Need Help!- Turning Rubber??? How to?

[zero5672]

Any advice on turning rubber? I'm making rubber expansion plugs

[multiplex]

guess it depends on the compound, etc.

I know some rubber machining is done frozen

[Geof]

Turning Rubber? It is not easy.

You can do it the sophisticated and cold way; do everything in a Big Deepfreeze at around -30 to -40 but maybe you want a more comfortable option.

Depending on how much turning you are doing it may be possible to simply freeze them and do the turning quickly before they warm up too much. Again you can add the sophistication of a blast of sub zero gas such as CO2 which can take you down to almost -80 or Nitrogen which is almost -200. Even air from a vortex tube at around -30 can help keeping things cool but then you need a big compressor.

Instead of turning try grinding. Surprisingly rubber will grind quite well with a nice new emery belt and you can 'turn' things in the lathe by rigging up a small sanding belt.

Or you can try actually turning them but they have to be fairly rigid rubber; as stiff or stiffer than a typical car tire.

Use a very sharp cutter with a large top rake of up to 30 degrees; you want to slice the rubber off not try to chip it off, it won't chip anyway at normal room temperatures. Use soapy water as a lubricant and you may find you can be quite successful.

[mmckell]

good day

working in the rubber molding industry... i do this a couple times a week
best thing is to build a fixture to hold (slightly squeezing) the plug.
you said expansion plugs so i'm guessing it has a center hole
a base to place in the chuck with a crush tube slightly shorter than the plug and a washer and bolt.
bolt your part in your fixture , spin the heck out of it.
i use aluminum cutting inserts - bright finish, on a grooving tool
they work the best for me.
no coolant - just makes a gooey mess.
take several small cuts on your first part till you get the size plug you need. because you are squeezing the plug you will end up with a radius along the length of the plug - best to have another fixture or the actual part to test the size in.
once you have your diameter set you can turn the rest of them with one cut
you will get a small amount of smoke so adjust your speeds and feeds and give 'er

hope this helps
Mac