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Can anyone suggest what technology and 3D printing material is most suitable for printing of dental models?
I'm looking for a 3D printer for applications in the dental field, for printing digital dental models (not for itra-oral use parts).
Resolution and finish are the main requirements that we consider necessary.
Any suggestion?

I strongly recommend against anything that's not approved by the equivalent of the  FDA in your country.

If it's only used for printing models, and not anything that will be inserted orally, I don't see a problem. But I think the answer would be rather subjective.

Hi, Electivo, and welcome to 3D printing SE! In it's current form, any answer to your question will primarily be based on opinion, since different users have different experience with various brands and printers. This is something that we try to avoid on SE. However, asking  "what printer technology (or perhaps material) should I use for dental implants" allows for more objective answers. I have put your question on hold for now, so that you can make changes to your question. When ready, please vote for your question to be reopened.

It still sounds like a proper answer to your edited question would be a specific model of 3D printer - again, this is something we try to avoid. Try to imagine what a good answer to your question would look like - it should an objective answer. Take a look here for more info. Also, adding details to your question could help. Do you have a model example? What options have you already considered, and why are they not sufficient?

I disagree, reading my question is very clear to me that I am not referring to a specific product, but to a technology and material (the same technology and the same print media are used by hundreds of printer manufacturers to around the world). If you, as moderator, considers "inadequate", then I suggest you remove it from the system. Grateful.

@TormodHaugene I think we should un-hold this question. The OP is asking for available 3D printer types, such as SLS is a typical technology for medical-grade parts. I can elaborate in an answer once we un-hold it.

Electivo and @tbm0115, we are currently debating these kind of questions over at the meta site, we would be very interested in hearing your opinions. It is a difficult type of question to moderate, so we are trying to find a common solution on how to respond. I am sorry for the inconvenience. The question has been reopened.

Hello Tormod Haugene,
Glad to know that my question was re-evaluated and found to be valid. It is very important to us, we can rely on the use of this as a valuable tool.
Often, we have to resort to the aid of translators might write our questions, and this ends up making them confusing for those who are reading.
Again, I would like to thank and congratulate the quality of work.

It sounds like any material would do the job since you are only making a model, which I guess has no features that are difficult to print. As for the technology, either you print models to scale and get an accurate enough printer, or you get any printer and print enlarged models. I'm not sure an accurate answer can be given here.

If resolution is your upmost concern then resin 3d printers are the way to go. They use a liquid resin that does not harden until a UV laser is shined through them. Apparently they get ultra high resolution and smooth finishes right out of the box. The downside is they are generally more expensive machines and the resin material itself is also a higher cost. but if you are in the dental field then money is not a problem. Look into resin 3d printers.
otherwise if you want to try FDM printers then try looking into .1mm brass nozzles which will increase resolution but vastly increase print time. Not sure what material would be best. ABS has toxic smelling fumes, but is the same as LEGOS and is able to be easily smoothed (if necessary) with Acetone fumes. PLA might work well at .1mm nozzle resolution though and is a starch/dextrin based non-toxic biodegradable filament.

As mentionned by Andrew, resins should do the trick : most commons processes are SLA and DLP (DLP is faster but more expensive).

If you aren't looking for precisions (or looking for low budget), FDM
machines should do the trick.
If you need metal, I think Solidscape or micro SLM should both work.

You should specify what are your exigences, it's not the same to do an ultra-high precision metal part and to have a $300 maximum-budget machine.


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Prints are now sticking too well to the bed. What to do?
I'm a beginner. I've a Printrbot Play with a heated bed add-on. I'm using it exclusively with PLA.
It worked great initially, but then I took the nozzle out and put it back in, and the Z calibration was lost (and I didn't know the calibration was a thing). As a result, I started having issues with the piece warping up and not sticking to the bed in the corners and around the edge, when the piece was large and flat.
I've installed the heated bed. I used Kapton tape. All these made it perhaps a little better.
Finally I started tweaking the Z axis calibration (the fine adjustment for the initial distance between nozzle and bed) and that made it perfect. No warping anymore.
But now I have the opposite problem. When printing pieces with large flat surfaces that are siting flush with the bed, it's next to impossible to tear it off at the end.
I went back to using plain blue tape instead of Kapton, but it's still sticking too well to the bottom of the piece. I tried to pry it off by pushing a knife under the piece, but that has put a few scratches on the bed. Obviously I don't want to continue doing that.
What can I do? How to prevent warping, while also making sure the piece does not stick too hard to whatever is underneath?

EDIT: The accepted answer was very good and I don't want to mess with it by adding my own "answer". So here it is:
I ended up adding a glass plate on top of the bed, with a heat conductive layer between bed and plate (it's a funny looking, rubbery, chewing-gum-y material that conducts heat). Now I just apply glue stick on the glass and print. Works great. Large pieces come off on their own sometimes if I let them cool down to 30 C or lower.
I had some issues with the Z calibration sensor due to the plate, eventually got solved, but that would take too long to explain here.

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

I just added a glass sheet on top of the heated bed, and changed the Z sensor to allow for greater sensing distance (ended up gluing thin steel sheet squares on the back of the glass sheet in the 3 places where the printer does the Z calibration). Small items stick to glass as-is. Large items may require a bit of glue stick to prevent corner warping. Everything comes off relatively easy once the bed has cooled down; some items are sticking a bit, but come off when I pry them off with a knife; others (especially the large ones) just pop off on their own when bed temperature drops below 30 C.

Options to check (in order of probability of occurenece and success):

Z-calibration

Maybe you should perform calibration again. It's possible that nozzle is now too close which causes the filament is spread on the heatbed, which causes that the bottom surface is "too flat". It means all separate filament tracks are spilled and they create "glass flat" surface. You did mention that the model sticks too much even to kapton. It suggests z-calibration.

Temperature calibration

Check if the temperature is not too high. Reducing it a bit can reduce sticking. If filament is too soft then material sticks usually better (causes the same as in #1)

Heatbed cleaning

If your HB is scatched (even not visible scratches) then it's possible that previous printouts left little grains in such scratches. Cleaning HB could then help. Are you using glass? if yes - change glass side to check this option. Eventually replace glass with new one.

Heatbed surface

If your heatbed is scratched then filament can penetrate such scratches and increase sticking.

Filament

Did you change filament vendor? If not then maybe your filament had changed during a time/humidity/sun/cigarete smoke. This is very doubtful option but who knows.
What methods you can use to detach model

Paper knife

I also have the same problem when I use paper glue stick. Some vendors produce such sticky glue that I affraid to break a glass (which I use of course). When this happens I use a paper knife. Glass is scratchproof enough. Be careful - if your model suddenly detaches releasing knife... just be careful. Unmount HB or unmount glass first of course.

Hammer

I know people use hammer to detach sticked model. I would suggest this method only for big and relatively simple elements. Especially for solids (fully filled with the material, without any grid/honeycomb inner structure). One short hit in the same surface as the HB. Be careful of course and unmount HB or unmount glass first.

Fridge

As HB material and filament have most likely different thermal shrinkage factor it might help. And guess what - unmount HB/glass first ;)

Yes, the bottom looks perfectly flat; there are no filaments visible there. I didn't know that was bad. The heatbed is just a thick aluminum plate; until now I didn't even know that glass was an option there. I never print directly on the bed, I always use either Kapton or blue tape. Can I print directly on the bed? And where can I read more about the glass option?

@FlorinAndrei It's not bad to have perfect flat bottom surface - rather the opposite - it's perfect but in terms of your issue it might be the cause of the problem. In terms of HB - please take a look on this link http://reprap.org/wiki/PCB_Heatbed

Can you explain what a hummer is? I presume you don't mean the brand of SUV.

@Tom - yes - why not? :P (fixed)

I have only experienced PLA "super sticking" if the print bed is allowed to cool too much. I would suggest running a mild preheat to your bed when you find a print has stuck and the bed is cool. (What you set the temp to for the preheat would depend on the filament in question but start low and work up and you may find a sweet spot/release point for your particular PLA)
I have never encountered PLA "super sticking" printed with rafts on (regardless of printbed temperature).
Rafts will give you a sacrifical grid of PLA between your actual finished piece and the bed itself. That way you can "pry" the printed object from the bed and have more leaway for increased leverage without damage to your actual piece(use a plastic razor blade common in cell/tablet screen replacement kits and you generally won't scratch your printbed/printbed coating/tape). The lattice/net of the raft would also, generally, have less, in contact with the printbed surface area than a finished piece and thus have less holding power.

IMO raft is usually used to increase sticking. Additionally raft will cause the bottom surface less sleek. The same is with HB temperature. We use heating the bed to increase sticking. When I don't use any additional materials like paper glue or hairspray then (depending on filament vendor) my models detaches itself when my HB cools down under 40C

A raft, in my experience, is used to increase the footprint of a piece to help"somewhat with sticking" and thus avoid tip over. However, I've also found them useful as a medium to remove larger, flatter, pieces as well. That's just personal experience--it's worked well for me. (You are correct that they can make for more cleanup to the finished piece though re. removal).
As for the bed, yes, heating to the correct temperature does make PLA stick more. However, I've found pieces easier to remove if the bed is not fully cooled, but of a low enough temp to not warp the printed piece.

hmm... interesting. My experience is absolute the opposite but, well, the man can learn everyday.

Darth, what are your thoughts on removable, and flexible, print beds? I've never used one. How effective are they and would that be a potential option for the original poster until he gets the underlying issue resolved?

worth to try I think. I've never used flexible bed but I can imagine it solves too-sticky-problem. How else could it be?

