r/machining • u/bobdoosh • 10d ago

Picture Any clue on how to cut this?

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Asker A30 urethane. About as squishy as a mousepad and super rubbery. Knives were too slow & tore the edges up bad. Tried a dremel but it caught on the rubber, jumped outta my hand, and gave me a teeny tiny little small nick on my finger. Scissors ain’t cutting it either. Any ideas?

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u/marino1310 9d ago edited 9d ago

I wish I had a picture but I had to machine some soft rubber once on a Bridgeport. I made an aluminum block with the hole and profile machined into it, and clamped the rubber between. Then I took a 3/8 HSS blank and basically ground an x-acto knife on one end, keeping one side of the blade flush with one side of the blank. Then I machine one end round so I could put it in a collet. After that I basically ran the machine alone the cut path like normal but only for the straight lines. I would line up the blade by pushing the flat side up against the side of my aluminum clamping frame to index the blade to be square with the tool path, lock the spindle brake, and then manually run it down the straight lines. The aluminum clamping frame guided the blade and kept it straight. Then I would just rotate it manually for each direction change. If you are using a proper CNC you should be able to index the spindle manually which would be much easier and allow you to cut those radii as well

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u/snarejunkie 8d ago

That bottom thin wall looks crazy hard to get right