Extruder Backlash

I'm in the process of building my RepRapPro Mendel and I've noticed that the extruder has backlash because the nut does not fit tightly into the center of the large gear.

Is this something critical that will wreck any chance of decent prints and should be fixed before using the printer?

I hope not because I'm not sure how to rectify it without a working printer to print a better gear.

Thanks, Andy

Edited 1 time(s). Last edit at 07/25/2012 06:06PM by ajayre.

Assuming it's not massively lose you can fix it by putting a space (say tape) in the gap.
In terms of effect, you'll potentially get some lag from the extruder when a print starts and the backlash is taken up, if you are printing a skirt it'll be irrelevant.
You'll also lose some of your retract distance to the backlash, that will probably result in having to specify a larger retract to eliminate stringing and potentially a small blob where the retract starts because of the slight retract delay introduced by the backlash.

Just wrap some kapton tape around the nut so it fits tightly. Then you can print a new large gear after you have it all up and running.

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Epoxy the nut in place. Lubricate the nut if you want to easily get it out later. Make sure its aligned and square as it dries

dean448 Wrote:
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> Epoxy the nut in place. Lubricate the nut if you
> want to easily get it out later. Make sure its
> aligned and square as it dries

That's probably the best option.

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Thanks for the help! I'll try Kapton tape first then print a herringbone gear set.

Andy

Hi there,

I have hunted high and low to find a herringbone set for my mendel's bowden extruder. Either I can't find them or can't correctly configure the relevant scad script to get a printable set. Can you help at all ?

Kindest