GCode change scale of an axis during execution

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dominfo
Posts: 12
Joined: Tue Sep 12, 2023 8:39 am

GCode change scale of an axis during execution

Post by dominfo » Tue Sep 12, 2023 9:02 am

Hello
I need for an application to be able to create this motion in XY plane, see joined picture.
arc_1axis_scaled.jpg
For that I would like to use the existing G2/G3 GCode instructions: this would output the red trajectory.
BUT the customer requirement is the black trajectory => an arc with a modified Y scale factor.

I know that a G51 scaling feature exists on some other CNC controllers.
the code would be like this
...
G0X0Y0
G51 Y100 (scalefactor for Y changed to 100 counts per unit, X not changed)
G2 X4 Y8 I2 J3 (arc motion)
G50 (cancel scaling)
G0 X0Y20 (move to this position with the "original" scalefactor)
...

The requirements are that only the arcs should have a modified scalefactor.
other moves should be done with the original scalefactor during execution

Is this possible with Kogna?

Maybe I'm wrong and there is an existing GCode programming possibility to do this "modified scale" arcs motions.

Thanks
Frederic from DOMinfo (France)

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TomKerekes
Posts: 2605
Joined: Mon Dec 04, 2017 1:49 am

Re: GCode change scale of an axis during execution

Post by TomKerekes » Tue Sep 12, 2023 5:44 pm

Hi Frederic,

I'm not aware of a simple way to do this.

You could change the Y axis scale but that would change it for everything.

You could create such a path with many short line segments. You might look at the Polygon.ngc example which can create a many sided ploygon to approximate a circle. You could modify it to do a half circle and use a different radius for X and Y.

HTH
Regards,

Tom Kerekes
Dynomotion, Inc.

dominfo
Posts: 12
Joined: Tue Sep 12, 2023 8:39 am

Re: GCode change scale of an axis during execution

Post by dominfo » Tue Sep 12, 2023 5:52 pm

Hi Tom
Thanks for your input. I will take at a look at this polygon.ngc example.
It's actually a showstopper to retrofit an existing machine from Baldor Nextmove (which handle dedicated Mint programs in memory) to your new Kogna board reading a GCode program.

I already used your KFlop on 4 axis milling machine some years successfully so I'm confident on your hardware.

I hope to find a good software solution for using Kogna to solve this topic.

Regards
Frederic

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