meme2704 wrote: ↑
Sun Sep 30, 2018 1:26 pm
know this is an old thread.
But I want to emphasize, that if you substract involute gear from a cylinder you DON'T get valid involute inner teeth.
I did it yesterday, but it was too quick thinkging. The result could be acceptable for some info graphics, but certainly not e.g. for 3D printing a real gear.
I think, that at this moment, the only way is to take an engineering handbook and draw a precise sketch to base the gear with inner teeth on...
Complete Fake news, you do not know anything about machining pinion, look at my answer 2 post above
Let's try to keep a more respectful tone, please.
Also not a gear expert, but I think the internal/external spur gear difference is a little more than just terminology (and, I am sure that "external" in this context means "spur that has the teeth pointing out" - the Part Design tool is the right way around). The addendum of one becomes the dedendum of the other, obviously, and the involute parameters will be the same. But, I think as a practical matter you'd not want to specify the root radius of the internal gear, by making a rounded tooth tip of an internal gear, then inverting it... Often the internal gear has to have different dimensions to prevent the tips of teeth from interfering, and that sort of thing too.
That said, looo has made a rather nice gear workbench: https://github.com/looooo/FCGear
As to the "bug" - mine looks fine when I ensure that the visualisation deviation is low enough:
OS: Ubuntu 18.04.1 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.14803 (Git)
Build type: Debug
Python version: 3.6.6
Qt version: 5.9.5
Coin version: 4.0.0a
OCC version: 6.9.1.oce-0.18
Locale: English/UnitedKingdom (en_GB)