text:
Cura printer settings for Alladinbox SkyCube 3D
I've just purchased an Alladinbox SkyCube 3D that I want to use to print board game miniatures and other fun stuff.
However, the instructions do not give the settings I need to put into software like Ultimaker Cura, and this is where I need some help so that I can generate the G-code files from models I download from MyMiniFactory.
I know it uses PLA and the extrusion temperature should be 210°C. However, I need help with the other settings.
Can someone please point me in the right direction? Is there a better software I could be using? Where can I find settings?
Thanks.
UPDATE: For those wondering "what" settings, I would probably start with the printer and extruder specifications. The following is my best guess.

and

I'm basing these settings on the device specs on this page:
Link to Alladinbox specs

we also don't know what is needed :), could you be more specific? Mainly you need to define printing capacity and firmware flavor.

Please see my edit. Unfortunately, I don't know the firmware. Marlin is just the default in Cura.

Okay, after some research and experimentation, I've come up with some settings that seem to work.
Firstly, some specs about the Alladinbox SkyCube 3D:

Firmware: Marlin
Nozzle diameter: 0.4 mm
Nozzle speed: 20 to 70 mm/s
Layer thickness: 0.1 to 0.4 mm
Printing area: 110 x 110 x 125 mm (WLH)

Note: There is NO cooling fan present and the base is NOT heated.
Now for the actual printing settings...
I'm using the PLA supplied with the printer so far, and it works well at a nozzle temperature of 210C.
I'm printing at 0.2 mm per layer, which seems to afford to a good level of detail. I've printed a scanned Greco-Roman basin, and the details are very nice indeed.
So far I'm using a 20% line filling, and this seems to give the structure a good solidity and strength. I'm also operating the nozzle at its maximum speed of 70 mm/s and it seems to work just fine.
Obviously, I'm still experiments, and different materials may require different settings, but overall I'm very happy. I hope this post helps someone.

Ultimaker Cura comes with pre-defined profiles for various materials. PLA filament is present in between them. This could be a good starting point to derive your specific profile for your own material. To do we usually print test objects and look at the quality of the product. Test prints can consist of simple X-Y-Z test cubes, temperature towers, retraction test prints, a "Benchy" or many more.
Generally 210 degC is pretty high for PLA, but may sometimes be necessary when printing high speeds. Just copying the material profiles from someone else may not work for you as it might involve different printer brands and even within the filament brands variations in between rolls of a single line may require additional tweaking.

Edit:
The original question appeared to hint at material settings, but the OP changed the question, hinting on printer settings with accompanying screenshots how to setup the printer in Cura. However, the OP's answer (that the OP accepted) also includes material and other slicing settings (infill, layer height, speed). To help other people I undeleted my answer which discusses using the standard Cura profiles to work on to make your own derivatives.

To start printing with Cura, you can select standard printer (aka Prusa i3) and set the x,y,z dimensions in the machine properties window -  it is a safe point to start.
Then you could print a test cube and try to dial in with speed/temperature setting to get the best quality.


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Extruding a (wall?) in Fusion 360?
I have a model that has walls with a volume of 0.00mm that I want to extrude so I can 3D Print it.
I was unable to convert it into a normal body in order to extrude it.
In addition I was unable to figure out what kind of body type this is, here a picture.
And here a Picture of the Model.
How can I extrude these walls?

I am not sure but I think if you take one section, duplicate it, offset it, then Union and Make Solid (Meshmixer command names), you may end up with a thick wall.  I am not familiar with F360, but: can you select segments and define the value of their third dimension?

I think the command you're looking for is "Thicken". Recent versions of Fusion360 have moved this around, but now it should appear under the Create Panel when you're in the the Model mode (see the image below for details). A detailed description and short screencast on the Autodesk website here.

source: Stack Exchange

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

sort: votes


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3D printing template material
I want to print a structure that I can embed in a resin and later dissolve. I know that some fancy 3D printing systems have raft materials etc., that can be printed and later removed easily.
Can any one suggest a 3D printing material that can be dissolved in say water or another readily available solvent?

Google search: water soluble filament

MIght want to start by listing solvents you can't use because they attack your resin

@professor79, Stack exchange and Google give fundamentally different types of help. Sure, Google may tell me what could work, but stackexchange actually gives insight I wouldn't otherwise find as easily that often makes a big difference...

Wash-away filament used for support in PLA printing is typically PVA, which is completely water soluble and may serve your purpose. It is easily 3D printed as the primary filament and attaches well to the build plate.
Many 3D printer filament suppliers will carry this type of support material. It is important to keep it in a sealed bag with desiccant as it will absorb moisture from the air, rendering it useless for printing.
One such resource is MatterHackers which prices a half-kilogram at US$45. The link provides suitably appropriate information:

PVA (Polyvinyl Alcohol) is a water-soluble material that is often used
  as a support material, but can also be used to print independently.
  PVA supports are useful for complex designs where removing support
  material manually is difficult or impossible, but leaving the part in
  a water bath overnight will completely dissolve this material.

This is fantastic. The resin I want to dissolve the support out of can transport water, so this should be good.

Not only PLA, PVA can also be used as support material for nylon. Printing PVA is not always successful even with the Ultimaker 3 special core for PVA, it clogs easily in my experience.

Im really having trouble getting the PVA to dissolve away after printing inside of weird internal structures. Are there tricks for this?

hot water works better than cool water and agitation improves removal. If the part will fit in an ultrasonic cleaner, you'd get water heating from the ultrasound as well as microscopic bubbles helping with the agitation. Refresh the water periodically, as the PVA concentration will increase as more dissolves, reducing the rate of removal.

ABS dissolves in acetone. Indeed actone can be used to clean up 3D prints, see What's smoother? Acetone treated PLA or ABS. PLA maybe not somuch as ABS, see the same post.
PLA dissolves in any chlorinated or fluorinated solvent, such as THF or Chloroform - both of which are significantly more hazardous than acetone.
Hence, as always take care when using solvents, see Safety precautions when using acetone
Also, as filaments are often not pure ABS or PLA, due to additives and dyes, etc., then the solvent may not dissolve the 3D printed part completely, and you may be left with a deformed, rubbery residue.

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


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Problem with 3D printer not accepting new print gcodes
Ok so I am trying to print a new fusion 360 file that I converted into an STL and then into gcode using cura and I got the gcode loaded onto the SD card and mounted into my Monoprice 3D printer, Maker Select 3D Printer v2, and tried to do a print. Now here is the strange part. When I choose "print file" and then select a gcode to print it takes me back to the main screen and from there the 3D printers screen displays "Printing...0%" for a few seconds. After this it just goes back to displaying "Stepper Disabled." And if it is not stepper disabled it is just a blank screen. I tried to mount and print multiple gcodes just to make sure that it was not the softwares fault and low and behold I was running into the same issue.
Now before using today all of the gcode was printing just fine, however for some reason today it decided to give me this issue.

Never mind. It turns out that I only needed to reformat the SD card. :D

Nice, I will to reformat a micro SD that is read some times.

Now that I think of it, I actually have experienced  similar problems that got away when the SD card was reformatted as well. Maybe this question should be saved for eternity after all! :) Please add the answer to your own question (should be possible within a few hours) so that you can accept the solution and people can vote.

I rolled the edit back because it was removing information like the printer and slicer...is it really necessary to go this hardcore with edits?  I'm sure everyone could read it the first time.

Determined Solution
Ok so after an hour or so of searching and trying to figure this out, I found that the best to deal with this is by reformating the SD Card once the problem starts.
Now I had to make sure that I made a backup of all the files so that I could recover them once the process was complete.
Also please note that the problem may have been with one of the files on the SD Card so backing up the SD Card and then restoring the files from your place of storage for the SD card may or may not work.
Also, this problem and solution were done on a Monoprice 3D Printer V2 so I am not sure how this would work with any other 3D printer.

As you found out, sometimes the SD cards need reformating.
And if they came with the printer they could be fake (Fake capacity), when you try to upload more than its real capacity they will just corrupt.
My Anet A8 came with an 8GB SD card and it turned out to be 128 mb. With RMPrepUSB you can do a capacity test and format it to the real capacity.


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How can I generate and export the support structure for an object as a mesh?
I want to render a visual of an mesh I created with a real support structure that a 3d printer would print. I haven't had any luck in finding a way to do this. Is there a program (ideally free) that can generate the proper support structure and export it into a mesh format, like .stl or .obj ?

Why do you need export as object or STL? if the gcode has all data to be printed and previewed before printing if desired.

@FernandoBaltazar I want to render the original object and the support structure in my 3D program. I'm trying to create a graphic that shows a real support structure for an object, and I want to have full control over how I compose the scene.

You could try Meshmixer its free and the supports generated with it are embedded into the 3D model.
Here you can find a reference on Meshmixer supports. Meshmixer is well known for making custom supports for complex 3D models.


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Connecting (Anet A8) 2004 display to MKS GEN L
Was anyone able to connect the default Anet A8 (2004) display to a MKS GEN L?
I've tried direct connection with re-wiring, and see white squares there, but I'm only able to see white squares on the screen as on screenshot:

Wiring:

The code that is currently used for the display :

Config.h uses #define ZONESTAR_LCD.
Also #define MOTHERBOARD BOARD_MKS_GEN_L
Config_adv.h uses #define LCD_PROGRESS_BAR
Pins were left as they were in config file.

Also I've tried replacing them with this numbering (which comes from MKS spec):
35  16  25  29  5V
37  17  23  27  GND

Are you aware that the default Anet A8 (ZONESTAR_LCD in Marlin firmware) has no SD card slot, nor does the MKS GEN L, so you would either need to get another display with SD card slot or get an external SD card reader. Unless you print through a printer server (e.g. like OctoPrint), having an SD card reader is a must have.

