Incorrect corner radius

[bmcd]

I've just finished cutting a Jazz bass pickguard and the corner radius of the pickup cavity does not match the drawing. It's supposed to be .125" radius but is much closer to .1875" and is close to interfering with the pickup. I used a .25" diameter bit. I'm thinking it may have something to do with the trajectory planner (?), but my understanding is a little light in that area. I'm running a KFLOP board with KMotionCNC as the controller. Setup is constant velocity mode and absolute coordinates. It's a K2 machine with servos. Any thoughts on what could be the cause of this would be appreciated. Thanks.

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[bmcd]

I did a close inspection of the toolpath in Mastercam and have found where the error occurred. If the pickup cavity is done as a pocket operation, the finish pass of the perimeter is an arc at the corners (rounded). If I program it as a contour operation, the toolpath is point at the corners (square) Not sure why, but at least I have a work around until the reason becomes clear.

[InMesh]

I think Vectric does a thing like that ,Pocket has radius profile square or similar not sure test piece I have done in the past save swearing.

[louieatienza]

I did a close inspection of the toolpath in Mastercam and have found where the error occurred. If the pickup cavity is done as a pocket operation, the finish pass of the perimeter is an arc at the corners (rounded). If I program it as a contour operation, the toolpath is point at the corners (square) Not sure why, but at least I have a work around until the reason becomes clear.

You should check the parameters you use to set up the job, possibly a parameter called "leave on sides" or "leave on corners" if it's a roughing pass. Can't say since I don't use MasterCam, but you probably be better setting no finish pass on the rough pass, and use the Contour toolpath as the finish pass.

[bmcd]

I haven't seen any parameters that would create this issue, but further digging will need to be done. I'm mostly self taught, so I may have missed something. However, this is the first time I've run into this and I've been using this set up for a number of years. To complete the pickguard, I did what you recommended. Roughed the pocket and finished it with a contour. Turned out perfect. Thanks.

[louieatienza]

Weird... do you have absolute I, J set in MasterCam also? Have you tried switching both to incremental? Also check your CV distance in general config that it's not too high a number.

[bmcd]

I finally figured it out! The pocketing operation was set as a High Speed tool path. That setting appears to round 90 degree corners. I reset it as Parallel Spiral and the corners are correct. I usually use the High Speed setting when doing large areas like control cavities and semi hollow bodies, but will double check the default setting when doing pickups or anything else with a sharp inside corner. Thanks for the ideas.