[ohallock]

Seeking info tips & advice for determining feeds and speeds for Corner Rounding End Mills on CNC, Corner Rounding End Mills 5/16 and 10mm and thereabout. Mine have radius cutting periferal teeth and no teeth on the bottom of the smaller diameter. I would like suggesttions for slotting? are the periferal teeth enough for me to approach from the side of the stock enter and periferal slot cut or should I consider cutting a guide slot with a flat end mill first and then slotting with the Corner Rounding End Mill with no teeth on the bottom. If I cut a guide slot should it be the same diameter as the small diameter end of the Corner Rounding End Mill or should it be smaller and have a finish allowance? I am cutting cosmetic surfaces in one pass in UHMW-PE prototypes and will have a cosmetic horizontal surface at the bottom of the rounded corner. I have been searching but have not found information or tips or data specifically on using corner rounding end mills. Thanks ohallock

[joesmachine]

Ohallock, yes you should have a slot first, you will want as much chip clearance as possible, the material you are cutting is a difficult one to get a great finish, judging by your question, there are two things you should consider, 1) your S&F should be based on the largest cutting diameter of your tool, the small end will have not problem handling the S & F of the big end but the other way around it would most likely burn the material.
2) I don't know what type of corner rounding tool you are using, one piece or inserts, if you are using a one piece keep in mind that each end of the radius will have a 3 degree lead, this is an industry standard, so knowing this if you measure the big end, small end & height you can calculate exactly where you full tangents are. The reason they lead with 3' is to give you a little room for deveation in height from part to part (a pre CNC standard)
I hope this helps in some way.

PS because of the shape of the cutter the chips will try to curl upon itself,
so good chip evacuation is important, if the UHMW looks like it is melting or smearing, try slowing down the RPM but keep the feed rate up.

Good luck.

Joe