Please add more information what you did and what does not work. E.g. post the link to the re-wiring and which firmware you use.

I've got the Anet A8 display working on a RAMPS 1.6 (which basically works exactly the same as a RAMPS 1.4 board). Note that at first connection I got exactly the same display when I connected the LCD to the EXP1 and EXP 2 headers using the "smart adapter".
To get the Anet A8 display working on a MKS GEN L (which is basically a RAMPS board as the pin layout of the RAMPS configuration are used in the firmware of the MKS GEN L) you need to forget about the EXP1 and EXP2 headers and the "smart adapter" for the Anet A8 display. Instead you need to connect the Anet A8 display to the AUX2 header. The only thing you would have to do (from the hardware side) is to switch the cables that are connected to the pin 1 and pin 2. I used Dupont connectors and cables. Pin 1 on AUX2 is VCC and pin 2 on AUX2 is GND, this is reversed on the Anet A8 display.
From the software side you need to set the following constants:
#define ULTRA_LCD   // Character based

and
#define ZONESTAR_LCD

Please note that in the photo you still see the "smart adapter" with flat ribbon cables, but they are not connected to a screen, the reason for them being there is I also tested the full graphic discount controller in a previous session. The Anet A8 display is connected to the flat ribbon cable on AUX2 just above the top-left most stepper driver.

UPDATE:
At the time of writing and the use of an older Marlin version, this required to set #define ULTRA_LCD. In Marlin 1.1.9 you do not need to set #define ULTRA_LCD explicitly, this is now intrinsically set by #define ZONESTAR_LCD. To elaborate on this, the #define ZONESTAR_LCD sets the constant #define ULTIPANEL which sets constant #define ULTRA_LCD in Conditionals_LCD.h.


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I want to use my 2 extruders simultaneously
I am using 2 extruders. Is it possible to use them both at the same time.
Now I can use one at a time but not both at the same time.
Is there a gcode that supports this action?

Does any of the answers helped you to get an answer on your question or helped you come to your own conclusions then please do vote and accept an answer. This helps us reduce the unaswered questions list. Found an other answer (then the already posted) yourself? Please add that answer (and accept after 48 hours) to share your experience with the community. If you have not been able to address the problem please update your question.

To print with 2 extruders simultaneously you need a firmware that supports that. Luckily, there is a firmware called Sailfish that is able to do that. The feature you are looking for is called Ditto printing.
Sailfish firmware is found here

nice find with the firmware - did you used it? how it goes?

@profesor79 I'm in the middle of adding another extruder, so I came across this firmware. I have not tried it yet, or don't know if I'll use it. Lots of people use it.

That depends what you want to achieve.
If you want to get a clone of your thing then - 0scar answer is a go for it.
In early days, I was thinking that this could speed up my printing, if both extrudes could work simultaneously - a piece here, a piece there on the same layer. But then I realized that this will be a good source of oozing (even with retraction a nozzle can touch already printed area by another nozzle) so my printout could get material drops.
Moreover, in most cases, we don't want to have one color printout scratched by another nozzle as that also decreases quality and visual outlook of printed thing.
From hardware point - there could be more strain on the CPU to drive next stepper (depends on the solution) and that can lead to slower printing alltogether.

If you want a ditto printing is not mandatory to have a specific firmware (or g-code), you only need to add extruder to your end effector and - because of electrical power requirements - add further stepper driver for further stepper motor.
Please note that the maximum footprint of your printed object is less than the extruders distance, for obvious physical reasons, therefore is not that common to see, the typical dual extruder goal is to use different filament/color.
Of course, you have to achieve a notable calibration skill, and of course you have to modify the electronics of your printer (but this can be done quite easily, you only have to share the enable/step/dir signals with all the stepper driver).
This has been already done with the MPCNC project.
Otherwise, if you want something more flexible, there are commercial printers with independent extruder. This one, for example
Edit: i can't comment your answer yet, but can you describe your current 3d printer setup? Because if you have the two hot ends that are only few mm apart it makes little sense to ditto-print something.


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3D Printing of a Swellable Material
I recently saw this video of super-swellable polymer and felt inspired. Printing a swellable structure would be sort of interesting. However, sodium polyacrylate isn't a printable material. Does anyone know of a material that is? Preferably, swelling activated by water.

sodium polyacrylate is also the primary component of a product known as water beads, small spheres which increase substantially in size when placed in water. For 3D printing, one might expect that the powder could be combined with filament material during manufacture, although I am unfamiliar with the reaction of sodium polyacrylate and heat. It's an interesting thought experiment to consider combining PVA (water soluble support) and sodium polyacrylate. When you add water, the entire structure crumbles?

@fred_dot_u - Would you like to make that comment an answer?

If you believe that it's a suitable answer, I can indeed convert it, but the question was if a material exists and I don't know of any, hence my hedge-type comment.

The video treats about sodium polucarbonate (C3H3NaO2) this is a superabsorbent polymer has the ability to absorb as much as 100 to 1000 times its mass in water. This is used as desiccant on products that moisture can be a problem basically during storage prior selling. The video shows the water how is trapped inside the particles of sodium polycarbonate, this happens inside a diaper or any product urine odor absorbing, also is used on waste liquid control.
Also you can find something similar on some products that has a little bag that says silica gel (SiO2).

I mean, that's cool and all. sodium polyacrylate is the same. However, I was hoping for something 3D printable.

@User2341 There is no data about melting point of this material, however can be dried again at 150°C, so assume that can be mixed with other material buy it will result as fragile. If you want to use for some action figures I recommend to use a molding process; I remember that we used to play with a kind of toys that grows on water.

My real hope in asking this question was to find something ready to be printed, rather than make my own printing material

There appear to be at least two papers which revolve around the use of hydroxypropyl cellulose (HPC) filaments.

This proposal/article, from Journal of Drug Delivery Science and Technology 30 July 2015 seems to, at least, partially fit your criteria, 3D Printing by Fused Deposition Modeling (FDM) of a Swellable/Erodible Capsular Device for Oral Pulsatile Release of Drugs by Melocchi et al.:

The aim of the present work was to explore the feasibility of fused deposition modeling (FDM) 3D printing in the manufacturing of capsular devices for oral pulsatile release based on a swellable/erodible polymer (hydroxypropyl cellulose, HPC). This involved an experimental evaluation of the possibility of fabricating hollow structures via FDM and the production of HPC filaments by hot melt extrusion (HME), which are not commercially available. Moreover, the set-up of appropriate computer aided design files had to be faced. A twin-screw extruder equipped with a rod-shaped die and a purposely designed pulling/calibrating device as well as a MakerBot Replicator 2 3D printer were employed for HME and FDM processing, respectively. Bodies and caps with satisfactory physico-technological properties were obtained. The release test of assembled capsular devices pointed out a lag phase before rapid and quantitative liberation of the drug. The morphological changes undergone by the device when in contact with water and their release performance turned out comparable with those of analogous systems fabricated by injection molding. The possibility of manufacturing capsular devices for oral pulsatile release by FDM 3D printing starting from HPC filaments purposely prepared was thus demonstrated, and the real-time prototyping potential of FDM was assessed.
3D Printing by Fused Deposition Modeling (FDM) of a Swellable/Erodible Capsular Device for Oral Pulsatile Release of Drugs | Request PDF. Available from: https://www.researchgate.net/publication/282800986_3D_Printing_by_Fused_Deposition_Modeling_FDM_of_a_SwellableErodible_Capsular_Device_for_Oral_Pulsatile_Release_of_Drugs [accessed Jul 30 2018].

Also, from Manufacturing and characterization of £D printing filament by tailoring materials by V. Mirón, S. Ferrándiz*, D. Juárez, A. Mengual

There are also references to the pharmaceutical field’s manufactured materials as it reflects Melocchi 4 in his
paper about filaments based on insoluble (ethylcellulose, Eudragit RL), promptly soluble (polyethylene oxide,
Kollicoat1 IR), enteric soluble (Eudragit1 L, hydroxypropyl methylcellulose acetate succinate) and
swellable/erodible (hydrophilic cellulose derivatives, polyvinyl alcohol, Soluplus1) polymers were successfully
produced

There is also this, which refers to the Melocchi paper above, Fused Deposition Modeling (FDM) 3D Printed Tablets for Intragastric Floating Delivery of Domperidone:

Domperidone (DOM)... DOM was successfully loaded into hydroxypropyl cellulose (HPC) filaments using hot melt extrusion (HME).
...
Several novel gastroretentive delivery systems have been explored to overcome the shortcomings above, including polymer bioadhesive systems, swelling and expanding systems, high-density systems and floating systems3

An image of the filament is shown in figure 1:

However, as a commercially available filament, you might be out of luck, or at least hard pushed to find one.


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How can you both reliably print and remove your item, without breaking it when detaching it?
I have had problems with items sticking on the build plate, especially when they were big (as they didn't stick well, they corners warped -> all kind of problems).
I also wanted to upgrade my printer (Scratch XYCore-Bowden) to have the ability to use flexible filament so first I modified my extruder motor/cog-wheel so it pushes the filament straight into the Bowden tube (classic modification).
This worked okay for small parts (as was the case with PLA).
The heat-bed seems to flex when heating in an uniform manner so it's not perfectly flat which means the Marlin 3-point test doesn't work out.
To alleviate this I added a borosilicate glass on top of the heat bed for perfect 'flatness', but the inductive sensor didn't reach through those extra 3 mm of the glass, so I bought another inductive sensor (old was 4 mm LJ12A3-4-Z/BY PNP with a voltage divider, new is 8 mm NPN) and this started to function somehow:
As the sensor doesn't sense the surface (or the glass at all), but senses the heatbed under, which isn't either flat nor stable according to temperature, I added aluminium tape under the glass pane. This actually works perfectly well!
Now I am able to tune in the first layer distance really well, but still the flex filament floats around on the glass so I added blue painters tape which makes it work, very very well!
All well for flex printing!
Switched to PLA (which always worked okay whatever some small errors in print height, and not too wide items) and I have all pieces sticking to the bed in a manner I just cant get them off...
They get big scratches from the pincers, get broken, etc.,...
I have tried:

Pincers (works for some items, doesn't work for some. About always makes marks);
Ripping off the blue painter tape (the tape was removed everywhere except where the item was stuck. Plus now I have to add new tape);
Chuck the build plate in the freezer for an hour. It helps a lot but:

Still not easy to remove without making marks;
It's a serious hassle;
It's also a time waster.