Pour some 70% IPA along the edge of the model with a Q-tip, it will pop out right away. For larger models aaply IPA from a  wash bottle. This method also works well on other plastic to glossy surface bonds, like, for example, hot melt glue to arylic sheet, see this -> https://www.youtube.com/watch?v=u9kdiZMqfmM

Several factors to consider, but don't get discouraged, it is definitely something you can solve.  Consider this...
Z height:
Lower Z squishes first layer more and increases sticking, higher Z results in less plastic contacting the print surface and reduces sticking.  Tweaking your Z-height can help you dial-in your first layer adhesion.
Print Temperatures:
Higher extruder and bed temps during printing will tend to increase sticking.  Lowering temps will reduce sticking.  Run several tests, just a few degrees can make a difference and finding the right balance can take some trial and error.
Removal Temperatures:
There is typically a warm bed removal temperature that works best, when the bed has cooled but not all the way.
Anti-warp "tabs":
If you're making your own models, you can add a breakaway tab to the ends of parts that are prone to warping.  This improves surface area for hold down where you need it, but takes minimal post processing to remove.
Dry your filament:
Warping is generally much worse when filament absorbs water from the air.  Some filaments such as polycarbonate are VERY prone to this, but even PLA warping can be reduced by drying the filament.  To dry your filament you can use a low temperature in your oven, make a drying bucket, or my favorite, put it under a vacuum with a vacuum pump.
Removal tricks:
Various methods of rapidly cooling the edge of the print with canned air, alcohol, etc. can really help. Thin metal spatulas can work wonders.
Try PEI on your print surface:
PEI is awesome.  Many common filaments stick very well while it's hot and release easily when it's cool.  Check out the way Lulzbot attaches their PEI print surface to all their printer beds.  It's a pretty easy and cheap mod.  The other factors I listed still matter, but PEI makes it MUCH easier.

Note that using PEI and PETG may lead to actually bonding the PETG to the PEI. Use a spray or glue on the PEI to be able to get the print of when cooled down.

I suggest that you make a support not that much massive (this kind of problem is often cause of a massive part printed directly on the bed). You should place some easily destructible material between your part and the bed.
I don't know your part, but even if you have a plane under it, don't stick it to the bed. Let a gap, like, 5 mm minimum, which you will fill up with support. Of course, your support must be something light.
For example, try to use the meshmixer supports (meshmixer is free) or some lattices supports if provided with your software's printer. As they're supports and not the part, you can destroy it more easily, without the preoccupation to save it, just caring about your bed.
Of course, it depends on the amount your "sticking" problem, if small things are sticky too, this won't save you.
For non-used to supports people, support is often a solution to main deformations and sticking problems. Deformations because it dissipates the heat better, sticking because it's much less massive material to remove.

When I started, I got a lot of failed prints due to loss of adhesion.  It still happens but much rarer.  Dialling in settings improved that, but downside is that parts stay stuck to my glass bed really well even when completely cooled off.
I now use a 30mm paint scraper to peel the brim up as far around the model as possible.  I only use a 5mm brim width now, and that seems workable.
I then use the same paint scraper as a chisel right at the end of a part, and push it into the bed so the blade is flexed.  Then I tap the handle end with a rubber mallet.  This generally either pops the part off completely, or at least lets the blade slip underneath where I can push it further by hand.
I'd prefer perfect adhesion, but would rather have over-adhesion than under-adhesion.

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Fan Fails to Start
SOLVED: I replaced the leads coming from the fan motor and it is working just fine. Thanks for the input. If anyone else has this model, I would suggest printing and installing a wire clip in order to prevent the issue. Here is the one that I am using now: http://www.thingiverse.com/thing:620627
I am running a Printrbot Simple Metal with a heated bed and have not been able to get my fan to run recently. The fan used to run just fine (for the past 3 months in fact--since purchase). I cannot be certain, but this may be related to the cord getting snagged by the hot-end last week (cables have begun to sag over time). Nothing melted or damaged except for the hard-plastic coil used to bundle all cables together, and that appears to just be minor, cosmetic damage.
I have checked Cura settings, ensuring that fan operation is selected (starting at 0.6 mm) and that it is being told to run at 100%.
I have also sent 'M106 S255' from Proterface UI (this, from what I have researched, should turn the fan on at 100%). This command had no results.
The firmware is stock (Marlin), all exposed cables seem intact and without damage, and the plug to the control board seems to be fine. Maybe I could apply current to it directly and see if it runs?
EDIT1: I put 2 6V lantern batteries in series (voltmeter shows 12.3V) and hooked it to the fan cable; the fan did not budge (even with encouragement in the form of a slight push from the hand). Is there a particular spot in the cable that is vulnerable to failing if pulled on?
Any thoughts, suggestions, or things to look into?
EDIT2: I have disassembled the cable bundle leading to the fan and hot-end. I have found a connection point where the fan plugs into an extension cable which goes to the control board. I have applied current here and the fan doesn't move. I tested the current on another 12V fan laying around and that fan runs just fine. So, it seems that the fan has gone bad...somehow. I am still quite confused on how this would happen. Is it possible for a DC fan to "overheat" due to poor airflow? I have a shroud on the fan (http://d17kynu4zpq5hy.cloudfront.net/igi/printrbot/CnoDPS5D1CZ5EgBR.standard) and there has always been a little back pressure pushing wind out of the back of the fan.
EDIT3: So I have resorted to tearing into the fan and have applied 12V to the wires which are soldered directly to the fan and the fan doesn't work. I then applied the current directly to the solder points and the fan runs. Is there a reason why a set of wires, which look perfectly fine from the outside, would fail to run the fan?

Assuming your fan actually runs on 12V, applying power directly should make it move. Are there perhaps any other points you can try to apply power so to check if the wire is broken?

It seems that the fan is 12V (https://printrbot.com/shop/fan/). I have looked over the cable and cannot seem to find another point. The only thing that stands out is a random, wrapped connection point, mid cable bundle that may or may not be related to the fan. I'll investigate more.

Are this solid copper wires? Maybe you replace them by a stranded one?

Is there a reason why a set of wires, which look perfectly fine from the outside, would fail to run the fan?

The internal conductor is broken. This can happen over time due to metal fatigue from the constant movement, and the cables getting snagged may indeed have something to do with it. You could try desoldering the current wires from the fan and replacing them with fresh ones, or getting a new fan altogether.

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What is a good strategy for removing 3d prints from an UNheated Glass bed?
I have a LARGE piece of glass (36"x26") that I will soon be printing on using my newly build MPCNC machine.  It is capable of printing about 34"x34"x10".
Anyway, I have had GREAT success printing on heated glass that is sprayed lightly with hairspray using PLA and being able to EASILY remove my prints after the glass has cooled.  I attribute this to the slight expansion and contraction that occurs when glass is heated and cooled.  This would weaken the cohesion of the PLA print to the glass.
I have another posting where I asked how to heat this LARGE glass bed.  However, there weren't any feasable (inexpensive and easy) solutions to heat the glass.  So, now with cold glass, what are some good strategies for removing large 3d printed objects without breaking them or the glass?

Because you will be printing on unheated glass, you will be using some form of adhesive material. If you use an off-the-shelf glue stick, you will likely find it is water soluble. If the bed is removable, immersing it in warm water for a relaxing soak will provide easier model removal.
I don't have experience with various tapes, so will avoid recommendations regarding masking tapes or similar material.
Thermal cycling will also provide release. Not a heat gun, as that will break the glass, but a hair dryer applied to the underside near the model, then cooling. Repeat until it releases.
I have used the Fleks3D print plate on my Flux Delta printer in the past, and it releases "like magic" but I don't think they make monster sheets of your printer size. I had also purchased a pair of 20" square Fleks3D plates for a similarly sized printer that never materialized. I'd be happy to sell you the pair, but I think they are too small for your full plate.
It has been said that one can use sand-blasted acrylic, which I believe is the construction of the aforementioned Fleks3D plates. If you have access to 1/8" or 3mm acrylic and can apply a uniform blast of abrasive, you may be able to construct your own easy-release build plate.
It is practical to consider to use a raft for your large builds. Rafts are useful for small items, to provide a greater bonding surface and avoid release, but it also provides a "wedging" location for your release tool. You can more easily slice away the middle of the raft and deal with a thinner layer after the model is completely freed.
EDIT ADD: If the bed is not removable, one can build a dam around the model with clay to hold the water for dissolving the glue.

It is quite common to print PLA on blue painters tape (such as this). This makes print removal very easy, since you can remove the tape entirely for those parts that don't pop off by themselves.
On the downside, you might experience issues with the tape itself lifting from the bed when printing parts that wrap a lot. A wide tape that adheres well to the glass can alleviate this issue. Also, make sure to thoroughly clean the bed before applying the tape.
That being said, if you print large parts that warp a lot, most blue painters tape that I have tried will eventually release from the glass to some degree. If you manage to strike a balance between stickiness and removability when using a glue stick/hair spray/PVA-mix etc., such solutions might be favourable.

3M Blue decorators tape works well for me. You can get it in different widths. I find giving it a little sand paper rub before each print helps corners to stay down and improves first layer print. I replace about every 10 prints depending on the importance of the print.


