I've got a little project in mind, and it requires some hard plastic that's easy to machine in a lathe and drill press. In the past I've bought some black nylon from a local supplier, but that's been a PITA to machine as the material tends to move away from the cutting tool and form a ridge that moves just in front of the cut. I've found it very hard to get a nice finish with nylon.

Can anyone suggest an alternative? I'm looking for something about 100mm in diameter, fairly tough, preferably black, dark grey or silver, and available at a sensible price.

Nylon is quite nice to machine,but tool needs to be sharp with a good rake angle.Acetal machines well also.

I machined a few bits from Delrin.

Turns well, firm - not sure of the shore rating but i think theres a range available.

Geoff

You need a support behind the piece moving just ahead of the cutting tool as well if the piece flexis at all.

Acetal or trade name Delrin is a good material to machine it is more like brass to machine wheras nylon tends to be softer and binds on drill etc but is ok with sharp tools.
Paul

Have you tried putting it in the freezer for a couple of hours before turning?
Machines much better if it is really cold, as do a lot of the other plastics. Worth having a go if you've already got some in the right size/colour.

Tufnol (phenolic/cotton composite) is very easy to machine and is very tough, but doesn't meet your colour requirements.