My question is: How can you both reliably print and remove your item without breaking it?
Little image of the last part that I broke (the square impact in the middle is after ripping of the "hook" from this hanger when I tried to detach it from the heat bed), as it didn't work at all I had to put it in the freezer for an hour or so to be able to remove the rest:

If your print is sticking too well, try printing directly onto the glass.
If then, your print isn't sticking well enough, try using something like a glue stick instead.
Most people use a paint scraper (a small one, like this) to remove prints from build surfaces.

Hey @craftxbox, I want to note that you can post images in your answers. That will allow your answer to last the test of time, in case the one you link is taken down. You can get free use images off wikipedia easily.

Thank you for telling me that i can do that @StarWind0, i had absolutely no clue SE allowed that

If you're ever in doubt regardless of what project you're working on... Tooth Floss.    You need the good old-fashioned braided kind, none of the new "Pro Glide" elastic stuff.  Pull a piece taut and just start sawing back & forth against the bottom layer in different areas (corners work best)... and you'll be on your way in very little time.

A bit of rubbing alcohol dripped on the print edges may help, especially if the print is still warm. Wait about 30 seconds and then gently pry up using knife-edge tool. If this technique works for you, dilute alcohol in a spray bottle or just buy a window cleaner. If you are designing models, minimize base area and always use a base layer fillet of about 0.5mm-1.0mm to permit knife-edge access.

First if you print directly to the glass with a glue stick, over time there will be enough oil build up that you will not have this issue.
Following, if the change in heat temp on a bare glass is not enough to pop it off, I personally use a thin strong blade, specifically a leather cutting blade. Note this blade will through mats with ease. That said that blade is made to cut leather, your thumb is easier to slice by a lot.
Last if you cannot do these, then simply print a few raft layers and don't worry about damaging at the removal point.

For PLA, I usually use hairspay directly on the glass, it keeps the object attached but is not at all a strong glue, sometimes I facilitate the part removal washing it under flowing water.
As OyaMist wrote, a small fillet in the perimeter helps because you actually want to push your object perpendicularly to the bed, and therefore you need to have some grasp point for the blade.
If this is not available and/or when an object is really impossible to remove otherwise, I use this technique:

Remove the glass with the object still attached;
Find a robust piece of furniture with a flat top and a (smooth) vertical wall;
Put the glass as high as possible but still pushed against the vertical wall; (the object must be on the furniture-side of the glass)
Move down the glass, a quite fast but still controllable movement.
The object is supposed to hit the furniture's flat top while the glass is sliding on the vertical wall.
The object will receive an impact, not a force, from the side.

Since this is more an impact than an applied force, the adhesion layer can't resist as a whole surface, but only the surface near the hit point can actually do something. That's the same concept of fixing a nail into wood, if you can only push you'll need a lot of force or -that's why we use hammers- you can just apply some relatively small hits. In fact, I usually see (maybe after few movements) that the object start to detach in some spots, then I can proceed with the paint scraper or I can just continue this way.
Be careful not to drop the glass, of course. :)

This technique is highly questionable! I am not sure what you are describing but it sounds dangerous.

@StarWind0: which kind of danger do you see? Except, of course, to drop and broke the glass. I do admit that this could be a danger, but it's not more threatening than having glass jars on an high shelf.

Well, do you apply force to a jar while it is over head and apply movement? I think you are trying to apply force from multiple directions. Or generate heat. The main issues are, Glass cracks under pressure. Print pops off and pane falls, slips or goes flying. Both of these are involving glass accident with you looking up with glass over head.

Unless some magic is involved, yes, sometimes you do apply force to a jar and -if enough force is applied in a profitable direction- you'll cause a movement. That's exactly what happen when you place anything anywhere, even a glass jar on an high shelf. I don't apply force from multiple direction nor i'm trying to generate heat. I'll try to explain technique better in the answer, because if you understood the procedure you won't consider a leather cutter a safer option.  PS: Glass actually do perform very well under pressure!

Technology has come to the rescue here. New printing surfaces are available that release PLA very easily.  I am using the WhamBam system.  A magnet is stuck to the AL bed. A flex steel sheet is placed on the magnet. The flexsteel has a PEX sheet stuck to it.
After levelling the bed, a print is done normally. When done, the flex steel sheet is lifted off the magnet. After cooling a minute or two, give the steel a little flex across the two sides, and the piece pops right off.
I've posted a video at this Stack Exchange topic
Printing PLA on PEX surface - is heated bed needed?


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How can I create PNG image files from STL files?
I need to add some simple image renders of STL files to a document.  I currently open the STL files in Preview or one of the slicers and grab a screen shot.
Is there an easier or automatic way to generate PNG images from STL files on a Mac?

The answer below sounds pretty good, so I'll just comment that Google turns up a number of options for generating postscript files from STL, and you should be able to convert those to other image formats.  I'm not sure how lossy that transition would be (and it'll vary by tool), but figured I'd mention it in case someone comes here looking for e.g. a non-Mac solution...

If you have OpenSCAD installed, this shell script will generate 100x100 pixel PNG images for each STL file in your current directory.
for i in *.stl; do
  T=__tmp__$i
  b=`basename $i`
  echo import\(\"$i\"\)\; >$T
  /Applications/OpenSCAD.app/Contents/MacOS/OpenSCAD -o $b.png --imgsize=100,100 $T
  rm $T
done

Credit to 0scar for pointing out STL files can be imported into OpenSCAD.
Update: This code does the same, and generates an html file with annotated images of the files rendered.  When I printed a batch of spare parts for my 3D printer I made a hardcopy and stuck it in the box so I could identify the parts later.
n=-1
H=00-catalog.html
echo >$H '
'
echo >>$H '
'
for i in $*; do
  n=`expr $n + 1`
  if test $n = 4; then
      n=0
      echo >>$H '
'
      echo >>$H '
'
  fi
  echo $i
  T=__tmp__$i
  B=`basename $i .stl`
  echo import\(\"$i\"\)\; >$T
  /Applications/OpenSCAD.app//Contents/MacOS/OpenSCAD -o $B.png --imgsize=200,200 $T
  echo >>$H
  echo >>$H '    '$i'
	'

  rm $T
done
echo >>$H '
'
echo >>$H '
'

I've been trying to understand this code for a long time. What does the echo import\(\"./$i\"\)\; > "$T" line actually do? I'm trying to edit it so I can convert files that contain spaces in their names.

Note: If using in a headless environment like CI/CD/Github Actions, you will need an x11 environment. A workaround is to start a fake X11 with Xvfb e.g ( Xvfb :99 & export DISPLAY=:99)

@erdostamasa - the line is creating a one line temporary script that does an import of the STL file. When openscad is called, it imports this file then the -o and --imgsize=100,100 from the command line do the rest. The rm $T then cleans up this temporary file.

Typically you would install a (free) 3D model program as Fusion 360, FreeCAD, or many more options to choose from. Once installed, import the STL file and use menu options to export a picture of your STL.
Alternatively, if you have some programming skills, you could import the STL file in OpenSCAD and render and export a picture from there. Simply create an OpenSCAD file with the code line below and it will import your example.stl.
import("example.stl", convexity=10);

Through the menu you can then export the view to an image. Note that you can do that also from the command line as shown by the OP's own answer (nice example of command line usage of OpenSCAD).
These are not the only options, there are many more. E.g. this is a nice example. It also describes how Thingiverse.com does STL to web image.

For those looking for a nautilus thumbnailer using this technique, I've written a quick one here: https://github.com/sbrl/nautilus-thumbnailer-stl/

If you don't mind using screen grabs,  you could use AppleScript or whatever it's called in the latest MacOS versions to build an automated script to open each file, grab screen, save, etc.

You can use OpenSCAD, as stated in the accepted answer.
Here is a version of that script that works for Windows for anyone who needs it, as I did.
# Change height and width to the desired output image dimensions, in pixels.
# The path to openscad.exe may also have to be adjusted based on your installation.

height=1080
width=1080

for i in *.stl; do
  T=__tmp__$i
  b=`basename "$i"`
  echo import\(\"./$i\"\)\; > "$T"
  C:/'Program Files'/OpenSCAD/openscad.exe -o "$b".png --autocenter --viewall --imgsize=$width,$height "$T"
  rm "$T"
done

What does the echo import\(\"./$i\"\)\; > "$T" line do? I'm trying to convert files with spaces in their names but keep getting various errors.


text:
Extruder clogs randomly during print
I don't know how to say this but during the print, the printer will randomly have difficulty extruding the filament. I will have to give the filament a boost for it to keep going. Once I done the boost, the extruder keeps going perfectly fine for a while.
I am using a Prusa I3 clone bought second hand. I am using the settings that the previous owner gave me (I personally know him). He previously printed a lot of stuff with those settings and they seem to work well. I also bought the brand of same filament as he did for my first roll.
My question is:
Has anyone had this problem or anything similar and if they did, how did they resolve it?
If anymore precision or clarification is needed, please ask.
EDIT
When I say boost I mean that I have to push it down a bit more for it to countinue extruding.
I am using 3D branche filament (it's a local store in Montreal).
I do sometime hear it click before the print. When it does that. I stop the print and restart it.

