Hi all,  Being new to the list, I've been in lurker mode.  I'll come
out of lurker mode and make my first contribution.  My comments are
below mixed with Christian Greinacher's message [040131 MMDigest]:

> Why should the diameter of the cutting wheels be about 5 inches?
> I can't believe you will find such big ones and if you do they will
> be very expensive!

I have seen these in surplus catalogs such as Scientific Surplus at
reasonable costs.  But, they are typically about three inches in
diameter.

> ... I learned that it works much better to cut the teeth from normal
> weak steel and to harden and temper it after having worked out the
> final shape of the tooth.

I have done a fair bit of this sort of work for various applications.
As Christian notes, shape, harden, then temper is the typical process
for making hardened parts or springs.

As mentioned elsewhere, the Dremel wheels will cut hardened material.
These too will shatter if flexed while cutting.  They are typically
about 1" in diameter and wear rather quickly on hard material.  It is
also somewhat difficult to get precision and nice finish.  But they can
be very effective for certain things.  They generate a lot of heat when
cutting, since it is basically a grinding action.  I've never tried
them with a liquid coolant...my guess is, the binder in the wheel may
not like it.

Bob "Mac" McIlvaine - Industrial Age Workshop
Brookline, New Hampshire