bent caliper

Though I imagine you've seen them at Woodcraft, too. Not direct readers, but mine work for as little as I do.

William,

I have both small and large Lee Valley Veritas calipers. They are my favorites. You can make your own, however, by bending up a stiff coat hanger or 1/4" copper tubing. With these, you can get into any shape you need by rebending the wire/tube.

- Bend the wire into the desired shape but leave a xx" gap between the points. I typically have mine set to 1/2".

- Move the caliper into the vessel. Touch the inside point to the inside surface.

- Measure (or visually measure) the resulting gap between the outside point and the outer vessel wall. If the wire gap is 1/2" and yo see

1/8" on the outside, the wall thickness at that point is 3/8". As the wall thickness gets thinner, the visible gap gets larger.

- Always use a calipers (homemade or store bought) such that the points measure perpendicular to the vessel wall at the measurement point. If you measure at a diagonal, you will get a false reading that will cause you to think the wall is thicker than it really is. Joe Fleming - San Diego

"william kossack" wrote: (clip) Are there any other options out there? ^^^^^^^^^^^^^ I assume you're talking about the "figure 8" type calipers. Why not bend them back into calibration?

I've been using the copper tubing idea for years, and it works great--better than wire. I use the smallest tubing commonly available, I think it's 1/8" ID.

You can form it into any shape you need for the particular job, and the copper tubing holds it's shape well.

Nip off the ends at an angle with tinsnips or wirecutters, and round the points over a bit with a file to avoid scratching the wood--which copper is less likely to do than steel wire because it's softer.

Ken Grunke

I looked at these in the lee valley calipers in the catalog. They might do the ticket.

I may have to hold off because my cash > William,

Starrett makes lock joint transfer calipers, inside and outside, in several different sizes. Expensive, but they will do the job.

John Martin