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Extruder drive gear slop :-(

Posted by cobrageek 
Extruder drive gear slop :-(
September 17, 2013 10:59PM
I'm still trying to finish my build and was about to start the wiring and noticed that the drive gear for the extruder has considerable slop. I believe it is a wades extruder design that came with my prusa 2 kit. The extruder shaft is held to the drive gear with some nuts and those nuts are supposed to fit tightly in and indentation so the shaft always turns when the gear turns. But the nuts are not a tight fit and there is probably a 25 degree rotation of the gear without the shaft anytime the gear changes direction.

Is the gear printed wrong or do I have the wrong nuts somehow? Is there some common way to fix this slop? Thanks!
Re: Extruder drive gear slop :-(
September 18, 2013 02:48AM
I've fixed extruder gear slop before with epoxy. But 25 degrees sounds like a lot of slop, I think I only had about 5 degrees. Sounds like the print precision wasn't top notch...
/Andreas
Re: Extruder drive gear slop :-(
September 18, 2013 03:40AM
Unless the set screws are loose, it could be the plastic is warped and damaged. Heat from the extruder motor drive shaft can heat up the pulley and make the nuts loosen up. Take it of and check. You might need to get a new pulley.

You might be able to print even with severe slop, if you disable retract.


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-Nudel
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Re: Extruder drive gear slop :-(
September 18, 2013 10:05AM
The gear on the extruder motor is nice and tight (set screw is working properly). The issue is with the larger gear and its connection to the "shaft" (bolt) which is really just a double set of nuts tightened together. It looks like the nut is just too small compared to the indentation in the gear where it is supposed to fit. I suppose it should be a tight fit and likely a print accuracy issue (ran into a few of those previously).

I'll see if I can take it apart and epoxy a nut in place. I think that would fix the slop if the epoxy will really hold.

I do plan to print a whole new set of parts once I get it up and running, but for now I need to make these parts work.

Let me know if anyone has any other tips. Thanks!
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