grbl Circles

Anonymous · ‎02-06-2017

Something is screwy all of a sudden.

This happened when I started with CAM and was originally because I had neglected to select GRBL as the post configuration.

When opening the cut file there are huge circles all over the cut file profile.

They don't show under the simulation in fusion 360 only when you look at the cut part.

Today I started with a face operation which worked as it should and then after the tool change I opened the contour cut file and it had these huge circles again. Ive closed and opened set another profile and back to grbl again tried with only the one half of the model to be cut buy nothing keeps adding the circles in again.

this is 2 parts of the same model cut back to back 1st one was fine then this all of a sudden.

Any ideas?

kb9ydn · ‎02-06-2017

@Redsalamander wrote:

Something is screwy all of a sudden.

This happened when I started with CAM and was originally because I had neglected to select GRBL as the post configuration.

When opening the cut file there are huge circles all over the cut file profile.

They don't show under the simulation in fusion 360 only when you look at the cut part.

Today I started with a face operation which worked as it should and then after the tool change I opened the contour cut file and it had these huge circles again. Ive closed and opened set another profile and back to grbl again tried with only the one half of the model to be cut buy nothing keeps adding the circles in again.

this is 2 parts of the same model cut back to back 1st one was fine then this all of a sudden.

Any ideas?

Is your gcode using R mode for arcs instead of center point mode (IJK) by chance? R mode can have problems like this. What do the G02/G03 commands look like?

C|

daniel_lyall · ‎02-06-2017

the same problem was found here https://forums.autodesk.com/t5/computer-aided-machining-cam/strange-toolpath/td-p/6847927

It was down to something going nananana with the tabs and not have done the setup correctly and not haveing the orientation set in the toolpath.

Anonymous · ‎02-06-2017

After looking around for some time. It does seem related to curves. The model had a few sweeping fillets which once removed it was OK. However that doesn't help for how the model should actually look.

I tried the suggestion of tabs causing it, but it made no difference.

If I had to hazard a guess at the cause it would be it seems that the entry lift point for some reason gets translated into a much bigger radius. the curve that caused it in the end looks like it was a fillet with a large radius that was on the same surface as the entry point. Possibly intersecting with it.

daniel_lyall · ‎02-06-2017

It would help a lot if posted the model, other wise it just a guess for someone to give you help.