Prusa i3 Not Extruding Filament

So I just finished building my Prusa i3 today. There's a lot of sweat and tears and repeated assembly involved, but it seems to be working, until I try to actually print something. I'm using a gcode file from Slic3r on an SD card, and printing from that, since the printer presently isn't close to a computer. It seems to print fine, but it doesn't actually extrude any filament. It seems like instead of pulling filament into the nozzle, it's pulling it out. If I try to manually extrude using the LCD menu, it extrudes just fine. I'm at a bit of a loss here, and I'm very new to this, so rather out of my depth. Any help or advice as to what I could try would be fantastic!

-Finkswitch

finkswitch;

It sounds like your stepper motor is running in the wrong direction . I dont know what board you are using but you should be able to just flip the extruder stepper motor connector 180 degrees
That should reverse the motor direction.
If it is pushing out plastic manually , its a good chance reversing the motor will solve your problem.

So, I removed the heat sink and fan, and ran the printer through a print without any filament so I could see if it's actually turning in the right way, and it looks like it is. I'm sort of at a loss now as to what could be the issue. The throat broke while I was disassembling it, so I've ordered a new one. I'm going to put that back on and hope for the best! Any suggestions as to what else I could do to try it? The motor did seem to occasionally pull back, but I suspect that's just when it needs to stop extruding. The teflon tube in the throat also looked a little singed and browned, so I'm hoping it's something with that... I should get the new throat soon, so I'll update once I've run a test with the new one.

So I got the new parts, same issue... I removed the fan and heat sink and took a video of it trying to print. If someone could take a look and let me know what they think the problem could be, I'd appreciate it!

[youtu.be]

The motor is stalling because it can't produce enough torque to extrude the filament. There are several possible reasons, so you need to work through them one by one.

- Check the Vref on the stepper driver - is it set to give the amount of current that the motor is designed for?

- Check the acceleration in the firmware for the extruder. If you try and accelerate too fast the motor won't be ablt to keep up.

- Check the steps/mm for the extruder matches reality, and particularly that you have the microsteps set correctly. Have you checked the basic extruder calibration by extruding 100mm of filmament (see [reprap.org])

- Slow the print down. The faster the print moves the faster the extruder has to go which increases the pressure and required torque. With a geared extruder you can even hit the max pulse rate if you go too fast, but since you are using a mk8 style extruder that shouldn't be an issue.

Good luck, and let us know how it goes.

Still looking into this, and after talking with someone, could it be that the Z-offset is too low?

Ok, Z-offset isn't the issue... I tried manually extruding some filament, and I still get nothing... Initially, the issue was the power supply was set to 220 rather than 110 (I'm in Canada, so it should have been at 110). This is why the heat bed wouldn't heat up enough, but I'm still at a loss as to why this motor is skipping. It's not related to printing, because even manually extruding filament at 0.1mm doesn't work. The block is heated to 190, and if I push the spring down, I can manually push filament through pretty easily. I took another video of it trying to just extrude filament manually, so you can see pretty well that the motor is skipping.

[youtu.be]

It sure looks like you've got a current problem. If you can push the filament through, but the motor can't, then there is not enough torque. A well tuned extruder will pull the filament so hard you can't hold it back by hand.

Have you tried adjusting the current using the potentiometer on your stepper driver?

So, I'm veeeery new to this whole 3D printing thing... And electronics in general... That being said, I have no idea how I would even do that.

What kind of board do you have? There should be some socketed driver boards on it. They should look something like this (this is NOT a RAMPS board, but uses the same kind of stepper driver boards):



The little silver circular thing in the corner is the current adjustment potentiometer. You'll need a small slotted screwdriver to turn it. If you're not very steady, you should use a plastic one as the pot is live (has a positive voltage on the metal parts) and can short out the board if you slip and touch something at a different potential. This is a "feature" though. You can attach a multimeter clip to your screwdriver shaft and measure the voltage at the pot.



Ideally, you adjust the voltage to the amount that produces the max current the motor can handle, then back off a bit, but if you don't have a multimeter, you can adjust by "feel" and back off until the extruder starts to skip, then advance it a small amount.

There are two different common driver boards in use: the DRV8825 (shown in the photos above) and the A498x. I believe the pots turn in different directions for each (one goes CCW to increase voltage ant the other CW) and I can't remember which is which.

If you're not comfortable doing this, find a friend who knows something about electronics to do it for you. You can fry things pretty easily. Luckily replacement boards are pretty cheap.

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There are two different common driver boards in use: the DRV8825 (shown in the photos above) and the A498x. I believe the pots turn in different directions for each (one goes CCW to increase voltage ant the other CW) and I can't remember which is which.

The DRV8825 pot goes counter clockwise to increase voltage, at least on my boards. It's rather counter-intuitive.

Awesome, thanks, I'll check that out! I actually got it about 65% through a print job tonight, before it just stopped extruding filament. Could increasing the voltage to the motor help with that? I had a couple times last night where it printed a bit and just stopped...

Also, the board is a Zirb.

Edited 1 time(s). Last edit at 04/06/2016 11:57PM by Finkswitch.

Finkswitch,

I am having the same exact problem, and it looks like i have the same printer as you. Did you every figure this out and resolve the issue? What did you do?

Sorry it's been forever that this has been sitting here. It was indeed the voltage. I turned it up, and I've been able to get some decent prints out of it since then.