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Author Topic: Cutting smaller  (Read 4998 times)

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Re: Cutting smaller
« Reply #10 on: September 23, 2016, 07:04:19 AM »

This is a new controller I never had this problem with  the previous controller.

If I would cut a pocket .750 X 1.00 I would get a pocket .750 X 1.00 not smaller.
This happens in what ever material I cut including Acrylic and plastics.
A job I do for a company requires all measurements to be spot on.






















x

Offline ger21

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Re: Cutting smaller
« Reply #11 on: September 23, 2016, 07:58:19 AM »
When you say new "controller", what are you referring to?

New drives?
New Motion Controller?
New Software?

If you cut the same part twice, one Climb, and then one Conventional, are they the same size?
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
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Re: Cutting smaller
« Reply #12 on: September 23, 2016, 10:19:23 AM »
Hi ger21

Using MACH 3 Ver. R3.043.062, USB Smooth stepper, PMDX 126,134 & Gecko 203V drives.
NEMA 34 640 oz 5.5 amp motors 3-1 belt reduction. motors and belt reduction checked they are fine.
Cut in both clim and conventional all cuts are 4 thousands smaller.

Offline ger21

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Re: Cutting smaller
« Reply #13 on: September 23, 2016, 11:36:29 AM »
What's different from the old setup that worked?
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Cutting smaller
« Reply #14 on: September 23, 2016, 12:25:02 PM »
Hi ger21

Old controller did not support proxi. switches ,tool changer, spindle speed control also used old Gecko202 drives that had caused problems.
Re: Cutting smaller
« Reply #15 on: September 24, 2016, 03:16:47 AM »
Hi Bill I,
when you calibrated the axes who did you go about it?. When I did mine I did the
calculation, the number of stepper pulses/rev times gear reduction time pitch. It worked
fine and have never had need to go back.

Imagine the situation where I had 6mm pitch ballscrews but are in fact 1/4" ie 6.35mm pitch.
The calculation would be persistently and consistantly wrong.
Could your problem be of the same type ie one factor in your steps/unit calculation be slightly
adrift of the actual?

Craig
My wife left with my best friend...
     and I miss him!
Re: Cutting smaller
« Reply #16 on: September 24, 2016, 09:10:29 PM »
I used the MACH Set steps per unit just like I did with the previous controller.

Offline rcaffin

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Re: Cutting smaller
« Reply #17 on: September 25, 2016, 05:28:26 AM »
One is left to wonder about some backlash creeping in.
Against that, the X & Y axes both show it.

If you start at 0 and make cuts at 20, 40, 60 mm, where is the error?
If all 3 are short by the same amount wrt 0, then I would look at backlash.
If the gap between each (20 mm) step is short by the same amount, I would look at calibration.

Cheers
Roger
Re: Cutting smaller
« Reply #18 on: September 26, 2016, 08:06:45 AM »
Hi rcaffin

Backlash was one of the things that was looked at when I worked with Gecko on this problem.
There is no backlash or bit deflection the resistors were changed and the belts were checked for tension and wear in the belt reduction.

Bill I

Offline rcaffin

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Re: Cutting smaller
« Reply #19 on: September 26, 2016, 08:19:52 AM »
But what about the measurements I suggested? Measurements give cold hard facts.
Cheers
Roger
PS - where do the resistors come into this, and what are they?