From time to time I need to make a flat round object of some kind-usually with a center hole. Think large washers.
I made a couple of these mandrels with different size threaded spindles. The shaft is about an inch in diameter and as long as my chuck jaws are deep. The shoulder is about half an inch long. The spindle was turned to be a tight fit for holes drilled with a specific bit. Only half the shaft is threaded. If I need to turn something particularly thin, I use the two aluminum washers under the nut. In fact, the washers were the very first thing I made with the mandrel.
All images and text Copyright Dale Austin, 1962-2008