home made chuck key

This weekend I spent a lot of time in the shop machining parts for my CNC mill, and ran into a problem with the lathe. The four jaw chuck has these adjustment screws to move the jaws in and out, but I can’t find the chuck key needed to adjust them. They use an inverted key–it’s and innie, not an outie, like most chuck keys–and it’s almost impossible to adjust without that particular tool.

I had a leftover piece of steel rod, so I made my own:

9x20 lathe chuck key CNC machined

The ends were machined on the mill, clamping the piece upright in the vise. The shoulder was turned on the lathe (in the three jaw chuck!).

9x20 lathe chuck key CNC machined

I milled a socket into the other end for a 3/8″ ratchet, although the fat body makes it easy to turn quickly by hand. (I tried to knurl the end but I still don’t know how to knurl properly, so I just mucked it all up)

9x20 lathe four-jaw chuck

 

Operational!

One Response to “home made chuck key”

  1. Dan writes:

    wow, machining a square hole that size is not something i would want to do. great job on that!
    as for knurling there’s a lot of tutorials on youtube. to sum it up the part needs to be a specific diameter depending on the pitch of the knurls.