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Exhaust air solution
Can you think of a preferably cheap solution for me? I need a machine that pumps air out of my 3d printing enclosure, about 4 meters of pipe length. (From enclosure to window) What kind of pump or fan can pump air out of the enclosure (4m pipe length) at the lowest possible price and low volume?
I need it for cooling purposes and for better general air quality in my room after opening the printer enclosure.
It doesn't need to be top notch equipment, just enough for my purposes.

Get a used cpap machine

Air flows from places of higher pressure to those of less.
Minimal setup
I propose to look at a very simple setup which works for short lengths of pipe:

Choose if you want a radial fan of a direct passing fan. get one, measure the intake and the outlet side holes
cut a fan inlet-sized hole directly into the back of the enclosure.
mount your fan onto it, most likely with some kind of foam to keep the airstream in.
get a flexible air vent hose (I have seen ~$10/10€ for a 100mm one) and measure the inner diameter.
print an adapter from the fan outlet to the vent hose.
mount the adapter, then the hose, use clamps to secure it.
lead the air vent hose to the window and out or into a wall through.

Even if the airstream doesn't seem to be very fast, you could test it with smoke to see that it will blow out the air on the other end of the hose. The large diameter lets quite some air out with just a "gentle" airstream. This is not a very efficient system though, as we build up a pressure in the pipe the fan wors against.
efficiency gains
To gain efficiency, we should move the fan away from the machine and closer to the outlet. That means, we need to increase the fan power. If you can get your hand on, for example, an in-pipe motor, that would be a solution, but usually an expensive one. If you are good with electrics, you could use a blower from an electric cloths-drier. You might get a clothes-drier to strip the motor from really cheap, for example from a renovation, recycling facility or Craigslist, e-bay or any other auction or classifieds-page.
Or you build your own from an electric motor (you could use your machine's power supply here), a housing made from wood and an impeller, which you can get as a "Dryer Blower Wheel" spare part for under $50. If you connect the power for its motor through a regulatable resistor, you could even control its spinning speed.
To cope with the suction, we need to use aluminium flex pipe on the arm between machine and exhaust.
go big
If you want to go industrial like if you want to run a laser cutter, you will need to go industrial in the vent size too. You use pretty much the same diameter aluminium flex pipe and a much stronger motor than the drier one, and you don't mount the motor directly to the machine back but somewhere downstream as it's rather loud. For what to look for in that case, I found a very good article here. Note though, that this is not a small setup, but you could possibly vent a whole batch of printers through one pump, using some airstream cutoffs to control which ones get currently evacuated.

I strongly recommend putting the fan at the exit port of the ductwork.  Most fans work much better dumping into open air (no back-pressure).

@CarlWitthoft true for most applications with a huge air movement. I would actually go with a two-fan solution (one to blow air into the machine to aid in having a pressure gradient, one sucking out)

@CarlWitthoft expanded on that thought - kinda the "middle ground" on pricing.

Well you can get a centrifugal fan and put it at either end of the pipe. You didn't specify a pipe diameter so I'll assume it's 1 inch. Just hook the pipe up to the exhaust. You will have to design and print an adapter.

I already tried using a standard fan but it was way to weak.. do you really think such a fan has enough power to blow air over 4 meters of pipe? The other fan I used could only creat a nice wind in a range of 30 cm...

@DonaldEnte  there's no such thing as "standard fan" :-) .  If you want to use a squirrelcage, pick one to match your ductwork diameter and check the CFM (cubic ft/minute) output rating.

@CarlWitthoft Do you know a specific squirrelcage fan that will do the job for me? Because I am not really a fan specialist and dont want to buy something that doesnt work for me.. :-)

mybe the VKO Turbo 150 pipe fan?


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Avoiding stringing with flexible filament
I have some flexible PLA filament (https://www.amazon.com/dp/B00VKSSA4E/, presumably a mix of PLA with some platicizer) that's supposed to be easy to print with settings similar to regular PLA. I've seen recommendations to disable retraction, and indeed I get huge failures to extrude at all for a while after retraction if it's enabled. But with retraction disabled, I get stringing all over the place, and since the material isn't brittle, it's really difficult to remove.
I'm using a bed temp of 60 and print temp of 220, increased from 210 for normal PLA since I had trouble getting it to adhere at lower temp. Printer is Creality Ender 3. Using CuraEngine for slicing. The extruder is feeding the material fine; there's no kinking going on or anything.
Where should I start trying to improve this? Might retraction work with a really really slow print speed or greatly reduced retraction distance? Or are there other ways to avoid stringing?

OK, this turned out to be really idiotic. The main source of the problem was Cura's custom start gcode for my printer (Ender 3), maybe duplicated for other printers too: it crams a massive amount of filament through the extruder to prime it. With flexible filament, this doesn't actually extrude most of it; rather, it just builds up as pressure in the bowden, which makes the first few [tens of] layers ooze like crazy, and then the hot nozzle picks up the ooze and drags it all over the place, and yay, stringing everywhere!
A previous version of this answer (see edit history) described a lot of options I was using to try to improve things, some of them rather dubious. Really, the core of the matter, which can manifest in lots of ways, is that if pressure builds up in the extruder due compression of the material being easier than forcing it through the nozzle, it will ooze during travel, or as a glob prior to travel during ineffective retraction, and either way it will eventually lead to catastrophic stringing. So to solve this, I needed to address all the ways it could happen.

First was the start gcode. I dropped the extruded material amount over 200mm for the priming from 15mm to 9mm (about 90% nominal material needed rather than 150%) and edited the custom end gcode to revert all but 1mm of the retraction it does, after homing. This reduces the need for wacky over-priming at print start, and makes the state after printing roughly match the state after loading filament, so that print results are independent of whether filament was just loaded or not.
Second, pressure can build up again if the extrusion rate is too high for the material, nozzle size, and temperature. At 30 mm/s print rate and 0.3 mm layers, I found I need a ridiculously high temperature like 235 °C to keep it flowing. This in turn produced a lot of sagging of overhangs, so really 0.3 mm layers seem to need significantly slower printing, defeating the purpose. 0.2-0.25 mm seems to flow marginally ok at 30 mm/s and 215°C, which is better behaved with regard to overhangs, and fine at 225 °C.
I'd noticed previously (in the previous version of this answer) a problem with layer adhesion with temperatures lower than 225 °C. This was not actually a layer adhesion problem but rather an underextrusion problem, the same one causing stringing.
The retraction amount still needs to be sufficient to account for the compression of the material in the bowden, plus enough to get it backed out of the hotend. I seem to need at least 15 mm, compared to 5 mm for plain PLA. Note that retraction min travel needs to be disabled (set to 0) to prevent skipping retraction for short moves, where stringing will be the worst.
Higher retraction speeds seem to work better, and without them the 15 mm retraction is miserably slow. However, I found that my printer's default limits on extruder feedrate and jerk were very low. Adding M203 E200 and M205 E25 to the custom start gcode made it honor my requests for faster retraction, and doesn't seem to have any ill effects.

In summary, the settings that work for me are:

All print speed settings: 30 mm/s or less
Travel speed: 250 mm/s
Retraction amount 15 mm
Retraction speed: 150 mm/s
Retraction combing: all
Retraction hop: disabled
Retraction min travel: 0 mm
Temperature: 235 for 0.3 mm layers, 215 for 0.2 mm layers

And the results:

You could enable combing in the slicer. Combing not only prevents retracts, it also uses already laid down paths for movement from one to the other location and as such reduces the amount of stringing.

Thanks! I wasn't thinking combing had any effect with retraction disabled, but of course it makes sense that it does, and I have combing disabled because it significantly lowers quality compared to use of retraction (for materials where retraction works). I'll try switching it back on and see if it helps.

Along with combing, you could enable coasting which will stop extruding slightly before it would otherwise in an attempt to prevent blobs and stringing.

@PerplexedDipole Yes, indeed coasting could help too, nice addition. But personally my experience with coasting is that a visible line along the height of the print becomes visible (regardless of the coasting length). This is caused by the sudden change in filament flow as a result of the pressure difference. If you don't mind that, coasting is indeed something the OP could check out.

@0scar: I'm not getting a noticable effect like that, probably because the material is so flexible - it doesn't notice a sudden change in filament flow. Perhaps what I need is a way to limit the acceleration of the extruder so that when it wants to stop extruding it slows down very gradually rather than expecting a quick response.

@PerplexedDipole: Now that I've solved the fundamental problem here, coasting looks like it might be a really attractive feature to use, to further mitigate problems from the possibility of pressure building up.

The right path seems to be enabling retraction, but tuning the retraction and print speed settings. I started out by dropping all speed settings to 30. With retraction disabled, this turned the stringing into solid walls between paths, with only a tiny gap at the very start of the wall, right after the extruder stopped:

This suggested that the sudden drop in pressure at the nozzle is cutting off the string momentarily. Back to that thought in a bit.
Independently of the pressure thought, I decided to turn retraction back on, but with really slow retraction speed. This helped a lot, but probably not the way I expected; I think what it did was give the nozzle time to ooze at the point where retraction happens, rather than in the travel path. I also turned off infill_before_walls, so that the retraction and potential oozing would happen in the infill region rather than walls, and increased the travel speed way up to 200 to take best advantage of the moment where oozing is interrupted.
At this point, I'm getting almost-acceptable results with retraction_retract_speed set to 5 (vs default 25), default retraction amount, and speed_travel of 200:

Back to the pressure idea, I'm thinking that the right solution is probably to perform the retraction concurrently with the travel, keeping some negative pressure the whole time, and possibly jerking the extruder back further just before hitting the travel destination to prevent a string from forming there. Cura has no features to do anything like that, but it shouldn't be difficult as post-processing on the gcode. I might try prototyping it like that to see if it works.

source: Stack Exchange

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

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Printer is Confused-Printing in Air Literally
So I got my 3D printer (Anet A8) a few years ago and put it together. I couldn't figure out how to use it. Then about a month ago I decided to try again now that I am older and got it to work. I know more than I did by far. I have printed about 15-20 different times now, but then this problem occurred just now that I have never seen before. I tried looking up what it could be and google results in nothing and this exchange leads to one thread that is close to what I am having difficulty with but doesn't really help. I got the stl file from the internet on thingverse, so I am fairly certain  they must have clicked the center and arrange when in the cad software to make the item, which is a phone stand. So my print all of a sudden starting printing in air. Here is a picture and thanks for the help.

