belt tensioner

June 9, 2011

Generally most things print pretty well… with the exception of the small RepRap pulleys which need a lot of ‘cleaning’. I could feel some backlash in both pulleys when the motors weren’t powered up. So, like other folks, I put a pencil on the nozzle and plotted an 80 mm diameter circle with fill.

I used the lash option in SF 40 to compensate but pulleys looked a bit odd.  So I designed up some crude adjustable belt tensioners in openSCAD which I could fit to both y-axis and x-axis without dismantling anything (except loosening the x-axis belt to fit the tensioner!).  The x-axis one fits under the prusa x-carriage onto existing bolts and the y-axis one fits under the bottom plate using the belt clamp bolts.

X-belt tensioner:

Y-belt tensioner (the bolt is too short so there are some other bits jammed in to raise the belt a bit more!):

Printed pulleys (left to right, original, SF40 lash, tensioner, tensioner with more tension):

It mightn’t be that obvious from the photo but there is a decent improvement, although there is a bit more tuning to do!

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