Proper bit to cut Komatex. (PVC)

I tried reading thru older posts, but didn’t find any that had the answers we’re looking for. We recently bought and assembled the Maslow and frame, so still relatively new to it. We designed our layout and ran a bunch of test cuts in 1/2" expanded polystyrene due to ease of access and it being cheaper than our production material (1/2" Komatex expanded PVC.) Got good cuts on the polystyrene and finally moved on to cutting our production material and have been having nothing but issues. We started with a 5/16" double fluted, straight, end mill, flat nose bit. On that cut, we generated too much friction and wobbled the bit loose. We then went down to an 1/8" double fluted, straight, end mill, flat nose bit and on that cut were getting rough edges and chattering. Decided to come here looking for advice instead of keep throwing bits at it and running $100 sheets of material… Any and all help is appreciated. 500 feed rate, 3 passes to cut thru, and router speed set to max.

it should cut like butter because it’s not dense. I’ve always used single flute upcut bits on plastics and they cut fine. I’ve cut 1/4" thick komatex with a single flute 1/4 upcut bit in one pass. Bits typically only work loose if you are really cutting big passes hard, so surprised to hear that. if you use a lot of that material, buy it by the palette for $45 a sheet or get it from china for $25 a sheet.
3 passes is conservative I’d do 2 personally, and you want the lowest speed, otherwise it just melts and causes issues. this material is even softer than pine wood.

Thanks for the response.

We’re working up to full pallets, but can’t afford that much until we have sold a few finished products.

When you say lowest speed, are you referring to router speed or travel speed for the sled? And, in your opinion, are we better off sticking with the 5/16" bit or the smaller 1/8"?

the slowest motor speed on the router 10,000 rpm depends on what router you use some go down to 8,000rpm.
if you look at a feed and speeds chart you’d want closer to (3mm) 1/8" bit. you can buy a ten pack off amazon for $15. I like the 4mm bits with a er-16 collet to hold them because they are a bit stronger.
many people use 1/4" bits, but they make excess dust, best to always use the smallest diameter bit that still performs well. they are cheaper as an added benefit

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