actually applies these settings to how it controls the stepper motors.

https://github.com/FormerLurker/ArcWelderLib does generate G2/G3 (arcs) from linear ones.


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What's the difference between "Initial Layer Width" and "Initial Layer Flow" in Cura?
I'm trying to increase adhesion of the first layer (as well as to fill gaps for a more even surface) by squeezing more material against the bed. The obvious way of doing that in Cura is by increasing the "Initial Layer Flow", i.e. to make the printer push out slightly more material than it normally would.
But then there is also a setting called "Initial Layer Width" and according to the the Cura Settings Guide (see image below), increasing line width will make the nozzle

extrude more material and that material has to flow wider outward. This causes the nozzle to press the material harder on the build plate (...) Not only will the lines be wider ... but they will also be farther apart ... by the same factor, so it would not produce overextrusion

This seems to imply that increasing the initial layer width will automatically also increase initial layer flow. If this is so, the question is: which setting is applied first?
In any case, it seems that the two settings should not be applied together, if they manipulate the same variable (but I have not seen this recommendation anywhere). Which leads me to my may question: what is the difference between the two settings? More specifically (based on my above reasoning): what else does "Initial Layer Width" manipulate, apart from the flow rate in the first layer? Just the distance between the lines so that increasing the setting will lead to fewer lines?

This question is closely related to this question: "Slicer line width vs. extrusion multiplier for layer adhesion?".

And also somewhat to this one (though it is not specific to the first layer): Tuning line width and flow compensation in Cura

Cura option Initial Layer Width will cause lines to be further apart or closer together, based on the value you set with respect to the default. The required filament flow to produce these lines is calculated based on the width of the line and the overlap between lines (and layer height).
The Cura option Initial Layer Flow adjusts flow for the current line width with a multiplier, this means that the distance between lines stays the same. I.e. with this parameter you can overextrude to push more material to the build plate. Note that for a well calibrated machine this is not necessary. My printers use the paper method to determine the initial Z=0 for levelling and never use a wider initial line width or overextrusion of the first layer to get perfect filled mirror finish first layers on glass. However, if (paper) tape is used, the bed may be less flat and overextrusion might be beneficial for better adhesion.
The options can be used together, the multiplier will act upon the calculated flow.

So increasing Initial Layer Width increases the distance between lines and compensates this with a higher flow rate to prevent underextrusion. If want overextrusion (e.g. to compensate levelling issues), I can also increase Initial Layer Flow, which will be applied to the already increased flow of the first layer, right?

@Christoph Exactly!

The typical consensus is that you increase the layer flow initially for better adhesion, though from my experience I decrease it!
My first layer is printed at between 70-75 % layer flow, this gives the best adhesion and best visuals when printing with ASA or ABS.
From layer 2 on I've 105 % layer flow.
The reason is that my first layer is printed "officially" at 0.27mm but in reality, it's more like 0.05 mm thickness. That's manually finetuned while printing after a material change, basically, the thickness is adjusted for perfect grip on the build plate.
When left at 100 % flow rate this will cause ripples or waves on the bottom, it's excess material that builds up along the printed lines.
At 70 % the wrong initial distance is compensated (visually) while maintaining perfect adhesion.
Conclusion: Fine-tune your printer and settings for each material used, a general answer is not possible. Especially true for difficult materials like ABS, ASS, or Nylon.
The best is to watch the printer while it is printing and adapt the mechanical properties first, then fine tuning the flow rates.

authors: محمد ابو الجود


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How do I remove a 3D print stuck to the glass build plate
I printed a model and now I can't remove it.
I have been chiselling away with a putty knife and made little or no progress.  I even heated the bed up to 70 °C.  That really didn't seem to help.
Last time, I put it in vice, and tried to free it that way, but instead I broke the glass.
Suggestion?

Use a stick/release agent (glue stick or hair spray or a dedicated print spray) or let it cool e.g. put everything in the freezer or refrigerator, it will pop off. There are multiple questions here that will hint to these solutions. Good luck!

Look into the WhamBam System for future prints.  Basically: a magnet is stuck on the aluminum bed. A print surface of PEX is stuck to a flex steel sheet. The sheet is then place on the magnet. When the print is done, the flex steet sheet is lifted off, after maybe 30 seconds, the flex steel is flexed, parts pop right off.  Print surface is very smooth, like glass. I have previously posted videos of if working.  We changed over after having to chisel a PLA box off of blue tape on the aluminum print bed.

