Unwanted tool marks on Acrylic surfaces

[Rastamandre (Q)]

unwanted tool marks Acrylic surfaces when pocketing with a plastic . am using both 51441-k and 51404-K to complete a project on acrylic for a silicone mold , this is important because as you know the mold will pick up any unwanted tool marks on the surfaces , any idea why these tool marks are left behind ? see image below, am thinking maybe my shapeoko is a bit tilted? thanks in advance

[Julien]

This may be a combination of things:

• single flutes like the 51441K are fantastic to cut through acrylic, but not great for floor finish.
• tramming of your router may not be optimal
• stepover looks too large. Reducing stepover will not necessarily remove toolmarks, but make them visually less noticeable

You could also try running a separate finish pass at full depth with a 2 or 3 flute 1/8" endmill, that would not cut any material but would just “burnish” the floor.

There’s also a popular trick for acrylic to torch the side edges to bring them back to transparency/smoothness. It may be worth a try on floor surfaces too (never tried it…use at your own risk)

[SLCJedi (Josh Tenny)]

I agree with @Julien. I run a good amount of acrylic and you can get good for finish, ebbed with a single flute of you do finishing passes. I go fast and hard to do the bulk work leaning 0.010"-0.020". Then run a slow finishing pass to final dimensions with less stepover. I also have the tram of that machine dialed in.