FYI Everybody - the problem turned out to be lack of rigidity in the stock.
The double-sided sticky tape was trash on the MDF spoilboard. Carpet tape solved the problem and my results have been absolute perfection for the past 5 test cuts I did, even at the most demanding settings I’ve done so far. No Chatter, absolutely crisp edges and valleys of cuts. Just perfection.
Now I know what the problem is, I’m devising a removable spoil board for machining metals where I:
- stick a plate of aluminium to the removable spoilboard permanently using the carpet tape, and then
- using the double-sided sticky tape, stick my metal stock to the aluminium ‘spoil board’ surface (coz the double sided tape sticks great to polished aluminium stock, but will be easier to separate than the carpet tape after finish cutting).
Wish me luck, coz now my MPCNC has decided it doesn’t want to turn on anymore… lmfao.