4 Minute Cylinder Recording Stylus Diameter

[donniej]

Does anyone have both a 4 minute recorder and a dial caliper or micrometer? I've been teaching myself how to machine sapphire rod and would like to try making some 4 minute styli but need to know the diameter. I'm assuming it's half the size of a 2M recording stylus, but knowing for sure would be preferred.

Thank you.

[donniej]

For those interested, it turns out the answer is .010" in diameter. The end of the sapphire rod is flat, cut at a 90* angle and has a small dimple in the center. I don't believe the dimple has any effect on performance.

[Inigo]

I've read somewhere that the dimple is a true demi_spherical hole the stylus end, so it produces a cutting edge all around the perimeter of the stylus. The wax is cut by the edge and the cup launches it away while running.

[donniej]

I've read somewhere that the dimple is a true demi_spherical hole the stylus end, so it produces a cutting edge all around the perimeter of the stylus. The wax is cut by the edge and the cup launches it away while running.

That is true for 2 minute cutters but not this 4M. The 4M I bought has a very small dimple in its center, to small be affect the cut. I'd guess it's .001" - .002". The 2 minute cutters are concave almost to the very edge.