Movement Distance Not Correct.

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25 May 2011 12:52 #10065 by blazedforever
blazedforever created the topic: Movement Distance Not Correct.
Hello,
recently i tried centering a shaft on my machine using a digitizing probe and i cant figure out why the DRO in emc is reading wrong ?
It reads about 0.040 more then the actual part size , why is this ? I tried setting the tool diameter to zero but it does not seem to help. The manual says its a scaling issue? I'm not sure what that means.

Thanks in advance

-Hans
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25 May 2011 20:11 #10071 by andypugh
andypugh replied the topic: Re:Movement Distance Not Correct.
Backlash? (Possibly backlash compensation, if you have that enabled?)

Can you give a more detailed description of what you are doing?
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26 May 2011 03:04 #10079 by blazedforever
blazedforever replied the topic: Re:Movement Distance Not Correct.
I'm sorry I could have been more verbose. I was checking X with the probe I had no code so i was just jogging around. I had a shaft in the vise and started on one side touched down, zeroed, and moved to the other side. The diameter was out +0.040". I then checked a parallel in the vise for width along X , This time i got 0.066" over. I checked Z and Y, Z was bang on the money and Y was also out 0.066". I checked for backlash using a dial indicator on X and that resulted with 0.002", which is not horrible. I also made sure no tools were loaded. My hardware includes a Gecko G540 driver, 280 oz 200 step motors (micro step set to 10 as per instructions), and a Taig milling machine. From time to time i have received a real time delay error , but not often, not sure if it matters . The docs said it could be that scaling is set wrong , not sure what that is?
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26 May 2011 09:38 #10082 by andypugh
andypugh replied the topic: Re:Movement Distance Not Correct.
blazedforever wrote:

I had a shaft in the vise and started on one side touched down, zeroed, and moved to the other side. The diameter was out +0.040". I then checked a parallel in the vise for width along X , This time i got 0.066" over.
...
The docs said it could be that scaling is set wrong , not sure what that is?


Do you know the true dimensions of the vice and the parallel? If it always measures things 5% big then I would suspect an error in the axis scaling in the INI file (ie, how many steps it takes to move the axis an inch).
If the error is approximately the same regardless of the size of the thing you are probing, then I would suspect a mechanical issue.
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