[John Coloccia]

I'm noticing that the break angle parameter doesn't seem to be working as expected. Just as an example, I have a 90 degree turn made from 18 line segments...let's just say 20. So there's approximately 5 degrees between each line segment. My break angle is set to 10 degrees, but the motion still stutters around the curve unless I set the break angle to 15 degrees or so. I don't understand why.

I've included the file. Look at the curves near Y=0. It stutters around every one of those with a break angle set to 10 degrees.

Attachment 181240

edit: Sorry....meant to say near X=0. There are several 90degree curves in that area.

[TomKerekes]

Hi John,

Hmmm... What are your Trajectory Planner Settings? I suspect what is happening is that the Collinear Tolerance setting is allowing multiple segments to be combined which results in a larger angles. Segments are combined together based on the Collinear Tolerance before checking the Break Angle. This is normally a good thing. For example a 1 microinch zig-zag would be smoothed out and not result in an unnecessary stop. See here.

But in your case the opposite is happening. The Collinear Tolerance is telling the trajectory planner there is no need to do all those tiny segments as several can be combined together and still meet the accuracy specification. But then the resulting path has bigger angles.

If I did the math right for the 125mil radius curve in your GCode the 18 Segments are each only about 10 mils long and combining two changes the path by only 0.4 mils.

Please try reducing the Collinear Tolerance to see if it resolves the issue.

Regards

[John Coloccia]

Thank you, Tom. I think I have the tolerance set to .001. I think I'll set the tolerance in KMotionCNC to .0001 and see what it does. It sounds like you are on to something. It also explains why it doesn't seem to stutter at every line segment but only about half of them going around the turns. I'll try it in the morning when I get back into the shop, but your explanation makes perfect sense.

[John Coloccia]

I couldn't resist. Went into the shop and tried it. My Collinear Tolerance is now .0001 and that fixed it right up. My current settings are:

Break Angle: 10
CL Tolerance: 0.0001
Corner Tolerance: 0.001
Facet Angle: 0.5

And it's running like a champ. This has been bugging me on and off for weeks. Thanks for the help, Tom!

This should almost be a sticky. I've seen other people with break angle settings of 50 degrees and things like that, and I wonder if they're not running into the same issue.

-john