Hi,

I'm trying to cut some parts from 5mm black acrylic and what I'm finding is that cutting on the short axis I get a decently smooth cut, but along the long axis I get a kind of streak of roughness, but it is not across the whole cut depth. Can anybody suggest what is causing this? I did cut in multipul passes and then did a finish pass a well. I'm using a 3.17mm cutter and went at half the speed GWizard suggested, halving both the mm/min and the spindle RPM.

The rough part is slightly inset from the rest of the cut, not proud, is that means anything. Also the rough part is at the top of the cut so it seems like things improve as the cuts go deeper.

Here are a couple of photos.