What do you mean by print all of a sudden starting printing in air, you mean that the filament stops extruding but continuous printing, or does it raise the head and prints filament in the air. Looking at the image I assume you mean the first option, but please make that clear in your question. If so, what you then are looking for is a defect called clogging.

Some thingiverse models are plainly broken, and you only see that when you switch to "layer view" in the slicer. Knowing the model can help in identiffying if it was this or some other fail. Also, the GCode you sliced would be helpful to see. I can assure you, that STL models don't contain arrangement information for the printer. In fact, they don't even contain any reference to the origin of the design program but a boundbox and a know length unit that then all the other lengthes are referenced against.

I can give the gcode file, but how exactly do I do that? Also, I opened up cura and I think I understand what you mean by "layer view" as there are 2 sliding bars (x and z or y probably) that you can slide to see how it will print. Sure enough it shows the exact thing that happened to me. So I agree that this model is broken and I will now check for this after downloading something from thingiverse. Thanks for this lesson as I did not know this, but I do now. However, is there someway I can fix this for the future if I catch it before printing?

To Oscar, I thought my picture was clear but it looks like it might not have been. What I mean was that the extruder is printing filament but is printing where there is no layer. If you look at the picture, you can see the filament coming out from the extruder where there is nothing there (hense air). You can take a look at my response to Trish as Trish hit it on the nail of my problem, I just want to know how to fix it now to prevent this from happening again.

@john please help us -- post the thingiverse link.  We can examine, and probably repair, the source file for you.

I couldn't find the orginal link to it, but I found where I downloaded it. Maybe this link can help?  https://cdn.thingiverse.com/zipfiles/03/d1/fd/7e/b5/Universal_Phone_Stand_even_for_large_phones.zip

You can see in the pronterface how your Gcode will be printed, there are some faces that can be interpreted opposite. So you wont get printing on that part. I got this error when I started to print 3 years ago slicing with the slic3r.

Here's the pattern.
The problem is, you didn't slice the g-code using support. It won't print right without it.

I see what I did wrong now. Thank you as I will now add support for all my prints that have overhang. I see where the support is in cura, its plain as day.

Not all prints need or want support material - Print in place regularily will fail or fuse fast with it, @john for optimal strength, I would print this on its side with support enabled and the everywhere choice.

I agree with @Trish  .  Print on its side to get greatly increased strength where it matters.

If printed on its side, I think the finish would be tremendously better as well, since the support material would only be used on the thin side and not throughout the entire flat side of the print.

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Replicator 2x getting too hot with silent stepper drivers
I equipped my Makerbot Replicator 2x with silent stepper drivers TMC2100. According to the product page I reduced Vref from 127 (factory default) to 25 in the printer settings as well as in my start G-code.
With this I get horrible layer shifting (a few millimeters!), even if I reduce print- and travel-acceleration to 300. The layer shifting is mostly happening on the Y-axis, but also on X-axis. Not only layer shifting was happening, also the extruder-motors lost many steps.
To fight this problem I increased the Vref little by little. At around 70 for X and Y axis (and 50 for extruders) all layer shift- and extrusion problems were gone. Also I had to install a dedicated fan for the stepper drivers, because they got very hot.
I was happy with this solution for about 10 minutes, then I noticed that the stepper motors are getting so hot I burned my fingertips by touching them. My guess for the motor temperature would be 80~90 °C.
So my question is: Are those TMC2100 stepper driver unsuitable for my usecase somehow or am I missing something? Is there a way to get the 3D printer silent while not overheating?

On behalf of advice in the comments, I mounted some heat sinks and measured the temperature via an IR-thermometer. With the old original stepper drivers I get 60 °C for the Y-axis and 66 °C for the X-axis. With TMC2100 it is 86 °C for both. (Each temperature measured at the heatsink)

Did you mount the heatsinks?

There are a couple recent questions on stepper temperature. First thing: check the specs on your motors to see what temp range they are rated for.

I have also found the given TMC21000 settings too low. Measuring Vref current seems to be around 250mA and 500mA would be ideal. So your values seem appropriate. I am also getting mightyboard power-loss (resets?) soon after printing starts on the first layer. Any progress in the past year?

@guru_florida I gave up on the Mightyboard. The printer is getting a trigorilla-board now. Mainly because I have this board and no other use for it at the moment. Maybe I will go for a Duet clone in the future.

Most Stepper drivers will have lots of energy passing through them so it is crucial to having a moderately sized heatsink to cool them off otherwise they will get too hot. Most stepper drivers found online come with heatsinks but you could search online for mini heatsinks.

I also own a Anycubic Kossel Linear Plus (driven by TMC2130) and a Tevo little monster with duet board (driven by TMC2660). On both machines the stepper drivers do not get hotter than 40°C. So obviously silent stepping is possible without massive amounts of heat.

What constitutes too hot? A Hybrid stepper motor operating at 80 degrees is normal. They dissipate heat via their mounting plate (which should not be plastic), otherwise you may need to use active cooling. Now if the motors are dying from the heat then you have a problem.

The mounting plate is plastic. Rather I would use the old loud stepper drivers instead of some (also noisy) active cooling fans.

Using stealth chopping and Klipper "interpolation" reduces torque (According to the Klipper configuration documentation). If you turn off both of these options for x and y steppers regardless of what firmware you are using, you may be able to reduce the current and get the same results (avoid layer shifting and get the same torque).
However, see user77232's answer since your motors can likely operate rather hot and be within the normal operating range of the motors. If your current temperature is within range, you may be able to keep stealth chopping on and keep the current you are using. Regarding your concerns for plastic parts, the glass transition temperature of ABS is around 105 degrees C (https://www.lorric.com/en/WhyLORRIC/Material/material-chemical-resistance-chart-ABS#:~:text=Acrylonitrile%20butadiene%20styrene%20(ABS)%20is,has%20no%20true%20melting%20point.) so you're probably OK on that front. If you're concerned that the temperature is higher than 80 C, consider getting a laser thermometer and check the temperature while the printer is operating (and after it has been going for a while).


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Stringing during travel on first layer with Ultimaker Cura
I'm using Ultimaker Cura 3.6.0 and I am getting some annoying "stringing" on the first layer. This isn't new to 3.6.0 as I have seen it on pretty much every version I have used.
What appears to be happening is that as it is laying down the first layer, it doesn't retract as it moves from one area to another. This leaves a trail of filament which then shows up as an unattractive line embedded in the print. (ignore the other extrusion issues in the example below)
A similar thing happens on the top layer. It ruins the look of the nice smooth bottom I get from a glass bed.
I don't have stringing issues elsewhere on my prints.
I thought at one time I had seen a setting to control it, like "retraction during travel" or something, but now I can't seem to find anything that sounds like it in the dizzying array of settings.
Does anyone know of a way to get rid it these lines?

Yes, if you are using the Combing Mode option, please ensure it doesn't do this in the skin, for a leak/string free first layer, it is required to set the Combing Mode to Not in Skin.

When the mode of the option is set to Not in Skin, combing is "off" for the skin; this implies that the material will retract and move in a straight line to the next print area. When material is retracted (and when properly tuned for your printer), the nozzle will not leak filament causing those (deposited) travel movement lines as indicated by the OP.

Combing. No wonder I couldn't find it on a search for "retract" or "travel". :-) I'll give that a shot when I get home tonight.


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How is the Ex.xxx calculated?
How is the Ex.xxx calculated, formula
G1 X129.000 Y126.322 E7.90758
G1 X128.476 Y125.548 E7.92045

This is an exact duplicate of How is the E argument calculated for a given G1 command? and has been answered.


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Printing with Nylon 6,10
Can Nylon 6,10 be used for 3D FDM printing? What range of temperatures be used to print with it? How does it compare to the standard 3D printing Nylon material (I think it is 6,6).

Based on the information from a Quorra question about what the difference between Nylon 6,10 and Nylon 6,6 is and a ULprospector article, we can establish:

6,6 is a smaller molecule than 6,10.
Base materials are different - hexamethylene diamine and adipic acid (6,6) compared to hexamethylene diamine and sebacic acid (6,10)
6,6 has a stronger tensile and compressive strength as it is more densely interlocked, but it also has a higher melting point. This means also that 6,6 is more heat tolerant.
6,6 is also known to have the least degradation of strength under moisture, compared to other Polyamides.
HOWEVER, 6,6 has a lesser resistance to weak acids compared to 6,10, it is also the most sensitive to UV-light and degradation from air exposure.
6,10 also bests 6,6 in regards to absorbing less moisture (a large problem with 6,6), but is more expensive than it.
Recently 6,12 is replacing 6,10 for it has very similar or better properties while being cheaper.

While I see no problem with the technical ability to make a Nylon 6,10 or Nylon 6,12 filament and print with it (the lower hygroscopic of the larger molecules might make that even easier), you will make a compromise in other areas of the material, most liekly cost and availability - to my knowledge no filament that claims to be Nylon 6,10 or Nylon 6,12 is on the market at the time of this writing (April 2019), and as such there are no known benchmarks for print settings needed are available. I would expect the print temperature to be slightly lower than that of Nylon 6,6 though.

Thanks for the thorough analysis! I had seen the Quorra article but got lost in it. In terms of the price, I am actually doing this in a school and we are doing a joint project with an organic chemistry class where they make the nylon 6,10 themselves. We have a machine that supports making filament from nylon as well and we are talking with them about the settings needed for making sure it come out well.

@thaimin make the nylon, then melt it into pellets, then melt the pellets into filaments to get the most even filament.


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Removing glue residue on part after printing
Following advice I read elsewhere, I have covered my (heated) print bed with blue painter's tape, and before each print I apply an Elmer's purple washable glue stick to improve bed adhesion.
After the print finishes and I remove the part from the bed, the bottom is covered with a white residue. I'm fairly certain this is the dried glue. It turns purple again when I wet it.
Is there an easy way to clean off this residue, or is there a better technique?