What do you define as a 'boost'? E.g. push the filament?

First, put in a fresh nozzle.  Second, what brand & type of filament are you using?  Some brands of ,e.g., PLA, have particulates which can cause jams.

Do you hear clicking noise?

@0scar added in the info int the question

Check your retraction settings. I had a similar issue and it was caused by the retraction, It retracted just about enough so the gears couldnt hit the hole properly to feed the filament into the nozzle. To fix that I lowered the value of mm on the retraction settings.

If the model you're printing is your own design, then sometimes the 3D model is itself the problem. If the printer spends a lot of time retracting (pulling back) on the filament to print things like walls with lots of gaps then the filament softens at the feed gear and nothing feeds. Slicing software should handle that use case but may not. I've had this exact problem with the Lulzbot Mini using Cura when trying to print a hydroponics netpot. I had to rethink my design after the extruder clogged.

I've adjusted the tension of the idler wheel (the bearing that pushes the filament against the extruder gear) and it seems to reduce the problem.
More thest to come.


text:
Hot end temperature varies during print
If I set temperature say 220 °C, printer heats up to it and it only varies +/- 0.5 °C under non operating condition. But if I start a print, there's a shift of +/- 15 °C.
I've already auto tuned PID parameters and when I run M503, the printer shows the updated PID values.

What could be the reason?
Electronics details:

Firmware used:  Marlin
Controller board: Printrboard rev D

The bed target is off, please explain why the bed temperature increased? E.g. did you shut of the bed prior to making the screenshot?

Hello Athul, I noticed your question has been up for a while now. Have any of the answers below been able to solve your question? If so, would you mind accepting the appropriate answer. If not, what is missing so that we may help you further? Also, if you have figured it out on your own, you can always answer and accept your own solution. Thank you!

@0scar I have replaced the Heater block, cartridge and Thermistor. I don't know which one of these solved the issue, that's why I haven't updated it as an answer

what program did you use to get this charting?

@user25313 OctoPrint

There could be a number of reasons for that behaviour:
Please check following items:

part blower/fan cools down the nozzle - stop the fan
material is extruded at high speed and takes the heat
loose thermistor (when the move occurs as it moves a bit internally)
the power supply unit voltage varies - so temperature reading varies as well - measure voltage and see if there are significant drops
nozzle heater and thermistor cables can be loose as well (check screw terminals)
bed heater connection cables having not a good connection (check screw terminals)

I am not using any fan to cool the nozzle.Fan which came with the extruder cools the metal part which holds the nozzle.This is my extruder link. Also the heating coil and Thermistor is fastened to the nozzle using grub screws. Thing that confuses me is that, sometimes the hot end temperature stays constant during print (+/- 0.5), but most times it varies drastically.

Could be the issue of power supply. May be it can't supply enough current to motors and heating coil at the same time.But It's a 30A supply. I was thinking about checking it. Also the power supply s powered  by an Inverter.

The point is that it could be broken wire (heater or thermistor) so it is not clear to see it. I'm case I replaced heater and got stable temperature

Dropping hot end temperatures can be caused by the filament cooler blowing too much cold air onto the nozzle, or a too high of a print speed so that the nozzle is cooled by the filament (in combination with a heating element that cannot heat that fast to compensate).
To rule out the PSU you could try measuring the voltage of the PSU before and after powering the heat bed, if it drops dramatically when the heat bed starts change the PSU.

nice timing Sir :)

Yours is more complete! But usually it is one of these.

My problem was like yours and after several test I found bad PID tunning in heated bed disturb hotend temperature process.
Before heated bed PID tunning:

When I fixed PID values for heated bed everything works like a charm :)

Can you also show a "power output" graph (or something like that, which show PWD duty cycle output to the hot end)?
Have you noted any relation between temperature raise and fall and the printing position?
Looking at graph I can only suggest the heating is suddenly stops and then the same sudden resumes.
It looks like you have a loose wire connection to the heater. When head is starting to move, it makes disturbance for the wiring, so heater occasionally stops to work.
There are usual two weak points: first it is where cable is connected to the board. Check is connector heated? Are any noises/sparks from there?
Another part: it is just at the point where wires going into the hot end. If wires are not secured to the printing head, then during printing those place experiences a lot of bending, which makes it weaker over the time.

Hello I have had the same issue, fluctuating thermistor temperature, all of them. Discarding the board, and accessories setup (loose the heater, thermistor and so on) the problem was on the PSU. When I have opened the PSU and touched gently all the parts  then closed again and connected it to the printer: temperature readings were stable egain, however just for a time.
Fluctuations of temperature due to heating have in general low frequencies due to the heat transport phenomena in material such as plastic and metals especially if the amount of metal material is of the order of 100 grams.
Changes over the time with supplied power of about 500 watt over 100 grams of metal and plastic flow of a fewer grams per minute, seldom, cant cause temporal fluctuations  in frequencies of the order of electrical fluctuations. It's possible but not in 3D printing case.


text:
How do skirts aid print bed adhesion?
In cura one of the options under "build plate adhesion" is "skirt", which seems to simply print a loop around, but not touching, my print. How is this supposed to help my prints stick to the bed?

The skirt will only prime the nozzle, which is something really important for the first layer adhesion.
Ususally the first layer has slightly more material (or a lower height) respect to the other layers, and this is done mainly to push the most material against the plate, and this will give adhesion. Without a proper priming of the nozzle this just won't happen everywhere.

From the Simplify3D guide:

Adjustments to the First Layer Height allow you to vary the amount of pressure the filament exerts against the bed.  There are actually two ways to adjust the height and pressure:
Percentages under 100% will reduce the height of the layer being printed (with no change to the extrusion amount).  For example, if you entered 75%, your first layer height is reduced while your extrusion remains at 100%.  Another way to think of this is that 100% of your extrusion will be forced into a space that is 75% of the layer height.  This reduction in height generates extra pressure and more surface area for that layer, which will help the first layer adhere to the print bed.
In other cases, using a percentage above 100% is helpful.  For example, if you are printing at very fine layer heights, such as 0.05mm, a tiny variance in your bed leveling can result in poor first layer adhesion.  Using a First Layer Height well above 100% can be extremely helpful in these cases. Many machines benefit from 200 or 300% for the first layer height when the layer height is 0.05 mm or 0.1 mm. The increased thickness of the first layer can help absorb small defects in the build plate and provide more surface contact area, which will result in better first layer adhesion.

Imho, the life is too short to print at 0.05mm, and my printer doesn't show bed issues, therefore i'll go with less than 100% first layer height.
I don't have the standard cura settings available, and i also think that with different 3d printers with different filaments it makes only a little sense to discuss about "cura standard settings". In any case, my very standard standard settings are: 0.2mm layer height, 0.15mm first layer height. With these settings and some hairspray on the glass i almost forgot about model pop off in midprint.

I disagree with first layer has slightly more material and lower height. Actually the first layer usually is larger (it includes the paper thickness), look at the standard Cura settings where the first layer has even a larger value than all other layers. Furthermore, more material is only given to the first layer when you have requested that, again, that is not standard, and either way not required.

What does "is larger (it includes the paper thickness)" means? The footprint of the object won't change, except for a fraction of the nozzle diameter if you squeeze the material. And in "even a larger value than all other layers" which property is larger?  Anyway, i'll reply editing the answer because there's not enough space here.

True, discussing tool setting is not a good thing to do, I merely added it as an example. I see Simplify3D does it differently. But, your first layer is not 0.15, the actual layer includes the paper thickness, so it is more or less 0.25 or something. Increasing the flow (or decreasing the percentage as you shown in Simplify3D) does help in adhesion, but this is not an advantage of the skirt. The sole purpose of the skirt is priming.

These skirts they don't contribute at all to help your product adhere better to the build plate other than priming your nozzle so that it is ready to lay down filament for your product.
A skirt does give a good indication of the adhesion prior to printing your product, if the skirt does not adhere, maybe it is a good time to stop the print and re-slice with different options or fix the bed level.

Helps to adjust Z height prior printing.

@FernandoBaltazar Yes! Hence fix the bed level :)

prior? it helps during: you can reach under and twist the knob if one corner of the skirt is too light/dark. Lowering the feed rate helps to avoid any indiana jones style just-in-time hand escapes...

@dandavis Yes prior, to me the skirt is not considered to be your product. If not adhering at all cancel the print, if uneven fix the level while printing the skirt. The printer types which raise their bed are easy to adjust as there is lots of space to get to the leveling screws.

Skirts prime the nozzle- getting the filament to first adhere to the build platform is necessary for the entire print. Once the filament starts to stick it usually will continue to.
Skirts can also help block any air drafts that might blow the filament away from adhering in the 1st layer of the print

To use skirts as a bed adhesion tool

Make the value of Skirt Offset from part to 0
Set the number of Skirt outlines to 10 or 15 ,so that it forms an extended outer perimeter of the first layer

notes:

This also doubles as a primer for the nozzle
Also can be used to make minor adjustments to the distance between the bed and the nozzle , before the first layer begins printing

Basically you are describing a Brim... :) And that is an extreme case of a skirt.


text:
German RepRep Neo can't heat the extruder
The printer stopped heating the extruder in the middle of the print and I noticed it getting cooled down. After a few seconds, I heard a ticking noise near the filament (which could probably mean the filament was being pushed into a cold extruder and was skipping. Now, when I try to heat the extruder, it won't heat up. What could've gone broken?

first, check the breakers

pic source
secondary stuff
please see a list of item to check, that could point you to the source:

heater cable cut/melted/loose => the best way will be to check the resistance (it shall be around 3.3 Ohms) from the heater cable terminals on the mainboard, if that fails it could be a wire on heater itself.
with the heating switch on - measure the voltage on terminals - shall be 12V, if not  - that  could suggest a mainboard failure or mosfet failure (in case of mosfet you could measure if there is an input signal given on the middle pin)
there also could be a breaker that was engaged due to short circuit on the wires (the main board layout is not known to me and it is not clear form manual I found online)


text:
Anet A6 install bed leveling sensor
After lots of hassle, I finally made the printer work.
I also got myself one bed leveling sensor from eBay, LJ18A3-8-Z/BX 3D Printer Inductive Sensor Bed Auto Level +Plug For Anet A8 A2 A6.
I'm not sure how to setup it. Should I print some holders for it first? Where are they?
Should I somehow update the firmware?

could you kindly google the phrase Anet a6 install bed leveling sensor and your problem will be solved :)

@profesor79 the point of this website is to help people and constantly telling them to go Google how to do it is not helping.  The traffic for this site should be coming from search engines because this site should be housing the answers to their questions.

