Davinci x belt manual tensioner - standard pulley

thingiverse

The standard item has a spring and a pathetic screw to keep the tension on the belt. I found the screw would tire and then the belt would loosen under load as the spring let it go. This is a remix of the belt tensioner http://www.thingiverse.com/thing:690090 that uses the original spring to tension the the stock pulley. This version uses an M6 bolt through the end, it's much easier to fit - Simply loosen the bolt right off, push it all the way in, slot the idler pulley in on the belt and do the bolt up until it sounds like a bass string when plucked! Dont use too long a bolt or it will catch on the side (the one I used is 20mm) I did a version with a captive M6 nut, but it's much more difficult to fit, the thread ramps in the hole work just as solidly and help stop the bolt undoing. Once I made this I actually remixed the ball bearing versions, which gives a much smoother x axis.