Using thornton cutters and measurments

[alexkoel1958]

I'm drawing clocks and has the problem that the measurments of the gears aren't completely ok. I'm using the Thornton tables and formulas.
For instance:
Gear with 100 teeth and a module of 0,8.
The outside or tip diameter should be 82,2 mm (teeth+2,76)*module. In FreeCAD it ends up at 81,7 mm!
The root diameter should be 76,8 mm (teeth-4)module. In FreeCAD it ends up at 77,99 mm!
The teeth width should be 1,256 mm (1,57module). It is 1,23 mm! This widt is also on at to large root diameter.

Is it possible to make the cycloidial gear part to be custimized.

I know that a lot of great guys are building FreeCAD and all off the Addons. But this extra feature should be great.
If interested I can supply the thornton formulas. They are also depending on the module and the number off teeth with pignions (teeth <= 16).

[looooo]

You can adjust the teeth height with the head parameter and the root can be adjusted with the clearence parameter.
The formulas used can be found here: https://github.com/looooo/freecad.gears/blob/master/pygears/cycloid_tooth.py#L39
and here: https://github.com/looooo/freecad.gears/blob/master/pygears/cycloid_tooth.py#L40

[alexkoel1958]

Still working from Z=100 and M=0,8
See the formula's of Thornton. With all due respect. If I calculate the Outside diameter (Da) from the formula in the source with a head off zero I get 82,4.. If I make a techdraw, the outside is over the teeth is 81,7. So somewhere it's going wrong. Not that it's a big issue. I can manualy change the measurements. But it would be great if I understand if I'm doing something wrong or the code :-).