A number of years ago I found this 4" lathe chuck at a pawn shop for a price I couldn't pass up so I bought it. It didn't have a chuck key, but the sockets for tightening and loosening the jaws were hexagonal, so I always just used a 7/32" allen wrench to open and close the jaws. Recently, I adapted the chuck to my HF minilathe and trying to center work with a hex key was a lot of trouble. Inserting the long end into the chuck didn't work because the short end didn't provide enough leverage to turn the key. Inserting the short end in the chuck didn't work well, because the long end would interfere with the headstock, lathe bed, or any other parts sticking out.
I decided to make a chuck key for it, then it occured to me that two chuck keys, one for each of the two jaws being adjusted at the time might be more useful. Turned out, I was right. Loosening one side while simultaneously tightening the other side is way easier than switching a chuck key back and forth from side to side.
I made the main shank for mine out of 1/4" drill rod. I gripped the rods in a 5C collet in my hexagonal collet block clamped in my milling vise as an indexing device and milled 6, 3/8" long flats. The handles are made of 5/16 cold rolled steel. I drilled a 3/16" cross hole and shouldered down the end of the shank to fit in the hole. I welded the shank to the handle on the outboard side then ground it off smooth with my belt grinder.
Nothing fancy, but a tip I thought might be useful to others.
Chuck
