I needed a small number of custom thickness rubber washers, and I needed them yesterday! I scrounged around for some thick wall rubber tubing that I had used to make custom length spacers. I had cut the spacers by hand with a single-edge razor blade, but I hadn't been able to get a nice, consistent finish. Despite my best efforts, it always looked butchered. With the washers I needed being so thin (about .080"), I knew I wouldn't be able to cut them by hand. The solution turned out to be fast, easy and safe.
Step 1: Tools, Materials and Technique
- Metal Lathe
- Single-edge razor blade (preferable new), a utility knife blade would be effective as well
- Locking Pliers (Vice-Grips®), small-type
- Rubber tubing of the size you needed. I bought a 6" length of 1" OD, 1/4" ID from McMaster Carr. It's listed under "Multipurpose Neoprene Rubber Tubes" and they come in a wide variety.
- Simply clamp the knife blade to your parting tool. I used a negative rake so the blade would be pushed away rather than pulled into the material if anything went awry.
- Ensure your parting tool is square to the axis of rotation.
- Running at a slower speed (less than 300RPM for a ø1"), gently feed into the material.
- With this technique, you can easily achieve a tolerance of about ±.005".
- Though I'm not sure if it's necessary, I found a little cutting oil on the blade to be helpful.