What causes this behavior, and how to correct it? PM 728 VT

[MLab]

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Very helpful replies, thank you all!

Will try conventional milling next, and reserve climb for the finish pass (although it does seem to work with aluminum). I never lock the table as I am using CNC, so can't use that trick; my quill is always locked maybe try it there.

I think 7milesup has it figured out. You're re-cutting swarf, or more precisely, swarf is following your cutter around and acting as an occasional wedge between your cutter and work piece. You might try air ( https://www.amazon.com/dp/B0BRYYY5LX?psc=1&ref=ppx_yo2ov_dt_b_product_details ) to clear swarf off your cutter as it exits your cut.