I am sure this must have been covered in other posts but I am making 3 arbors to use in the lathe. One each with 1/4", 5/16", and 3/8" sizes. I have been trying to make a worm-gear drive unit and needed to get some 1/2" aluminum plate cut into a 5" diameter disk. I mounted the rough cut disk on a 5/16" bolt and clamped it into the 3 jaw chuck, but, it wiggled like a waffle. So I drilled a 5/16" hole all the way through a 1 1/2" length of 7/8" rod and reamed it to 5/16". I slipped a 2 1/2" by 5/16" bolt into the hole and then mounted the disk, securing it with a star locking washer, and chucked it up. Now it only wiggles enough to be noticed very slightly. Great improvement. I then tig welded the head of the bolt to the rod. I am looking forward to using these arbors as they should cover 95% of the bolts I use.