I recently made a new lathe chuck key wrench as I only had one well-used key and I really wanted another for when I use the four jaw independent jaw chuck. Having two wrenches makes the setup procedure considerably easier when dialing in a four jaw. I used the original shop-made key I received with the lathe as a pattern, duplicating the wrench in virtually all dimensions.
I started with square 9/16″ bar stock that my friend Dan had given me and milled the key square key engagement tip to slightly less than 1/4″ square, taking equal amounts off each of the four sides. I left the end longer than eventually required so I could drill a hole to utilize a live tail stock center for turning the piece round in the lathe. The stock was chucked into the lathe 3-jaw chuck, using a piece of 1″ OD PVC as a simple collet to hold the square stock relatively true. Using the aforementioned live center in the tail stock to support the outboard end, I turned the square body to 1/2″ round. The taper where the body reduces to near the 1/4″ square tip was turned by using the swiveled compound rest method.
Once I had the diameter and end taper turned, I cut the extended engagement tip off with a hack saw, removing the tail stock engagement hole in the process, then faced the end to square it up. I used the mill to drill and ream the hole for the 5/16 handle, which is drill rod. The handle is a slight interference fit by design, so I used the shop press to press the handle into the body of the wrench.
The last steps were to hardened and temper the engagement tip. I heated the end to a cherry red, non-magnetic state using a MAPP torch, then oil quenched. This was followed with heating in the oven to 600 degrees (F) for two hours to stress relieve and temper the tip so it wasn’t too brittle.
The photos show the finished wrench, along with a side-by-side view of the two wrenches, and the finished key with an example of the square stock I started with.
Note: I’m aware import chuck key wrenches can be bought quite inexpensively. However, that’s not the point and contrary to why I have a shop. It’s the journey, not the destination that’s important to me… trying new things, creating something, developing my skills. That’s why I work on so many different types of projects, so I can try and learn new things.