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

I am using PLA.  I did not use any spray of any kind adhesive or not.  The binding force seems to increase with printed surface area.  Objects of greater than 1-2 sq inches seem to bond impossibly with the surface.  Its bonding force is so great I would not even consider adhesive.

I had to use a lot more than a few drops, but it works.  Thanks.

In the future print at 60 °C and try to see if by cooling it will pop out by itself

i'm in a similar boat, but i've got the creality ender 3 tempered glass bed.  would you recommend the same method, or a different method?  this one:  https://www.amazon.com/Creality-3D-Platform-Tempered-235x235x3mm/dp/B07FSM8DK9/ref=sr_1_5?crid=5Z96VKXLZTEF&keywords=ender+3+glass+bed&qid=1577808496&sprefix=ender+3+glass%2Caps%2C159&sr=8-5

@DForck42  I found a local vendor who made me a custom sized sheet of glass.  As long as it is tempered glass you should be fine.

I don't have a glass bed, but I've had a lot of luck with using dental floss to get stuck prints loose.
If you can get the floss under the edge of the print, then you just pull it through to the other side.
This technique takes some practice but works really well once you get the hang of it.

I tried yesterday with an ABS print stuck to blue tape. It cut the tape. I ended up removing the print with the tape.


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Spiral bevel gears in OpenSCAD
I'm trying to design a "Lifting Table" in OpenSCAD which will consist of 2 concentric cylinders. On the inner cylinder I plan to mount 3 un-powered bevel gears vertically plus a 4th powered  one each at the proper location/angle to interface with external cylinder's spiral bevel gear and keep the external cylinder level.
OpenSCAD's involute_gears library makes a bevel gear pair that is close to what I need, but the bigger gear is flat instead of a spiral.  How can I get the bigger gear to be a spiral and more than one rotation (level) 720 degrees for example?

Did you get the parametric file for OpenSCAD? Have you found the parameters which represent the change you'd like to make?

I think I did, I'm using involute_gears.scad for the parametric file. I have not found parameters to make a spiral gear.

What I picture you are seeking is a large diameter worm gear pinion (bigger gear in your question) but with teeth instead of a flat surface. That's going to be quite challenging!

Are you looking for a library like this parametric "Gears Library for OpenSCAD"?

I read this question a few months ago, and thought I knew what you wanted.  Re-reading it now confuses me a little.
But, I think you may be asking for a large, flat surface with a spiral in it, like the tightening mechanism in a 3-jaw chuck.  In effect, are you using the large cylinder as a worm gear to drive four gears which ride on it?
I thought you wanted more general bevel gears, and today I found a package in OpenSCAD that looks quite good.  it is found at: https://github.com/dpellegr/PolyGear
If this is the answer you were looking for, great.  If not, please comment here and I will delete this answer.

Wow, saving that link.


text:
E3D V6 nozzle seized into heater block
The 0.4 mm brass nozzle in my Prusa i3 MK3 is worn out - the extrusion hole is visibly larger than the replacement nozzles I have to fit. So I’m trying to replace the nozzle.
Unfortunately the nozzle seems to be stuck in the heater block. So far I’ve tried:

Heating the hotend up to 285 °C, rotating the heater block slightly and trying to unscrew the nozzle with a wrench. (I exactly followed the Prusa YouTube video on changing nozzles).
Leaving the hotend at 285 °C for 15 minutes and trying again - I found some other reports online this had helped. However it made no difference in my case.

In an effort to try and remove the nozzle from the heaterblock, I’ve now accidentally bent the heatbreak, so I’m going to have to replace some or all of hotend. But I need to get the nozzle out, so I know which parts to order - if the nozzle breaks off in the heater block I’m definitely going to need a new heater block as well.
What else can I try to free a seized nozzle?
This is the original factory-fitted brass nozzle, and the hot-end was pre-assembled in the kit I received.

Make sure you're turning it the right way! If you're looking down at the extruder the nozzle unscrews CW, not CCW.

Good point - however I am definitely rotating the right direction - CW. This is where following videos is a great help.

Nozzle clogged with ABS can be soaked in acetone. Regarding whole heatblock, all electronics would need to be removed first. But maybe this idea is still of some use...
But to the point: if overheated PLA can change to black coal, then heating the setup up to 285 °C for long period seems to me like asking for trouble. Because all remainings sandwiched in the thread will change into obsidian, won't it?
So I bet it depends on material, and maybe there is some chemical solution for that?

