Build and Intro

**irving2008** · 23-10-2013

Re the belt tension - you need to minimise backlash, 1/8 of a turn is way too much. Use one of the online belt calculators to see what the centre distance should be - it will depend on pulley size. If you can't get the exact centre distance you will need an idler pulley or other tensioner - e.g. a bearing on a stud pressing against the back of the belt.

**swisscheese** · 23-10-2013

Hi,

Sorry maybe I should have been clearer. The belt is too big, i.e. tensioner is needed and have made one. Just not sure how tight to pull it. Is it weird that if I pull the belt tight the ball screw bows inward a little bit? Is this normal. It's 1.6m long. Bows in a few mm.

**swisscheese** · 27-10-2013

Anyone have any opinions on this?

Also with the pulleys the length of the bore is about 29mm and it has two set screws. The shaft for the pulley on the end of the ball screw is only 15mm long. Should I be concerned that the shaft isn't long enough? Is tightening down the set screws onto the round shaft fine or should I grind down two flat areas on the shaft for the set screw to tighten onto?

thanks in advance

**JAZZCNC** · 27-10-2013

Originally Posted by swisscheese

Anyone have any opinions on this?

thanks in advance

Yes Grind one small flat the other is fine on round shaft.

There is another option but requires a lathe to do easily. Bore and Thread the Boss end of the pulley the same diameter has the threads on Ballscrew and use this to replace the Locknut on the Fixed end. This then gives full engagement on shaft and combination of grubs screws and threads lock it solid.!