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Author Topic: Steps per confusion  (Read 1970 times)

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Offline Tef9

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Steps per confusion
« on: October 17, 2010, 03:49:06 PM »
Ok s I have spent the better part of a year converting my mill to CNC, and sucess 3 weeks ago as it moved for the first time.

I had lots of problems during the conversion that were just unfortunate but hey ho I got there in the end, with pure bloody mindedness and the  help of the good folks over at CNCzone.

So now I have a problem, I have DTI'd the X and the Y axis and found that I have backlash on my new ballscrews (bugger!) the x is .2 and the y is .22

When I cut a circle I have a verry small flat on the circle, sadly even with backlash comp on (at least this time its only one side).

Hence the question about steps per...could this be the problem...I only ask as got my current figure by trail and error (160)

The ballscrews are supposed to be 5mm but as I bought them from china direct I think I have some problems with pitch they seem to measure 5.4, unless my digital calipers are broken.
Ok so 5mm pitch. 200 revs of the motor, direct drive no blets or gearing. 16 microsteps.  can anyone who is better at math than I confirm that htis should be 160.  Any other possiblites that could explain why i have one flat side one a circle.

Thanks for any help.

Andy

Offline Hood

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Re: Steps per confusion
« Reply #1 on: October 17, 2010, 04:06:35 PM »
200 steps per motor rev x 16 micro steps = 3200 steps per rev = 3200 steps per 5mm = 640 steps per unit.
So either your microstepping is not set to 16 or when you command a 1mm move it only moves 0.25mm
Hood

Offline Tef9

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Re: Steps per confusion
« Reply #2 on: October 17, 2010, 04:55:28 PM »
Thanks, I think you got it there hood, ill have to check but I think that I have the drivers set to 1/4 not 1/16th.  So ok the circle should be round ... why would it have one flat side?  Could the tool 'wander' ?

A

Offline Hood

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Re: Steps per confusion
« Reply #3 on: October 17, 2010, 04:57:00 PM »
Can you post a pic of the circle.
Hood