I do a lot of shopping from www.widgetsupply.com because of their great prices and selection on carbide Dremel bits, so I wanted to use these bits in my MaxNC 10CL mill. The really small bits have a 3/16" shank, but unfortunately there is no 3/16" collet. So, I took a 5/16" roll pin (sometimes called a split pin) which has a 3/16" inside diameter and inserted it into the 5/16" collet. The roll pin acts as a sleeve to hold the bit and keeps the bit centered. Works great? :D