There are a number of things that stand out. The original post implied that there were straight cuts in the 8-10" range in acrylic mirror that had to be made. Your latest post shows a laminated material, with materials of different densities and curvy letters - not the same animal at all. There are several concessions that have to be made or you might as well just use a jig saw.

Quote Originally Posted by magazines View Post
Unfortunately another user broke our o-flute bit, so I have to wait to try that.
You absolutely need to have o-flute tools to cut this layup with any degree of quality. An end mill isn't going to give you the edge quality you want & you'll spend a TON of time on the back end cleaning up. You need to get single and double o-flute tools to make your best effort. A triple flute may be in order if you need to sneak up on final edge quality. Find your Onsrud dealer & let him tell you what tools you need. This is what they do for a living.

If you still require a beveled edge, then you do the majority of your cutting (say 90% through cut) with the o-flute tool, then swap out for a SQUARE end mill with taper to just kiss the edge and go the final depth. This will result in a cleaner edge than using the taper itself, but still not as clean as a square cut o-flute bit will.

This entire job - laminated dissimilar materials with beveled edge - is a lesson in compromise. You need to experiment with tooling and technique and carefully select the best overall compromise in edge quality, time, expense and hold that up against what the customer wants & is willing to pay.

-B