Polyurethane Cutting and Machining

[phil....@gmail.com]

Hi,

I am looking at changing a bath room sink, that sit on top of a cupboard, I was needing something to sit the skin on like a bit of worktop.  I was thinking of cutting down a polyurethane chopping board and routing the edges.

I was wanting to check if anybody know how well it machines, to make sure that it's not prone to melting, I have had bad experience with using hole cutting on plastic in the past.

Thanks

Phil Milman

[Stephen Rodway]

Hi Phil,
Polyurethane is generally machinable although there are some things to
watch out for. It's a bit of a "grabby" material so go carefully and
don't feel the work into tools too rapidly or they may snatch it, but
also don't feed too slow or it'll get hot and melty from friction. So
long as it's making nice chips then the feed rate is probably fine and
the feed will probably be higher than you're used to for other
materials. Chips tend to be large and difficult to clear, so strong dust
extraction or even air-blast can help

Tools should spin slower than is normal for timber if you can, and the
cutter must be absolutely razor sharp, much sharper than is normal for
wood or metal. The diamond hones we have with the sharpening stones
might help there. HSS tools will work better than carbides if you can
get them, and if you're buying your own tools then it may help to grind
an increased rake and clearance on them.

Table saw is unlikely to be effective here owing to the carbide teeth
not being THAT sharp. Bandsaw with a brand new wood-type blade and
running in metal-cutting gear might work well

Watch out for heating, some people even go as far as putting the work
in the fridge or freezer first to chill it, this has been reported to
give better cuts because it makes the material harder and cut nicer.

Steve

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