Thanks for all your feedback- they help a lot. I have one problem left. There are grooves before and after tabs in the cutting material. I use cut2d- the plunge is set to 150, but it goes up fast- can this be the cause?
If it's plunging at one side of the tab, doing a full-depth cut, then retracting at the other side of the tab, that could absolutely be the cause. Try a ramp instead of a plunge, or move the plunges elsewhere to test. If not, it may be a system flex issue with the tool digging in.
I've tried to add spiral ramping but it extended cutting time from 16minutes to 1hour43min on one small element only. Not sure if I'm doing it right- never did it before. How do you add ramps properly without extending cutting times dramatically?
Ramping into a cut isn't the same as a spiral pathing strategy, it should only be an inch or two long and not significantly alter the length of the cut. You can choose to ramp in Z, or you can require an entry/exit strategy in X-Y, or whatever. The options are there in Fusion's operation options window. If you're not using Fusion 360, I'm not sure. Typically CAM algorithms and options are generally pretty similar though.
