Figure 14-26.--Development of setover and depth increase.
9. Diametral pitch (DP)
select a cutter. The only way to select a cutter is by sight.
Get a large selection of bevel gear cutters, then match
one of them to the side of a good tooth.
To find the amount of setover, first establish the
circular pitch angle
One circular pitch equals
360. Therefore, you can divide 360 (one circular
pitch) by the number of teeth (NT) to find the circular
METHOD OF MANUFACTURE
You can solve for the amount of
pitch angle
setover by using the triangle in figure 14-26, view A.
If you buy a stub tooth gear cutter, you can
manufacture a straight or helical stub tooth gear by
Setover = Root radius Tan
using the procedure you use for spur and helical gears.
If you use a fly cutter, use the old gear as a pattern to
Where the root radius is the outside diameter (OD)
grind a single-point tool bit to the desired shape.
divided by 2 minus the whole depth (WD).
A properly fitted gear must have a setover and a
Root radius =
depth increase. You should calculate these after you
14-28