I'd bet acetone, but you might want to try it on a very small spot before you do to make sure it doesn't mess anything up with the print. It'd take the goo off, but whether it is harmful to the print I'd not be sure.

being made for kids to use, it's water-soluable. warm water and gentle scrubbing with a sponge or rag will rinse it right off, or you can soak it for a few mins if you have a lot of parts.

i'd been using tape/glue sticks. I now use a thin coat of hairspray on the glass itself. It also sticks to the print, peeling when the bed cools and the print's removed. I apply a THIN coat after clearing the bed, and let it dry on a hot (60C) bed for 5-10 mins. It adheres well and unlike glue or tape, i never have to completely "overhaul" it, i just touch up bald spots with a quick puff or two. It also rinses off easily with hot water.

Apart from the glue residue, your first layer is awful, you might want to lower the distance between nozzle and bed or invest in a sheet of glass and use hairspray or 3DLAC or any other spray adhesive.

I've been using name brand blue painters tape with a 60C bed for PLA and don't find I need any extra glue for adhesion.  I have been able to print 5 chesses back to back on the same spot on the tape even. The 6th piece broke free after the base was printed.  I've been slowly pulling the pieces off after the bed cools about 5 degrees C, and then start the next one so there is not a lot of time waiting for bed reheating.

Elmer's Purple Gluestick is pretty much based on PVA with a water-indicator. It is a water-soluble material. Tossing the piece into a water bin and brushing it with a toothbrush should remove everything.

I have two different makes of masking tape. The print stick so well to one of them that I end up ripping the tape up to get it off and the bottom of the print has the tape suck to it. The other roll was the complete opposite, nothing would stick to it. I ended up using the non-stick tape and applied a diluted (30% PVA - 70% water) glue to the (tape covered) hot bed. Works wonderfully.
Mike.

Hi Mike, while sharing experience is great, and much appreciated, this answer as such does not answer how to remove the glue residue.

HI Mike and welcome! Hmmm, I have to agree with @0scar. Your answer is a great insight, but it might be better posted as an answer to a more relevant question, such as Filament moving around and not sticking to bed. If you posted it there, instead, it would be sure to be upvoted... :-) This post being here, may end up getting downvoted or deleted, as it isn't addressing the issue of removing glue residue. Thanks in advance for your understanding.


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Can I replace a damaged firmware of a 3D printer based on Arduino Mega?
I have acquired a second hand 3D printer, the GEEETECH I3 Pro B. The previous owner tried to change the firmware but he made a mistake and he bricked the board.
I want to substitute the firmware of the board (which is an Arduino Mega 2560 based board). Do you think is possible if the board doesn't respond to the controls?
I have inquired and found an open source software called Marlin I want to use to restore the printer.
If you have an advice or you think that I can do it in any ways tell me.

Welcome to 3dPrinting.SE!

I'm only familiar with flashing phones and computers, but it depends on if the method to do the flash will still work on the board in it's current condition.

it's hard to truly brick a mega, the bootloader is separate from the code...

It is hard to diagnose the board without hands on experience. It is even more difficult if you get a board that has been "updated/upgraded" by a previous owner leaving it not in working condition.
But, there are at least 2 solutions.

You could buy a new printer controller board, upload new firmware and connect all connectors.
You could try to burn a new bootloader onto your current board and upload a new version of the firmware.


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Which software do I need to start print something?
I'm still new to 3D printing and I want to print something. I expect that I'll mess it up since I find nothing to adjust it but it is now laying around for 4 months and I'm sick of it.
So my question is where do I find Windows software to print something and of course where do I get a 3D model?
I own a Geeetech i3 Pro W.

First; find a model!
To print something you require a model (usually this is in STL format, look into websites called Thingiverse and MyMiniFactory for examples). Once you have a model file, you need to make it readable for the printer firmware.
If you can't find suitable model, then you need to design a model yourself (or ask someone to do it for you) or adjust an existing model to suit your needs. "Good (preferably free) Beginner Software for Part Creation?" is a good place to start.
Second; use slicer software
For a printer to be able to print the model, the model needs to be sliced into layers. These layers need to be printed at specific speeds, temperatures, etc. Search online and look at the filament packaging (usually the ideal temperatures are on the packaging) to find the ideal temperature for your filament. If you are not using the right temperatures, your print will most likely fail. Programs that are able to slice models are called slicers. The most popular free (and Windows compatible) slicers are Ultimaker Cura and Slic3r (or its Prusa distribution).
The slicer produces a printer readable file called a G-code file (file filled with printer instructions for e.g. movement and heating). This G-code file can be sent to the printer using specific printer software (e.g. OctoPrint, Repetier-Host, etc.) but more common or simple is to put the G-code file on an SD card and print the file using the print menu on the printer LCD.

Got my first print. Yey :-D

@rekire Congrats! As you print simple models and fail at more complex ones, you will soon learn about settings that make prints better and easier in the slicer. One of the most common ones is activating support material. Don't worry about a bad print or two.

@rekire Once you are comfortable with your slicer, look for a CAD design program to make your own models. The learning curves can be rather steep, but once you manage, you can manage to all out.

@rekire Seconding Trish. Learn a CAD (Fusion360, FreeCAD) for tech stuff and/or a 3D modelling editor (Blender) for artsy creations, and you're cooking with gas.

If you're just starting out then Tinkercad (website) is a good place to start designing your own objects. Later you can get to grips with OpenScad for more complex shapes. Both are free.

The models generated with those programs are however not yet printable - you forget to mention slicing!

I'm confused, TinkerCad produces stl files same as OpenScad etc. What files can't be printed from TinkerCad?

You don't print STL but the gcode made by the slicer. STL is the model, gcode the print instructions. While you can use the models provided by pages like thingieverse, you need to slice them for your machine, which your answer fails to mention.


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How to prevent z-fighting in OpenSCAD?
Z-fighting is a 3D rendering artifact of coplanar surfaces (means, of triangles located in exactly the same plane and overlapping each other).
It can happen in OpenSCAD's preview mode when doing a difference() or union() operation. In case of difference(), the rendering artifacts can prevent seeing into a hole in the object. The "compile and render" mode in OpenSCAD does not have z-fighting issues. But since it can take some time to render an object in that mode, it is not a practical solution during development.
How best to avoid z-fighting?
If the answer involves changes to my OpenSCAD code, I would love to see an idiomatic answer / established convention of OpenSCAD coders, if that exists.

The general advice in the OpenSCAD community is to "extend your cuts and embed your joins" (source). The rendering artifacts are one thing but rather just an annoyance; however z-fighting can also cause unexpected errors during STL export (I did not experience that myself so far, just read this somewhere).
So you would change the dimensions of your objects very slightly (0.01 mm works fine) so that:

for a union(), there is overlap volume between the parts
for a difference(), the intersector has volume both inside and outside of the intersected part

Now you could adjust both the size and position of your parts to keep the mathematically exact dimensions for the resulting part. But I found that for the purposes of 3D printing, such accuracy is not worth it because it complicates the formulas so much.
Instead, I adjust either position or size of a part, depending on what is simpler in each case. A measure in the final design will be off by 0.01 mm, which does not matter.
And I keep the 0.01 mm offset in a variable called nothing (picked that up somewhere and liked it …). This keeps the calculations intuitively understandable.
Example
To create a cylinder and cut a hole to half of its depth, I would do this:
//!OpenSCAD
nothing=0.01;
height=40;

difference(){
    cylinder(h=height, r=20, center=true);

    translate([0, 0, height/4 + nothing])
        cylinder(h=height/2, r=15, center=true);
}

Now the hole is nothing=0.01 less deep than half of the cylinder – that's the inaccuracy I accept.
(Note: If you don't have OpenSCAD installed, you can also try the above code online by copy & pasting it into OpenJSCAD. Include the magic comment in the first line to switch it to OpenSCAD syntax.)

Your answer is the one I'd post for this question. You add the parameter "nothing" while I use "addabit = 0.1" for most z actions.

This may improve the STL generation.  OpenSCAD has two rendering systems.  The first is used for quick display of the code.  The second is much slower and must be run before generating STL.  In my experience, the first is prone to this problem with zero-thickness layers, but the second is more accurate and is not prone to this problem.   Your experience may be different, but I have not generated bad STL files for images with this display artifact.

@cmm Same here, I also only saw z-fighting in the preview rendering mode so far. The STL issue is something I picked up somewhere else. I made this distinction explicit in the answer now.

You could increase the height of the object by nothing to have a perfect part.

I also saw this variable being called tolerance, which I personally find less amusing but more descriptive.

I've seen eps used to mean epsilon--the mathematical arbitrarily small interval used for limits and integration.


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The first layers while printing look strange
I own a Geeetech i3 Pro W and I started printing today. Amazing how it works.
I just recognized while printing my first bigger model something very strange: At the beginning some parts are missing and there are huge holes. However when I keep it printing the following layers "fix" the issue. I'm wondering what I'm doing wrong.
I almost forgot to mention that I think I'm using that PLA, the bed has a temperature of 60 °C and the extruder 200 °C.
Here are two pictures after about 1 layer and after about 4 layers:

You're having bed adhesion issues. Are you sure you've leveled the bed correctly? The distance to bed for the initial layer is critical.

I used a peace of paper, might be I still need to lower it more. It fits now easy everywhere without having much space (I haven't tried it, but I don't think that two layers would fit).

When I level my bed, the paper drags quite a bit. I like a lot of squish which gives good adhesion. You can only get good squish if you have the distance tight. The drag is enough I can't push the paper under the nozzle, I have to pull it both ways.

From the first layer image it can be seen that your nozzle to bed distance is just too large:

the lines of deposited filament e.g. in the brim are not touching,
deposited filament lines are not "squished" or "flattened" to the build plate,
filament is cutting off corners as it is dragged while being hot and not stuck to the bed,
filament leaves the nozzle in "blobs"; it sort of free flows from the nozzle as the bed is too far to give resistance.

