75D Polyurethane

[Lumpnut]

Anyone have any experience milling this stuff ? I guessing max rpm/feed with good quality endmills.

 

TIA

[Bruce Caulley]

NO NO NO NO NO!! Use HSS or polished inserts and go easy on feedrates as the material will just push out of the way and not cut if you hit it too hard. Workholding can also be fun as it will squash if held in a vice or clamped. If one of the stock edges is the shiny top skin this will leave quite a big rag and will need manual trimming with a sharp knife. I could never find a happy medium machining any of the PU grades except the really hard ones (I just can't think of the number at the moment) It still had some give, but would break if hit hard as it was a little brittle. One clown actually wanted us to machine 40D bushes for him rather than molding them

 

HTH

 

Bruce

[Lumpnut]

Thanks Bruce !! Great advice. I'll be attempting to cut the parts Monday morning. I'll post the results when I'm done.