How to turn off ease out/in motion?

Discussion about the arduino based g-code interpreter, grbl
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Jimmyalenius
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How to turn off ease out/in motion?

Post by Jimmyalenius » Wed Dec 28, 2016 5:01 pm

Hi! When laser cutting you want a continuous/linear motion for the laser beam to cut nice. Is it possible to turn off the ease out/in motion in GRBL?

Regards / Jimmy

chamnit
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Re: How to turn off ease out/in motion?

Post by chamnit » Wed Dec 28, 2016 5:15 pm

You mean accelerating and decelerating? This keeps your stepper motors from losing steps and stalling. It allows you to run at fast rates as well. You don't want to get rid of them. But, if you want to reduce them, you can try increasing your acceleration settings and lighten up your laser head by removing unneeded mass.

Otherwise, you can try using Grbl's dynamic laser mode that modulates laser power with acceleration. To use it, command an M4, rather than an M3 to power up your laser. Or, use a CAM program that accounts for the acceleration by adding some overscan distance.

CastIrony
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Re: How to turn off ease out/in motion?

Post by CastIrony » Wed Dec 28, 2016 6:29 pm

chamnit wrote:Otherwise, you can try using Grbl's dynamic laser mode that modulates laser power with acceleration. To use it, command an M4, rather than an M3 to power up your laser. Or, use a CAM program that accounts for the acceleration by adding some overscan distance.
Just to clarify, dynamic laser mode was one of the features added in 1.1, right?
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Jimmyalenius
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Re: How to turn off ease out/in motion?

Post by Jimmyalenius » Wed Dec 28, 2016 6:41 pm

I have one Chinese laser machine build on GRBL that behave exactly the way I want. I can cut in speeds up to 1500-2000 with very nice result. The laser module cut with full power and the motion is linear (it don't slow down/speed up around corners). I'm going to look at the settings and see how they solved that.

chamnit
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Re: How to turn off ease out/in motion?

Post by chamnit » Wed Dec 28, 2016 10:34 pm

@CastIrony : Yes. Only Grbl v1.1 officially supports lasers with a special laser mode.

@Jimmyalenius : It's possible that the Chinese laser has a modified version of Grbl. So you will not be able to glean any information on what they changed. However, you will want to maximize your stepper acceleration and slightly increase the junction deviation parameter to have your machine not slow down in corners. But you will begin to see resonance issues (machine vibrating) the more aggressive you get. It'll effect your repeatability and smoothness of cut.

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