Use the plain paper technique while levelling the bed. The paper should give a slight drag/resistance when pulled/pushed. Proper levelling and a proper nozzle to bed distance for the first layer are essential for successful prints.
There is also an option to integrally lower the print level in the slicer software, but it is advised to properly level the bed (hardware solution) instead of using software tricks to sort out the problem.


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Damage to bed surface from heat or chemical or..?
The original bed surface of my Ender 3 has become brittle and finally cracked, requiring replacement. I'm trying to figure out what the cause might have been to avoid it happening again. It seems to have started after using "flex PLA", which involves both high temperatures (225 °C) and plasticizers mixed in the PLA. Could either of these have contributed to the problem? I'm not sure what material the bed surface is - it's the new one that's removable and held on by clips. If it's PEI, the glass transition temperature is supposedly 217 °C, just above what I use for normal PLA but well below what I'm using for the flex, so perhaps that's the cause?
Image of the damage:

The build surface on the Ender3 is a BuildTak clone. The picture is a bit unclear, but given my experience with BuildTak (clones) this certainly damage because of heat. You can, as suggested before, replace the bed surface, but I do not think it is necessary at this stage.
Normally these surfaces do not get damaged that easily but to prolong the life try to keep the following points in mind:

Correct height between nozzle and bed.
Don't let the nozzle heat up/cool down close to the bed (for example after a failed first layer).
When using sharp tools to remove prints be careful nut to dig into the surface.
Don't use too high of a bed temperature (my BuildTak clone once had bubbles forming because the layers separated)
Clean/degrease the bed, although this is more to ensure proper bed adhesion.
I found out that if the bed stops sticking you can revive it by sanding it a bit.

It is necessary - it's hard to tell from the pic, but around the two cracks it's lifted enough to make bottom surface of prints non-flat, and the nozzle scrapes on them and could dislodge first layer depending on exactly where it runs.

Thinking about it more, I recall one print that stuck to the bed really badly, and feeling like I was breaking the adhesive under the bed surface when I eventually got it off. It seems plausible that, after that, thermal conduction away from the affected area was poor, and combined with a few bed height mistakes with hotend at 225 (and one with the first few layers of an aborted print still on the bed), that might have resulted in heat damage.

Re: cleansing and sanding, if anything I have too much adhesion, so I think I'll pass. :-)

@R.. yeah, I have the same, but sometimes because of hand grease the bed adhesion suddenly fails ;)

@R.. If this answer answered your question please click on the checkmark next to it.

The material used for the Build surface is not PEI but a BuildTak Clone that offers adhesion through a rough surface texture. I do not know what exactly is in the composition of the polymer, but I can say that my bed surface needed replacement about 9 months after purchase after I vigorously removed a piece I printed. As a matter of fact, most build surfaces - even PEI - are pretty much going to wear out over time and need occasional replacement. Luckily, a build surface isn't expensive usually.
To prolong the life of the bed surface, I suggest:

check the nozzle distance to the bed, as printing too close can make plastic residue extremely hard to remove.
be very careful when using sharp tools to remove parts - don't let a corner bite into the surface!
don't use a soldering iron or hot air gun on the build platform to remove stuck parts, you'll melt the surface and degrade it
clean the surface at times.

However, replacing the bed is easy enough, as I found out here.

Re: "here" link, my Ender 3 is the newer one without the surface glued to the aluminum, but instead to a removable non-metal plate. So removing the adhesive residue might be different.

@R.. you would still pry the bed off, then remove the 3M adhesive that holds the Build Surface to the steel and then add a new.

The adhesive came off almost entirely just by peeling, and the remainder came off easily with paint thinner. Whole replacement took about 5 minutes and $6 (well, $12 for 2), so not bad at all.

@R.. when I did it, I got myself a pack of 3, having some spare beds and nozzles around never hurts, keeps the downtime for these wear-out parts low.

Yeah. Actually I wish I could find identical replacements for the plate it adheres to. I'd buy an extra or two just to have them ready in case of future damage. Already have lots of nozzles. First pack I bought was assorted sizes, which I still haven't tried, but quality seemed really bad. Now I've got a bunch sold by Creality that seem to be same as original. :-)


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Filament mixer?
I've seen questions about (like What is stopping us from mixing 3d filament colors in an Extruder?) and some solutions for mixing filament colors/materials at print time for multi-color printing, but my question is different: Are there any (affordable) commercially available devices, or DIY/homebrew solutions, for taking 2 or more 1.75 mm filaments, mixing them in proportion, and extruding back as 1.75 mm filament for use in a printer?
In principle it should just take N extruder drives fed a the right proportional rates, one of the multi-input hotends, a 1.75 mm extrusion nozzle, and another drive to pull the extruded filament at the right rate to keep the diameter stable. But I'm curious if anyone's tried and tuned this. Another approach might be taking a hotend made for 3 mm filament, drilling the nozzle orifice out to 1.75 mm, and feeding 3 pieces of 1.75 mm filament into it at once (size seems to match pretty closely).
My interest in this is that I mostly print small things, and it takes months to go through even a single kg of filament, so it's impractical to buy and keep around a bunch of different colors. I'd also like to be able to experiment with mixing flex PLA and plain PLA to get a material with a lot less plasticizer, so that it's not flexible, just less brittle.
Shredding into pellets and measuring out ratios is too much overhead to make it worth it. The key part of the question is doing it direct from filament to filament.

the issue is not as easy as it could seem at first glance. get two and mix them in some proportion... "mix" is the key word and it really hides the main issue. IMO this is the most difficult part of the topic

My experience (from switching filaments) is that enough mixing takes place in the hotend during printing that even just splicing ~1mm segments would suffice.

that's right. i was more referring to mixing shredded particles (i know it's not  clear in my prev comment)

OK, it just turned up on Thingiverse that someone has demonstrated a trivial machine to do exactly what I asked for: any FDM printer.

Its sounds crazy, but it works! This technique will allow you to create one offs, and to color match your 3D-prints.
It works by changing the filament (and the color) of your filament while printing, and this causes a multi colored filament, that can be printed again to archive a homogenic-color.

Source 3D-Printable Filament! -Print Your Own Filament for Multi-Color!, with demonstration video.
I'm in the process of trying this and it looks promising! The filament:

measures 1.65-1.75 mm in diameter and feeds and extrudes cleanly.
The first test print:

came out somewhat underextruded, but decent, with uniform mixing of color. Mixed filaments were white flex PLA and blue regular PLA, and the plasticizer seems to have mixed as expected too, but the print feels brittle due to underextrusion still. I suspect with some tuning of flow printing the filament, very good results could be had.
On further inspection, the brittleness/underextrusion seems to be somewhat localized, so it likely comes from inconsistent diameter/density of printed filament. This actually seems consistent with what I saw from the slicer output for printing the filament: there were regions at +/- 45 degrees (+ or - depending on layer) in the spiral where it seems like wall gaps differed and extra gap fill material did or didn't get printed. This could be a slicer bug but it seems more likely it's a bug in the model, and I'd probably do better to recreate it myself in OpenSCAD...

This might be not so easy, especially as one of the linsk is a video (although it can be done), but could you provide a synopsis of the content of the two links, as if the links die, due to link-rot then the answer won't be as useful as it is currently. Thanks.

I thought what I quoted was sufficient to get the idea across. I'll add an image that hopefully does the rest.

Making your own filament
Theoretically, this could be done with any filament producing equipment by taking the two filaments and shredding them into pellets and feeding them to the machine in the right mix for the color you want. Industrial setups like a Filabot are heavy, large and expensive though.
Luckily, hobbyist filament making setups exist. They vary in price and quality but can achieve ok to good results, if you tinker with them a little. Among the kits that I have seen to work is the Filastruder, but there are also DIY instructables that cost less than 200 $.
Obtaining pellets
If you are good with mechanics, you might design a feed mechanism that pushes the part filaments with known feed rate into a cutter to pelletize the filament in the wanted amounts to each other, creating a homogenous mix over the length of the filament.
Blended waste
As an alternative to self-made pellets to mix in the hopper for the filament maker, one can use shredded waste prints/support structures. After smashing the material to rough chunks, using a blender to gain evenly sized small chunks of 1-2 mm, the stuff should be small enough to feed through the hopper without a problem. the blender also would take care of proper mixing and could take raw filament to mix with used ones.
Mixing in the hotend
Mixing filaments in the hotend would need a specialized hotend with two feed ends into the melt zone and two extruders that push the filaments with the same feed rate. The modification of the feeding system would be extensive and demand a custom firmware.
Splicing filaments
Another possibility would be a machine that splices the filament in a defined manner. One machine that might be able to do this seems to be the Palette 2 by Mosaic, but it costs (April 2019) round 600 USD. Another possibility could be to use the multi-material upgrade of a Prusa i3 Mk3.
This would generate however a non-homogenous mix of the filaments, the transition zones changing from high concentrations of material A to high concentrations of material B whenever the materials swap. Even with very short areas of spliced material the mix will be inconsistent. With colored filaments, this could generate a rainbow pattern.

@R.. could be done with an automatic cutter blade that slices pieces from both filaments as they are fed into the hopper for the feed of the filament making machine. Would need 2 motors running at equal speeds to control feed and a DC one for the chopper.

One feed motor might suffice with good setup of gearing, even allow to adjust ratios based on the teeth of the gear train

Yes, but seems like a lot more gear and places something could go wrong than just mixing in the hotend.

@R.. I added my thoughs on both mixing in the hotend via dual-inlet (an idea that was dropped by most makers after how they encountered problems) and splicing. The mixing and making custom filament generates the most homogenous result.

Re: "modification of the feeding system would be extensive and demand a custom firmware", this question is not asking about mixing of filament just-in-time as part of a modified printer, but production of a mixed-color/mixed-material filament in advance, in small quantities, to be fed to an arbitrary unmodified printer.

As I told you, the best solution in my opinion is to make the filament from 0 instead of either mixing in the hotend or splicing the filaments. To properly make the filament from 0, you need to pelletize it to get a) a good and homogenous mix and b) guarantee feeding properly.

