Cutting sandblast stencil

[bg 0]

I cut 45-48 mil heavy rubber sandblast stencil(anchor with yellow mylar liner) for monument deathdates. I use Windows XP, Corel12 with SignTools 3 bridge program, Refine MH-721 plotter 60-degree knife,4-8 speed, 360-380 pressure. I get distorted letters, such as the bottom curves in the "U", the outer curve of the "R" and the number "8" where it crosses. The tops and bottoms of serifs are slightly slanted. I'm thinking this is a friction drive problems, but the corners or the lettering does not cut cleanly. There are always little crumbs of rubber in the corners. I have the latest drivers installed.

I had a P-Cut 630 that worked a little better, but the LCD malfunctioned. I sent it to Montreal for repair a couple of years ago and they could find nothing wrong with it, but have never returned it, so I bought a Refine.

Any thoughts? 

[kenimes 42]

45-48mil is over the max cutting thickness, so it would not surprise me if it did not cut it as detailed as you would like. Max cutting thickness is 1mm, which is about 39mil, so if possible, use the thinner resist material for better qulity cuts, such as the 25 or 30mil.