Planetary Gear Inner Gear

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OakLD
Posts: 99
Joined: Fri Jan 12, 2018 7:38 pm
Location: Brno

Re: Planetary Gear Inner Gear

Postby OakLD » Fri Oct 05, 2018 8:08 am

ian.rees wrote:
Wed Oct 03, 2018 6:10 am
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.
I'm still unsure about correct profile of internal tooth, I get some indicies from university papers, but there's nothing in my engineering reference book, nor on the internet. It's not important application, just a little gearbox for a RC toy, but I'd like to know it. I'll probably have to construct it in CAD.
ian.rees wrote:
Wed Oct 03, 2018 6:10 am
That said, looo has made a rather nice gear workbench: https://github.com/looooo/FCGear
Yes, I'm using FCGear :-). Simple to use but powerful tool.
ian.rees wrote:
Wed Oct 03, 2018 6:10 am
As to the "bug" - mine looks fine when I ensure that the visualisation deviation is low enough
May I know, how do you ensure low visualisation deviation? I don't get any results googling the term itself...
Regards,

Oak
UR_
Posts: 1016
Joined: Tue Jan 03, 2017 8:42 pm

Re: Planetary Gear Inner Gear

Postby UR_ » Fri Oct 05, 2018 8:59 pm

OakLD wrote:
Fri Oct 05, 2018 7:47 am
I still may need to export correct object in DXF
As mentioned, latest DxfExporter from TechDrawWB is able to write Bsplines.

used workflow:
- DraftWB:"Draft to Sketch" for making a sketch from involute gear containing bsplines
- Create a view from Sketch with TechDraw
- export it as DXF

File:
InvoluteGear2dxf.FCStd
(31.95 KiB) Downloaded 10 times

dxf:
ext.dxf
(31.16 KiB) Downloaded 15 times

view from QCAD 3.21.3:
ext.dxf - QCAD-000076.png
ext.dxf - QCAD-000076.png (28.87 KiB) Viewed 201 times

done with:
OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.14838 (Git)
Build type: Release
Branch: master
Hash: 0d228bce02f3a4aa39f2b0f2bfbd5ca5eb2a6d4b
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: German/Germany (de_DE)
ian.rees
Posts: 696
Joined: Sun Jun 15, 2014 3:28 am
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Re: Planetary Gear Inner Gear

Postby ian.rees » Sun Oct 07, 2018 11:42 pm

OakLD wrote:
Fri Oct 05, 2018 8:08 am
ian.rees wrote:
Wed Oct 03, 2018 6:10 am
As to the "bug" - mine looks fine when I ensure that the visualisation deviation is low enough
May I know, how do you ensure low visualisation deviation? I don't get any results googling the term itself...
There are a few different places where the deviation matters; the visualisation deviation is in the View tab of the property editor, called "Deviation". This just effects what the shape looks like in the FreeCAD window. If you wanted to export as STL, there's a separate setting "Maximum mesh deviation" in the "Mesh Formats" tab of the Import-Export preferences - IIRC you need to load the Mesh Design workbench before that becomes visible.
Kaspers
Posts: 1
Joined: Sat Nov 17, 2018 3:05 am

Re: Planetary Gear Inner Gear

Postby Kaspers » Sat Nov 17, 2018 4:11 am

thanks ian.rees, it works
Property -> View -> Deviation = 0,05 works for me ( before it was 0,20 )
But it is Slow to update the chagrin ( i still dont know how to get it to update : )
you can try save it, then reload it then you will see the chagrin : )

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13541 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 9948ee4f1570df9216862a79705afb367b2c6ffb
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: Danish/Denmark (da_DK)
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meme2704
Posts: 2926
Joined: Sat Apr 01, 2017 2:47 pm
Location: Vosges

Re: Planetary Gear Inner Gear

Postby meme2704 » Sat Nov 17, 2018 10:05 am

Scregneugneu; Saperlipopette :mrgreen:
I can not make external gears in V.18, when I activate the command, I have the red fault sign that appears, while in the internal toothing everything is OK
if I made the outer gear in V.16, save it, open it in V.18, OK, but if I want to change it ie nb of teeth, new red label :mrgreen: