I had a meeting with my machine shop guy this morning.
We need to find on the internet the exact angle of the ends of the bits, for the tapered slot to hold it in the adapter. He measured a bit I had and said it was somewhere around 3.25 to 3.5 degrees. But using my measured drawing I have it as 4.29 degrees. So probably my drawing is wrong.
He suggested I do a search to find the standard for these bit ends. These are the bits we use in a bit and brace.
Who invented this?
What is the correct name for this bit end?
What is the correct angle if you know?
Thanks any help would be appreciated.

Jim Rogers