I have seen many versions of tap holders, but I decided to try to make one using the Irwin 3/8" socket tap holders:
There are two different holders, both with 3/8" square sockets. I took a 3/8" extension and cut off the socket end. I made a holder that is held by the drill chuck that also has a hole that the cut off extension fits into. Onto the extension, there is a hollow cylinder that has a hole drilled through it and through that hole, I put a scrap rod to be the handle. As you can see, the handle is about 1/3 the diameter of the extension.
Here are some more images:
All the parts
There is a little wobble in the 3/8" drive socket, but it tracks the hole nicely once everything is lined up. I have tapped both on the mill and the lathe and both with small and larger taps. One thing I like is that there is quite a bit of depth in the extension holder, so I can set that holder into the chuck, add the extension part, and then add the tap with only a short engagement to the square drive - works well for me.
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