I recently ran across a Fray 8-inch sweep brace in a Restore Habitat shop. In the Fray's chuck was what I call a Frankenchuck: a shaft with a square tang on the back and a threaded front end that fits into an ordinary wood drill chuck, letting the user mount and use ordinary wood drills in a brace. I have made two of these myself from surplus auger and drill chucks.
In this case because the threaded shaft was 1/2-inch in diameter, I was hoping to take off the nice little brass chuck (3/8" max capacity) and replace it with a 1/2" capacity chuck. However, it turned out that the threading on the shaft is 24 tpi.
Which raises two questions. Has anyone here on GJ ever seen a drill chuck that mounts on a 1/2-24 threading? Lots of options available (Jacobs and McMaster-Carr) for 1/2-13 and 1/2-20, but I can't find any with the 24 tpi thread.
Second, since this no-name 3/8 brass chuck does in fact mount on that 1/2-24 shaft, where (what drill) did it come from?
(In the photos, the shaft threads look like an Acme or other flat-top thread, but that's from camera jiggle on my part. They are indeed sharp-edged.)
In this case because the threaded shaft was 1/2-inch in diameter, I was hoping to take off the nice little brass chuck (3/8" max capacity) and replace it with a 1/2" capacity chuck. However, it turned out that the threading on the shaft is 24 tpi.
Which raises two questions. Has anyone here on GJ ever seen a drill chuck that mounts on a 1/2-24 threading? Lots of options available (Jacobs and McMaster-Carr) for 1/2-13 and 1/2-20, but I can't find any with the 24 tpi thread.
Second, since this no-name 3/8 brass chuck does in fact mount on that 1/2-24 shaft, where (what drill) did it come from?
(In the photos, the shaft threads look like an Acme or other flat-top thread, but that's from camera jiggle on my part. They are indeed sharp-edged.)
