On Tue, 6 Mar 2012 11:25:38 -0700, "Bob La Londe"
wrote:

"Karl Townsend" wrote in message
.. .

I either have the time or the money, but never both at once. Actually I
was
looking at some of the lathe turned gear cutters.

Sounds like the story of my life. Only sometimes I have neither.



http://www.youtube.com/watch?v=8UBxNPbg0ls He talks a lot, but it's a
good
example of what I was thinking of.

Maybe an oil hardening drill rod to make the cutter. I don't know, but
this
little adventure got me reading all kinds of new stuff.

Now you're getting more advanced. Hobbing involves coordinated motion
of two axis at the same time. You'd need a good CNC 4rth axis. The
advantage is one cutter does all gears from tiny to rack. I'd start
with the involuter cutter idea.

I don't see why it needs coordinated 4th axis motion. Don't see why the
table couldn't be advanced manual by my calculation chart method just like
using an involute cutter.

Watch that video, the hob cutters are trapezoid shape. If using your
method with this cutter you get something that will look like a timing
pulley. if you rotate the blank in unison with the hob set up at an
angle you will get an involute gear shape. the advantage of the hob is
one cutter makes any number of teeth for that gear type.



You want to read Ivan Law's book, "gears and gear cutting". there's a
section in there on making involute cutters starting with round HSS
blanks to make a fly type cutter.

I just ordered a copy from Amazon. Interestingly a new copy was cheaper
than a used copy. Still a single point "fly" cutter type setup is going to
be so sloooooow.

True, thank goodness for CNC. Just let it run and do something else.
back to that old time or money thing.

Karl