Try to,
First, remove the heat block from the extruder/heat sink. Heat the hot end to ~ 230 'C. Then try to unscrew the nozzle while holding the heat block with a wrench or plier. Be extra careful with the heat block and with the plier.

If by force, then in limited set - I agree. I also like Trish's practice to use a small vise to hold the block.


text:
How to know if I should replace my power connector?
I have seen several postings in forums about the power connector on some ender 3's being bad and causing issues or just burning out, potentially causing a fire.
How can I tell if I have the bad power connector?

Where is the connector located precisely?

If you can measure the voltage at the main board where the bed power line is attached, or at the last point in the wiring prior to the connector, then measure the voltage at the bed, you can compare the difference to determine if there is loss related to a failing connector.
One certain indication of a failing connector is to separate the components of the connector and see corrosion, discoloration or any sign of burning. The Robo3d R1+ used 10 ampere connectors and the bed draws 14 amperes, according to the research I've done. When I discovered that information and separated the connector, it was an easy answer, as one side was scorched and the pins on the other were corroded and discolored.
Another method, not for everyone, is to use an IR camera and examine the leads carrying the power to the bed. The failing portion will be absorbing some of the power and heating itself, which will show up as a bright portion in the power path.

Unless the connector has already started failing - by getting warm, creating a voltage drop, eventually melting away -, you will have to remove the shrink tubing near it.
Earlier batches had the connection crimped by the supplier of the cables, which is wrong. XT60 connectors should always be soldered to.

If the connector or the wires are hot, you have a severe problem.  The heat of a high-resistance connection encourages additional oxidation and corrosion, which escalates the problem.
If the wires do not get warmer as they approach the connector, you don't have a problem, at least not yet.  If the wires get warmer as you approach the connector, you probably have a budding problem.
Soldered connectors are not generally used, with crimped connections preferred.  The copper-to-copper connection is lower resistance than copper-tin-copper.  Also if something happens to the connector pins which cause them to heat (such as corroded surfaces), solder can melt.
Another answer suggests that the XT60 connector should be soldered.  A quick look at some spec sheets show solder-cup connections which should be soldered and aren't suitable for crimping.  I have not seen that there are no XT60 style connectors with crimp connections, so I can not rule out the appropriateness of a crimp connection.


text:
Inductive Sensor Causes Print To Stop
Just added inductive sensor to my printer (MKS Gen L Board) using Marlin 1.1.9
After some tweaking it works great!
The problem is when it starts print the sensor detects the bed and stops the print because it gets triggered.
Can I tell Marlin to ignore the Z-min readings while printing?

Are you using the sensor as a normal endstop or did you modify the firmware to enable automatic bed levelling?

i was able to solve it, here is my Configuuration.h file https://bitbucket.org/OrAzran/marlin_sxw1/src/pinda/Marlin/Configuration.h

Great! Please post the solution as an answer. Copy the interesting parts of the configuration file in the answer. This may help other users with the same problem!

Solved the problem, I was missing this line:
#define ENDSTOPPULLUP_ZMIN_PROBE

Apparently the sensor required a pull-up to better define the signal.

Thanks for posting the answer! I removed the link to the configuration, the pull-up hint should be sufficient for a self-contained answer. Also, linking to external content is usually not very wise as all things on the internet die from link rot eventually.


text:
Why does my PLA filament keep snapping?
Why does my 3 mm PLA filament always snap near the spool some time (usually a few hours) after a print has finished?
I have had it snap mid print but this is quite rare.
I have 3 rolls of 3 mm PLA filament from Velleman and 3DPrima. They all exhibit this behavior. They are between 2 and 3 years old. Each roll is stored in a foil bag with some desiccant, although this was not the case in the first year. The temperature in the room ranges between 14 °C and 18 °C in winter and rarely up to 30 °C in summer. Current relative humidity is 49 %. In summer I think I have seen it as high as 70 %. I baked one spool in the oven at about 50 °C for a few hours but this does not seam to have helped. When I remove the loose end of filament from the extruder after it has broken, some length of it seams to snap easily and some of it will just bend.
The printer has a direct extruder so there is no bowden tube.

Welcome to 3DPrinting.SE!

I believe this is one of the disadvantages of 3 mm (vs 1.75 mm) filament - coiling or uncoiling it puts it under a lot more strain.

PLA seems to become brittle with age. Micro-fractures develop on the surface, and they will grow if filament is taken off the spool and held straight. This behaviour does not seem to be linked to moisture content. The best course of action is probably to use PLA quickly. Don't give it time to age.

