Machining Rubber Compounds

[MagneticFlux]

As a "general rule" and not so specific to a type of rubber compound. What would be some methods of machining in a lathe? Cut Vs Grind, how do higher or lower work speeds affect the finish?

What I have is a vulcanized roller with a pitted and uneven surface. My plan is to remove some of the surface and make it usable again. ANY input is appreciated.

 

[btrueblood]

Have had success using various grit sanding blocks while turning part on lathe.

You can try chilling the part first, and using single-point tools. The temperature at which the rubber becomes stiff enough to cut with sharp tools depends on the compound. Try sticking the part in the freezer first...

 

[MagneticFlux]

Btrueblood,

Sanding blocks worked pretty well. Much better then the lathe mouthed grinder. I knew the heat generated from the friction of the grinding wheel working against the part was probable cause for the rough finish. The sanding blocks eleimated the majority of that heat.

Cooling the part maybe difficult (long roller), but it sounds like the best method.

Could you elaborate on the "single-point tools" a bit. Is a High Speed Steel tool ground to a threading point OK? Or are you thinking something more exotic? I have seen a setup the looked like a knurling tool with spinning carbide blades that was used to machine soft materials. Any ideas on that?

Thanks for the input, really appreciate your help

 

[btrueblood]

I have only second-hand experience with chilled rubber. The part in question (~1" diameter rubber plug, probably a vulcanized natural rubber, but could've been a nitrile) was pretty stiff coming out of the freezer. He used (I think) carbide and HSS turning tools & HSS drills. The tricky thing is that the part would start to warm up as soon as it was chucked into the lathe, and warm faster as soon as cutting began. We tried again (this was a small "toolroom" lathe) by moving the lathe outside on a chilly (20F?) clear day, and he was able to get his part made with only 3-4 trips back and forth to the freezer.