"xpzzzz" wrote in message
...
On Mon, 30 Jul 2012 10:14:07 -0400, Jim Wilkins wrote:

The problem with this design is rapid point wear. I had to
resharpen the
point for each tire.

Use a pair of conical recesses and a bearing-ball.

Static friction would be much higher, though it wouldn't increase as
fast. Right after sharpening it was sensitive to the weight of the
valve cap.

The music wire point has degraded to a half-round ~0.015" in diameter
and needs to be resharpened. I can't tell the shape of the recess. If
the truck wheel wasn't so heavy I'd use a ball point pen tip.

jsw