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Re: Cutting wrong dimensions in only one spot
« Reply #20 on: October 31, 2019, 01:39:25 PM »
I have tried CV off, on.... currently on .1 setting. No other CV checked.

Backlash comp on, and off. Same results
Re: Cutting wrong dimensions in only one spot
« Reply #21 on: November 01, 2019, 08:54:07 AM »
i just printed on paper the file Rich posted, and printed my cad drawing. They overlay exactly.

So I'm open to suggestions to try please!

Is there a bug in Mach3 version? What's the best version I should be using? Is there a stuck modal (correct term?) in my gcode I need to clear? Does this clear everytime I re start my computer?
« Last Edit: November 01, 2019, 08:57:06 AM by jonny quest »

Offline BR549

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Re: Cutting wrong dimensions in only one spot
« Reply #22 on: November 01, 2019, 09:21:49 AM »
First thing to test is to put a pen in your spindle and let teh machine DRAW teh part to see if cutting forces are contributing to teh problem.

(;-) TP
Re: Cutting wrong dimensions in only one spot
« Reply #23 on: November 01, 2019, 10:21:53 AM »
It's not cutting forces. I can do a .001" skim cut, take part in and out of fixture... black marker up part, cut again to exact same size and it will just rub original cut part.

Re: Cutting wrong dimensions in only one spot
« Reply #24 on: November 01, 2019, 10:32:53 AM »
Could G64 be the problem? Where does this function get it's rounding properties from?

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Re: Cutting wrong dimensions in only one spot
« Reply #25 on: November 01, 2019, 10:33:52 AM »
Taking a skim cut is not like doing a full cut on teh machine flex wise. The pen trick will tell teh story.

Have you by chance tried reversing teh direction of cut to see IF it changes anything ? As is you are doing a climb cut.

(;-) TP

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Re: Cutting wrong dimensions in only one spot
« Reply #26 on: November 01, 2019, 10:36:43 AM »
You said you already tried turning CV off with no change ??? Here I see no difference between G64 and G61
(CV on CV off) when ploting teh Gcode.

(;-) TP
Re: Cutting wrong dimensions in only one spot
« Reply #27 on: November 01, 2019, 11:46:37 AM »
I would turn CV on and off with the check box in MACH3 config only.

The post processor is still the same.  Should I remove a string in post?

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Re: Cutting wrong dimensions in only one spot
« Reply #28 on: November 01, 2019, 12:44:00 PM »
Just change the Gcode file for testing . Change G64 to G61 in the preamble.

(;-) TP

Offline RICH

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Re: Cutting wrong dimensions in only one spot
« Reply #29 on: November 01, 2019, 05:23:18 PM »
So your CAD file agrees with my backplot of the gcode you posted.
So it's not a gcode problem.

Do what TP said in reply 22. Have the machine draw over the full size print using
both G61 and G64. That will eliminate any doubt on those modes.

Someting that I would try is changing the Gcode to get rid of the two G01 moves.
Join the arcs such that there is no  small lines between the before and after arcs.
Arc difference will only in ten thou's of an inch probably!

Seems like the machining goes off path because of  G01 X-0.305 Y1.503
or the G01 X0.787 Y1.260. Easy to change and paper plot to check!

FWIW,
RICH