Re: 4th axis gear cutting question

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Bill Kichman"
><billkichman@c...> wrote:
> I am nearly finished with my ballscrew conversion, but a question
>has been
> nagging me....I want to do some gear cutting projects as a first
>real
> project on the cnc setup, and with little real machining background
> experience, am wondering whether this is a viable project. What I
>want to
> do specifically is cut a set of change gears for my South Bend
>toolroom
> lathe to permit cutting metric threads.
> I located a web based utility that permits entering gear pitch
>information
> and it spits out a really cool dxf you can save to the hard drive
>and finish
> tailoring to suit your thickness and other particular 3d info
>before running
> in a cam app (VisualMill in my case). But is this a reasonable
>project for
> my full size cnc setup and what cutters should be used?
> Also is this a reasonable job to do using only 3 axes? I don;t
>ahve the
> rotary table converted just yet.
>
> thanks as always for any insight.
>
>
> R. William Kichman, P.E.
> Kichman Engineering Associates

Bill,
These programs are more suited for wire erosion machines that cut in
the flat with a 0.005" wire as a cutter.
Due to the depth of cut and the shape of the tooth profile on
something like lathe changewheels you cannot get a small enough
cutter deep enough.
This type of program works fine when doing something like chain
sprockets with 2" pitch where you can get a decent sized cuter in.

For your application the 4th axis and form cutter is about the best
way to go. I know this isn't what you want to hear but it is the way
to go.

John S.