This

http://www.bhjproducts.com/bhj_content/products/measinst/dhc1.php
if you have a 12" caliper you can buy or make the radius adapter

Or this

https://www.summitracing.com/search?Sort...ASAAEgKeTfD_BwE
any machinist could make one of these pretty quick.

Last edited by GomangoCuda; 02/28/19 03:46 PM.
In theory, there is no difference between theory and practice. In practice, there is.