Pocket leaving small raised areas

[agapemusic65 (Brad Smith)]

I am carving 3/4 inch PVC and am getting small islands left in some areas - or perhaps I should say deeper cuts in some areas of the path that are maybe 1/64th of an inch or less. (please see photo) What could be causing this? It happens quite often.

I should say that this pocket area was all cleared with a 1/8 o-flute bit. But this has happened with my 1/4 inch bit as well.

[LWSIV (Lester Shaw)]

Check the tip of the V-bit for damage or unsupported geometry (radius or flat). These can lead to the V-bit carving too deeply because they Bit setter is measuring the actual tip not the “perfect” point.

[flynnjs (Jason)]

Is this a single pocket CAM? It looks like 2D pocket (with stock to leave) followed by a 2D contour (without stock to leave)

[mhotchin (Michael Hotchin)]

What kind of Z Axis? It looks like you have backlash (slop) on the Z carriage.

If you have a Z Plus, you may have a worn anti-backlash nut:

Z-Plus Leadscrew Nut Replacement - How To Guide

I was having issues with excessive depth of cut that I finally tracked down to a worn leadscrew main nut/anti-backlash nut assembly, documented here: Z-Plus play/backlash question Support was kind enough to expedite repair parts, it took about 20 mins to replace and was easy enough to do. Here are the steps for anyone else with the same problem. This is the assembly that needs replacement. Note that the nuts are plastic (feels like nylon or similar). The main nut is held on with the 2 screws a…

[agapemusic65 (Brad Smith)]

Thanks mhotchin. That is something I should really check out. I’ve had my Shapeoko Pro for over a year and have been using it pretty heavily. Even if thats not the issue - it would be a good best practices. Thanks!