"Grant Erwin" wrote in message
...
Some time ago I saw a design for a tool to center a punchmarked piece in
the 4-jaw on a lathe. The guy made a shank which clamped a piece of rubber
sheet vertically in his toolpost, exposed on both sides. There was a tiny
hole in the sheet and through this he inserted a bicycle spoke with a
spoke nipple threaded way on, flange towards the rubber. Then another
spoke nipple threaded onto the end sticking through the rubber, and
another spoke threaded into the second nipple. The effect was to suspend
two spokes roughly in alignment with the lathe axis, mounted on a rubber
sheet. He cut down the spoke towards the headstock to about 1", and
sharpened it, and the other spoke he cut off at about 10", and he
sharpened it too. To use it, you catch the short end in your punchmark,
spin the lathe, and adjust your 4-jaw until the far end ran true, pointing
right at a center in the tailstock. There's a 10-1 magnification factor.

Wouldn't it be easier to use (and maybe to make) if you drilled out a block
sized to fit in your toolpost, and glued the wiggler (centered) inside the
hole with a little RTV silicone?

You don't need heaps of flexibility, since the wiggler ordinarily wouldn't
make excursions of more than a couple of degrees. The mounting system would
be conducive to quick setup and teardown, and could be adjusted to
near-center easily and quickly with no more tools than it takes to mount a
cutting tool.

LLoyd