@tjb1 thank you for the comment, AFAIK OP needs to demonstrate that there was a try to solve problem on OP own.

@profesor79 -  whilst you are correct, could you kindly take a look at the answers to Post Closing Issues. We are having a bit of a problem with [new] user retention, and we would like to address that. :-)

You need to do two or three things:

Print a holder or bracket for the probe, if your probe did not come with one, and looking at the eBay item listing, it doesn't appear to include a bracket. There are a number of designs out there, take a look at thingiverse, for example:

Installing the BLtouch on Anet A6 - This one includes a PDF guide.
Anet A6 Autolevel Sensor Support 18mm

Change the firmware - SkyNet 3D, Marlin is a good choice, or Anet's own
You may need to change the Z-stops

There is a step by step guide here, Autolevel for the A8 Anet 3D Printer. It is for the A8 but most, if not all, of the steps will apply to the A6

Please note that Skynet3D, which was a fork from Marlin Firmware, has been merged into Marlin for quite some time now.


text:
What is causing the walls of my prints to separate?
I have been having an issue with certain portions of the walls of certain prints becoming separated from the rest of the model. It happens with smooth vertical edges.
Specifically, this model,  ID Badge Holder, on the edges where the lanyard would be attached. And on several places on this model, Cat Necklace.
Here is the resulting issue:

I am quite new to 3D printing, so I'm sure this is an easy fix, I just don't know about it yet.
I am printing with a Monoprice Select Mini V2, using Hatchbox PLA, and the default slicing settings inside Cura. I don't have problems with any of the D&D figures I've printed, or some of the other thicker square pieces I've printed. I know I've got kind of a bargain printer; if it's just a quality issue I have to learn to live with, no problem. But if an expert knows of some slicer settings to tweak for these kinds of prints with flat vertical walls, I'd love to give it a try.

Can you post the default settings in use for extrusion speed, wall thicknesses, layer height, at the least.  "Default" varies by defined printer and by Cura version.

Please include the photos. Also please include photos of the model as links do not last the test of time.

@StarWind0, I've attached an image of the issue I'm experiencing.

@CatsAndCode Looks like your lines of the faces and not touching; under-extrusion? Or are you printing with no top and bottom faces and high infill? Have you checked filament diameter, filament settings in slicer and checked the length your extruder prints (when you ask for 50 mm, does actually push 50 mm forward)?

@0scar The more I'm reading everyone's responses, the more I think it IS an underextrusion issue. I am not sure how to create the "top and bottom faces" you mentioned in Cura. I'm printing at 10% infill. Filament diameter is set correctly in Cura, but I haven't done any calibration/verification on my printer. It was allegedly set up at the monoprice factory, so that's been working for me thus far.

@CatsAndCode I updated my answer. If you select 0 mm layer thickness and 95% infill you get the exact same faces as your print. I print stuff for a colleague who uses the products in a vacuum chamber as molds, without skins you cannot trap air :)

does it work better if you slow down the print speed?

I have faced the same issue if it concerns just gaps between the walls (to the point you could put a nail in between the outer and inner perimeters, so clearly the perimeters were not bonding), for me this was fixed with proper tension of the belts of my Prusa i3 clone, and for my other (CoreXY) printer reducing the friction of the X-Y system. Both help position the head better for proper wall adhesion.
Now that you have posted a picture of your product I do not think the above is applicable to you. Your print looks as if it has an under-extrusion problem as the lines on the faces are clearly not touching, you see the diagonals of the layers beneath. This under-extrusion also may contribute to the vertical wall bonding problems you mention. To fight under-extrusion you need to check a few things:

Be sure the slicer has the actual filament diameter as mentioned on the box, or measured at various points (if it varies, take the mean value).
Check your extruder setup to see whether you have play or friction preventing filament to extrude freely.
Also check whether your extruder gear is not loose, re-tighten the grub screw.
Final step is calibration. You want to be certain that when you demand 100 mm of filament to extrude, you actually extrude 100 mm. Put a mark on the filament and extrude 100 mm using a tool like Pronterface or Repetier-host. If this is off you should readjust the steps per mm in the firmware (if you are able to do so), or increase the extrusion multiplier or flow in your slicer.

Please look here or here for more information.

"You want to be certain that when you demand 100 mm of filament to extrude, you actually extrude 100 mm"
This. On my MP Mini I've noticed that the default extruder steps per mm is wrong. I think the default is something like 97, and every time I calibrate it, it's more like 105. This was leading to constant underextrusion for me until I did an extruder calibration.

As I saw this efect come in gradually over time, I knew it had to be something with the printer itself. And indeed, tensioning all belts resolved it.

I dont know if I understand you correctly, but let me try...
It could be that the wall-thickness of the part you try to print is to thin or is not "compatible" with your nozzle size.
Lets say your nozzle and output size is 0.4mm. You now try to print a wall with a thickness of 1mm. So the printer will print 2 wall-perimeters (left and right) with a 0.4mm thickness. Between these walls there is now a 0.2mm gap. The slicer cannot fill this gap as its to small for the nozzle, so it is left empty.
I run into this problem multiple times already with different models using Cura.
But, atleast in older versions of Cura, if you go to the layer-view you can kind of preview/see the problem.
(Iam still using an older Version.)
This problem can also effect the overall print quality of the part.
(For example I had a part with very big stringing problems but only on the inside of a specific wall. The wall wasnt even thin, it was a couple of mm, but the overall thickness of the wall was not a multiple of my nozzle-size so it created problems.)
Some say you should design a model with a nozzle size already in mind, however this is not really practical, as everybody uses different settings/printers and not everybody creates his own models.
Here are some more infos regarding this issue: (and more "walls-not-touching" issues)
https://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#wallspace
So maybe try varying your nozzle size and wall thicknesses and see if this changes something in the cura preview already.
This problem can also happen if you have some very tight corners, which are to small for the nozzle.

When printing someone else's model, your print is at the mercy of their design. Designing for multiple printers is hard work, and even if something is printable on 90% of printers, you may be in the 10%. Sometimes designs use walls too thin for other printers. On this design, the lanyard wall looks a bit thin but workable. My own card holder has a thicker wall at that junction: https://github.com/firepick1/taz-shield/blob/master/STL/Cardholder.stl
Vertical walls are the weakest part of 3D printing. Walls are made up of overlapping filament strands. They'll come apart if your printer belts are loose and the strands don't align (tighten belt if there is play). They'll come apart if you print too fast and the contact area is too thin (slow down for better contact and more accurate motion). They'll come apart if filament head temp is too low and the strands don't fuse (bump it up by 5C and try again).
Slicing software normally takes are of all this for you, but it's good to understand what happens on the print bed because your slicing software will often have options that you will need to tweak for your specific printer.

I respectfully disagree -- wall thickness is generally well-controlled by the slicing software, and a quick check by looking at "layer view" or similar should show if there are any unprintable sections.

Yes. Wall thickness is indeed well-controlled by slicing software. However, I think it's important to have a conceptual model of the printing process to understand how to use the slicing software. For example, Cura has three speed settings for non-expert mode. I use slow for accurate/strong prints and super-fast for prints with massive walls.

@CatsAndCode, I've updated my answer with my own lanyard cardholder I've used for years. If you have time, I would be most curious if you could print out this: https://github.com/firepick1/taz-shield/blob/master/STL/Cardholder.stl

Yup I can tell at a glance it is under extrusion. I bet the issue is temp.
Test your steps per MM for E. See https://reprap.org/wiki/Triffid_Hunter%27s_Calibration_Guide

Measure Required tools: vernier caliper with depth gauge, or similar
  tool that can precisely measure 100mm. Your hob effective diameter is
  unlikely to be exactly 7mm.
Remove the hot-end from extruder so you don't waste filament. Feed in
  some filament. Using the extruder body as a reference point, mark the
  filament at 120mm. Tell the printer to feed 100mm of filament. Measure
  the distance from the extruder body to the mark you made. It will be
  over 20mm if it moved too little, under if it moved too far.
  new_e_steps = old_e_steps * (100 / distance_actually_moved) … or,
  old_e_steps * (100 / (120 - distance_to_mark)) Set this value in your
  firmware. You may need to re-flash your board. Sprinter/Marlin
  supports M92 Ennn to set this value temporarily. Repeat from Step 3
  until you get between 96-104mm. Then continue with this guide. You'll
  dial it in perfectly later on. Don't flash firmware yet. There's a
  further refinement to this value below. Why? The back-pressure from
  the hot-end alters how much plastic each hob revolution pushes, and
  you'll probably end up tightening your idler more which reduces the
  hob effective diameter. Re-attach hot end.