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Loss of extrusion in Stratasys FDM liquefier
I am running a Stratasys Dimension 768 SST, with a "rebuilt" extruder (dual setup includes support + model). This extruder, basically, follows the OEM design with exception to the tubing diameter (few mils smaller for rebuilt, although there is a generous inlet taper and/or bushing, larger than the filament diameter feed stock) and the way the tubing has thermal contact with extruder body and cartridge heaters. The OEM design, apparently, had some thermal epoxy to "bed" the 2 nozzle tubes, which are brazed into the nozzle tip block. The approach, I am using, is Al foil packing around the SS tubes, tight to the Al extruder body (still brazed connection to the nozzle tip block). I had no choice but to recondition the extruder, because of a breached nozzle tube. In any case, with a cleared out nozzle inlet to start each time, I do get transient extrusion at standard temperatures of 250 (support) and 280 (model ABS), and in an adjusted temperature range, with some preliminary experiments. I clear out the nozzle inlet with a metal pin, down to the tube bend (I don't get why the design had this problematic 90 deg bend radius close to the cold end, feed wheel!) For the support, the extrusion goes for about 5 secs, then slows down, and the support filament feed stock stalls and strips out the filament, turning it into white debris.  For the model, the extrusion goes longer for about 20 secs, and also slows down, and, in this case, the model feed stock splits and gets fed outside the nozzle tube inlet, but no white debris in this case. This cycle may be repeated by cleaning out the inlet clogging with the stiff metal pin.
I realize this is not a perfect description of the system, but I am hoping that someone who knows this extruder configuration or a similar one (system is quite old, unfortunately), may chime in here with suggestions. I will add, that I am running the system in a so-called maintenance mode and have some minimal adjustment of the firmware (like the hot end temperatures - defaults mentioned before) for the build mode (which is only during actual part run).
Thanks in advance for your help or suggestions!
Here are some diagrams/link to descriptions for the extruder as well:
My exact extruder (i.e., head) system:
http://www.amtekcompany.com/pdf/dimension_bst_sst_elite_768_head_clog_guide.pdf
A similar extruder (showing heaters, extruder body to isolate model & support paths, tips, and thermocouples)
https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwifyLnJsu7OAhVIOCYKHaSIDLQQjRwIBw&url=http%3A%2F%2Fwww.3dprintforums.com%2Fshowthread.php%3Ft%3D2237&psig=AFQjCNGM1BTAiWzUn4fNJ8-z5HDWxa6OEQ&ust=1472824417165187
This site shows another user take apart/redesign the extruder in question (pay attention to the 90 deg bend in the nozzle tubes)
(see attached picture)
I also have a few documents: user manual, service manual, etc. that I may share, if I knew how to upload to this website.

Hi MF1, and welcome to 3D printer SE! For users who don't know the insides of this specific printer, your question can be very difficult to follow. Could you for instance add a simplified drawing of the part of the system that doesn't work?

This isn't a "turn this knob and all will be well" answer, because your machine setup sounds pretty unique to what most people will have experience with. Not being familiar with the older Stratasys printheads, but based on my overall experience with 3D printers, there are three things that could be an issue:

The nozzles are obstructed. The way you talk about clearing the jams of pushing a tool up through the nozzle end would not effectively clear a jam, it would only push the debris back into the print head, just waiting to be pushed by the plastic back into the nozzle. It could even be a piece of aluminum foil from the rebuild process. The typical way jams like this are cleared is to do a "cold pull" where you heat up the hot end just enough to be able to pull the plastic out, before it has really had a chance to liquify, hopefully trapping the debris in the plastic, then cut the end of the plastic off and reload. The 90 degree bend in their design may make this very hard if not impossible to do.
Heat creep. The tubes are a slightly smaller diameter, and if heat is creeping up the print head and letting the filament expand in these tubes, it may be expanding enough that it will no longer move through the print head. Diagnose this by letting the printer jam, then cool off for a few hours. If you can print again for a short time period before it jams again, this may be your issue, where as an obstructed nozzle would not allow any more filament out. Either turn down your temps, or increase your cooling on the print head to address (or get the original size tubes if possible).
Print head temperatures too low for the print speed. The Stratasys Fortus 250mc I use runs ABS at about 300 degrees. Many of the reprap printers run even higher than this for ABS. The other thing to remember when ever you see people mention what temperatures they use, is that this is relative, and only a guide, as what the temperature reads at the thermocouple or thermistor is usually slightly off from the temperature that is melting the plastic based on heater location in relation to the plastic and thermistor. This can be diagnosed by printing until it jams, pause the print for something like 30 seconds to let the hot end melt more plastic, and then resume printing. If resumes proper printing this may be your issue (and it will jam again shortly if you do not adjust temps).


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How to make E0 and E1 to act as slaves of X and Y in Marlin firmware?
I am currently building a CNC machine and have a plan to use my spare MKS Base 1.2 board. I have successfully activated dual X but when ever I try to activate the dual Y option, it throws a compile error.
BTW, I want to run 5 stepper motors without parallel wiring:

2 for X;
2 for Y, and;
1 for Z.

What is the compile error? Can you edit your question to include the error?

I've voted to close as the poster hasn't been back since posting this so getting the required information looks unlikely and without that extra information we can not answer the question.


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Will this printer be good enough to make prototyping models?
I'm new to the 3D printing world, but I've been doing some research over the past couple weeks.
I need a printer that is decent enough to make prototypes using simple 3D software (I use Blender for 3D models, but won't mind suggestions there also). The prototypes are for cases to hold small electronic components and will be generally  around 2*4*4 inches. They will meet to be sturdy enough to hold and run screws through etc. I'm probably going to do about 1000 models before getting the right one and creating enough prototypes.
I'm fairly good with electronics and should be able to put it together easily.
I've generally heard mixed reviews about different printer sets and I don't have the budget to get one of the higher end models.
Found this little number on Amazon :
[REPRAPGURU] DIY RepRap Prusa I3 3D Printer Kit With Molded Plastic Parts USA Company https://www.amazon.com/dp/B01E06IHJ0/ref=cm_sw_r_cp_tai_PgmYxb6DMARET
Given the pieces of requirements, do you see this working for what I'm looking to do? AND is blender going to be the easiest way to get prototyping models onto this thing or are there easier free software?

Your question about the printer may be a bit too broad for this forum. I suggest that you perform a general search for that model, especially videos on YouTube, to see what others with experience will say, and use that as guidelines for your objective.  Blender will NOT be a good choice for your goal. There are many more free programs which will be easier to learn and better suited. Consider looking at OpenSCAD if you can code, also TinkerCAD, and search for Free Parametric 3d Modeling Software for more choices.

Hi, FallenFate, and welcome to 3D printer SE. As @fred_dot_u mentions, your question is currently too broad for this forum, which means that there almost no limit to the kind of answers you will get (pretty much every 3D printer on the market should fulfill your criteria!). I will therefore put your question on hold for now to avoid users simply listing their favorite 3D printer and software. :) I encourage you to edit your question if you want to know anything more specific, and then vote for it to be reopened. Best of luck!

Please do not post multiple (unrelated) questions in one single question.


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TPU filament usage for dental application?
Can the flexible TPU filament be used in the case of printing a dental fixture?
Filament - SainSmart 1.75mm 1kg/2.2lb Flexible (TPU) Series Filament for 3D Printers RepRap.

Hi, what are the requirements of a dental fixture? Is it for practical usage or simply a showcase model? Could you link the filament you have in mind?

@TormodHaugene For practical usage. Filament - http://www.sainsmart.com/sainsmart-1-75mm-1kg-2-2lb-flexible-tpu-series-filament-for-3d-printers-reprap.html

Would it require FDA approval?

@JKEngineer Nope. Just for experimentation.

So your question boils down to whether the physical properties of the TPU filament would match the requirements of a dental fixture, right?  If so, @Tormod Haugenge 's question regarding requirements becomes very germaine.

@JKEngineer I want to understand the possibility if TPU filament is good enough to test for dental fixtures and possibly customized solution in the near future for dental application before getting FDA approval.

@JashJacob, for those of us not into dental implants, could you perhaps edit your question to give a brief introduction on what the requirements are? :-)

There are a Ton of issues with using this type of material. First off there is no way anything that comes out of your FDM printer will be sanitary enough to meet the requirements for medical applications. Your nozzle might even be contain Lead. Last you would need this printer to be cleaned to clean room standards. As well as stored and operated in one..
Second I have not heard of a flexible material that meets FDA requirements. (which is not the same as does not) You have to worry about even the additives they add for color. Or straight up contamination of the material.
I do want to mention that there are people who use SLA printers for dental items. I cannot say how SLA would meet food or medical grade requirements. My guess is a lack of regulation.
So a bad idea I would say...

Thanks for the input. So looking into SLA printers could take me in the right direction? I only want to see what is the possibility for dental requirements!

Yeah check out Form Labs article about it. https://formlabs.com/industries/dentistry/


text:
3D printing forum community
Is there any forum where expert designers can help beginners like me?
I am starting to design a panel for my car, and I am having some difficulties with finding a modeling program and using it.

See DesignSpark - DS Mechanical is good, free and fun to use.

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


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Is this very large flat panel printable in ABS?
I am designing an part for my car. It is a panel for the rear door. I want to add it some cases for tools, but before going on, could you tell me:
It is a large flat panel, around 100cm by 35cm.
Is it going to be suitable for printing in that ABS material? Is it too big?

I have edited your post to make the title more descriptive of your question, and added in the measurements in text. Using an image for essential details of your question is discouraged, because images are not accessible to those using screen-readers and can not be indexed by search machines.

ABS would be fine, as a material, for the application.
The problem, given the scale, would be the printing device used. I would suggest that you have the piece cut to spec for you using a polycarbonate.
If you have access to a workshop you could do so yourself if you set up proper fencing using a larger sized bandsaw(with a very fine toothed blade), had rollers to help support the size of your piece(as it would not fit on the tool's platform) and likely need a second set of hands to help control the outfeed. You would also need to drill access for the cut out then cut the perimetre.
You could also consider printing(ABS) in smaller sections then fusing each section together edge to edge(solvent welding of ABS is very strong and permanent), if you were really dead set on using a typical 3D printer for this. It would, in theory, be possible, but it would be very tedious. The adhesives, and cleaner, would be available from any plumbing supply and/or (home depot, lowes, walmart et al.). If you go this route be sure to have ample ventilation and plan your work space well in advance. I would not recommend this option but it is "possible".
Given the scale of the piece though, and for sake of accuracy, going to a shop with CNC equipment and using polycarbonate would be your best bet.