OK, that's a reasonable answer, but from my perspective it just translates into "what the question is asking for isn't practical". :-(

@R.. it is practical, with some work. another way to make useable pellets is putting waste material (including fresh material) into a blender in the right weight amounts and then shred to a fine mix of evenly 1-2 mm particles, then feed the hopper with that. This would skip the pelettizer.

Indeed, waste material makes it somewhat more interesting, but also dependent on having it present and sorted, and I really don't have much waste. It's still a lot of extra equipment, and not something you'd just prepare on a whim and have ready to use in a matter of minutes like I was hoping for.

@R.. Without either a filament splicer or a filament manufacturing setup, yes, it is not something in a matter of minutes.

Do you think my proposals in the question (using a hotend made for 3d printers, with the nozzle modified to 1.75mm output) just won't work? Or that overcoming quality (e.g. consistent diameter) problems would just be too big an obstacle?

@R.. Industrial filament making machines costs 10k (filabot) and get perfect results. Hobbyist machines like the Filastruder or self builds exist and if you tinker them enough, you get good results too. They have nozzles not the filament diameter and rely on the filament's hang and die-swell to get to the right diameter. You need to feed the arbor with small particles, which means pellets or shredded plastic. You could use any plastic though.


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Specifying Z offset in Marlin firmware
I need to set a Z offset for the Flying bear P902. I calculated the offset (-2.98). But, every time when I try to input this using the LCD screen of my 3D printer, the value jumps to either -2.99 or -2.97. As -2.97 is just a little bit too far from the bed and -2.99 is just a little bit too close to the bed (and -2.98 is perfect), I really want to input this specific value. I have tried many times on the LCD screen and also in the firmware itself.
But, even after uploading the firmware, it still displays -2.97.
This is the line of code I was changing:
#define Z_PROBE_OFFSET_FROM_EXTRUDER -2.98 // Z offset: -below +above  [the nozzle]

Is there a way I can input -2.98?

I really doubt that 1/100 of a mm would make that effect on adhesion, the deviation of the positioning accuracy is most probable even higher than that!

Z-offset persitently stored in memory?
Maybe the value of -2.97 for the Z_PROBE_OFFSET_FROM_EXTRUDER  is retained in the EEPROM memory when you upload new firmware.
You could try to send the G-code M502 to the machine to re-load the values from the firmware overwriting currently stored values.
Alternative Z-offset using G-code commands
Note that there is a different (and more common) solution to set the Z-offset using G-code M851, you can do this after you uploaded the firmware to the printer. Sending G-code commands can be done using printer software and a USB connection to the printer through a so-called terminal interface. This can be done in OctoPrint, Repetier-Host, Pronterface (Printrun software suite), and probably many more. Alternatively, you could make seperate G-code (basically text files with extension .g) files with each step in a single file and "print" the files through the SD interface of the printer menu.
The following strategy must be followed to specify the Z offset:

Heat your printer up to your printing temperature and allow a few minutes for it to expand and settle
Reset the existing Z-offset to zero M851 Z0
Home all axes G28
Move the nozzle to the middle of the bed G1 X110 Y110 (if your bed is 220 x 220)
Turn off the software endstops with M211 S0
Move the nozzle down so it is just gripping a piece of standard printer paper
Set the Z-offset to the displayed value. E.g. if the printer displays a Z-Value of -1.23 enter M851 Z-1.23
Store it to the EEPROM M500
Important notice! Enable the endstops again with M211 S1 or the printer head will collide with the bed on the next G28 command

Thank you very much. This helped. I used Repetier-Host and was able to calculate the new z offset and store it. After that, I printed something and it was successful!


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Print came out like a wafer
I'm not sure how else to describe it. There's probably a name for this but I just don't know it. But the bottom few layers came out great, but the rest came out kind of like a triscuit. Below are pics of my print and settings. I am using a delta style printer. Can someone tell me what this issue is called and how to fix it?

The phenomenon you experience is called under-extrusion. Under-extrusion is the effect of extruding lesser filament than required for the print. The result of under-extrusion (depending on the amount of under-extrusion) can be described as spongy prints, gaps in prints/layers, failed prints, etc. As the amount of plastic flow is less than required for the print, the quality and print strength is much lower than that of a normal filament flow printed part.
Most severe under-extrusion is usually caused by incorrect filament diameter setting. E.g. Ultimaker Cura (to date, April 2019, the version is 4.0) is notorious for resetting the filament diameter to 2.85 mm after you upgraded to a newer version (because that is the diameter of the filament the Ultimaker machines use) while most people use 1.75 mm diameter filament.
From the settings if appears you have set the correct filament diameter (i.e. if you use 1.75 mm filament). Please measure the filament over a few meters and determine the average filament diameter to be sure.
In your case it must be something else!
A higher temperature causes filament to be more fluid (do check if the temperature you use fits the type of filament you use), so an increased temperature should help against under-extrusion (less friction for the extruder to push the filament through the nozzle). Please do check the extruder stepper; is it skipping?, is the tension the extruder gear exerts on the filament enough to prevent slipping?
Finally, blockage of the nozzle; partial blockage of the nozzle can prevent consistent flow from the nozzle. It is advised to rigorously clean the nozzle (e.g. using the atomic cleaning method where you heat up the nozzle insert filament and turn off the heat to pull the filament out when temperature is about 30 °C lower than the printing temperature of the filament) or replace the nozzle.

To complete the answer, another source for under extrusion that is seen from the beginning of 2020 of Marlin firmware operated 3D printers is that instead of normal extrusion (where E in the G-code file denotes extrusion of filament movement in units of length), the printer assumes it is volumetric displacement. From the Marlin menu of the graphical controller you can change volumetric displacement to length displacement by disabling volumetric flow.

I upgraded Cura (I got the version from the support page of my printer https://gearrev.com/pages/support). You are correct in the filament issue diameter too. I had this set to 1.75, when i opened it, it was at 2.85 which i figured was a mistake because i remember setting it to 1.75 before print. So i changed it for the screen shot figuring it maybe reset when I shut down cura last time.
Then I checked the nozzle, which was fine, the heatbreak however; That needed some work. The teflon tube was warped. Printing now and even the raft looks better.
I appreciate the answer!

The Cura issue seems to be that they moved filament diameter to a per-extruder setting when adding multi-extruder support, and now the default is wrong and needs to be fixed for each extruder.

Underextrusion.

I suggest upgrading to Cura 3, as you are working with a version 1.5.
If you print PLA, you print WAY too hot (190-200 °C Nozzle, 60 °C Bed), if it is ABS, knock down the temperature a little.
Check for a clogged nozzle.
*

I have no idea why the heat is at 245. I didn't catch that. The filament box says PLA+ 205-225 so i used 212. I think this old Cura version was an issue. Weird because I got it from the support page of the printer (https://gearrev.com/pages/support). Upgraded and also found that the filament diameter reset itself to 2.85 and the heatbreak's teflon insert was broken.
Also appreciate the term for this because when googling for "triscuit 3d print", i didn't quite get what i was looking for lol

Yeeea, filament resetting to 2.85 mm is an old bug. PLA+ is printed higher than normal PLA, so 210-220 sounds ok-ish.

Just to add to the already made answers:
Check out heat-creep!
When heat from the hot-end creeps up in the filament, it melts and blocks the extrusion (more or less severely), and under extrusion results.
It's basic characteristic is that the print starts out great, and then some time in, under extrusion happens.
The solution is to cool down the cold part of the hot-end which is usually done with a small fan directed onto the cold part, e.g the top part where the filament enters the hot-end.
Most hot-ends have a heat sink on the cold part, but in my experience this is not enough and for me a fan has always been needed.

Good addition! Usually it stops extrusion as a whole, but indeed sometimes heat creep could cause partial blocking.


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Is it possible to know which is the correct temperature range and speed for any model?
Trying to print a 3D model for my mobile phone, but I see that when printing the sides, being thin, increases the retraction and the recoil seems a little abrupt and makes a coarse sound.
I would like to know if it is possible to know what speed and temperature is recommended to print a model.
In my case I use Simplify3D, and when I'm going to save the file in .gcode format, I see that there are some ranges shown in colors, how does this apply to the models?

The first indication for print speed and temperature should be taken from the box the filament comes in. Generally it specifies temperature ranges for the hotend and the heated bed. Sometime, mostly online, more parameters can be found amongst which is the printing speed.
Do note that temperature and printing speed are linked, if you want to print faster you should increase the temperature. But, if you are printing small or thin things you should print slower so that the part cools enough for the next layer. Basically, part cooling is then also important, but not all filament types (e.g. the ones with a high melt temperature like ABS or PETG) like being cooled too much. So you have another parameter to consider.
It is difficult to instruct you to print at a certain speed and certain temperatures as it is highly depending on the filament (e.g. also the filament diameter), the machine type/make and model, extruder setup (direct or Bowden), the print, enclosure, etc.
Because of the many parameters affecting printing, it is usually suggested to calibrate the printer by printing a temperature tower or performing retraction tests to find the print window for your specific setup.

Thanks for your answer, my filaments mostly have temperature rangue between 180 °C - 220 °C (356 F - 428 F), and the speed 50 mm/s - 100 mm/s.
My Printir is Core XY DIY, have a bowden extruder, the extruder is E3D V6. I was investigate and make question, and  some recommended to me layer fan, what you think?
I am using PLA Glow in the dark. The brands of my filaments is Amolen.

Note that most dye's used for glow in the dark require a hardened nozzle. You probably have PLA, this print perfectly at about 195-200 °C at about 60 mm/s, you can increase the temp range to 210-220 °C if you want to print up to 100 mm/s. Print some tests, e.g. heat towers at different speeds to find out what works best for you.

But, if use 210 - 220 °C range, and the 60 mm/s, this will be the opposite the teory, when the temperature is high, the speed too, obvious this is directy proportional?, well i have to practice with the some tower and how separate process with simplify, o what software you recommended for this?

3dSimplify calculates according area, infill and borders vs your settings, but you can override with higher values. The calculated values were taken by some testing which developers made before releasing his software, new version has new parameters to improve your printings. Of course you can calculate your owns.

