For gear cutting every pitch or module has either one hob that cuts any number
of teeth, which requires a machine able to synchronize rotation of the hob and
blank, or a set of 8 different single tooth cutters, each of them marked with a
range of the number of teeth on a gear they're suitable for. For Diametral
Pitch gears there are also two different Pressure Angles, 14.5 or 20 degrees.
Thus a complete DP set has 2x the number of cutters than there are for metric
Module or Mod gears.
Cutter #8 in the sets has straight sides, made for cutting some large
(somewhere over 100) number of teeth to a flat rack ("infinite" teeth). Hobs
also have straight sides on their cutting edges. It's the rotation of the gear
being cut which forms the involute curves.
An in-between measure often used by hobbyists is a straight hob instead of a
spiral hob. With 3 or more rows of cutting teeth (larger gears will need more
rows on the hob) and the center row aligned with the axis of the gear being
cut, the flanks of the cutters above and below center will cut facets on the
teeth above and below the gullet being cut in the middle. This also works with
a straight hob with an even number of rows, cutting with a tooth on center
matching a groove in the hob. Dunno if after finishing a gear with gullet on
center then switching to tooth on center with the hob moved then doing a
cleanup pass would make the teeth smoother by cutting facets in slightly
different places on the teeth.
The same manual setups work with straight hobs and single tooth gear cutters,
in a vertical or horizontal mill.
On Friday, July 24, 2020, 1:11:39 AM MDT, andrew beck
<andrewbeck0...@gmail.com> wrote:
Greg can you educate me on what what gear cutters are enough for most gear
cutting needs? Fusion 360 has a nice gear profile generator I can use.
But I'll have to model all the cutters after that I think... Thinking keep
them pretty simple with no helix angle or anything. And maybe plan to cut
most of it out with a endmill straight down the middle before putting the
gear cutter through the cut
I will have to model this I think. Otherwise they will say it's to hard.
But if I can send them the model then it's all go
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