End Mill Recommendation for UHMW

CNC Machines Shapeoko
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I bought several 6" x 12" x 1" sheets of UHMW from McMaster-Carr for some tool holders that I intend to make (link: https://www.mcmaster.com/#4296a182/=17y8weu). I cut my first sheet last night using the stock #201 1/4" end mill. My impression…it sucked! I don’t like cutting this material. I should have gone with ABS or delrin which is what I normally cut. I chose UHMW to save a little money on stock.

Anyway, the 3-flute 1/4" end mill doesn’t appear to be the right end mill for this material. Can anyone recommend a better end mill? The chips aren’t cleanly cut. Lots of leftover shavings and strings that I have to trim away by hand. My settings were 75" feed rate, 22" plunge, 16,500rpm, DOC .1"

uhmw.jpg1600×900 379 KB

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There’s some discussion at: https://www.shapeoko.com/wiki/index.php/Materials#Plastics

A single-flute endmill is the usual recommendation: https://www.shapeoko.com/wiki/index.php/Endmills#Plastics

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A 0 flute will do the job nicely. Follow the speed/feed guides. Looks like 140 ipm, 18000 rpm, .125 stepdown. or thereabout.

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Well I learned something new. Wasn’t sure what a 0 flute was…sure enough, it is recommended for plastics like UHMW.

http://www.onsrud.com/plusdocs/Doc/index.html?model.code=TECH029

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Excellent! Thanks everyone. I’ll get something on order.

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