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Milling 75A duro polyurethane sheet?

Terry Keeley

Titanium
Joined
Oct 18, 2005
Location
Toronto, Canada eh!
Need to make some 1" diameter "spiders" for a lovejoy type coupling out of 8mm (5/16") PU sheet. Was going to have them water jet cut but only need a few pcs so was thinking to maybe cut them out on the mill.

I've turned some of this stuff and it was a PITA, sharp HSS worked best. Any ideas for mill cutters? Techniques?


spider.jpg
 
In short it's a PITA material to m/c

I used YG uncoated HSS (they're almost ''wear gloves to change'' sharp) with a degree of success, but found Onsrud down cut router cutters better.

I stuck the parts down with double sided scotch tape, and didn't cut through - left about 10 - 15 thou and trimmed that with a knife

If you can get them water cut - do it!
 
In short it's a PITA material to m/c

I used YG uncoated HSS (they're almost ''wear gloves to change'' sharp) with a degree of success, but found Onsrud down cut router cutters better.

I stuck the parts down with double sided scotch tape, and didn't cut through - left about 10 - 15 thou and trimmed that with a knife

If you can get them water cut - do it!

Something like this?


Ever try to freeze the stuff first?
 
Generally grinds better than it cuts. I have cut out shapes with a knife and then ground them to the correct shape on a drill press using an abrasive spindle. For the shape I glued on a printed template. Pretty rough method but it worked for me.
 
Yes, grinding works good. I use a Precise (Brand) electric grinder with 1/4 shank carbide burrs. Grinding removes material with less deflection.

I have made a holder for the Precise grinder that goes on my mill, so it works as a poor mans jig grinder.

Chuck
 
We needed to machine a lot of urethane for press tooling at Toyota. Tried freezing, neat oil, sharp tools etc. Grinding always gave the best results. It's really dirty.
 








 
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