gtslabs wrote:
I am making an attachment to my knee mill height hand crank. I drilled
a hole in a rod to match the diameter of the crank shaft. However there
is a keyway that I need to mill out of my adaptor on the INSIDE
Diameter. I dont see a Woodruff cutter working in this 5/8" hole.
I can mill it but it will not have square corners. What is needed to
get the square slot?
Thanks
Steve

Another option would be to make your own broach and bushing. HSM had
an article on that quite a few years ago, and I made one to do a keyway
job. It worked well.

The bushing is simply a piece turned to fit the bore, with a shoulder
to keep it from dropping through and a milled slot to take the broach.

The broach is a single-tooth one, easily made with a mill and file. I
didn't have any tool steel of the right size handy, so made mine from
low carbon steel and case hardened it. Works fine.

The main difference between this and a commercial broach and bushing is
that the commercial broach has many teeth set progresively deeper, and
can often make the keyway in one pass. With the single-point broach,
you need a bunch of shims. Make a pass, add or change shims, make
another pass....

With the single-point cutter, you don't want any side clearance, so
that the cutter will make and follow a straight slot. Top clearance
only.

John Martin