Machining Hard Rubber/Plastic

[adam1071]

I need to select a hard rubber or plastic material that I can machine non-slip feet out of for a laptop support designed to sit on an office desk. As far as I know, the "machinable" plastics all seem to have low coefficients of friction and would slide around on a desk surface... Can anyone recommend a material that machines well but retains the non-skid properties of rubber? is it possible to cleanly machine a hard rubber with a spindle speed up to 6000 rpm?

Thanks

[Dorsal]

I have a sample pack in my desk from Western Roller Corp., with 6 different hardnesses of rubberized material, that I got at a trade show. 50 or 60 durometer Shore A polyurethane feels like it might meet your needs.
That means nothing to you, except to give an example to you and tell you to contact them or a similar manufacturer for their input. Maybe they'll have some samples they can send you.

[ephratabrian]

In my experiance machining ureathanes(which might be a good medium for you) you would want to go with a slower spindle speed and jack up the feedrate. For example 1/2 inch 2 flute end mill speed 3200 feed 250ipm. BJB enterpises has pourable rubbers that are machinable. If you need sheets their techs could steer you in the right direction.

[adam1071]

Wow, very cool stuff. I'm definitely giving JBJ a call. I had no idea urethanes were so versatile. I'd REALLY like to get some samples of various plastics and other materials... Until I hold it in my hands, I can't know if its right for a project.

So when ARE high speed spindles used? Are they generally just for wood and engraving with small diameter bits? As a rule of thumb, what is the minimum speed required to mill a softwood like pine without chipping and tearing out the grain?

[ephratabrian]

My max spindle speed is 10000rpm and I generally run that when doing artistic engraving in wood with a feed rate of 250ipm. You will be fine with 6500rpm just play with your feed rates.

[Frantic Fab]

ADAM,

hello i read over your post for machinable rubber. we specialize in working with silicone molds and polyurethane resins with shore strengths and coefficents all over the scale! have you thought about having these feet made as actual cast parts? it would be alot cheaper, quicker and we could make them alot faster! if you may be looking to make a bunch of these its something worth concidering! we have alot of experience with these products! i would love to point you in the right direction! Masterpiece Models that site is full of cast parts we specalize in!

thanks,
Garrett