ER-32 Chuck and Drawbar
I bought a full set of ER-32 collets (every 1/32" size) and a cheap MT3 collet chuck. I eventually plan to make a collet chuck that mounts to the spindle like a normal chuck and allows me to pass stock through the spindle, but this lets me use the collets right away. The nut and spanner will be used for my own chuck. There are a few different MT3 ER-32 chucks available, but I bought the version with a 1/2"-13 drawbar thread.
I found a piece of mystery steel in my pile that was the right size for the main piece of the drawbar and threaded the end 1/2"-13. 13 TPI is about the coarsest thread I would want to cut in steel with the mini lathe. I suppose you could go coarser, but it would require many light cuts. Once I had the correct fit, I measured the needed length with the collet chuck in the spindle. I cut the drawbar to the proper length, faced the cut, and turned a small shoulder. I drilled and tapped that end for the hex bar. I can't remember what size I used, but it was either 1/4"-20 or 5/16"-18. I took a piece of 1/2" hex bar (12L14), turned down the area for threads and single pointed matching threads.
I then took a piece of 1" 12L14, turned it true, drilled a clearance hole for the threads on the hex bar and counter bored to fit the shoulder on the end of the drawbar. The counter bore keeps this piece centered by registering on the shoulder at the end of the drawbar. The last piece I made was a stepped washer. This was also made from 1" 12L14. It spins freely on the drawbar and the stepped portion fits inside the spindle with virtually no slop to keep the drawbar centered. I assembled the pieces of the drawbar using permanent thread locker on the hex bar threads. So far this has held up when I loosen the drawbar, but I can always cross drill and pin those threads if it doesn't.
Click the pictures below for larger images.
I found a piece of mystery steel in my pile that was the right size for the main piece of the drawbar and threaded the end 1/2"-13. 13 TPI is about the coarsest thread I would want to cut in steel with the mini lathe. I suppose you could go coarser, but it would require many light cuts. Once I had the correct fit, I measured the needed length with the collet chuck in the spindle. I cut the drawbar to the proper length, faced the cut, and turned a small shoulder. I drilled and tapped that end for the hex bar. I can't remember what size I used, but it was either 1/4"-20 or 5/16"-18. I took a piece of 1/2" hex bar (12L14), turned down the area for threads and single pointed matching threads.
I then took a piece of 1" 12L14, turned it true, drilled a clearance hole for the threads on the hex bar and counter bored to fit the shoulder on the end of the drawbar. The counter bore keeps this piece centered by registering on the shoulder at the end of the drawbar. The last piece I made was a stepped washer. This was also made from 1" 12L14. It spins freely on the drawbar and the stepped portion fits inside the spindle with virtually no slop to keep the drawbar centered. I assembled the pieces of the drawbar using permanent thread locker on the hex bar threads. So far this has held up when I loosen the drawbar, but I can always cross drill and pin those threads if it doesn't.
Click the pictures below for larger images.