You should perhaps also mention that warping will be a huge problem with ABS at this size.

Agree with easier to buy a sheet and cut.    If your set on ABS it also can be bought in sheets.    A third material that is easy to machine and extremely durable is UHMW plastic (like used in cutting boards and chain roller guides).      I have only seen one commercial 3d printer that could approach size given.

That would just fit in my printer, but Tom's point about the warping is right -- I can't imagine it coming out very well, and it would take several days to a few weeks to finish.

It is a huge part that would not fit in most 3D printers, do you have access to a 3D printer this big? Even if it does fit it will take a long time to print.
Considering it's a simple flat shape, maybe laser cut / CNC acrylic or wood would be better, as you will have a stronger part, and most likely faster and cheaper.

Some webpages offer you the possibility to print and send home. You have to send them the slt file


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tips for pinching down onto an object
I was wondering if anyone could give me tips for designing a 3d printable structure that can "pinch" down onto a hockey puck shaped piece and hold it tightly.
I'd like for the structure to normally want to "pinch" two edges together, but I can pry/force them open when I shove the hockey puck into it. Once I let go, the two ends are now holding the puck fairly tightly.
My first thought was something like a potato chip bag clip, but that would require a couple pieces and a spring.
Is there a way to do something like this with one solid piece?

What kind of printer are you looking to use?  What materials are available to you for printing?

on the other aspect, what orientation is required/desired to approach the puck shaped object? Will the puck be flat on a surface and the grippers approach from above? Will the grippers be in the same plane of the flat-surface puck? If I understand your criteria properly, you'd prefer to have the grippers pre-loaded and use "force of impact/insertion" to spread the grippers, then apply external force to release? I very much enjoy design problems and look forward to your reply.

I have a makerbot with PLA filament. The grippers will need to grip onto the flat part of the puck. The grippers will be suspended in the air, so it needs to grip down on both flat parts (top and bottom). Ideally I would just push the puck into the part by pushing it in one horizontal direction, but I am not opposed to other options (prying the grips open with my hand and then placing the puck in and releasing with hand).

If you want a single piece, you'll need to use material with a decent spring constant and minimal flex-related fatigue.  Easier said than found.

Here are first 3 the most simplified and generalized options you have:

All you need now is to give use more details about your needs. If you reveal more details we could help you to apply (and modify) one of these  options.
Each of above has its own pros and cons of course. You said you don't want to have spring... so maybe a rubber ;)
But in fact whole-red is one-piece-clip in which the force comes from material elesticity or stiffness.
Please tell me what is the application of such clip.

If you are looking for a solid piece, the red one darth pixel showed is the best. An important consideration for something like this is making sure that it is able to flex outwards around the puck without fracturing. In order to keep the stress low in the arms, you can reduce the stiffness by either:

Increasing the length of the arm
Decreasing the thickness of the arm in the direction it deflects

This might be helpful in designing it to be printed. If your part breaks when inserting the puck, make the arms longer or thinner. If you aren't getting enough force, the in-plane thickness (coming out of your computer screen) can be thickened to your heart's content without changing the stress.


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Conversion of DICOM files to STL files
Good morning everyone,
I am developing a consulting job in a clinic of dental CT scans.
This work involves the development of administrative software, and preparing a routine for conversion of tomographic files in DICOM format to STL format. The files in STL format will be used for both visualization and analysis of 3D models, such as printing in 3D printers.
Our problem is just the conversion DICOM to STL.
Has anyone come across this kind of situation? We did not find any documentation or tool for this purpose in our searches and we are really with a gande urgency in the solution.
Advance grateful for any assistance.

The marching cubes algorithm can convert voxel data into a surface mesh. A global threshold to determine the surface in the greyvalues is used.
This article might be helpful.

there is a nice software to do it, a brazilian one, called Invesalius (http://svn.softwarepublico.gov.br/trac/invesalius). Itksnap is probably a better initial choise, since it is more intuitive (http://www.itksnap.org/pmwiki/pmwiki.php).
But anymways, it is not a easy job to do, and probably you will need other softwares to help you clean the mesh, like meshlab or Geomagic.
Good luck

Yes, invesalius (free software) is the way to go. I was able to export a CT scan a few months back using invesalius to either OBJ or STL format for 3d printing (can't remember which). But i do remember i was then able to open it in Lulzbot's version of Cura (a free 3d printing slicing software). But there are 2 things to keep in mind.

The image i was able to export was a huge file.
The image i exported had lots of extra junk that i did not want to 3d print, so another software like meshmixer or some other mesh editing software would probably be needed. It's not an easy process, but it can be done for those willing to do it.

There is this software that should work: https://www.slicer.org/
If that doesn't cut it, I use this site to convert images to STL: http://www.online-convert.com/
They do have DICOM listed as a supported format, but whether it would convert correctly or not I can't say for sure. I've had varied results.

This software may be of some use to you.
Whilst looking into software/firmware for a Frankensbox FX-800, I came across this document For medical use - Dedicated series 3D printer, on the Dedibot website, which on page 4 states the following:

The relevant part (in text form) is this:

It can be used to read DICOM format CT/MRI/Micro CT/Micro MRI/Industrial CT images and non-DICOM common image formats BMP/TIFF and so on.


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File from Blender is different in Shapeways's preview
I am trying to print a model I designed in Blender on Shapeways.
The object has a hole in it:

But when I upload it to Shapeways as a STL file, fixed the sizes, but the hole is filled up in the preview window for the object in Shapeways:

What could cause this? Will the model print properly?
(I cannot share the model here).

without a model for precise reference, much of the answers will only be guesses. My guess is based on your next answer. What wall thickness does your model have at the circumference of the hole? If the model is "skin" only, or can be considered to have zero thickness, it would not be a manifold model, hence the "repair" effected in Shapeways. If the thickness is below some unpublished (or published) minimum, the same may apply.

6.106mm

That's substantial enough to not generate such a failure. The more recent versions of Blender have built-in 3d model checking features. Have you run those options to see what points of concern are displayed?

Double-check that your model is solid (i.e. watertight). Holes in the mesh, or (as other's mentioned in the comments) or problems with thickness can cause those issues. You can use Netfabb's Cloud Services, or download the free version of their app. There are other model repair services, too.

Just like the other already have mentioned, most likely your model has 3D printing errors. Either way, I would run it through a repairing service just to make sure it's free of 3D printing errors. I repair my models using this free automatic tool https://makeprintable.com/

Are you affiliated in any way with makeprintable? Your only other post on the stack exchange networks also happens to promote this service.


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3D Printer seem to "Forget" Tool Path
I've run into a strange error that keeps reoccurring my with my prints. Part way through the printing process, it appears that the printer "Forgets" the tool path and stops all together or starts to move in random patterns. It still extrudes material and the result is mess of wasted filament.
At first I thought this might be a levelling issue, but this does not appear to be the case. This only seems to occur on prints taking longer than maybe 2-3 hours. Does anyone have any idea whats going on and how to correct it?
I am running an Ultimaker 2 Extended with using Cura for slicing.

I believe what you are experiencing is the stepper motors getting offset during  the print, usually due to the nozzle colliding into the model (but possibly also due to very high printing speeds).
Basically, the stepper motors used in most 3D printers will always make moves relative to their current position (as opposed to absolute positioning). In other words, the stepper will for example be told to move 10 steps left, regardless of where it is currently at. If you therefore forcefully move the printhead out of position during the print, the electronics will never know it happened, and continue with instructions that are no longer viable.
In order to fix this, do what you can to avoid the nozzle colliding into the model:

Make sure your printer does not leave large deposits of filament, typically due to over extrusion or too close Z-leveling of the first layer.
Make sure the model sticks to the bed, so that warped parts don't lift up, obstructing the toolpaths.
Add Z-lift in your slicer software, so that the printhead lifts slightly between travel moves.
Reduce travel speed (if it is set very high): the strength of stepper motors is lower at higher speeds, which means nozzle collisions at higher speeds most likely will offset the motors.


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Ultimaker original X-axis not moving - possible electronics problem
I'm writing this question here hoping someone will be able to help me with the fixing process that I'm currently involved in!
Last week during a printing session my Ultimaker original unexpectedly stop working. The problem was on the extruder step motor which push the filament from the back and literally is not moving anymore! The first thing I have done was to check if the motor was burn or something similar. So I swap the extruder motor with the X-axis one and it then worked fine.
Then later the X-axis motor into the extruder connector and is not moving! so I decided to check the step driver and they seems to work all well. So the problem must be on the Arduino or on the motherboard! I bought new step driver a new step motor and new Arduino + motherboard, connected all up and nothing, still not working for the same reason! It is just the extruder motor that won't work anymore!
Do you guys have some idea or tips to find out what the problem can be or how can be fixed in alternative ways? Your help will be much appreciated and looking forward for some answers.

I#Don't know if I get what you are saying. You exchanged the Stepper motor, the stepper driver(That tiny PCB connected to the Ultimaker PCB) and the arduino and still have the issue? If so then it must be the Ultimaker PCB right? Do you have the chance to measure signals (multimeter)? Do the capacitors look good?

Have you found & fixed the problem? If any of the answers helped you to get an answer to your question or come to your own conclusions then please do vote & accept an answer (using the tick button next to it). This helps us reduce the unanswered questions list & stops the question from being bumped once in a while. If you found another answer (than those already posted), please add that answer (& accept after 48 hours) to share your experience with the community. If you have not been able to address the problem please update your question.

I'm not sure I know exactly what is wrong or what steps you've taken so far, but it seems like your extruder motor is broken and you've narrowed the problem down to electronics.