Therefore PLA is a perishable good?

@user77232 Some user claim to be able to store it for years. Mine seems to last about a year on the roll.

I know that moisture breaks the long chains, but I never heard of micro cracking,do you have a source for that. Note that all materials have defects that can act as start points for cracks, but what drives the cracking when it is stored?

"age" is better described as "poor storage conditions". Some homes can store PLA without enclosure, others need to store it in airtight boxes.

When water gets absorbed into the filament, it causes some of the long chain polymers to break. This is a permanent reaction that cannot be fixed by baking the filament, which typically results in the embrittlement of the material. This is true for both the filament and the printed part.

it can be prevented by proper storing in a dry place. brittle filament also can be used with the proper setup that avoids bending and unbending.

PLA snapping is pretty universal.  The best countermeasure is to always remove the filament from the printer after a print and place it in a low-humidity chamber.  Other answers speak of moisture-induced micro-cracks, for which I have no evidence for or against.
This has occurred for me when I've been lazy about putting filament away after a print.
I've seen it with several brands of PLA, perhaps more often with filament with a glassy surface finish.
My filament is 1.75 mm.  3 mm filament may be more susceptible because of higher stresses on the surface for the same radius bend, or straightening from the same radius spool.


text:
Replacing jerk with ridiculously high acceleration?
After a string of one problem after another with both classic jerk and junction deviation in Marlin, and coming to understand that the whole mathematical model for both of them is rather bogus (as I understand it, there's nothing to keep jerk from junctions of multiple tiny segments from accumulating to unbounded near-instantaneous chage in velocity), I kinda want to just disable jerk entirely (set it to zero). But of course this would give really slow printing.
What I'm wondering, though, is if it makes sense (and if so, how) to try to compute and use an acceleration value sufficiently high to achieve what jerk was trying to achieve, without it.
Mechanically, if a printer can handle a given jerk without skipping steps or harmful vibration, it should be able to handle acceleration high enough to achieve exactly the same stepping at corners/junctions. However, perhaps acceleration limits also involve current to the motors, heat dissipation at the motors/stepper drivers, or other factors that make "instantaneous" extreme acceleration okay but sustained extreme acceleration bad. (Of course, without extreme max speeds, extreme acceleration should only take place momentarily, in some sense proportional to as much a jerk takes effect.)
Am I crazy for thinking about doing this? If not, what would be a good model for determining the appropriate acceleration to try?

Not an asnwer, but for information: jerk is a trick used by Marlin to cope with limited processing power, since it simplifies acceleration calculation. Klipper firmware, not having processing power limitations since it runs on a host computer, does not need and use the concept of jerk but calculates pure acceleration profiles. See https://www.reddit.com/r/3Dprinting/comments/9zy863/what_does_the_jerk_setting_in_marlin_do/ead1bie/ and https://github.com/KevinOConnor/klipper/blob/master/docs/Kinematics.md

In order to evaluate whether this is possible, it's necessary to realize that following a curved path with zero jerk (in the classic jerk sense) requires stopping and restarting at each junction point in the piecewise-linear approximation of the curve that occurs in the gcode. This is because there's no way to accelerate/decelerate the individual axes continuously through a non-smooth corner. So paradoxically, as the number of segments approximating a curve goes to infinity, speed goes to zero. If the length of any one segment is bounded below by a constant, then acceleration can be chosen high enough to ensure that arbitrarily close to 100% of the segment is at full nominal speed. For example, for a minimum length of 0.1 mm, speed of 60 mm/s, reaching speed in 10% of the nominal segment time (1.6 ms) would take an acceleration of 360000 mm/s². So, not happening.
On the other hand, with very low but nonzero (classic) jerk, just to handle the matter of smooth curves approximated by small segments, this might be practical. Just looking at 90 degree cornering between segments long enough to run at nominal speed, to match the time spent cornering with 60 mm/s speed, 20 mm/s jerk, and 3000 mm/s² acceleration, it should only take 4500 mm/s² acceleration (original, scaled by 60/(60-20) to account for having to decelerate/accelerate to/from 0 instead of 20). This is completely reasonable.
How small can jerk be without breaking motion for approximations of smooth curves? As the number of segments approaches infinity, the lower bound should go to zero. For a circle approximated with 15° steps, one component of the change in velocity looks like it can be around 25%, so "25% of nominal speed" seems to be what you get. Oops. For 60 mm/s, that's 15 mm/s. Not very low at all. I may have gotten this math wrong; I'll review it later. But it doesn't look good for declaring this practical.

