Planetary Gear Inner Gear

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OakLD
Posts: 131
Joined: Fri Jan 12, 2018 7:38 pm
Location: Brno

Re: Planetary Gear Inner Gear

Post by OakLD »

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 amThat 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 amAs 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_
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Re: Planetary Gear Inner Gear

Post by UR_ »

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 40 times

dxf:
ext.dxf
(31.16 KiB) Downloaded 36 times

view from QCAD 3.21.3:
ext.dxf - QCAD-000076.png
ext.dxf - QCAD-000076.png (28.87 KiB) Viewed 787 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
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Re: Planetary Gear Inner Gear

Post by ian.rees »

OakLD wrote: Fri Oct 05, 2018 8:08 am
ian.rees wrote: Wed Oct 03, 2018 6:10 amAs 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

Post by Kaspers »

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
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Re: Planetary Gear Inner Gear

Post by meme2704 »

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:
rockstorm
Posts: 1
Joined: Sun Jun 13, 2021 10:49 am

Re: Planetary Gear Inner Gear

Post by rockstorm »

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
I know it is an old post but for future reference, if anyone arrives here looking for how to get an internal gear with the mentioned workbench. Attached there's a image of a gear subtracted from a cylinder. The green line represents what the profile should look like for an internal spur gear. The key parameters to generate the gear to be substracted via the FCGear workbench would be the following. Note that, as of version 0.3.1, there's no option for tip radius and therefore a root radius on the internal gear was not produced. We'll hopefully get this feature on version 0.4.

Code: Select all

clearance = -0.4
head = 0.25
undercut = false
2021-06-13_22-20.png
2021-06-13_22-20.png (5.25 KiB) Viewed 491 times
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