If so, replacing the Arduino, motor, and driver leaves only the Ultimaker PCB as the source of the problem. I would suggest ordering another - but not until you've contacted Ultimaker with the problem you're outlining here.

Your title says "x-axis" but your description leads me to think that your extruder is the part that's not working.  Here are some tips which may (or may not) help...

Make sure your extruder is not clogged.
Make sure your temperature setting is high enough to allow the filament to melt quickly enough to support your print speed.  If your extruder stepper is getting very hot, you may be pushing it too hard.  Modern stepper drivers have various protections that will cause them to shut down in this situation. (Over current or thermal shutdown being the most likely in this case)
If you swap stepper motors and swap stepper drivers and the issue stays with your extruder, look for other things that you haven't swapped.
You haven't swapped the extruder, so the problem could be there as I mentioned above.
If you haven't swapped wires, the problem could be there...I've struggled through troubleshooting many times because of intermittent connections in wires.  Since 3d printers have moving wires, this is a prime suspect in older machines.
Rule out all of the easy and cheap stuff before you conclude that it must be the main board...it could be, but it's probably not.
Seek help in the Ultimaker forums or with their technical support.  Printers, like cars, tend to have certain things that are more prone to failure as the machines get old and worn.  The Ultimaker techs will know these things and can help you pin down your issue.

Good luck!  I hope you solve your issue and that this answer is helpful.  :-)


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G-code firmware for handheld plotter (Arduino)
I'd like to build a plotter to work without a PC (power supply by battery).
Plotter will write only several numbers on a card (really short G-code).
Do you know any firmware, which can be easily modified for this reason?
Or do you know G-code library which could be easily implemented into my stepper controller in Arduino?
My plan is to use Repetier (printing from SD), but I prefer to print without SD.
Repetier is also too big, there are a lot of functions that I don't need.

Have you found & fixed the problem? If any of the answers helped you to get an answer to your question or come to your own conclusions then please do vote & accept an answer (using the tick button next to it). This helps us reduce the unanswered questions list & stops the question from being bumped once in a while. If you found another answer (than those already posted), please add that answer (& accept after 48 hours) to share your experience with the community. If you have not been able to address the problem please update your question.

Your question may be useful to people interested in 3d printing (the purpose of this SE Site) so, even though you're not asking a 3d printing question per se, I think this answer will be helpful...
GRBL:
GRBL is a well known and mature g-code interpreter that will run on an Arduino Uno and is free and open source.  Check it out here.
I hope this helps!  :-)


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How to split a model in SketchUp for printing
I have a file I want to print, but the problem is that the dimensions that came with the model are just too big to print. I used the Tape Measure Tool on SketchUp, and it came in at a whooping 5.56 meters. Is there a way to split the big model into smaller, printable sized models that can be reassembled after printing?
Thanks Again

SketchUp is likely to not work well for you if your objective is to create a printable STL file in pieces. You would want to determine initially that the un-segmented model is manifold and 3d printer ready. Once that is determined, consider using an alternate program for your chop-up actions.
You do not specify the size of the printer you intend to use, but that is obviously a factor in the segmentation of the model.
I have some experience with Meshmixer, which has an edit feature named "plane cut" which will do as you require. The plane is placed on the model and the options are selected to keep both pieces after the slice is performed.
For a huge model of the type you describe, one would hope you have access to a printer with a one meter print bed or larger, although such printers are rare and of course, expensive.
My printer has a 200 x 300 mm build plate, up to 200 mm high, which would entail substantial segmenting.
If your model is mostly a shell, your segments would have to have wall thickness. It would be best accomplished, again in Meshmixer, by using the hollow or shell features. Those are a bit more challenging to understand, but there are plenty of videos and tutorials specific to creating hollow shells from a solid model. Once the shell is created, segments would be managed easily enough.
I suggested that your segments would "have to have" wall thickness, but it isn't a requirement. Solid segments would be like bricks and you may have a large number of rectangular solids that compose your model. Lego models are difficult or impossible to create with only an outer shell, so the interiors are often solid bricks, but 3d printers are a bit more flexible. Not using solid interiors would save money, of course.
I envision a jigsaw puzzle in three dimensions. Taking a nearly six meter dimension and chopping it into 20 slices multiplied by width and height means a carton of 3d puzzle pieces.

I am planning to use a 200mmx200mmx200mm printer. It is a shell. I will meshmixer, havent heard of it but heres to trying! Thanks for your answer

Another caution. If your SketchUp model is currently a shell with wall thickness, use the Meshmixer Analysis/Inspector button to check for faults prior to chopping it up. If you start with a model with failure points, you will likely have them when you have the individual pieces. Also, a feature within Meshmixer is that when you've sliced the model, each individual slice gets a unique name identifier, which you can rename for convenient identification later.  Use File, preferences, File, Export to set

Dude. You are just amazing. Meshmixer is exactly what I am looking for. Thank you so much!

Use File, Preferences, File, Export, to set the export feature to "Selection only" to ensure that each export is one part rather than the entire collection. If you view this video:
https://www.youtube.com/watch?v=l4RCLuUwETU you'll find that Angus of Maker's Muse has a great understanding of the program, and directly addresses your need at the 3:40 point. It might be useful to watch the entire thing if time permits, as he offers many tips. He speaks quickly, but the pause button is handy for that! The Object Browser should appear. If not, it's in the View menu. Please post your results.

How do you measure the distance between two points in Meshmixer?

That's a peculiar feature with Meshmixer, but it can be done. Use Analysis, Measure and then select the type of measurement desired. It's a bit cryptic from the icons. Also consider to use a Google or YouTube search for "measure meshmixer" to get clearer results. It usually takes me three or more clicks to get the measurement I need.


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How to debond cyanoacrylate glue from pla
I have used cyanoacrylate glue aka superglue to bond PLA. I have created several electronics enclosures. (Definitely the most time-consuming part of the project.)
Now my question is which debonder/solvent can I use to separate the pieces again without destroying the PLA parts?
Wikipedia proposes the following:

nitromethane
dimethyl sulfoxide,
methylene chloride,
gamma-Butyrolactone.

Hah!  Wikipedia wants to kill you!   Try hot water -- unless that will warp your parts too much.   "Pro Tip" -- don't bond things you want to take apart, and in general try to design things which use either connecting features or bolt holes to assemble.

Acetone
Acetone will dissolve cynoacrylate (superglue) and should weaken it enough to be able to separate the parts.
A readily available cheap source of acetone is nail varnish remover (just make sure you don't buy the acetone free version!).
Give the pieces a soak in nail varnish remover for 10-20 minutes and they should come apart with some prying.
Acetone does not dissolve PLA, so the PLA parts should be undamaged. If you were to try this on ABS parts however, they would begin to dissolve.

I don't think PLA is completely unaffected by acetone though (and if it is, acetone might affect additives or colorants in the specific brand of plastic you have).You might want to try first on a test piece you don't care about before you try this.

I tried to dissolve some PLA by leaving it in a jar of acetone -- no visible effect even after a few weeks. But it's still good to test first just in case.

Gamma butyrolactone is by far the best product to remove cyanoacrylate and also great to dissolve PLA.

if it dissolves PLA and CA, then it is a bad idea to use it to remove CA from PLA.


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Which is the best 3D printer to print bodies scanned?
I want to print people's bodies scanned (or get 'minimes', see the Figure 1). And I watched that the printer 'project 660' is very good to do this (Figure 1). But, the price of that printer is really expensive, roughly $60'000. And If you want to get a 'minime' printed by that printer, the cost is $230 for a model of 10cm. For me that price is expensive too.
Does anyone know what printer I could use in order to print 'minimes' with:

Good resolution, or details of the person's face (for a model of 10cm) and a good smooth surface of the model printed (Figure 1).
Ability to print complex models such as bodies (Figure 1) without problem.
Inexpensive: less than $150 per 'minime'.
An option to print in color.

Thanks.
Figure 1: Models printed

Hi! This question is very broad, as it has many possible answers. Almost any printer could be an answer, as you haven't included many criteria on what kind of printer you need. Questions that ask for "the best" X are not very suitable for stack exchange, because what is "the best" is very subjective. Could you maybe add some more information based on which the potential answers to this question could be narrowed down?

Hi, Francis. For the reasons pointed out by Tom, I have to put it on hold for now. You may vote for your question to be opened after eventual edits.

I edited the post, please let me know any problem.

What does "no expensive" mean? Under $100? Under $500? Under $1000?

Less than $150. I've just changed it

What I need to do to skip from the hold?

Hi, Kuroro! While recommendation questions generally are discouraged here on 3D Printer SE, I am willing to open your question due to your particular requirement of "a cheap printer that can print in full color". In my opinion, this requirement is specific enough to eliminate most common 3D printer alternatives. Good luck! :-)

where did you get the idea that printing a 10cm "mini-me" costs 230$ ?

In this video, I saw a copy of a hand if someone knew what it was https://youtu.be/cEJHXDsYeww

I do not think there exists a printer that meets your requirements. "Cheap"/hobbyist printers roughly fall into two categories:

FDM: does not meet your requirement for sufficient detail and smooth surfaces in the face (and can not print in color).
SLA: meets your requirement for detail in the face but can not print in color. If you are willing to drop the color requirement, this would be a good choice.

There are some hobbyist projects to do full color printing, but they are in a rather early stage. One option is colorpod that can be used to convert an FDM printer (such as the Ultimaker, but the principle works with any printer) however it is in a rather early stage of development and not very reliable yet. Another option is Plan B but that is a DIY project and not available for purchase (and is not very mature either).
That leaves you with the commercial color options. You've already ruled out the 3D systems/projet machines. Another (slightly cheaper) commercial option is MCOR IRIS but it also runs in the tens of thousands. While researching this question I stumbled upon 3D Pandoras but it seems a relatively new company so it may turn out to be a literal Pandora's box (they mention "most affordable filaments" as one of the advantages of their printer even though it doesn't use filament at all) - and prices are not listed on their website.