If that comes out correct, your Temps are too low.
To fix this, you will need to play around and increase your temps by 2-3 degrees until the infill comes out correctly. Do not go over the minimum needed else you will have other issues.
Also check for obstructions such as carbon buildup in the nozzle. In addition to the tightness of your filament tensioner on your extruder drive if you have one.
I will say, I had this issue on my Ultimaker 2. An apparent design flaw caused the filament drive to lose power over time or possibly wear on the tube causing extra drag (bowden tube only issues). I corrected it by increasing the extrusion multiplier in simplify3d.  However that is a bandaid and the real issue should be addressed. In my case in the end I replaced the drive with a bondtech.


text:
Extruder clogs with HIPS
I've got a Prusa i3 MK3. I have printed with PLA, PETG and tried HIPS. Haven't had any clogs with PLA and PETG, but with HIPS I've got a weird problem.
My first three test prints in HIPS went fine, but then I got a very bad clog (required total disassembly of the extruder) twice. And every time, it was at the same moment during a print. The object I was printing was a hollow cylinder. The walls were about 5 mm thick, getting thinner near the top edge. At the moment the walls started getting thinner, the problems started.
I've read that HIPS can clog if the filament moves too slow through the hotend. At the moment the clog occurred, the printer was printing a very narrow part, and the extruder had to move around a lot. Is it possible that, at that moment, the filament moves too slow and the problems starts? I have also printed two copies of the object in a single run, and then the problem didn't occur.
I hope my explanation makes sense, but here's what it comes down to: Does HIPS clog easily when the filament moves too slow, and if it does, what can I do to solve this?

This has been sitting for a long time without an answer, so let me answer with an experience I've had with PETG rather than HIPS.
PETG seems to be a relatively soft plastic.  It isn't soft like TPU, but it is softer than PLA or ABS.  The HIPS filament (which I have but haven't used) appears to also be softer, so it is possible that my PETG problem could relate to your HIPS problem.
I was printing and re-printing an object with PETG that had worked fine with PLA.  Three times in a row, I got a filament jam in about the same place.
The problem was that the filament was retracting, returning, retracting, and returning many times within a very small amount of extruded plastic.  My extruder was set for high pressure between the drive roller and the idler.  When the filament went back and forth through the extruder, it flattened enough that it would jam from being too wide to fit through the next stage (in my case, a Bowden tube).
When I reduced the compression of the filament in the extruder, the problem stopped.  I also reduced the retraction distance, and increased the minimum travel before the slicer would do a retract.  Both were intended to reduce the number of times any single bit of filament would pass through the rollers.

HIPS does better with a wider nozzle; try a 1mm nozzle.


text:
Perplexing Y-axis shifting problem - only in positive y direction, and only on moves of a very specific radius
I'm running a RepRap based ORDBOT Hadron on Repetier firmware version 1.0 that I built from a kit.  I've slowly worked out the kinks but this one is an utter doozy.
Basically I occasionally get shifting in the y-axis - the print bed moves on this axis - but only in the positive y direction.  Never in the negative y direction.  I'm not sure if I'm using those terms correctly, but the bed shifts forwards (negative y), so subsequent print moves are displaced in the positive y direction relative to the rest of the print.  I'm calling that a "positive y direction shift".
The offending y-axis is belt-driven by a single NEMA 17 stepper motor.  The belt is tight (not too tight I don't think) and well-aligned.  It would be difficult for it to become unaligned or lose tension since it runs along a piece of extruded aluminium that is very rigid.
It took a long time to notice the pattern.  Some prints don't have the problem, and some prints I simply cannot finish no matter what I do.  Finally I found a model that reliably reproduces the problem, on the same move, on about 50% or so of its layers.
This piece is supposed to be straight up & down.  Wild.

The moves that cause the shift are on this red line.

The issue seems to only occur on curved moves with a radius of approximately 2-3 mm that point their convex side towards the y-negative direction.  Larger or smaller radius moves don't cause the problem.  In fact sharp turns don't cause the problem either.  Only 2-3 mm radius moves with their convex side towards y-negative produce the issue.  No other kind of move causes the problem.
I think the offending move is highlighted here in red, but it might be one of the two moves either side of it.  I haven't been able to narrow it down.

Also note that there is no opportunity on this part of the G-code for the hotend to snag on the model, and I see no evidence of this when it happens.  If it were, I imagine a small model like this would simply dislodge, rather than jamming the y-axis.
I've tried lowering the y-axis acceleration, to the point where you can hear the y-axis spooling up and down as it slowly accelerates to and fro, and the problem remains.  What is especially baffling is that if I leave the y-axis acceleration at 300 mm/s2, the shifting never happens in the negative y-direction, only in the positive.  And even if I lower it to 50 mm/s2, the shifting still happens towards positive y.  So somehow this problem is independent of y-axis acceleration as set in the firmware.
One thing I have noticed, is that even if you can visibly see how slowly the y-axis accelerates, when the problem occurs, the y-axis seems to launch itself into overdrive and whip around that corner as fast as possible, to the point that it overwhelms itself.  I'm almost certain the moves that cause the skip are breaking the acceleration limit, but I have no idea what to do about it.  It seems like a bug in the firmware, like instead of reducing the acceleration it's increasing the acceleration.
I would guess that somewhere in the code there should be a mathf.abs() around a term, so it slows down the move whether it's positive or negative, but that's pure speculation.
The above paragraphs no longer appear to be true.  I changed the y acceleration limit to 50 mm/s2 and the piece printed perfectly.  It's possible the firmware update made a difference.  I've also enabled EEPROM, so that may have changed something as well.  It's also possible that by re-compiling the firmware every time I made a change in the past, I made an error that misled me about the problem.  I will try to reproduce the problem and post an answer about it if I manage to, otherwise I may just close the question.
I'm hesitant to say the firmware is the problem because a) I don't know enough to confirm it and b) it makes the solution super difficult: either wait for a solution from the developers, or write it myself.  Whilst I could find & write the solution, it would take a lot of work and I'm hoping it's simpler than that.
I've recently upgraded the Repetier firmware from 0.92 to 1.0, and the problem has remained.  This also has happened when controlling the printer from Repetier Host, Repetier Server and Octopi, so I'm confident it's not the controller.  I'm also using Slic3r.
Here are some photos of the y-axis belt as requested:
Motor:

Idler:

Also it would be generous to call my phone a potato; perhaps it is a much more primitive form of tuber, if such a thing exists.

how you manage belt tension - could you add a photo of that

Added! Also I need a longer comment... ok good.

You could try Cura to slice the model and see if it persists, also you may opt to install Marlin Firmware. Have you tried slowing down printing?

You see this for a few reason.
First you are going too fast and you are getting belt shift from the whip lash. You can mitigate that by going slower and adjusting your Jerk settings to lower. Though usually this is not a consistent wall. Usually you see this.
That said it is likely you have not adjusted the current to your stepper motors correctly. I don't know if your system has pololus, but you will want to adjust your current carefully. If you hear thudding from your stepper or the stepper cannot move, you have not done this correctly. Note I've fried many boards adjusting these, make sure to do it with the board unplugged or with a ceramic screw driver. Here is a more complete guide.
A last option is your system has too much friction as Ultimaker points out in their trouble shooting guide. You said your belts are very tight. I wonder if you have them So tight you are actually creating binding. Check to make sure the belts are not rubbing in any way.

Leaning: A leaning print is usually caused by friction causing the
  print head to move a shorter distance than expected. Make sure that
  the short belts that connect the stepper motors to the axes do not rub
  up against the main body of the printer. Similarly make sure that the
  pulleys on the stepper motors that the belts ride over are not
  touching the side of the printer. If they are you must move the pulley
  closer to the stepper motor.

My bet is it's current.

It does have pololus. I'm still not certain how current explains the behaviour where sharp corners, even at high speed, don't cause this problem, but turns of a specific radius, and only in one direction, do.  Also there's the issue of why tweaking acceleration has no effect.  However, I haven't touched the drivers since I built the kit, and to be honest I had no idea what I was doing. So rather than sit here and theory-craft about what the problem should be, I'll try tweaking them and let you know how it goes.

I've updated the question - I have found a firmware solution, but I'm trying to reproduce the problem as described - I may have been mistaken about the nature of this problem.

When photos fail videos can be of help.

Okay, the shift-faulter print that I discovered worked up to 150mm/s^2, but another new print failed.  So I tried adjusting the pololu, touched the wrong thing, got a spark, and now it's dead.  The printer went non-functional completely, but it turned back on after I removed the pololu, so I think that's the only issue.  Ordered another one to pick up tomorrow, so we'll see how we go then.  The lesson for me here is:  don't work when you're tired & frustrated.  You make mistakes.  We'll see how many more times I need to learn that one...

Also, I'm not sure what I would video. I did mention that it seems to speed up when going around this move, but I only remember that from a while ago. When I had the printer sitting on a rickety fold-out table, the whole thing would visibly shake when this move was encountered, but I now have the printer in a dedicated enclosure built into shelves, and it's not as apparent. I don't know if the rickety table only created the impression of a speed-up, or if it was really happening. I've kind of lost track of everything I've tried. I'm hoping a current change will do it; that would be simple.

A quick question about binding:  when you have binding, can you detect it as an increase & decrease in the resistance as you push the axis back & forth?  If so, I know what that feels like, and my bed feels pretty smooth to me.

Replaced the pololu, adjusted the current limiter - 0.8 * 2.5 = 2A, which is what they're rated for with heatsinks & forced airflow, and the NEMAs are rated much higher.  I'm just about to print something, but for now I can say, when I tried to manually push the y-axis after homing, it was very difficult to do.  Prior to this it's been pretty easy, so that's promising.  I take it the y-axis should have a fairly high holding force when the motor is on?  That's something I didn't know.  By the end of tonight I'll have attempted the print again and will let you know.

Aaaand fixed!  Stepper current was the issue.  Thanks a bunch.  That guide was very helpful.  That's an issue that's been bugging me for a long time.

