There isn't a standard for bit brace tang dimensions as far as I can tell. Easiest way to measure the taper was with my vernier protractor. All the bits I measured have different tapers.
Here's another way of measuring.
Measure twice...
or thrice.
It seemed that 10 degrees was a good average so I selected a 5 degree angle to support the work.
Then I drilled out some 1/2" tool steel to be a press fit on the hex circle of a magnetic bit holder.
And reamed it for a slip fit on the outside diameter of the holder for about 1/4".
Then I pressed the holder into the steel.
I knew it wouldn't run true so I checked it against an indicator and whacked it to get it within about .005" which is way more precise than needed.
I then turned a taper at the other end.
I set up the mill with the angle clamped in the vise.
Then put a 5C collet block in the vise against a stop.
It was a simple matter of milling a flat, turning the block 90 degrees and milling another flat.
About halfway done.
I then turned down the shank so it was smaller in diameter than the tapered section.
And it works.
I figured that since I had the mill and lathe set up I'd make another adapter.
Turning the other end 3/8"
.I used a die to make 3/8"-24 threads. The tailstock chuck keeps things square
And a drill chuck threads right on.
More milling...
And turning...
And I have a nice adapter.
I gave them to Kiko and he gave me a wooden spoon.
2 comments:
Hi Nick
I read your last post with interest as I have a similar problem of needing to hold brace bits in a normal drill chuck. I don't what to cut the brace tang's off yet. Any ideas?
If you don't want to cut the tang off? Hmmm...I'm not sure if there's a way to do that. Possibly you could find another bit brace and remove the chuck & shaft and adapt a shank to it that will fit your drill chuck? The tang is usually around 1/2" square so any adapter you put around it means it will only fit in the larger drill chucks.
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