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Position Error Problem Stepper machine
« on: June 12, 2007, 01:22:31 PM »
Hello All,

Just got my new machine running this week and I have a problem that I can not figure out. Any help would be appreciated!!

First of all I am running mach 3 with stepper motors on a 3 axis milling machine. A machine I built

I set the machine up, to start, by using a indicator to insure that it was moving the correct distance when commanded. After I had that set to an accuracy of less than .001 per inch, I made a program and cut some circles and squares. The circles I cut were out of round and the squares I cut were not square. Both figures were off the same amount in each axis. So I reset the "unit per" for each axis to cut the squares and circles to the correct size. Everything then looked good until I cut larger squares and circles. Now the larger figures are not the correct size. Any suggestions as to where to start looking for this problem?

Thanks For any suggestions you may have to offer!!

Allen James

« Last Edit: June 12, 2007, 02:13:22 PM by freak_brain »

Hood

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Re: Position Error Problem Stepper machine
« Reply #1 on: June 12, 2007, 03:30:41 PM »
Check for backlash, this could be in the ballscrews/leadscrews, bearings or motor couplings/pulleys.
Hood
Re: Position Error Problem Stepper machine
« Reply #2 on: June 13, 2007, 12:21:50 PM »
Hood,

I appreciate your help. However, it is not backlash. I took the machine and cut two slots in X axis using a 1/4" endmill in mdf. One slot should have been 6" long and the other should have been 1" long. I took the slop out by feeding above the part, in the same direction for both slots, before move z down into the part. The 6" slot was on size and the 1" slot was .04 long. Same result in both x axis and y axis. If I adjust it to cut the 1" slot correctly the 6" slot will be off. Any other ideas from anyone?????

Hood

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Re: Position Error Problem Stepper machine
« Reply #3 on: June 13, 2007, 01:17:00 PM »
Thats a strange one :( What setup do you have hardware wise (drives etc)?
 Can you post your xml so I can have a look, probably wont find anything but its worth a look.

Hood
Re: Position Error Problem Stepper machine
« Reply #4 on: June 13, 2007, 01:46:07 PM »
I have gecko drives, G201...10 microsteps. The thing that gets me is that both X and Y are doing the same thing. I could understand that one drive could be bad or causing a problem but two? I'm lost!! I will post the XML file when I get home later. It's on a different PC than the one I am on now. Thanks again Hood!!!

Allen James