Good FDM gives better result than bad SLA and still costs 10 times less.

Anyone Knows -Mcor ARKe?. It uses paper ... but, is the quality really good for 'minimes'?

@Kuroro You can see some sample pictures on the product page. They don't look bad, but the 3D systems/project/ZCorp machines do a better job.

Hi Tom van der Zanden.
Is MCOR really bad?, because you wrote: "runs in the tens of thousands". Could you explain me a little more?.

There are several options for printers that can produce high-quality 'minimes' at a lower cost. One option is the Formlabs Form 3, which has a maximum build volume of 14.5 x 14.5 x 18.5 cm and can print in color. Another option is the Prusa i3 MK3S, which has a build volume of 25 x 21 x 20 cm and can also print in color. Both of these printers have good resolution and can handle complex models. Another option is the Creality CR-10, which has a larger build volume of 30 x 30 x 40 cm and can print in color. However, it may have a slightly lower resolution compared to the other two options. These printers range in price from \$500 to \$1000, making them more affordable than the 'project 660'.


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What is the strongest filament to use?
I'm looking for a strong filament that can handle a large tension load and no bending deformation when a perpendicular force is applied to it. Any suggestions?

What application do you have in mind?

Hi, Aaron! Could you please provide some more information of the application you need this filament for, or some other requirements in general. Should it bend or break? Should it handle particular weather conditions? Etc..

Due to the lack of specificity and activity on this question, I will put it on hold until further improvements are made. Feel free to improve the question so that we can reopen it.

Carbon or glass fiber reinforced PLA likely has the strongest without deformation. PLA will snap before deforming.
Fiber reinforced ABS is also an option. ABS is stronger but will bend before breaking.
Both are hard on nozzles and may require a stainless steel nozzle.

As far as I know, Nylon filaments are among the strongest. I'd look at the technical specs of Taulman3D's Filament. They're the only nylon I've ever tried, and I know they have in-depth specs of how their filament holds up. I'm sure you can find other providers, though.

The question asks for "large tension load" and "no bending deformation". While Nylon is indeed very good for the first requirement, it's actually rather flexible so it's not a good fit for the second requirement. In this case, not enough information is contained in the question to properly answer it (since it is not clear what trade off between tensile strength and rigidity is desired) so therefore it might be helpful to request clarification before attempting to answer the question.


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Frightened of Cheap Chinese Power Supply as I hook up the heated bed
My 12V DC 30A Power Supply 360W Power Supply is really cheap, and it's worked well for setting up the motors; but now that I'm on to the heated bed, which uses considerably more Ampage than that of just the motors, I'll confess, I'm getting frightened to continue using it;  if the summer was a bit longer, maybe it wouldn't bother me, but we're getting into the cold months, and now I'm afraid of ending up using too much ampage just trying to heat the bed in the winter months...(and I don't mean my bed).  Is there anything I should look out for in terms of using the either the cheap power supply I already have, or are there certain specs on a new not-so-cheap power supply that I ought to be using instead?

What bed do you have? What is the bed itself rated for?

MK2a...I guess...I'm afraid of that old AC thing too!

A MK2 heatbed will draw around 12A. The motors and hotend draw only very little power (around 2A, 5A peak), so the 30A supply you have has significant headroom (it is often recommended to derate a power supply by 20%, so a 30A supply would be good for 24A - you're still well under that). It should work fine, even given its dubious provenance.
Winter versus summer should not make a big difference. The largest power draw is during the heat up phase. In winter, the bed will use slightly more power to stay warm, but regardless of whether it is summer or winter the peak power draw during heat up will be the same.
The cheapness of these supplies tends to be reflected in more output ripple (but for heating the bed and running the motors you don't need a very stable voltage) and improper filtering. This may inject noise back into the mains, possibly affecting other equipment nearby. Should this occur, you can just stop using the power supply. However, in my experience, they can deliver the rated power just fine. They're not completely horrible.
Your biggest concern should be whether the wires that lead to your heated bed can handle the current and whether the screw terminals are properly tightened. During the first use, you should check that the power supply does not get extremely hot. If it's so hot it's impossible to touch for more than 1-2 seconds you should not use it.

I've used a similar cheap psu before. It'll work without blowing up but my heatbed struggled to get up to 60c, swapped psus with one I had lying around from a desktop and there was a huge difference.


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12v 25A 300x300 Heater bed Mosfet
I'm building a 3D printer from scratch (My first one, so yeah, tall order), so I'm buying all the parts separately, now one of the things I bought was a 300x300 12v 25A Silicon heaterbed (Yeah, I know, should have gone for a higher voltage, but that's the only one I could get at the time)
I have a RAMPS 1.4 board in all it's crappy MOSFET glory, so I tried giving my math skills a shot in trying to find a decent MOSFET that won't explode, though I'm still having issues deciding. And due to where I live, getting anything very specific is not the easiest thing to do.
So can anyone recommend a MOSFET that I can use to switch 25A and mention if it will need a heatsink?
I live in South Africa, So one place that I can get them from is from RABTRON Electronincs
There are a couple other places, but I'd prefer to get them here if I can.

I have looked over the 20 or so most expensive MOSFETs in that shop, and none are suitable.
It might be easier to go with a DC Solid State Relay rather than a bare MOSFET.
If you do want to go with a bare MOSFET instead, a TO-220 package MOSFET can dissipate around 1W without a heatsink, and around 3-4W with one. For 25A of current, that means the resistance of the MOSFET can be at most 1.6mΩ (without heatsink) or 5.6mΩ (with heatsink).
The IRLB3034 might be suitable. It is readily available on ebay (for under $1 shipped). 195A, 40V and an Rds(on) of only 1.4mΩ. A caveat is that this resistance is specified at a gate voltage of 10V, whereas it is slightly higher at lower gate voltages (1.6mΩ-2.0mΩ at 4.5V). This is on the upper edge of what is acceptable without a heatsink, but should still work (junction to ambient resistance is 62C/W, so in the worst case of 2.0mΩ the temperature would get to 77C above ambient - the MOSFET is rated for operation up to 175C). With a heatsink it will definitely work well.
Note that the gate charge is much higher (10x) than that of the MOSFET used on RAMPs so you should use a low switching frequency.

Thanks man, I'll try and get the IRLB3034, I was considering an SSR, though I've heard the DC ones tend to wear out over time at high frequencies, not sure if it's true, but I figured sticking to a MOSFET would keep things simpler.

Will probably run wires to it off the board to mount the MOSFET to the aluminum case, and keep the frequency low.

Just got the IRLB3034 and it's awesome, doesn't heat up at all, I do have a small heatsync on it, but yeah. Great advice, thanks!

Awesome, good to hear! I wrote this entire post just going by datasheets, so I don't have any practical experience with this MOSFET. Glad it works for you.

I wouldn't have expected you to buy and test a bunch yourself, but yeah works like a charm :), your reading docs skills came in handy.
For anyone else in South Africa that might be trying to get that component, I found it here
http://za.rs-online.com/web/p/products/6887204/


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M3D Micro printer stops extruding but is not clogged
I have an M3D Micro 3D printer that printed fine for a couple of weeks and then was plagued with issues afterward. I've done the fixes from the forum to get proper heating and cooling of the nozzle (I've added aluminum foil around the nozzle to make sure the hotend is fit snug against the nozzle and I've added an external fan, powered externally, to compensate for heat creep).
This works very well for short prints and it usually finishes successfully. When I do a longer print it always stops midway and usually at the same exact point.
I tried printing at 200 °C with black PLA and then again at 215 °C with the same filament and it stops at the same exact point. I also tried M3D brand white filament. I am using CURA slicer with Octoprint GCODE sender and M3D Fio.
I know it is not clogged because if I stop the print and press extrude without letting it cool down, it extrudes fine.
What is causing my printer to stop printing?

does this happen with different models or the same model each time? Are you able to use an alternative means to present the g-code to the printer, such as an SD card or direct USB cable from the slicer software? If there is a communications problem with Octoprint, the above steps will help to isolate it.

I started to try repetier host to send the gCode over, but I cannot get it to run on my system it starts up and crashes immediately. Also, in order to use anything else, I will have to reflash the printer's firmware to an open source version. Can you recommend a good gCode sender for Linux machines?

It's not a gcode sender specifically but I would be surprised if it would exclude such capability, try Craftware. A quick visit to their home page shows there is a linux installer for the program. It's currently in Beta stage, per the web site https://craftunique.com/craftware but it has received good reviews from various 3d printer locations.

I have one that has a bad extrusion motor that the extruder starts and stops. I took it apart and could feel the motor slipping when I told it to load filament. I thought it was a heating problem too until I put the micro + kit on and it still had the same problem.

@BigggBen I have tried replacing the extruder motor in my machine, but the same issue still presents. Has the micro + kit improved performance?

I'm not sure how similar the two systems are, but I use a Stratasys uPrint SE Plus and I've run into a similar problem.
There are two rollers in the head that pull the filament through to the extruder nozzle, and in one instance they appeared to have heated up, melted the filament enough to create two "indentions" on either side of the filament, making it such that the rollers had no purchase on the filament itself. There was never any clog, no material feed error, but it was still failing to print. Wound up having to replace the head altogether.
Again, not sure how similar the extrusion mechanics are in the M3D, but suggest checking the components that actually advance the filament, and the filament itself.

