Routing plexi

Hello all!
I'm trying to cut 5mm thick plexi with a 1/4" 2 fluted up cut spiral bit using a cnc router. I am making lenses that will be back-lit for a nice glow effect.

I've been having some problems and have been experimenting with feeds and speeds.
Best i've come up with is 0.1 onion skin(the lenses are thin so the onion skin is necessary), 2 passes, 9500rpm, 5000 feed.
I've found that the up cut bit eliminates the rewelding effect but the edges aren't as clean as i'd like them to be. Also, it has happened that the bit pulls up the plexi and ruins the whole thing.
I think ill try 3 passes to minimize the risk of it happening again but i still have the feeling i don't have it right.

i'd love some help, guidance, opinions and ADVICE please!
I really hope to hear back soon.

Thanks in advance

I have settled on 0.5 onion skin, 9000rpm, 3600 feed with 2 passes. Every piece will need to be hand routered out after but it'll do.
Adding more onion skin really helped keep the plexi from being pulled up and with a lower feed, the edges have smoothed out enough but it isnt perfect yet.

I would still appreciate any tips, tricks or suggestions for routering plexiglass.

Try a single flute "O" flute bit.

You should get a cleaner edge, and no melting. You're feedrate is probably on the low side.
Try leaving a small amount of material for a full depth finish pass as well.

Machine rigidity may have a lot to do with the edge quality.

I will definitely keep that in mind for next time. I don't think we have any single flutes bits around here, I'll have to ask to have a few ordered in.

Thanks Gerry