Yeaaah I've done that. I've also fried whole boards. That is why I did mention " Note I've fried many boards adjusting these, make sure to do it with the board unplugged or with a ceramic screw driver. Here is a more complete guide." That said I will likely fry boards in the future. Glad you are up and running!


text:
Strange grooves with ABS
I am experiencing strange grooves in my ABS prints; with PLA everything is fine. Some layers seem to randomly overextruded and others underextruded.
My parameters:

Temp: 240°C
Retraction Distance: 5 mm
Retraction Speed: 70 mm/s
Print Speed: 35 mm/s
Combing mode: All
Max Comb Distance with no Retract: 5 mm

It shouldn't be a problem with the Z-axis or the temperature control. It also only appears on large objects.

try lowering the temp 3-5c. I'd also stick with thin wall tests for calibration. Check belts next.

Retraction distance, print speed (I don't know about Combing mode or Comb Distance but I doubt that's the problem) have IMO nothing to do with this.
Neither would hotend temperature.

It shouldn't be a problem with the Z-axis or the temperature control. It also only appears on large objects.

You have a very fine X/Y layer so albeit your affirmation, I must raise the idea that it might actually be exactly the temperature control of the heat bed (if you have one) and it definitely seems to be the z axis. How would this problem appear otherwise?
You say it affects only large objects, and also that it doesn't affect PLA, does it affect large PLA objects? Photos would be helpful :-) !
My hypothesis is that you have a heat-bed and that the heatbed is changing the z-height.
It does so when it changes temperature (because material contracts/expands according to temperature), and heatbeds change temperature all the time.
Usually you have the same temperature control method all the time, so small or big objects doesn't change the method, but what they change is the time they stay on the same level; small objects less, big objects much so the z-bulging will be seen if you spend 2 minutes on one layer, while it might be mitigated on a layer taking 20 seconds.
What's your heat bed temperature control software / how is it configured?
FYI I use Marlin and I get these problems when I don't (correctly) auto-tune the heat-bed pid or use bang-bang beat-bed heating.

I am quite sure that the PID is correctly tuned (see my post here): https://3dprinting.stackexchange.com/questions/3554/3d-printing-problem-waved-walls/5770#5770
In this test I printed only the small cube, and it was working fine.

If you are sure the z-height is okay, then the only thing I see could do it (except bad filament maybe) is that you do some overextraction, do you use linear advance or some other scheme to calculate pre-retraction etc? Have you tried calibrating the extraction?


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How to sort G-code on SD card based on material (ABS|PLA|SBS)?
I have various G-code files stored at SDCard attached to my Prusa i3 MK2S printer. They are either for ABS, PLA or SBS. The more files I had on the SD card, the more I was running into trouble of finding for which material is which G-code.
To tackle the situation I created folders ABS, PLA and SBS and put new files into those directories.

Is there any better method of finding, backwards from G-code, which material settings were intended to be used?
If so, is there a way to read temperature settings from G-code by Prusa i3 firmware without printing the actual model?

Not an answer, but sort of related and a good idea: Best Practices - Labeling GCode Files. Use a filename format such as {Machine+State}_{FileName}_{YYYYMMDD-TTTT}_{FileID}.gcode, for example, UM2+PLA8_NozzleMag_20160911-1520_ym9450.gcode

Good question as I also ran into some files not remembering for which purpose or which material I printed these. The online G-code visualizers do not display the temperature or the correct filament width, so basically that won't help you (unless you modify the open source programs...). Reading from firmware would not be possible without adding a new feature, as far as I know, this is not implemented in Marlin Firmware or in Prusa firmware (which is based on Marlin).
When using a printer server like OctoPrint, you can store your G-code files in a folder structure that you can define yourself; so basically create a directory structure based on the material type, brand, etc.
However, it is relatively easy to write a small program in Python to read a file and interpret the lines (even if you're not a programmer). There are lots of tutorials and examples to find to open files read the file e.g. line by line and detect strings to identify the settings for G-codes M104/M109 (hot end temperature) and M140/M190 (bed temperature). Usually you slice your models with a specific set of bed and hot end temperature (which you know), so basically you can find out which material was meant to be printed with the G-code file. You could even let the program sort the files for you by moving them into separate folders.
I'll add it to my list of things I'd like to do some rainy day! :)
Note that some printers use different, or even custom G-codes to control bed temperature; e.g. when reading Ultimaker 3 G-code files you cannot see the bed temperature!

You could also add comment line to the generated GCode, usually it begins with ; symbol. The comment can be inserted in slicer as a startcode.

@jnovacho Good point you raise, but if you have never done that, you are stuck with the files you have. It is a good idea to insert a comment based on material settings in new files!


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Z-Axis zero/home position is higher than the actual print starting position
I'm having an issue with my very first printer, a Monoprice Select Mini V2. After doing about 20 successful prints on it, the Z axis is suddenly acting very odd.
When I 'home' the Z axis and move the nozzle on the X and Y, I can do the paper test on all four corners of the bed without issue - the leveling is near-perfect. But when I start a print job, the nozzle is much lower - by at least 1-2 mm.
This causes the print head to grind against the print bed, which I unfortunately need to replace as it's pretty much destroyed. The nozzle is so much lower at the start of a print job than it is at the home position that it ground a permanent line on the bed. It's trying to go so low, there's enough pressure on the nozzle to not let any filament escape - leaving a bad gouge like I dragged a screwdriver across the print surface. Not good.
It's not the Z-axis limiter switch. I confirmed that is both working and secured tightly to the printer body. When homing the Z axis, I can hear the switch click and the printer stops at that position correctly. It's only when I start a print job that it ends up lower, almost as if it's ignoring the switch.
I also eliminated my slicer software from the equation by printing something I had printed successfully just a couple hours prior - without reslicing or modifying the GCODE file at all. I'm at the point now where I can't print anything that I could before, without having this problem. My heat and speed settings remained untouched.
How can I solve this? The issue popped up just after doing a successful print. What gives? I've heard of the opposite problem (Z-Axis 'too high'), especially after changing nozzles, but not 'too low', and I've never seen it where the print job actually starts lower than the true zero position. Help!

Check the Z-drive for any component looseness. Look at belts, gears, anything with screws. Wiggle things mercilessly checking for play.
At the start of a normal print run, the the print head typically rises up very high as the head warms up (depends on software) and then lowers to print. If your homing paper test happened with the head near the limit switch, then the difference between those two use cases is the Z-distance traveled to get to the same place. You have eliminated software and electrical considerations, which leaves mechanical considerations. A slipping gear or belt might contribute to this odd behavior you describe.

Sorry if this is a noob question - but how much tension should the belt have? Is there a best practice there or just eyeball it?

I pluck belts and listen for a musical note. Too high is too tight. No musical note is too floppy. You can also compare with other belts on your machine. Similarly, check frame for loose screws.  This is very strange behavior you're seeing. Not normal and I've not seen it in years of printing.

This answer is ultimately a better one as it would apply to any scenario where the slicer software can be ruled out. In my case I thought I had eliminated that variable, but I hadn't actually, so I'll mark your answer as correct for those who might find this question and actually do have mechanical problems with the Z axis.

This ended up being a combination of print bed height and an unknown slicer profile parameter (probably the first layer height setting).
I completely uninstalled Cura, wiped out my profiles and downloading the ones from Monoprice, installed an older version of Cura and loaded them in. I also issued an M502 and M500 command to reset the EEPROM/firmware.
That seemed to have a tiny bit of improvement, but my first layer was still maybe 0.5 mm low (it was no longer grinding against the bed but was still creating a 'canal' with the plastic). I then did a tiny adjustment on each bed screw to lower it on the Z axis, just barely turning the screws, as evenly as I could.
An initial print after doing that seems to be going well. I may have to do one more teeny tiny adjustment to the bed height again. So it was probably a combination of slicer settings and bed height, the latter I probably made worse when initially trying to solve the problem. Lesson learned...kinda. I still need a new print bed!

I just had this issue with my Monoprice Select Mini V2. It seems there's some bug in the software if you already have the 3D printer at its lowest Z-elevation before starting the home calibration. To make sure it prints correctly, move the head up using the manual controls, then hit home. It should then go to the correct default location. I then adjusted my print height to that default home location and it seems to be working again.
Hope this helps other people still having difficultly with this is

Welcome to 3D Printing SE and thank you for your contribution. When you get a chance, please take the [tour] to understand how the site works and how it is different than others.


text:
3D printer filament will not load after running the printer out of filament
We wanted to test the post process properties of PVA but did not want to print anything.  We unloaded the ABS that was in the printer and then started loading some PVA.  After the PVA was loaded we let it keep going through the loading process until it pushed all the PVA out and we had our test sample.  We then stopped the loading process and started the loading process again to put the ABS back so we could continue with normal printing procedures. Now, the ABS will not load into the right side and started making a clicking/ticking noise.  Our printer is a Flashforge Dreamer.  What is wrong with my printer and how can I fix it?

Run some cleaning filament through the extruder at the printing temperature of your PVA or ABS filament, whichever is greater, until the old stuff has been completely displaced. Then load the new filament until the cleaning filament has been completely displaced.
This should be done every time you are switching materials, unless you don't mind disassembling the extruder and/or hotend and clean it out manually.

When trying to load a cleaning filament, the filament doesn't load in and instead the machine makes a clicking sound. It resists the feeding

Sounds like your filament feed is jammed. If you can't run cleaning filament through it, be prepared to disassemble it and extract the debris manually.

@RussellRowe I think you are missing the point, you should not feed it automatically, you need to push it in by hand while pressing down the lever on the extruder or remove the Bowden tube (printer dependent). Just cut some strips of ABS and feed in manually like advised in my answer; it is key not to let the machine feed, you should do it instead. I've done this multiple times on an Ultimaker 3, you just need to bypass the feeder!

