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wrote:
Wow, I'm surprised someone is making gears with shapers... I thought it
would be too time consuming to do, well, almost any thing with a
shaper. I'd think he's use a horizontal mill or something for gears.
I'll admit, though, on this subject my ignorance is vast... Is there
some special reason for using a shaper for gear hobbing?

What Fred said. To elaborate, it rotates the gear blank and the
cutter simultaneously (and slowly), while stroking the cutter
up and down. The cutters look sort of like gears themselves,
except the face is dished to give it rake, and the teeth angle
back to give it relief.

Hobs are faster, but have a limitation: If you have a small
gear and a large gear on the same blank, you can get the two
gears only so close before the hob starts rubbing on the large
part of the blank. A shaper cutter can cut the smaller gear
even when the two gears are almost right on top of each other.
For gearbox design, the less space between the two gears, the
smaller you can make the gearbox.

--Glenn Lyford