So as someone else on here mention, those settings shouldn't be for the model but for the filament. Sadly, you will need to test 99% of filaments to really figure this out. I have a modify tester, and on the description it tells you how to set your temp. https://www.thingiverse.com/thing:3347967
You can look at the remix if you want to grab the blank model and put your own numbers on it.
It should be noted that things like water in the filament can mess with how the filament reacts to speed and temp. If you have questionable prints coming out of a filament that sat there for a long time. You can easily run it through the test to figure out the temp.
Anything else I could add is would just repeat what most of 0scar said.

a different filament in this is "a different combination of manufacturer, color and plastic type"


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Can I repurpose most of the components of this Prusa clone for a Delta?
I have a generic Prusa clone that I'm not using (my primary issue with it is the lack of rigidity in the frame housing as built). Will the motors (ks42sth40-1204a) and controller that come with it be good for a large-ish Kossel? Something no smaller than 200x200, preferably closer to 300x300? How do I reason about this?
Also - I know the Duet board seems to be recommended for Deltas, but can I use the RAMPS board that I already have here?
I don't have a design finalized, but have been looking at this Kossel, Building a Large Kossel Delta Printer – pt. 1: Parts and Planning, which uses a Flex3Drive effector.

what design are you using? What is the weight of the print head including arms and belts?

@Trish added design link

What is the make and model of your stepper motors, is there a sticker on them anywhere? Or is the only information that you have about them from the Prusa clone link that you provided?

Please ask only one question per question. This question is too broad, as the question about the controller is entirely unrelated to the question about the motors.

@TomvanderZanden given the excellent answer below, I'll keep this together, but will adjust the title to reflect the overall question - can I repurpose most of these prusa clone parts for a delta.

kolosy, did you look to see if your steppers have any stickers on them, indicating make and model?

@Greenonline I did - just added it to the q.

Hmmm, it is interesting that the holding torque on the stepper specification (4.0)  differs quite significantly by ~20% from that on the printer's link (4.8). Although it is still higher than that of the Wantai below.

Stepper motors
For equivalence, 4.8 kg⋅cm is 0.471 N⋅m or 47 N⋅cm.
Looking at the RepRapWiki - Nema17, the most common steppers are:

Kysan 1124090/42BYGH4803 (54.0 N⋅cm),
Rattm 17HS8401 (52 N⋅cm), and
Wantai 42BYGHW609 (39.2 N⋅cm).

The Kossel that you refer to is of a similar size to the Kossel XL. Again looking at the RepRapWiki - Kossel, the recommended stepper is the Kysan 1124090 Nema 17 Stepper Motor which has a Holding Torque of 5.5 kg⋅cm.
So, without knowing the exact make and model of your stepper motors and assuming that the specifications for your stepper motors given in the Prusa clone are correct, your steppers are not as strong as those recommended (apart from the Wantai). However, the recommended steppers may be over-engineered and provide [much?] more torque than is strictly necessary. After all, the holding torque of your steppers isn't that much below the recommended values.
If I were you I'd build the Kossel using your steppers and it might, in all likely hood, work out fine. FWIW, I have used the Rattm 17HS8401 in my Kossel Mini and Kossel XL. I got them on eBay and were quite reasonably priced.
You should probably read this article, RepRapWiki - Choosing stepper for a delta. Whilst no concrete values for holding torque are given, this is interesting:

A good practical setup
The Fisher, a small delta printer was designed by late RRP company. As for all their printers, they were using small and compact steppers with a torque of 2.2 kg.cm. This is lower than most repraps but is sufficient if there is no mechanical problem (friction).
These small motors have a low nominal static torque, but they also have a low inductance (2.5 mH), while due to their small size, the nominal current remains reasonable (1.2A).

as is

High inductance motors
You find on the market steppers sold for 3D printers, with a torque ranging from 2.6 to 4.4 kg.cm and a current of 0.4 A. This low current appeal builders as it make the electronic driver heating much less.
However, it came at a cost, which is a very high inductance which varies from 30 to 35 mH. That means these motors are totally incapable of any speed. They are unusable for a delta and a bad choice for another printer. As an example, a 4.4 kg.cm motor wired for this low current, while having a static torque twice the Fisher motors, simply cannot reach the maximum speed used by the Fisher, effectively having a near zero torque over a given speed. Same motors with a winding giving a nominal current of 1.5 to 2 A will be more usable.

Controller
Also, yes, RAMPS is fine for the Kossel, although the firmware calibration is obviously different, as it is a delta and not cartesian printer. For calibration, refer to How do you calibrate a delta robot 3D printer?.
Although, as Scott Lahteine states early on in this video, How it's Made: The Marlin Firmware!, using an 8-bit controller for delta printers is pushing their capabilities somewhat.
Extruder
I'm not familiar with the Flex3Drive, but it certainly looks interesting. I have used the 3325_0, this NEMA-17 motor has an integrated Planetary gearbox with a 52/11:1 ratio. It generates 16.2 kg⋅cm of torque at 1.68 A. I wrote a short blog about it here, The extraordinary extruder.
Building Tips
Also, if you are planning on building a Delta/Kossel, then I'd seriously recommend watching the series of videos on YouTube from BuildA3DPrinter.eu as they are extremely informative and helped me a lot, Build manual Kossel XL & Kossel Mini. I just checked their website to try to see which make and model of steppers they use, in order to get an idea of the holding torque, but they seem to have stopped trading. However, their stepper motor page states the following:

The standard motor for most 3D printers including ours, the 42byghw811
from Wantai Motors.
Holding torque is 4.8 kg⋅cm or 47.1 N⋅cm. Shaft diameter is 5 mm and
stepping angle is 1.8 degrees.

So, to sum up, your steppers should be fine.

@TomvanderZanden - lol, I had removed all of the dots, but you're correct in reinstating them, I've just checked. Thanks :-)

I was mostly annoyed at the kg/cm notation being used in some places, because that's plain wrong :-)

Have you thoughts about adding a small gear train in a 3:2 reduction stage to gain about 50% more torque and steps/mm on the cost of increased backlash and complexity?

@Trish - wouldn't that reduce the speed though? I'm not really sure whether additional torque is necessary. The issue is, I guess, that I haven't seen any concrete figures, from empirical testing for the absolute minimum torque required for a particular delta printer, of a particular dimension. It would be most interesting to see if anyone has actually done such tests.

the speed reduction should be mitigated by using more steps/mm in the firmware, but one might run into the physical limitations of the motor. The idea of using some gearbox only came up from the thought if torque might be too small, how to get the torque up?

authors: ريناد الحربي


text:
What materials would be appropriate for pool parts (chlorine & UV exposure) using SLA or FDM?
I've got a printer on the way later this year that's supposed to be able to do both FDM and SLA (with the appropriate accessories). I'm interested in printing some parts for swimming pools (the types that generally cost fifty cents to make, but with markup and shipping end up costing thirty or more dollars).
I need to find a material that can withstand exposure to chlorine (up to 15ppm for the rare nuclear shock) and UV from the sun, hopefully for several years.
I think that I'd prefer an FDM filament initially in order to test, but understand that FDM processes may require more post-processing in order to keep water from penetrating layers.
What are some other considerations that I should be aware of? Having a white color would be preferable, but if it's available in other colors and would be suitable, it might be fun to make some different colored eyeball fittings.

Have you thought about using ASA filament? ASA filament is very strong. ASA filament is similar to ABS filament (if you have ever worked with that). When contrasting it to ABS filament, ASA has a higher resistance against UV and chemical exposure. It will also have no problem with the water. Both ASA and ABS filament print at about the same temperatures.
Here are some links that might be helpful :

UV-Resistant ASA Filament: Properties, How to Use, and Best Brands
Want to Use ABS in Hot Sun? We Compare ABS vs ASA Filaments

Hope this is helpful.

Welcome to 3dPrinting.SE! Are you in any way affiliated with the link you provided? You should state one way or the other on it so it doesn't come across as spam.

I am not affiliated with the link provided (I just think that it is good a good overview). But, you are right. I will update the answer

That does indeed look like a good option. Especially since it can also be vapor smoothed with acetone like ABS to reduce the porosity and surface area.


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Power OctoPi from printer
I'm wondering if there is some trick to power my OctoPi with the power supply of my 3D printer. I'm using an Geeetech I3 Pro W.
The power supply itself should be able, but the output is as far as I'm aware of 3.3 volts. Not my desired 5 V for USB, it would be a shame if I really would need to buy a new power supply when I have a strong one actually running. My current power supply causes a lot of "Under-voltage detected!" warnings.
After thinking a little about the specs, there are cigarette lighter adapter for cars they use 12 V. Has anyone experience with using that on his printer?

Presumably, the PSU is 12V or 24V (for extruder and steppers), and there is a lower voltage regulator on the printer which you are trying to use. Depending on the version of PI you use, up to about 2A is a good spec for the supply you need.

What you are looking for is called a "buck converter" or a "step down module". These literally cost about half a buck/Euro a piece. These converters convert a high voltage into a low voltage, the better ones are able to draw 2 to 3 Amps, which is required for stable operation of the Raspberry Pi.
If you have an old computer power supply of a decent brand (probably not as you refer to a kit/assembled printer, but added for completeness), you can even use the standby 5 V line out and switch the power supply on using a relay to short the green wire of the PSU to ground. This is how I use it on one of my printers.
Note to power the Raspberry Pi through the micro USB port, to not bypass safety features.

