Hi Everyone,
I am cutting 8" circles out of 1" acrylic on my CNC router. I am using a porter cable router with precision collet and an onsrud 1/4" 0 flute bit. The router is running at 10000 RPM at 25 IPM with 5 passes at .2" each.
The 8" circles were coming out strange so I observed the cut closer. Each pass seems to look fine however there was a misalignment between them. If I run my nail along the edge of the acrylic I could feel the passes on certain sides protrude. This also resulted in previous passes being over cut by the latest pass on the opposite side of the protrusion. The minor miss alignments on each cut cause the circles to be misshaped. Some time the miss alignment was as much as .02" - .03"
Just to check my insanity I proceed to do the same cut with a single pass on 3/16" acrylic and I was able to produce a perfect circle.
I will likely look at roughing the shape and doing a finish pass in the future. My concern or questions at this point are:
1. Is it normal for each pass to be slightly miss aligned when using multiple passes?
2. Should I always rough out the shape and perform a finish pass?
3. Could this be a configuration issue?