MakerBot Support Forum/Technical Support/Older Products
Extruder Troubleshooting
makeme
asked this on January 02, 2011 11:25
I've been trying to figure out why my TOM has suddenly developed extruder problems. It was just fine for a week or two, and then all of a sudden extrusion became a hit-or-miss affair. I was inclined to think it was a mechanical problem with the motor since I had to unseize it when I got it, and the motor would stop spinning during a time when it was supposed to be extruding even with the filament plunger backed completely out so there was no load on it. The only way to get it moving again was to spin it with a separate 12V power source. Then the extruder controller would spin it for a little while, but it would inevitably stop again (matter of seconds or minutes).
However, the motor never got hot when it wasn't extruding, which I would expect if it was trying to turn but caught on something.
As far as I know I've got the latest firmware, which implies this ISN'T the same problem outlined in the Great Motor Mystery http://wiki.makerbot.com/the-great-motor-mystery since they claim to have fixed the bug. Also, mine won't just malfunction after I press stop; it will also just not work from a complete reset (overnight) of everything.
I took the motor off of the extruder (still electrically connected to the extruder controller), and took the front plate with the bearing and the shaft off of the gearbox. Then I just sat it on the counter and watched the open gearbox turn. There's nothing in the gearbox preventing the motor from turning. I watched dozens of revolutions of the (top) slowest gear and it never stopped in the same place twice.
So, the problem is earlier then the gearbox; either the motor itself, the extruder controller, the motherboard, or the powersupply.
Now things are extra awesome. I WAS checking the leads from the extruder controller for voltage yesterday. The V to the motor varied depending on whether or not the various heaters were on, but didn't seem to drop below 10.3v. About the last thing I did last night was watch the motor, with no load on it, start, then stop (nothing unusual there) and then start, shudder for a few seconds, and stop. Now I can't get ANY voltage out of the extruder controller. The motor still works just fine (external 12V power supply), the heaters work, and the various stepper motors work.
Comments
I had a very similar problem with my thing-o-matic. The extruder motor would work fine when connected to a 12v power supply, but not work when attached to the controller. I worked with the support staff and they sent me a relay board kit. Once this was in place everything has worked perfectly. I recommend getting a relay board kit to solve this issue.
@Cjbissonnette
I've been sent the relay kit from Makerbot, I'm just assembling it now.
I can't see how this will work - I take the extruder motor output from the extruder controller and connect to B+ & B-, but when the exruder motor is put in reverse doesn't that means that the B+ & B- change polarities to reverse the motor direction,,
Does the relay board cope with the polarity change and send the reverse to the output connecter?
Thanks for any advice
Regards
Adrian
Actually I don't think the DC motor will work in reverse with the relay attached. This leads to slightly more cleanup work, but I have not found it to be a practical problem. Honestly the best solution this this problem now is to buy the MK6 stepper driven upgrade kit. This completely alleviates all the hardships faced with the DC motor. That being said, I have been using my MK5 with relay board for months now and it works reliably.
Hi
thanks for that, my Makerbot is now working fine but no filament reverse - C'est la vie!
I've also ordered the MK6 Stepper Upgrade so more fun later on
Regards
Adrian
You can put together a MOSFET solution that will allow reversal. But I don't think anyone's gotten much use out of reversing the DC motor. http://rayshobby.blogspot.com/2011/02/mosfet-based-fix-to-makerbot-...
Hi Adrian, I would like to ask, did it actually work the additional relay kit in the end?No more stops in the middle of printing?
My cupcake is here doing nothing after 10 prints and I'm seriously thinking on unpluging the dc motor from the extruder board and connect it directly to another power source altogether (with the necessary electronics to not burn it), it should work but it would stop being automatic...
Sorry the double post, forgot to ask, if you add a second relay kit, how to wire it in top of everything else?
Hi Raul,
The relay kit works fine thanks - however I did try the motor with my bench power supply first to prove that a higher current would turn the motor.
Before I got the relay I could make the motor work buy stripping it from the extruder, taking it apart and rebuilding it (or powering it from my bench supply for a couple of seconds) and then putting it back - it would then work for 1 to 2 hours before failing again
But with relay all now works fine - I wouldn't use a second relay so can't help you there.
I've got the step struder to install - but work is getting in the way (DOH!)
Good luck
Adrian
I just had the same problem with my Cupcake Ultimate. My extruder controller was not energizing my DC motor. I have a relay board already, so rule that out BTW. I had disconnected the motor and tested continuity to it, and then on the offchance that the motor was blown, I hooked it up to a separate 12V supply: the motor turned. So I thought it must be the extruder controller, until I just read this post and I decided to hook it back up again. Success!! So my extruder board is not blown (phew). Still weird behaviour though.
I just put my cupcake back together, after "zapping" the motor with 12V so I could extrude again. I got about 2 layers into a calibration print when the motor failed again. I will note second the opinion that the failure is earlier than the motor (I'm thinking extruder board again).
My Makerbot was working fine until i went to the 1.75 mm filament. it never pushes out plastic now - like the nozzle is jammed. I have completely reinsulated everything - why doesn't anything come out?
The problem described here originally was solved when we went to stepper-based extruders. However, for those of you who haven't switched over, there are some fixes available on Thingiverse that work by feeding additional current to the motor. Have a look at this one: http://www.thingiverse.com/thing:5492
Keep in mind that PWM won't work anymore after this -- use only 255 or 0 as your setting, full on or completely off.