On Mon, Dec 11, 2017 at 4:04 PM, Erik Levin via OldTools <
oldtools@s...> wrote:

> . What I would do is run a soft, formable material into the hole and back
> out to get as much information as possible. Thread pitch is easy this way.
> George has suggested wood, and it has worked for me, but I have also used a
> variety of plastics. You need a material that will form, not break, and
> hold dimension.
>
>
On larger holes I have used aluminum foil by itself.  Soft wooden dowels,
and high end round toothpicks for smaller ones.

I imagine foil over a small toothpick might work if you didn't have plastic
rod available.
-- 
Kirk Eppler in HMB, CA