Placing this suggestion as an answer, because all information appears to point to the slicer software and/or the operating system. Consider to use alternative methods of slicing and sending the model, such as the previously mentioned Craftware or other free slicers, such as Slic3r - both of which have Linux versions. If, as you suggest, your firmware is so tied down that it won't run alternate versions without re-flashing, that would be your next step. Unfetter yourself from the limitations of the current suspect software.
If you are able to use other slicers and discover that the problem remains, the re-flashing of the firmware is likely the only solution.


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What parts are strictly necessary for a 3D printer?
I've built the mechanics of my 3D printer myself, because I need to print parts that are really huge, (and for budget reasons). So, I already have the 3D movement functionality.
But what I need now, is the printing mechanism itself. I've been reading a lot, but it became clear to me that things are more complicated than I thought.
Let's skip mechanics and software, I'm just interested in how the print head works. Can somebody explain me that?
To be honest, I was so naive that I thought that I just had to buy one part with one data wire (print/noprint) and the 5 V/GND wires. But it came to my intension that things are way more complicated.
For example, these RepRap printers have some kind of air tube attached to the print head. I'm not sure what that's all about, is it cooling?
Perhaps I'm always reading the wrong manuals (i.e. the more advanced ones). Can somebody enlighten me or point me to a good starting point?

Depends: do you want it to work well, or at all?

I think @fred_dot_u's answer is excellent. Despite being a simple concept, the print head is a fairly complex piece of design that juggles several conflicting requirements: lightweight, able to apply reasonable filament pressure, rigid, hot in one place not in another, quite tight temperature control, able to operate consistently for tens of hours flawlessly, and more. Any working system like this is the child of hundreds of improvements. One of the joys of owning a 3d printer is you start really appreciating things like this!

In all honesty, the more I read about 3d printers, the more I understand how delicate everything is. I guess the following proverb applies here: "don't touch it if it works". :)

Keep in mind -- one thing you will have trouble with as your print area grows is warping of parts -- because they will cool as you print them. -- For larger cartesian robots, CNC (i.e. subtractive manufacturing) is a much more attractive option.  And it's way easier to control, because you just use a relay to turn a well mounted dremel on and off and you're good to go.

You will certainly find that the print functionality of a 3d printer is a bit more complex than you suggest. The mechanical portions include a means to push the filament into a heated nozzle as well as the software portion to regulate the speed of the filament movement. You haven't referenced the heater cartridge and temperature sensor, but you will discover that aspect soon enough.
The "air tube" you think you've seen is likely called a bowden tube. Such designs permit lighter weight print heads, which is beneficial for speed, acceleration and precision, but has complications with respect to compression of the filament as well as retraction considerations. Non-bowden print heads will have the extruder motor as part of the moving assembly, with the drive wheels very close to the nozzle opening. This allows for flexible filament and more precise control of the filament feed.
Either design has compromises, so one must determine priorities for the design.
Cooling is also a factor. The heater cartridge is designed to heat the nozzle to a specific temperature for the type of filament used, but also requires a means to keep the heat from traveling to the portion of filament not in the nozzle. You'll discover terms such as heat break, referring to narrow threaded portion connecting the nozzle assembly to the heat sink. There will also be a cooling fan to blow air over the heat sink and very often a cooling fan to cool the filament as it exits the nozzle and attaches to the model being printed.
You suggest to ignore the mechanics and software, but it's important to be aware of both when considering the principles of the print head assembly.
Simplified, filament enters bowden tube then into heat sink, pushed by extruder motor (or) filament is pushed into heat sink by extruder motor. Filament travels through heat break, gets melted in heater block and exits nozzle. Sheesh, that's way too simple.

Your post helped me to realize that I had to get out before I sank in too deep. :-) Thank you. For others who read this: just buy a 3D printer (if even a simple one) but more importantly, don't try to do all of this yourself, even when it seems that 1 specific feature is missing for you. Don't.

The first point to start would be the RepRap wiki entry for extruders:

cold end
The "Cold End" is usually the bulk of the extruder. It is
often the actual carriage on one axis and supports the rest of the
parts. In some designs, the "Cold End" is split into two parts; one
part does the driving of the filament that is stationary and connected
to the carriage portion, of a lighter weight design for easier
movement, with a flexible tube. The drive is a motor that rotates a
knurled, hobbed, or toothed pinch wheel against a pressure plate or
bearing with the filament forced between them. Usually, the motor is
geared to the pinch wheel to increase available torque and extrusion
control (smoothness). The gearing can be a 3D printed pinion and gear,
stock worm wheel and gear, or a more expensive integral motor gearbox.
Stepper motors are used almost universally after initial trials with
DC motors did not achieve the required repeatability. Servo motors are
an option, though they are not seen in the literature yet. The final
function, some form of cooling, keeps the "Cold End" cold. With the
close proximity to the "Hot End" and possible heated build platforms
and enclosures, it is sometimes necessary to have additional passive
or active cooling of the cold end parts. Heat sinks and fans are often
used; water and Peltier effect cooling is also discussed. Much of this
bulk is usually made from 3D printed parts and the temperature is
maintained within safe limits.
hot end attachment
The "Cold End" is
connected to the "Hot End" across a thermal break or insulator (the
Bowden tube if used is on the cold side of this thermal break). This
has to be rigid and accurate enough to reliably pass the filament from
one side to the other, but still prevent much of the heat transfer.
The materials of choice are usually PEEK plastic with PTFE liners or
PTFE with stainless steel mechanical supports or a combination of all
three. A Hot End is frequently joined to the Cold End using a Groove
Mount where the thermal break or insulator is part of the Hot End
assembly and the Cold End body is provisioned with a cylindrical
recess. Many cold ends push the filament out a large hole centered
between 2 small holes about 50 mm apart. (Is there a name for this
de-facto standard?) Some people rigidly attach a groove mount hot end
to such a cold end with the mounting plate adapter and two short
bolts. A few people put 2 long bolts through those holes and then put
a spring around those bolts to make a spring extruder.
hot end
The
"Hot End" is the active part of the 3D printer that melts the
filament. It allows the molten plastic to exit from the small nozzle
to form a thin and tacky bead of plastic that will adhere to the
material it is laid on. The first RepRap hot end was made of brass.
Researchers have also made hot ends from glass or aluminium. The hot
end consists of a melting zone or chamber with two holes. The cold end
forces the filament into the hot end -- into the heating chamber of
the hot end -- through one hole. The molten plastic exits the heating
chamber through the other hole at the tip. The hole in the tip
(nozzle) has a diameter of between 0.3mm and 1.0mm with typical size
of 0.5mm with present generation extruders. Outside the tip of the
barrel is a heating means, either a wire element or a standard wire
wound resistor. The heat required is of the order of 20W with typical
temperatures around 150 to 250 degrees Centigrade. For feedback
control of the nozzle temperature, a thermistor is usually attached
close to the nozzle, though a thermocouple may serve with suitable
control hardware. High temperature materials are needed here. These
include metals, cements and glues, glass and mineral fibre materials,
PEEK, PTFE and Kapton tape.
mount to rest of machine
The ways
extruders are mounted on the rest of the machine have evolved over
time into informal mounting standards. These informal standards
include the Vertical X Axis Standard, the Quick-fit extruder mount,
the OpenX mount, etc. Such de-facto standards allows new extruder
designs to be tested on existing printer frames, and new printer frame
designs to use existing extruders. (Does the "greg-adapter.scad"
adapter in the Prusa i3 Build Manual let me mount an OpenX extruder on
a Vertical X Axis machine?)

You can also google for extruder and/or hotend in combination with 3d printing for a first starting point.

This is effectively a link-only answer. If you think a question is too much effort to answer ("because of its sheer mass") then don't answer and vote to close as "too broad".


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How to create attachable/detachable printed parts
I am making a part that needs to come apart, so I don't want to use glue or similar adhesives. I saw an article about printing snap-fit pieces, but it seems like you would need a lot of expertise to make it work well. Does anybody know of an easy way to non-permanently attach PLA parts, while still maintaining a sturdy connection?
EDIT: (more detail about specific project)
I need to attach plastic to plastic, in a pretty small surface area. This is a prop knife/sword in which the "blade" retracts into the handle.  For the prototype I printed the handle in two halves lengthwise, which I do not want to do for the final product. I want to print as much of the handle in one piece as possible. Because I need to get the blade into the handle (and remove it for working on parts, painting, etc) I need part of the handle to detach. I am thinking that the front bit (examined more closely below) would be the best place to detach.  As the wall thickness is about 1/4 in, there is not a whole lot of room to work with. However, I remain hopeful that there is a way to attach it such that it will remain securely together and retain the "blade" properly.
Thanks for the help so far.

This seems quite similar to Designing Clips that Won't Break.  Can you give us more detail on what kind of part is being attached to what?  Anything to distinguish it from the existing question on the subject?

This question may yet fall into the too-broad category, but I'll give it a shot.
You don't want to use glue or adhesives, but does that exclude bolted or screwed fasteners? Threaded inserts are metal "nuts" with knurled grip extrusions that enable one to use a matching bolt. The insert is heated with a soldering iron or similar source and embedded into the part. It's especially useful when the part thickness provides sufficient strength and the threaded insert is on the surface of the part opposite the bolt head.
Another option you have is to design into the part a "conventional" joint such as a dovetail or slot with the matching dovetail or T shape on the adjoining part. This requires access to the end of the part to enable the sliding action of joining them together, of course. Some testing of prints should be performed to ensure proper mating.
Directly related to that method is pins and holes. With suitable testing, one would create a hole on both parts and print a pin to match. If one is well versed in the software of choice, one hole with a built-in pin on the adjoining part would work too.
Yet another extension is provided free from 3DKitbash:
http://www.3dkitbash.com/free3dmodels/
in the form of friction fit pins. I've constructed one of their models using this design and find the straight-line pins eventually work free. The pin model with "mouse ears" allows for a bit stronger gripping due to the compression of the shape on insertion.
The friction fit pins would be considered to be the snap-fit parts you want to avoid, but the level of expertise should not be beyond that of a model designer.
Trial and error works wonders when it comes to putting these things together. I printed an Overwatch logo for a fellow makerspace member. The part used a pin on the insert and a hole on the logo. I was astonished when the two different colored parts slid together quite snugly. I have not calibrated my printer and it was indeed a snap together build. On the flip side, when I pried the two pieces apart (low infill) the pin remained in the hole, snapping cleanly off the insert. Should I be asked to do this again, I would have much more infill on the pins.
For clarification, consider also to note what software you are using for your design. Some programs lend well to creating connections, others not so much.


