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Author Topic: Hesitation between Lines of G-code  (Read 8881 times)

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Offline RICH

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Re: Hesitation between Lines of G-code
« Reply #10 on: February 18, 2011, 06:49:53 AM »
Dan,
Mach is computing X & Y velocities  / change in Y with respect to x  and as you aproach 0-90-180-360 one axis velocity is realy slowed down
to maintain position. So there seems like a pause and in CV mode it is transparent. Since there is a change in time at those points the tool
dwells there slightly longer and with tool runout you will get marking. Depending on axis resolution, accuracy of the axis, and spindle run out  you won't get any flat spots.
RICH
Re: Hesitation between Lines of G-code
« Reply #11 on: February 18, 2011, 08:34:10 AM »
Also make sure there is not a G61 in the header of your gcode file.  Regardless of how you have CV set in Mach, G61 will turn it off.  You should have a G64 in the file header, which turns CV on.
Re: Hesitation between Lines of G-code
« Reply #12 on: February 18, 2011, 10:20:32 AM »
So if I'm understanding, get settings to CV mode, without additional options checked as mentioned in a previous post, and/or add G64 to the initial string/header and I should be good?

I'll try it.

Tested this with a pen to eliminate tool deflection, and I removed the motors, to eliminate the possibility of backlash, and observed the behavior of the shaft: only where the line change in code occurs do I get the dwell/pause.
Re: Hesitation between Lines of G-code
« Reply #13 on: February 18, 2011, 10:21:03 AM »
I should also say, THANKS for the feedback!!!
Appreciate it!
Re: Hesitation between Lines of G-code
« Reply #14 on: February 23, 2011, 11:30:15 PM »
I've updated my CV options as described and I still have this problem. I've pulled my motors and observed the pause at the change in code between the semicircles. Any help much appreciated.

Thanks,
Dan

Offline Hood

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Re: Hesitation between Lines of G-code
« Reply #15 on: February 24, 2011, 01:50:49 AM »
Can you attach your xml please.
Hood
Re: Hesitation between Lines of G-code
« Reply #16 on: February 24, 2011, 02:11:18 PM »
I don't have it with me but will attach it this evening. Thanks for your response!
Dan
Re: Hesitation between Lines of G-code
« Reply #17 on: February 24, 2011, 07:36:38 PM »
Hi Hood,

I've attached my XML. Let me know if there is something I should change.
I am running a 'home brewed' machine (originally brewed by someone else...), with Gecko drives and servo motors.

I appreciate you taking a look.

I have had a strange issue with my General Configurations. Sometimes when I load G Code, my Distance Mode will flip to Incremental from Absolute, where I typically have it. Then I will get an "Abnormal Condition" flashing button and an error at the end of a semicircle line of code, saying the next location cannot be determined (don't have the exact verbage). Any thoughts on that appreciated.

Best regards and thank you,
Dan

Offline Hood

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Re: Hesitation between Lines of G-code
« Reply #18 on: February 25, 2011, 03:18:02 AM »
I dont see any problems in simulation here  with the xml and hesitation, can you attach some code that you have the issue with?
Regerds the distance mode, it is likely your code that is changing the IJ mode. Because the mode has changed and not been set back the next code that is loaded without a G90.1 or G91.1 in it may be wrong. It is good practice for your code to have the correct IJmode in it, that way no matter whether you use Abs or Inc as default your code will change it to the mode it needs.
Hood
« Last Edit: February 25, 2011, 03:19:45 AM by Hood »
Re: Hesitation between Lines of G-code
« Reply #19 on: February 25, 2011, 08:21:46 PM »
Hood here is some code.

G17 G20 G40 G54 G64 G91
...
N660 G00Z1.0000
N670 X27.1768Y4.8232
N680 G01Z0.3700 F15.0
N690 G17
N700 G03X18.8232Y13.1768I-4.1768J4.1768 F90.0
N710 X27.1768Y4.8232I4.1768J-4.1768
N720 G00Z1.0000
N730 X31.2603Y8.9860
N740 G01Z0.3700 F15.0
N750 X31.2611Y8.9720 F90.0


The issue occurs between N700 and N710.

Thanks for the info on the XML. I'll add the IJ code to my header. (Isn't that the G91?)

Best,
Dan