Where are you plugging in the USB power to the Pi? If you are back powering it from the data connection, you will bypass the fuses and potentially ruin your Pi or worse. Look at this wiki under the power section:

Back-Powering; (powering the Raspberry Pi from a USB hub through the uplink/data port, single cable) Back powering is possible on the Raspberry Pi, but not advisable. Revision 1.0 boards have to be modified to back power, this is due to the 140 mA "polyfuses" that are installed in the USB port circuit. Revision 1.1 boards do not need modifications to back-power, they have replaced the polyfuses with 0 ohm resistors in their place. Revision 2.0 boards do not need modification, they have neither resistors nor polyfuses. It is advised that short (12" (.3 meter) or less) USB cables be used for back-powering a Raspberry Pi. Cable resistance plus connector resistance can quickly reduce operating voltages below the proper range (5.25 V to 4.75 V). But do note that if you do not power the Raspberry Pi in the "official manner", that is through its micro-USB port, but use any alternative way (such as through the GPIO header, the test points TP1 and TP2), but also by back-powering it, you are actually bypassing the Raspberry Pi's input polyfuse protection device! This can have extreme consequences if ever you manage to put more than 6 V on the Raspberry Pi, even for a very short period. As this causes the overvoltage device D17 on the Raspberry Pi to trigger and short the 5 V supply! Without the polyfuse limiting the current through D17, it will burn out, probably melting the Raspberry Pi's enclosure with it, (if you have any) and possibly causing a fire-hazard. It will probably also create a permanent short of the 5 V supply! So be warned, and if you use back power make sure your hub or its PSU has a fuse to prevent this from happening. If not, add your own fuse.

As far as powering the Pi through a 12 V to 5 V converter this will work as long as the current is rated above what the Pi will use, preferably a lot higher. You will also have to consider how this option will cut the power abruptly when you switch the printer off and the Pi will not boot down properly.

It's always best to include the info from the link, for two reasons: (a) link-rot, and (b) saves people time having to click links and search for that to which you were referring... :-) Interesting info about the back-powering anyway.

Thank you guys for your help. I ended up with a suggested "Step Down Power Module" which works fine for me. I connected that module directly with the power supply of the printer with a blade connector. The first startup showed me a couple of low voltage warnings, but the second start worked fine without any warnings. I didn't know how the UI looks like without the warning on the top.
So I avoided that fancy and risky back powering since I power it now as intended. Now I have one power supply less which is great out of my opinion.

I’ve been using a buck converter for quite awhile with no problems. However just as importantly as proper voltage and amperage is using a good cable. I had my step down properly set, but was still getting low voltage warnings until I switched to a thicker cable.


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What is causing these strings in the overhangs?
I am consistently getting these strings in the overhangs on models that folks say they are printing without supports.  Can anyone tell me what is causing them and what I can do to fix them?
I've attached a picture mid-way during a BB-8 print.  I'm using PLA at 75 % speed.

Welcome to 3DPrinting.SE! Can you please edit your question and include the other parameters you are using?

Could you please tell me what to add? (I've just started 3d printing recently, not sure what's important to know)

Take a look at this Meta post..

At which layer did this happen, or at what height? You can look into that layer/height in your slicer. E.g. in Ultimaker Cura you can watch each layer and e.g. show travel paths. This helps you to define where the strings come from, from the part itself or oozing during travel. Please add print temperatures and speed (in mm/s) as absolute minimal data.

What's your layer height? Looks like 0.3 or so which is unlikely to work for a print like this.

While this looks a lot like stringing, it's not what I would call stringing. I usually reserve that term for material that should never have left the nozzle to begin with, due to insufficient or missing retraction or excessive compression of the filament between the extruder and the nozzle. The "strings" you've shown look like desired wall extrusions that did not adhere to the adjacent walls in the same layer or to the previous layer.
This is common when printing concave perimeters that are overhanging, due to a combination of minimal-to-no contact with previous layer and acceleration of the nozzle away from the previous wall in the current layer. Sometimes under-extrusion can also be a factor.
You can often mitigate this by:

using thinner layers (for the whole print, or "adaptive layer height" that will dynamically adjust as needed). For a given wall slope (fixed rise over run), this will reduce the "rise", and thereby place the walls of the next layer such that they overlap more with the previous layer. Sometimes this makes the difference as to whether they overlap at all.
increasing hotend temperature. This will improve bonding with adjacent wall and with previous layer, if there's any contact with it.
decreasing print speed, especially for outer walls. This will reduce the effect of the nozzle pulling the wall away from the adjacent wall it's supposed to bond to, and will also deliver more heat to the adjacent wall and previous layer wall you want to bond to.

All three of these will also help if under-extrusion is part of the underlying cause.
If you can't get any of this to work, using supports is always an option, but spherical (as opposed to flattened) domes generally "shouldn't" need support to print.

You did print overhangs without supports. I have printed a Thermal Detonator for StarWars day (May the 4th be with you!), which is pretty much an empty pair of domes. To ensure that the upper layers stay up, I have activated support starting at 40°, and it came out perfectly fine. Without support, the lines would have had nothing to hang on and sag down like in your print.

I've downloaded the model and sliced it in Ultimaker Cura, it does not look like it needs supports to be printed. The original maker also suggests to print it without supports. It must be the settings that are incorrect.

this needs an overlap to avoid the bridge over hang


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Good profile for slicing ABS in Slic3r?
Does anyone know of a good slicer profile (i.e., an .ini file.) for Slic3r for printing ABS for a Prusa i3 MK3S printer?

Welcome to 3DPrinting.SE! I'm not sure I understand your question? What's wrong with using Slic3r as the slicer for ABS? The slicer is fairly filament agnostic, meaning, it doesn't care. You as the user setup the parameters for the filament when you slice. The slicer then creates the g-code which your printer can interpret. There are presets within the slicer which can be used, then tweaked if needed for your specific needs. Again, this is filament agnostic to the slicer. Can you clarify what you actually want?

So you are after a profile for Slic3r. A profile that works for one printer may not work for another printer. Basically, as such, this is not a good question for SE. Every slicer is able to produce printer files for ABS, it is usually the printers that have difficulty to print ABS properly because of its high tendency to warp because of the large shrinkage. If you rewrote the question to explain what your problems with printing are, people could answer you what slicer settings you could change to produce better prints. ABS has a good alternative that can be printed as PLA; look into PETG.

ABS is a plastic type that has a relatively large shrinkage when cooling down compared to other filaments;e.g. much more than the popular replacement PETG (which prints similarly as PLA but has properties like ABS).
As of this shrinkage, it is the operator of the slicer to produce an environment to properly print ABS. This not only implies that correct settings for the slicer itself need to be chosen (depending on the brand: high hotend temperature; about 220-240 °C, high heated bed temperature; 90-110 °C, using a large brim), but also that the printing environment is optimally setup to allow printing successful prints. You should think of adhesion to the build plate, modifying parts to include so-called Mickey Mouse ears and an enclosed printer space to regulate the temperature. ABS doesn't like temperature changes as that will result in split layers. This is why ABS is difficult to print for most people, it is best not to choose this when you just starting printing, nowadays much better alternatives are available called Co-polymers like PETG.


text:
Help-build a decent 3D printer for a beginner (any ideas/tips/info)
Hi I'm a beginner looking for an helpful advice on how I can build a 3D printer for practice before getting an official 3D printer. If you have any suggestions/tips/info/etc. Please let me know as I will be doing more research on 3D printers.

Hi and welcome to 3D Printing.SE! This question is too broad to be answered and would attract opinionated answers and a start for discussions. As such this question is difficult to answer as an SE question, this is more a type of question that is found on forums. SE is not a forum. Please take a look at the help section relating to asking questions, in particular [ask], and take the [tour] for more information on how stack exchange works.

An interesting question that can be distilled is why you think you should build a printer yourself before buying an "official" one?

I think this will be closed for the reasons Oscar mentioned, but there are a variety of detailed plans for building a 3d printer from components such as a Prusa i3 or Railcore. But as Oscar mentioned, another option is to buy an inexpensive kit or printer in the $200 range and you can learn a lot from that as well that would be possibly more difficult or time consuming to learn by building from scratch.

See Building a 3-D printer. You'll learn more by building one than buying one, but also have more headaches :-)

I think this is a duplicate (as well as being too broad), and I've closed it as such. If you wish to edit your question to be more specific (and reduce it's breadth) then the question can be re-opened. Oh and welcome to SE.3DP! :-)

I'd get a kit you have to assemble  https://www.3dprintersonlinestore.com/  I got a Migbot from 3D Electron.  Learned a lot mechanically assembling it, fixing assembly mistakes, fixing stuff on the pre-assembled extruder (feed gear not aligned to the roller), bad nozzle thermister, and most recently loosened setscrew on the extruder tube, requiring disassembing and reassembling the extruder to get at it.  Finally have it all working, and have 13 pieces of a chess set printed.  Start printng with PLA, ABS curls too easily off the print bed and ends up not usable for larger pieces.

www.microcenter.com has a good price on PLA, just $15/roll and free shipping. Many colors to choose from. I am waiting on 5 rolls to be delivered. I bought 2 rolls of MG Chemicals PLA locally on Saturday to use in the meantime.  Little pricey, 22 dollars a roll, but I got a done this weekend (like figure out stuff above) and did a lot of the chess set printing and was able to stop fighting with the ABS.  We printed the 3 pieces of an Ipad stand, and the curling and non-circlular holes left it useless.

A 5-lot of thermistors was ordered on Amazon when the bad thermistor was discovered the prior weekend and stopped us dead in our tracks with a "min temperature" being shown.

You'll need some small hex wrenches (allen wrench) I think 1.5mm for the smallest set screws, 2mm, and 2.5m for others, and a 5mm wrench to hold nuts as you tighten some of the screws.  It needs to be thin to fit between one of the fans and the extruder motor.   You may also need a very small screw driver to release the pins from the cable harnesses to rewire them.  For example the pins might be 1-2-3-4 on the 4 pin header, but 1---3-2--4 at the 6-pin header on the motor. I bought some T-handle wrenches to make it easier.


text:
How to add a patch to "Marlin_main.cpp"?
According to this question, MKS 12864OLED Display setup, I need to add a patch to "Marlin_main.cpp" but this a large file with 14789 lines of code! I don't know where I have to put this patch. Please help me.
patch:
/*---------------MKS OLED patch_3-----------------------*/
#if defined (MKS_OLED96_128x64_FULL_GRAPHICS_CONTROLLER)
pinMode(LCD_PINS_DC, OUTPUT);
pinMode(LCD_PINS_RST, OUTPUT);
digitalWrite(LCD_PINS_RST , LOW);
delay(1000);
digitalWrite(LCD_PINS_RST , HIGH);
#endif
/*---------------MKS OLED patch_3-----------------------*/

The question you refer to has an incorrect answer, I've investigated it but never got the time to post a proper answer. If I recollect correctly, the latest version is not compatible with the suggested fix. Parts are already implemented in the code. When I have the time I will look into the problem again and post an answer. Note that I do not own such a display.

