MakerGear Forum

Well, this is no fun - I managed to clog the brass tube on my V3b - as Jim said -it has gotten too tight for the filament due to a buildup of hard plastic.

Unfortunately it burned out my Extruder motor in the process. (Sucketh le eggs.)

Anyway, I've sent an email to customer support and I'll order another motor on Monday, and I guess I'll be drilling out that tube.

Can anybody tell me how to avoid that buildup next time? I'm extruding nothing but PLA so far, at about 218°. Should I not be running that hot? Could it be melting it too soon in the barrel?

Major bummer!

I Found i really only got a buildup when i switched plastic types alot and that took weeks. Your machine is brand new and even if it was clogged up you would not burn out your motor. It doesnt work like that. If there is too much resistance on the stepper motor it just skipps steps which is harmless. So.....tell us why you think the motor is fried? Did you take it apart? What did you find? Did you disassemble the hot end? What did you find there?

Even if you lock the shaft of the stepper you will not burn it up due to how it functions internally. There are no windings to "burn up" in a conventional sense. It will make a terrible noise but it's actually harmless. What're the symptoms of the broken motor?

The hotends are more or less consumable, just at varying rates depending. If you're natural PLA or natural ABS only, they'll last at least ten thousand print-hours (not bad for a $50 part!), but switch back and forth and a dozen colors of each and you'll clog in a few weeks. It's not a problem with the hotend, just all the different colorants and solvents in the plastics will form a concrete inside the nozzle, which can only be fixed with powerful chemicals or fire.

You can brute-force the clog out by ramming a 2mm allen wrench down into the hotend. I'm sure Rick was sitting on his couch watching TV and just got the chills for no reason just now, but that's what I do. It takes a good shove but 90% of the time it shoves a little blackened wad through the nozzle and it works afterwards. If the plastic squirts back up the allen wrench and out the top (that's happened exactly once), jam a high-E guitar string up into the nozzle to push the clog upwards, then do cold pulls until it finally is dragged out. Taulman 618 is a miracle here, absolutely get some and use it for cold pulls.

The extruder motor gear won't turn - even after removing the hotend (with the clogged tube) and cutting the filament. Commands sent from the Control Panel do nothing - either retract or extrude.

What it did on the last print was run rather fast, which I thought was a bit strange since I hadn't changed any speed settings, and then it just stopped extruding about half an hour into a 2 hour print. (I probably should have stuck around and stopped it at the beginning when I noticed it running fast, but this is still fairly new and hindsight is 20/20. I remember thinking that the higher speeds might have been in the code for the print that I'd downloaded.) Still don't know why it was running so fast, because the codes are all the same as I'd been using.

When I looked into the hotend assembly, I could see that the filament was just chewed up and that was why the extruder wasn't moving it. But it must have been trying to move it against the extremely clogged barrel, so i thought that was why it might have burned out.

This is what the filament looked like:
You can see the chunk cut/worn out of it by the spinning gear. There are teeth marks farther down on the filament, so the tension was probably okay - it just hit a point where it couldn't be forced into the brass tube any more.

Didn't know that at the time of course - I did disassemble the hotend, and the diameter had been restricted to about 1/2 of the diameter necessary to let the filament pass through it. So the extruder had obviously been forcing it through for a while (obviously it took some time for that much buildup in the tube).

I've printed the better part of a roll of the MakerGear black PLA, then i switched to a Brown PLA from eSun. And at that point I did start to notice some issues. I had put it down to a different manufacturer, but now I'm thinking that's where the buildup started. I was having to use a much higher extrusion adjustment, and that was making the extruder motor force through the desired volume. Probably compounded the problem.

Finally I switched from the Brown eSun back to MakerGear, but the White PLA, which has a different texture (less smooth) than the black. And that was what finally jammed it. I'd just started with that one, and I did have a harder time getting that to extrude. (Which was why I asked earlier about how to recognize partial clogging.) The nozzle flow was fine - I didn't realize the tube had buildup.

And this buildup is not like a wad - it's a smooth, rock hard coating all around the diameter of the tube - it was just restricting the diameter.