PVA is nasty filament to print (from experience). I use it in the Ultimaker 3 in a separate designed core (BB) and even with that core the filament frequently cooks up and carbonizes clogging the nozzle resulting in grinding of the filament at the feeder (it also attracts water really easy, so keep it in the bag with desiccant bags).
To clean the inside of the nozzle, a few techniques exist to remove blockage. E.g. by performing a cold pull or using the atomic method. Both techniques rely on the mechanism to insert the (cleaning) filament when it's hot and remove it quickly at a lower temperature. E.g. see here or here.
The trick is that you pull out all the goo inside the nozzle, you do that by raising the temperature and sticking some (cleaning or high temperature) filament (your ABS will do fine) to the goo. When the temperature lowers, you quickly pull and hope that some of the goo sticks to you cleaning filament. Cut of the tip and repeat until no goo or burnt particles come out and you can push the cleaning filament through the nozzle. You do not need the automatic feeding, it's all manual labor, just raise temperature through the menu and press the lever of the extruder to load the cleaning filament, lower temp and pull back after cooling a bit while pressing the extruder lever.

PVA will carbonize if you look at it crossly. The cleaning filament method stands the best chance of getting all the debris out. Nylon works really well, as the temperatures are a bit higher than most common filaments. You may find references to "yanking" the filament. Don't. Use a strong steady pull with pliers, perhaps using a solid location as a fulcrum for a long-advantage lever action.

@fred_dot_u Indeed, I use strips of POM filament (close to nylon), works really well!

Or just accept that nozzles are cheap, and toss 'em when really mucked up. (at least the bronze ones are -- I can understand wanting to save SS nozzles)

@CarlWitthoft Eh... I wish... the Ultimaker 3 cores cost about 100 Euros each (nozzle cannot be replaced), but indeed if you can change the brass nozzles just replace them!


text:
What can cause the build plate to slip?
2 days into a 5-day build, I came home from work and found the build ruined because the build plate had slipped.
I'm using a Raise 3D N2 Plus printer, with the standard glass build plate that comes with it, attached via 4 clips: two stationary ones at the back, and two standard binder clips at the front, which shipped with the printer, which hold the glass build plate plate to the heated surface beneath.
The left-side clip had come off of the heated surface, remaining clipped to the top and bottom of the glass plate, and the whole thing slipped an inch or so.  I immediately canceled the build, and I can start another one, but before I do I'd like to know how this happened and what I can do to prevent it from happening again.
What typically causes the plate clips to come free?  Is there anything I can do about it?  Will adding more clips around the edges help?  I'd really prefer not to ruin more builds if I can help it...

Your nozzle may have caught up with the print somehow pushing the binder clip off by moving the glass slate.
Apparently this is a more common problem. Try adding more binder clips, this has been reported to help preventing shifting.
Maybe with some ingenuity you could develop your own fastening system depending on the bed. Alternatively, you could make the underside of the glass a little sticky so that it does not move easily (a little PVA based glue maybe or hairspray, I've done that with my mouse mat with 3DLAC :) which is now not slipping from the desk).

Before two month ago I tested double-sided tape between bed and glass plate. It's awesome and really works perfectly. No more clips, so I'm able to print to the complete area. And no more slipping. Don't use that much tape, just a little bit at the edges should be totally fine.

What type of tape are you talking about?  When you say "double-sided tape" the thing I think of is clear Scotch tape, but I wonder if it would be strong enough, and if the glue would still work when heated to 60 C (around 140 F).

I'm using this Tesa tape in the section "The Structure of Double-Sides Tapes". Works great for me, even when printing ABS @93°C.

Here, exactly this tape it is, but it's german only store, I think. Can't edit my comment.


text:
Laser Engraver with Smoothie, RAMPS 1.4 or AWC708C?
I have an old laser engraver that runs from Windows 98SE and DOS-6. Yup, still works fine but a pain as I regularly have to open it up and unplug and re-seat all the ribbon connectors. Fifteen of them and I tire of that fast.
I am thinking of pulling out all the electronics and installing a TB6600 stepper drivers and Arduino to run G-code. My order of desire is based on price, RAMPS, Smoothie and the AWC708C. I'd actually like to stay away from the AWC as it is closed source and I would be stuck with whatever it has.
With the existing NEMA 17 steppers I can get rapids to 400 mm/s. Will a RAMPS system drive this fast enough? It doesn't have to be that fast, but close to and certainly not below about 200 mm/sec.
I have been searching but cannot find any actual figures achieved. If not then I guess my second option is the smoothie.

I can get rapids - Is that a typo?

@Greenonline No, "rapid" is CNC terminology. It refers to a non-cutting (or in this case, non-engraving) move. The 3D printing equivalent would be "travel move".

Thanks Tom, yup many CNC machines in the garage. Didn't even know I had written "rapids."

Why not either clean or replace the connectors, assuming there's still some slack in the ribbon cables?  MIght be a lot simpler than a major electronics + software change.   (or, if it's really a loose connector problem,  see if there's a way to cable-tie them securely in place)

Marlin supports a stepping frequency of up to 40kHz. For a pretty typical setup with 100 steps/mm, this translates to 400 mm/s - obviously, if you use higher microstepping settings or use finer pitched belts you will get a lower maximum speed.

Thanks Tom, I want to use the existing mechanical set up so the 2mm belts will have to stay. I suspect I will need micro stepping as the current resolution of the laser is around 0.01mm. It was a high class laser in it's time. So looks like I go with the smoothie then. I might give it a try as I have a spare Mega+RAMPS here that came out of a Delta printer when I put a smoothie in it. :)

I do not think you have understood my answer properly. It looks like RAMPs would be perfectly suitable, it will let you hit your 400mm/s speeds (but just barely). The 100 steps/mm figure matches up perfectly with your 0.01mm resolution and already accounts for a certain amount of microstepping.

Tom, thanks again, but I did understand your answer, I just do not like making something that is working at the upper limit. I will be doing some major surgery on the machine so if RAMPS is at the high end to duplicate what I have then it is worth the $60 to get an MKS SBase smoothie board. I have since found that the laser can be pulsed above 40khz so the faster MKS board will give me room to move -- a little.


text:
Linking the 3D printing path coordinates to CAD for modelling
I was reading this research paper titled Sub-modeling Finite Element Analysis of 3D Printed Structures. In this, firstly, the author is trying to create a sketch for Engineering analysis using the 3D printing path coordinates and integrating it to a CAD software like Autodesk Inventor.
It says,

By analyzing the corresponding G-code for the desired structure,
  important information can be extracted, such as the coordinated of the
  3D printing path, key points, paths of printing and non-printing
  paths.
...
The coordinate of the 3D printing path can then be imported into CAD software to obtain the corresponding sketch and consequently a solid
  body for each layer. Most of commercial CAD software packages are
  capable of this task. For this Purpose we have chosen Autodesk
  Inventor.

Paper is attached here: Research Paper in subject
Can anyone help me out with how this can be done?

This is very interesting to me . Are you planing on developing a software for this ? . Currently there isn't any adequate tool for FEA on 3D printed parts that actually takes into account all the nitty gritty stuff of 3D printers and successfully prepare a simulation  for analysis .

Indeed very interesting and carries great practical utility too. Considering the complexities involved in merging the geometry of 3D printing to a CAD model, I have put this project to hold, at least for the time being. Do you have any domain specific knowledge on this? We can get together to make this happen!

this is all i do mate . I make solutions for the 3D printing industry and this problem is one i have been contemplating to tackle for ages . I though about using Autodesk Forge platform to make it but gosh there is a lot of work , mostly programming to be done . I don't mind starting a project and see if we can get developers on , but the solution should be on a mainstream platform  to actually make any financial sense .

The developing work is only the Herculean task here, once the model is developed rest is piece of cake. What kind of solutions do you provide to the industry?

Have you found and fixed the problem? If so, has the answer below led you to the solution? Please vote to accept the answer so this question is not bumped up once in a while and can be removed from the unanswered question list. You may even add your own solution and accept that after 48 hours! If you have not been able to address the problem please update your question.

The wording in the paper is quite verbose and somewhat unclear. All it says is they read the G-code file and somehow turn it into a 3D model.
A g-code file is just a list of linear moves. Here is an example snippet I took from a random file (keep in mind a typical file would consist of thousands of such lines):
G1 X140.621 Y114.840 E0.0065
G1 X140.804 Y114.765 E0.0129
G1 X141.016 Y114.737 E0.0199
G1 X158.984 Y114.737 E0.6070
G1 X159.196 Y114.765 E0.6140

Each move is relative to the previous, so the second line of the code (for example) tells the printer to move to X=140.804 and Y=114.765 from the previous position (X=140.621, Y=114.840) while extruding an amount of material equal to 0.0129-0.0065=0.0064 mm of filament.
It appears that the authors have developed a toolchain to turn a G-code file into a 3D model, translating every extrusion segment into a part of a solid body (from the pictures, it appears that for a given move segment, they create an ellipsoidal extrusion and merge all of these together into a single solid body) - see Figure 9 in the paper.

Thanks for the help. But I struggled with the last paragraph in your answer, how can one create such a tool chain that converts the G-code into sketch and then in-turn a 3D model in CAD? Are there specific tools one can use, I only know Autodesk Inventor. I apologize if the answer is trivial to a heavy user, I'm relatively new to this.

@Kv07 Sadly, that is extremely complicated and well outside the scope of a stackexchange answer. It would take an experienced programmer many days to create such a tool. There's nothing ready-made that does this. A good starting point would be reading up on the Inventor API.

@TomvanderZanden ( This is a random brainstorming comment ) So wouldn't it be easier if they run a slicing algorithm on the 3D File , like create a .CLI and then convert it back into a mesh with an approximation of the distance between the layers taken into account , by maybe using a random value function with limits in place  . After that if they run an FEA analysis they should be able to head in the right direction . Got any thoughts on this ?

@AxelFernandes They already run a slicing algorithm like you suggest. That's how they get the G-code from the 3D model.