authors: Емил Станчев


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Which material "creeps" (plastic deformation) the least (or nothing at all) under pressure after being printed?
I would like to build a standing shelf where the supports which hold each successive plank are 3D printed (to obtain special shapes).
However, I read that PLA flows under constant stress/pressure. Still, this doesn't stop the author of the article from using PLA for a hanging shelf, which obviously is subjected to constant negative pressure.
Which material suffers the least from plasticity/non elastic deformation under stress?
Answers with data for multiple materials are welcome.
I found that the phenomenon is called "creep" and is related to ISO 899, but I couldn't find any data for the common filament plastics and I don't know the theory behind it, so I'm not sure whether it's unavoidable or it appears after a threshold stress is reached.
Information: it's a living room shelf which will hold books and other stuff and is supposed to last a decade. I will of course add a safety factor and I could even fix the planks to the wall (in hidden places), but ideally the 3D printed material should have NO creep.

Would you be willing to spend money on an abrasion-resistant nozzle so that you could use carbon fibre-reinforced filament (which also costs more)?

I was thinking about non-reinforced filaments, but if you can find creep data and/or how to calculate a threshold to completely avoid creep for reinforced materials, I think the answer would be fine. I don't know how creep works (is there a threshold? is it unavoidable for plastics?), but if a reinforced filament is the only way, or if a pure filament requires twice as much material to avoid creep, a reinforced nozzle is definitely not an issue.

Potentially this question could be moved to the Chemistry section of SE.

I don't think it would be a good fit for Chemistry.SE as it is about the mechanical properties of the material. As I don't have much experience of 3D-printed items under stress, I can't really give an answer. Maybe you could print one support which will take the maximum forces and keep it loaded at three times that for some time. If it fails in a month, you know the material wasn't suitable. Or just print new parts every time the old ones are looking suspicious. Or there's lost-PLA casting for metals.

@AndrewMorton you are right, Engineering.SE would be better. Related question (unanswered): https://engineering.stackexchange.com/questions/19111/long-term-deflection

We're doing 80+ °C high load inter-laminar stress rupture and 4-point-bending tests on fibre reinforced nylon that has been fabricated with tape robots, that seems to be very creep resistant! I'm with @AndrewMorton, various brands sell nylon/CC filaments, the ColorFabb filament prints very well and has a nice matte finish. But as you mention, it also depends on the design, if the stress is low there will be (virtually) no creep.

Your question can not be answered theoretically -- only empirically.
You need to print some trial brackets with materials of interest and measure them.  The question is: under what conditions should you test them?
The problem is that creep involves both compression and tension, and the behavior may be different.  It is also impossible to fully translate material specifications into component behavior without a really good model that includes the details of the infill, adhesion to peripheries, and all the microscopic detail of a real 3D-printed part.
The problem with typical PLA may be the low temperature.  Raising the temperature of a normal PLA printed object to 160°F (70°C) softens it to the point of nearly being limp.  I have used this for force-fitting PLA parts by warming a pot of water and placing parts in it for a few moments.  That temperature is hotter than your room, but a hot summer day in the sunshine could soften the part to the point of failure.
For anything load bearing, I would want a material with a higher plastic temperature.
There are PLA formulations which are annealed after printing.  This is claimed to allow the PLA to slowly recrystalize and become both stronger and usable at higher temperatures.  I don't have experience with this.
Depending on your printer, you can also consider using a higher temperature filament, such as ABS or PC (polycarbonate).  PET-G is a little better than PLA, but it softens at a lower temperature than ABS.
As important as the material itself is the anisotrophy of the printer parts.  Be sure to print the parts so that the major stresses are along the strongest axes, typically X and Y, and not along the weaker Z asis.  Choose your infill to contribute to the strength, and use plenty of it, or design the part so that the infill is not intended to contribute to the strength.

mind using °C too, as printers are operated using °C usually? °F is not used in most countries worldwide.

I know, and usually C is used, but in this case, because it represented the thermometer I used for the purpose, and I was using temperature below the boiling point of water, I thought the F would be appropriate and stick out as being an unusual temperature for 3D printing.  I can edit in the C values.

Thanks! the main benefit Celsius has, it is easily transferred to Kelvin.

I had one of those Kelvin thermometers, but it stopped at zero.  I figured it must have been a bad design.  :)

authors: Александр Аникин

authors: ชัยธวัช พาลึก