Once I drill out that restriction, I'll be able to see which of the filaments contributed to that coating inside the tube - so far, everything I've managed to ream out has been the white, but that was the last one used so I expect it in the center area. I'm expecting to find a rather large layer of the brown closer to the walls of the tube.

(I do have a spare hotend, so I'm just cleaning this one out to see what caused the problem.)

Would it be easier to melt that out? One thing we've got at this house is a heck of a lot of torches. (Husband sells them - very handy .)

Well, I always prefer to burn the hotends out, but then again I solve (and cause) an inordinate number of problems with fire. I'm still 99% sure your motor is good, although I can't explain the gear not moving anymore. There was a period of weak pinion gears, but I thought we were past that ... yours is a pretty new machine, right?

If you are going to clean the hotend with fire PLEASE start a new thread about how to safely do it. Just taking the whole thing and applying fire to it will ruin it very quickly! You have to remove all the heat-sensitive plastic bits first and disassemble the nozzle from the barrel so you can clean them independently.

Just making sure, when you try to command an extrusion, is your extruder at temperature? The firmware will not allow "cold" extrusions below a certain temperature, I forget the exact number. Check the console and it will say something like "cold extrusion prevented".

I'm pretty sure the magic number is 170º.

-Steve

Yup 170 is it.

The stripped out filament is such a common thing its not funny. After awhile youll get used to that. If you cant pull the filament out then take an xacto knife and cut it right there at the bearing, pull it out the top then us a small pair of needle nose and pull the piece out from the hot end side. You may need to heat up the hot end to release it. If you have just run pla i dont think your hot end is tight either. You could have a partial clog or just a dirty nozzle then the machine wouldnt be able to extrude as fast. If the speed was high then the filament just stripped out. Did you happen to notice the movement jog dial in s3d? Did you accidently speed things up with that? As for the plastics. Remember different manufacturer, different color all can have different melt temps. The esun you may need to run hotter.

Well, don't I feel like a complete idiot!

I could have sworn I tried at least one of those extrusion/retraction attempts under temperature, but I must not have, and gentlemen, you are correct - when you take the temp up to 170°, the extrusion gear starts turning again. I just put one of the spare hotends on the machine and tried again under heat and it turned without a hitch.

Well, that will save me 50 bucks, but I'll need to send another email to support to let them know the motor is actually okay. Thanks guys! (Should have come here first, would have saved me from looking like a complete newbie. Oh wait, I am a complete newbie! )

And as far as cleaning the hotend with a torch goes, unless you happen to have a very specialized set of tools, I wouldn't try to take apart the hotend. Getting the insulator off required a special set of pliers that could provide traction without damaging the insulator (is that what you are calling the peek?), and that particular set of pliers probably cost well over the price of a whole new hotend, several times over. Fortunately we have one here, but hubs is a Manufacturers Rep for the plumbing industry - we've got a lot of unusual tools that most folks don't generally keep on hand. And that end was wedged in there very tightly - there was no other way to get it off. (Actually had to call him over to do it too, I wasn't strong enough. Very well made and assembled parts on this machine.)

If I do clean this out with a torch - the only parts that will be cleaned under heat are the brass bits, and they are hard to get off without damaging the hotend. You also need to work over an asbestos pad with a torch and wear the proper protective gear. So most folks will probably want to just buy a new one assembled. It would be a lot cheaper, and take less time. (I'm wondering, since it should only be PLA in there if it couldn't be softened in an oven and melted out? Might try that first.)

Anyway, I've just got to put all of this back together and I'm back in business! Thanks ever so much guys!

Here is a thread from a time I had to clear out my clogged v3b, it has some helpful techniques and links: viewtopic.php?f=7&t=732
That solvent soak really works and makes your nozzle squeaky clean.

I don't remember what I used to get the barrel off, but I'm in sort of the opposite of your situation in that I have very little in the way of what you might call tool infrastructure (every time I need something, I have to go out and buy it), so it couldn't have been that hard. Anyway, if you have a busted hot end, the options are fix it, replace it, or try to fix it, possibly break it, and then replace it. So attempting a repair is a free action, in that you're no worse off than you would be if you didn't try it.