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Prusa i3 hotend not getting to the temperature that I want (180 to 230 celsius)
I recently finished building my first printer. The only problem that I'm having is that the hotend is not getting hot enough to start printing with PLA (180 to 230 degrees celsius), the hotend getting hotter stops at 170 degrees. Please help I've been stuck on this problem for days. Thanks in advance.

Usually, this kind of problem is due to an issue with the control loop of the temperature. You can try to do PID Tuning by running the command M303 E0 S200 C8. This will heat up the hot end and cycle it around 200C a few times, and afterwards tell you Kp, Ki and Kd values which you need to enter into the PID settings of your firmware configuration, or store them in EEPROM using M301.
If this does not solve the problem, then disconnect the heater cartridge and check its resistance with a multimeter. For a 12V system, it should not be higher than 6Ω (24Ω for a 24V system).
If the heater cartridge is okay, then perhaps it is a problem with the power supply. While the hotend is heating up, measure the voltage across the heater cartridge. It should not be much less than the nominal 12V/24V your printer runs at. If it is, you may have a bad MOSFET or power supply.
Finally, if you have a very powerful fan blowing on the hotend this can cause issues with heating up as well. Adding a fan shroud (or pointing the fan away from the nozzle and only at the print) can help with this.

There are software limits that might be set low by default depending on the software you are using. I know there is with Marlin.


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Typical plastic strength at 1500 RPM
I'm planning to print a certain sample holder which is going to be placed on a CD-Rom BLDC motor and spun at about 1000-1500 RPM. The holder would essentially be a 2-3 mm thick 100 mm square platform with 1-2 mm thick hooks rising up from outer edges of the platform to hold the sample. The bottom of this platform would also contain a 15 mm diameter crevice designed to latch onto the disc holder attached to the motor. How durable would this printed holder be under these conditions, if it was made of ABS plastic, for example?

Please consider to add specific details to your query. You likely would be able to spin even PLA at those speeds if the sample item was fairly small in diameter, while it can be expected that ABS would fracture if the sample part is 200 mm in diameter and 2 mm thick. Please also consider to reference item shape, thickness and direction of print layers. As Johnny Five would say, "Need more input!"

The part would essentially be a 2-3 mm thick 100 mm square platform with 1-2 mm thick hooks rising up from outer edges of the platform to hold the sample. The bottom of this platform would also contain a 15 mm diameter crevice designed to latch onto the disc holder attached to the motor.

@Osta: I suggest you update your question with this information, so users don't have to scan the comments in order to get the relevant information.

Is your sample going to be contained within the perimeter of the hooks, or will the hooks be used to secure the sample as it whirls about the outside of the manufactured part? If the sample is contained within the perimeter of the hooks, is it of uniform or symmetrical shape? That is, will it balance about the center point?

The hooks would be used to press the sample to the platform. The sample itself should cover most of the area of the platform and retain the center of mass of the whole structure near the rotational axis.

If the sample covers the platform, does that mean there is a hole in the approximate center or that the platform has a recess to prevent the need for holes in the sample? The selected answer suggests printing hooks in profile, but that's virtually impossible if you have more than four hooks. Consider, however, a raised ring at the perimeter, which will provide retention and a bit of designed-in strength. Reinforcing the platform with light weight fiberglass cloth and epoxy resin will also add strength (and weight) and may require a different choice of motor.

I hope this is for a temporary prototype. Over time ABS absorbs water in the air and becomes brittle (it maintains its strength for longer in air-conditioning of course). Noticed it on my laser printer chassis, give it 12 years or so i guess.

Really the only thing that would matter for this project is the amount of torque the motor has available and subsequently how heavy your setup is that is connected to the motor. A part that size may just be too heavy for a CD-ROM motor if you intend on adding more parts.
However, to answer your question, ABS should be able to endure the stress. I recommend paying attention to how the hooks are printed. You'll want to make sure that the hooks are printed in profile, meaning that the profile of the hooks should be printed with each layer. This will help provide structural integrity to, what sounds like, the most stressful area of the part (the outer edges of a spinning device and a clamping feature).
Something to keep in mind for projects like this is that most of the time the design will likely be the cause of failure, not the capabilities of the material.

Printing the hooks in profile results in layer structures that are weak across the surface of the holding design. A hook of 2mm height will have very little general structural strength, regardless of print orientation. Of course, ABS will be stronger than PLA, but I suspect that some additional reinforcement will be necessary.  Subsequently, additional weight will be added.

@fred_dot_u I think this highly depends on the actual design of the hooks. In the end, if the design is flawed, the part will break and OP will have to adjust and re-print. That's the beauty of 3D printing, it's a low-cost prototyping machine.

2 mm height does not leave much with which to work. Aluminum or other metal might be okay with such a small or low profile, and injection molded plastic or similar near-monolithic construction might be okay, but as strong as ABS plastic can be, it's formed in layers of reduced strength. It would be interesting to have an engineer provide the real world figures of such a model spinning at the speeds noted.


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Heated bed is not heating anymore
I have built a RepRap Prusa i2 a while back. It worked for a while, but then I moved the printer from place to place and after a while I noticed that the printer's bed is not heating anymore. The thermistor shows the temperature (room temperature), but the bed is not heating.
The wires are connected and the heated bed has a resistance.
Did anyone else confronted with this? Thanks!

Do some probing around with a multimeter. Is there voltage across the beds inputs, check for continuity in the wires, etc...

diagnosing a heated bed
Switch the hot end and the heater bed wires on the board. See if there is a difference. (Note that it will not reach a thermal limit when plugged in this way! So don't leave it on too long!)
After that, if you see that your heat increases with the hot end's wires and the hot end being set on in software then you know the issue is likely with the board. At which point try updating / reflashing the board.
Alternatively, you can try a second board and see if it makes a difference.
If the bed does not heat up even using the heater cartridge connectors, then your heated build plate likely needs to be replaced. Or the wire needs to be replaced.
If you are running Ramps or a board that uses 2 hot end outputs you can likely reprogram it to use hot end heater 2 as the new output for your heated bed.

using a hot end heater output on the electronics to heat a heated bed could damage the electronics. It is probably not a problem for a short test but definitely not a long time solution!. This is very dangerous. The heated bed draws a much higher current than the hot end. This could damage the electronics, melt the connectors or even start a fire!

The test is correct switching the heatbed to the nozzle heater, just be careful to set the temperature for 50° as maximum to not burn the heatbed. The electronics can support this changes.

I have a Prusa i3 and the same case happened to me. I checked the continuity of the wires and discovered one badly soldered wire in the heated bed. After soldering the wire correctly, the heated bed turned on again.
Your problem is in all likelihood the continuity of the wires.
I hope that I helped you with your case.

Be extremely cautious if you switch the hot end wires with the hot bed wires as StarWind0 said, only do it for a couple seconds and stop as soon as you've confirmed that temperature is going up. I did this on my FLSUN C Cube and it started smoking something fierce and just about lit on fire within seconds of my turning on the extruder with the wires swapped. I suggest you be extremely quick and also don't do this by a smoke detector if you attempt it: just in case. This is pretty much guaranteed to happen due to the amount of current draws the two components use being vastly different. I re-flashed my board and it still did not work, probably should have done that in reverse order, please learn from that mistake haha. I seem to have somehow burned out my heated bed mosfet (prior to switching the wires) and have the same problem that you do, I'm just going to buy another board because it's pretty cheap but for the sake of future people with this problem to solve I'd:

check connections, especially at the screw connectors as they have a nasty habit of getting worn
use a multimeter in DC voltage mode, put your black (-) probe on the DC power negative lead, turn on the hotbed and using your red (+) probe make sure you are getting about 12V through all your relevant connections including the fuses (mine are very tiny surface mount fuses, 15a and 30a located right behind the power supply, don't know how standard that is for all printers though)
If everything checks out so far then cry a little bit
It's probably a burned out mosfet (buggers are sensitive) but just in case, re-flash your board and hope the problem goes away
test the mosfet for the heated bed with your multimeter (same way you tested everything else)
I don't suggest switching wires between the extruder and the heated bed except as a last resort to make sure your bed is working, but if you have resistance readings going through the bed and wires then your bed is not likely broken and this would be an unnecessary risk. If you are going to proceed anyway then do as follows: remove extruder and heated bed wires, plug bed wires into extruder terminal, hold the power cord in your hand, turn on the extruder and as soon as the number goes up by 3 degrees (or you see/smell smoke or crackling whichever comes first) pull the plug and pray you didn't burn anything on the board. Make sure you are by a window or door and can quickly extract smoke from the room so as not to set off the smoke alarm in your apartment complex like I very nearly did.

Hope this helps somebody someday.

I have a Prusa i3 and the same case happened to me. However, only the power cable to the mainboard was bad.
I cut it in order to solder a new one to the 4 pin connector but inside the cable sleeving, there wasn't any copper, only grey powder. With a new connector, and cables, it is working very well now.

It's probably a fuse or the MOSFET fried?
Try checking for continuity on the fuse and voltage on the MOSFET.