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Author Topic: Expected backlash  (Read 1256 times)

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Expected backlash
« on: January 21, 2013, 09:08:25 AM »
Hi folks, as a result of a slightly unexpected error in the dimensions of a piece I profiled I realised that I could not ignore the backlash on the slides of my little Novamill.  Measurement showed it to be 0.03 mm on X and Y, 0.02 mm on Z.  I have turned on compensation and set these parameters and it seems to work fine, but I was wondering what level of backlash was to be expected?  I have posted this question on the Denford forum and Angeltech has suggested I adjust the thrust bearings, which is good advice that I'll follow, as well as looking at the gibs, but would be nice to know what I could expect?  The machine though oldish has spent most of its life gathering dust in a school, having clearly not had anyone who had a clue in charge judging by the cutter jammed in a collet when I bought it off ebay!  So I don't think there will be significant wear.

John.

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Re: Expected backlash
« Reply #1 on: January 21, 2013, 10:02:22 AM »
Hard to say what to expect without knowing the quality of the ballscrews and how much pre load is on them, if any.
With no pre-load then 0.02 would not be out of the ordinary. Also the quality of the bearings holding the screws will play a part. The wee Conect lathe I have was very poor in that respect, there was one thrust ball bearing and the motor was being used as another, not a good setup at all.
Hood