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Speed Key For Your Four Jaw Chuck


I find that when I'm trying to dial in a four jaw chuck, I spend half the time removing the key, spinning the chuck, and replacing the key. There has to be a faster way. 

Why not have a key in all four holes ? There's not always room to do that, especially when the chuck is mounted on the mill. So, for the initial dialing in, when you don't need a lot of force on the key, I cobbled this little gem together.

The handle is about .500" diameter x .750" long. I turned down the non-knurled section to about .440" so that it slides inside the Sherline chuck.

The end is drilled .160" about 3/8" deep. I cut off a piece of a hex key to about 3/4" long and pressed it into place with an arbor press. The whole thing took about 15 minutes. I'll use it for a while, tune up the design a bit, and make three more.


The speed key fits quite snugly in the Sherline chuck


You can see where the diameter needs to be reduced to fit the Sherline chuck.

For non-Sherline chucks, just make the end to suit and scale as required.

For the lathe, where they may tend to fall out, they could be magnetized. I'm going to make a set for my Myford Super 7 lathe too. I think the end may be large enough that I can embed a small rare earth magnet in it.


It was a bit too easy to get the hex wrench segment heading a bit off center so I made up a little jig to slide ( shown upside down on right) over the blank, drop in the hex key blank, and press into place. 

The large inside diameter is about .002" over the size of the chuck key so acts as a quick way to measure the key as it gets cut to size on the lathe.


Hex key segment in jig ready to be pressed into key blank


All four keys made.

One thing that I found is that once the object is loosely held between two opposing jaws, you just turn both keys in the same direction simultaneously to adjust. Very slick. I'm very happy with the result.

I have had some comments that the keys could be forgotten in the chuck when the lathe is started up so a little bit of extra diligence must be maintained when using these. My main purpose for making these was for using the chuck to hold material on my mill where that isn't an issue.

Updated: December 13, 2012

Design David J Morrow 2012