I did post an answer on Connecting OLED 128x64 LCD; dogm_lcd_implementation.h is missing for patching. I guess that is part of the solution. Do note that we are active on [chat]!

Yes, thank you. but it's not working yet. I guess the patch for "Marlin_main.cpp” is needed too.

Please join in [chat] to prevent a long comment discussion. I'll be looking into it tomorrow.

I've seen that kind if ifdef in the .h file, before setup(), in other Arduno programs.  I've never had  a sketch that used  .cpp file, but I suspect if it goes there, it would be after  LCD_PINS_DC and  LCD_PINS_RST were assigned to pins.

From your comment, it seems as if @0scar's answer to the previous question fixed your issue. Therefore, closing this as a duplicate.


text:
Does the X/Y bed orientation of a model affect the print detail quality?
My FDM printer bed moves on the Y-axis and the print head moves on the X-axis and raises on the Z-axis. When printing rectangular objects (a model of Notre Dame in this case), are there print detail quality advantages to aligning the model perpendicular to the X or Y axis, or at 45 degrees? Part strength is not an issue and support is not needed.
Thanks.

Bowden or direct drive extruder? You know, it’s all about inertia...

Also cooling air flow could influence the quality. windward usually looks better than leeward as the filament cools quicker

@darthpixel this could easily be solved by using a 360 degree cooler like the DiiCooler (or CiiCooler) https://www.thingiverse.com/thing:1025471/

@RobertoLoGiacco If you use a Prusa style printer with the bed as constantly moving Y axis, bowden vs. direct drive is the least of your inertia worries.

@towe I’m not sure I agree, stepper motors are quite heavy... Aluminum is not that much

@RobertoLoGiacco I still got some 330x330 heated beds laying around. I'll put them on scale later, maybe you're right. My Titan clone hardly weighed more than the metal extruder cage that came stock on my X5S though.

Let me know what are going to be your results, I’m curious

In short: Not really.
longer version: It depends.
The main culprit of losing details in this case would be the weight and speed of the thing moving. So if you have a heavy X-axis carriage, acceleration and decelerating the carriage won't be instant. Same with the bed (Y-axis).
Another culprit can be slop in the system, so check your linear bearings and belt tension.
Also keep in mind that you are printing on the bed, so the weight of the Y-axis increases while the print progresses. This shouldn't be a problem for small prints, but if your print becomes bigger it can decrease the quality. Another factor is that every print will bend a little the higher it gets, so if you print a tall slender object, don't accelerate the bed too fast ;)
To summarize, for high detailed prints:

Lower the speed
Check the system for slop (tighten belts, and align linear bearings)
Take the lightest axis for the highest detail (keep the weight of the print in mind)

One thing that you can do to test your machine is to test the ghosting on each axis (https://www.thingiverse.com/thing:277394).

I'm under the impression that your question hints on rectilinear motion by aligning the print part to the axes motion of the printer. So, placing it under 45° would suggest movement of both steppers to make a straight line opposed to one stepper movement for a straight line.
Basically, the weight of the carriage and the play in the system determine the quality of the details. Not how much steppers are involved to print the part. As an example, CoreXY or H-bot style printers use 2 steppers to print a straight line and a single stepper to print diagonally. These printers are capable of producing very accurate prints.
On a Prusa i3 style printer it is not expected to see large differences unless you print very fast so that the inertia or play take a predominant role in the quality.


text:
Laser scanning to 3D printer
I have one *.xyz file (from a laser scan) that I wanted to mesh and create a 3D printable file.
I saw some YouTube videos from Meshlab and try to follow the steps explained in the video, 3D Laser Scanning - Meshing Point Clouds in Meshlab;
When I reached the step: "Remeshing, Simplification and Reconstruction I discovered that "Surface Reconstruction: Poisson" does not appear in my Meshlab (V2016.12).
I search on web to see if I could use another modelating method, but everybody said the «Poisson» method is the "one"!
I have two questions:

It is possible not have the "Surface Reconstruction: Poisson" in the program (there is something I need to pay for use it?);
Not having the "Surface Reconstruction: Poisson", is there any other possibility to create a surface from a xyz point cloud?

Welcome to 3dPrinting.SE! This question, I think, covers your request a lot better than the previous question. Hopefully someone can help you get an answer.

What operating system are you running Meshlab on? This question may have your answer. https://stackoverflow.com/questions/41428698/poisson-mesh-reconstruction

Jose,you seem to have to different accounts, would you like to have them merged?

Same menu, different location in the sub-menu (at the bottom):

As T.M. states in their comment, see Poisson mesh reconstruction on StackOverflow:

MeshLab 2016 now uses the new version of the Poisson merging, and the
  filter is called:
Screened Poisson Surface Reconstruction
it is in the same submenu, on the bottom. The relevant parameter
  (octree depth) is called Reconstruction Depth. It is now possible to
  merge multiple layers at once, without flattening them beforehand (as
  before). If source layer(s) have color, the result will be colored
  too. If you want to have the same result of the old version, put 0 in
  the "interpolation weight" parameter


text:
Software for processing laser scanner images
I have a Ciclop laser 3d scanner, sold as a kit (HE3D), that I've had for several months now without being able to use it, because the official Horus software is completely unmaintained and bitrotted - the API for several Python modules it depends on has changed out from under it, and it looks like the v4l2 interface (or perhaps OpenCV's interface to it) for the camera has also changed in ways that it doesn't grok. I could try to setup an outdated system or VM just to run it, but I'd rather avoid having to use it completely.
In principle, it seems like you should just be able to step the stage, taking images with the laser on and off at each step and differencing them, and feeding those images into the numerical algorithms that construct a point cloud and model. Are there any free software tools that can take and process this kind of input? If so, I can handle scripting the sampling.


text:
After homing all is fine, when printing the Z-axis stops advancing
My Prusa i3 has developed an issue.
It homes fine and has no issues. But, when I press the print button it gives a sneeze (quick screeching noise from the Z-axis stepper motor) and start to print. The only issue then is that there is no lifting on the layers when it prints! When I kill the print, it stops, lifts and goes to the home position as if nothing is wrong.
Video link: Prusa I3 Z-axis issue
Does anyone know of a remedy for this issue?

Hi and welcome to SE.3DP! So the Z-axis does actually work (as you say it lifts after after killing the print)? But it just doesn't work whilst printing? Would it be accurate to say that the Z-axis doesn't work, whilst the X and Y axes are actuating? Or, when you kill the print, are all three axes working fine simultaneously then? I only ask, as I wonder if it some strange issue to do with lack of current - although this is an unlikely stab in the dark, on my part...

HI, yes, the x and y works fine, the z is just not lifting the 0.28mm  for the layers. this mostly results in a very flat model and blocked nozzle. I'll post a video shortly.

Awesome, I got it fixed!
I've restored to default the Firmware EEPROM Settings in the driver program and it's all fine now. I have no idea how that got changed as I would never go mess around there.
I CAN PRINT AGAIN!!
The program I'm using is Repetier. It has a Firmware configuration setting under the printer settings. The values in there was a bit odd so I took a chance and pressed the Reset to Factory Settings and it worked. There is no version number attached to the setting

That's great that you found a solution! :-) Still, it is rather strange as to what caused it. If you ever do find out, please update your answer. Don't forget to accept your answer in 48 hours time, using the green tick, in order to remove your question from the unanswered list. As we are a beta site, we need to keep the unanswered question queue short, in order to graduate to a full site. Thanks in advance.

will keep you posted if it happens again.


text:
Can a model change size when using a different filament type?
I printed a case for my phone, a Motorola G4 Plus. I found the model of the casing on Thingiverse
I just downloaded the model, used Meshmixer to check for issues, after that, opened Simplify3d and saved it for printing using an SD Card. The printed size of the model was smaller than expected.
The model designer, says in the description that he used flexible filament. Is it possible than if I change to that filament, the model result is completely different?
Print result - phone casing:

Of course it can change size... but definitely not in scale you've presented.
Filament as same as many other materials can subject something called shrinkage. It depends on physical properties of the material and as its name suggests cause the dimensions to shrink.
Here is wikipedia article.
The same happens to almost all plastics.
But this phenomenon is almost unnoticeable in terms of PLA... well not really...
Bending is mostly caused by shrinkage. We have heated beds (among others) to prevent it. And we use adhesives also to prevent bending so to prevent effects of shrinkage.
It can be also noticed when you print specific volume (and/or specific base surface) and you left the model on the HB until it cools down - the model can come off the HB on it's own even when adhesive was used.
But your "shrinkage" is definitely not that one.

Maybe this happeneded, when i was prove that use the meshmixer for check the error's and add better quality

@PedroMiguelPimientaMorales you need to edit your model to resize it, then create your gcode again. Some times but some times I got some thingiverse files but I forget to read de instructions which specify print at 90% or print at 120% scale and so on.

No, choosing a different filament type will not result in a different size (unless you use PLA that foams on extrusion, it increases size but then again all other dimensions would not fit either as it expands uniformly). The overall dimensions are defined by the coordinates in the G-code file which is based on the geometry of the model. If the printed model has dimensions that differ in the region of centimeters (like shown in your images) a different filament type will not change the size. Differences in the order of fractions of a millimeter are possible.
Probably the size has accidentally changed while loading the model in one of the tools prior to slicing to G-code.

Sidenote; there are techniques to anneal PLA after printing, you will then observe changes in the size of the part you printed, but I don't think you have annealed the print. From the link above:

On average, you’ll see PLA shrinkage of about 5% and growth of about 2% along the relevant axes. If this shrinkage and growth is going to be a problem, you can compensate for it beforehand during the design and printing processes.

I think the same about the problem are in some tools i use for check error from model. I will try again, but just print the first five layers and comparate size.