Z depth consistently off for 1 bit

I have a large 1/2 in single flute bit that doesnt seem to want to cut the right depth. It seems to consistently be cutting at .34in deep when the pocket depth is only .25 and the pass depth is .125.

I have the bitsetter and bitzero v2. I use bitsetter whenever I change whats in the router and I probe the corner and then double check the z with a center placed z probe.

It seems to have just started with this bit. It wasnt a problem with my 201 bit or my quarter inch compression bit.

I had some trouble early on with the bit slipping out of the router thanks to the increased vibrations from the too deep cut but I cranked it tighter and have watched the bit closely and havent seen slippage since but it still takes too big a bite.

I adjusted the depth per pass from .25 to .125 and it seems to have made the passes slightly shallower (but less than the .125 I’d expect more like .06).

I moved the bit to 1inch over the z zero and it measures 15/16 of an inch. But moving it to 6mm over the z seems to measure correctly.

Gcode attached:
Fancy box base v2 edit.nc (906.1 KB)

Edit: It might be my retract height. I think its trying to retract too much before the cut and is then plunging too deep. I’m new to this, does the retract height measure from the zero or just from whatever point its at when it needs to do a rapid movement? Because i have it the retract height set to my piece’s thickness so it doesnt hit when i do the deeper pockets or after the cut out.

Retract height is from Top of Stock. So, if you are using top-of-stock as your Z zero, then retract is measured from that Zero.

If you are using the wasteboard as your Z Zero, then CC adds the stock thickness, and uses that value as the starting point for retracts.

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This may seem far fetched but have you checked your GBRL settings. Some people have issues with the X and Y cutting a circle they get an oval. This can be caused by several things like mechanical issues, belt tension OR GBRL settings for the stepper motors. If the stepper motors are set to the wrong pulses per MM you can get deeper and/or shallower cuts. It is easier to recognize in the X and Y if you cut a perfect circle but the Z is harder to detect.

One thing to try is to move your bit so it is exactly 2" above the spoilboard. Zero your bit out and measure the space between the spoilboard and the bit. Then job your Z down 1" and again measure to see where the bit is. It should be 1" from t he spoil board. If it is not then again check mechanical first but check your GBRL settings. I cannot remember the exact setttings but they are on the forum.

You can get your GBRL settings by typing $$ at the MDI and the paramaters are printed and you can pull them from the log to post here.

Your retract height seems to be 1.25" — is there that much Z-axis space to lift above the top of the stock?

So i tested it with a lower retract height and it worked great. Thank you everyone for the responses.

I have my height set to .25 inches or .5 inches depending on the clamps I use. Cuts down on run time if you set it so it clears the clamps and not much more.

I have used cam clamps for a long time. Recently I have started using painters tape and super glue. I really like this. I still use an l bracket to get my material on the machine square. After the material is set with the super glue I sometimes remove the l bracket and no worries about hitting anything.

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