Bevel gear - module/script/tutorial

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sgrogan
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Re: Bevel gear - module/script/tutorial

Postby sgrogan » Mon Oct 19, 2015 7:01 pm

mafer78 wrote: sgrogan : I've tried to install but any appear on the workbench window (?!!!) , I've followed the istraction on the github.
What OS are you on?
EDIT: Only copy the "gear" folder inside the "FCGear" folder
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mafer78
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Re: Bevel gear - module/script/tutorial

Postby mafer78 » Mon Oct 19, 2015 7:10 pm

Hi sgrogan,
windows 7 enterprise edition Service Pack 1

Mafer
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sgrogan
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Re: Bevel gear - module/script/tutorial

Postby sgrogan » Mon Oct 19, 2015 7:18 pm

I'm on Win7 also so copy the "gear" folder only to:

Code: Select all

C:\Program Files\FreeCAD 0.15\Mod
I think you need administrator privileges.
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quick61
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Re: Bevel gear - module/script/tutorial

Postby quick61 » Mon Oct 19, 2015 7:32 pm

Oh, you want something like this -
BevGear1.png
BevGear1.png (26.38 KiB) Viewed 2474 times
The file ends up being quite large once the Grove tool is used, but here it the trick -
BevGear2.png
BevGear2.png (149.59 KiB) Viewed 2474 times
First create a small helper Pad so you have a face to map a sketch to, (the little cube hanging off the bottom that has one of it's corners coincident to the root point), then use external geometry to pick the top and bottom points on the beveled gear to string a construction line between. Then make your sketch with the line that will be the inside of the grove to be perpendicular to it using the perpendicular constraint, then inclose the sketch and use the Part Design Groove Feature on it. From there everything else is straightforward. See... easy. :P

Let me know if you really need the file and I'll upload it to Dropbox. (it's 8.8 meg).

Mark
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mafer78
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Re: Bevel gear - module/script/tutorial

Postby mafer78 » Mon Oct 19, 2015 7:41 pm

Hi expert....you're really expert.....
sgrogan: great now appear....in attachment image with the parameters, could you details?
quick61: fantastic yesssss , if you can share the freecad file I really appreciate.....I can study on it your steps description below.

br
Mafer
Attachments
gear_wb.JPG
gear_wb.JPG (29.37 KiB) Viewed 2472 times
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quick61
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Re: Bevel gear - module/script/tutorial

Postby quick61 » Mon Oct 19, 2015 7:44 pm

OK, here is a much smaller file using a cone instead of an Involute shape. Same principle of construction though. ;)
BevGear3.png
BevGear3.png (21.64 KiB) Viewed 2472 times
BevExamp.fcstd
(63.59 KiB) Downloaded 56 times
Mark

OS: Kubuntu 14.04.3 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.5764 (Git)
Build type: Release
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Python version: 2.7.6
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sgrogan
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Re: Bevel gear - module/script/tutorial

Postby sgrogan » Mon Oct 19, 2015 8:53 pm

mafer78 wrote:sgrogan: great now appear....in attachment image with the parameters, could you details?
Unfortunately I do not know gear design, so I can't detail the parameters.
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looo
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Re: Bevel gear - module/script/tutorial

Postby looo » Tue Oct 20, 2015 1:48 pm

short description for the parameter:

backlash: not working properly for bevel gears as it is difficult to define the mean profile of the shape. it's a factor which makes the teeth thinner
clearance: there should be a distance between "head" and "foot" of the teeth of two interacting gears. This parameter is a factor for this distance.
height: maybe should be called thickness
m: module = distance between two teeth for the mean-profile measured on the base radius (I think it should be the same for two interacting bevel gears)
numpoint: the number of interpolation points
teeth: number of teeth
alpha: 90° - pressure angle (this is a little bug I have never corrected)
gamma: pitch angle --> drawing

Image

@quick61
the bevel-gears you have made are looking quite good, but taking the (cylindrical) involute gear profile to produce them will lead to wrong kinematics and won't work for bigger transmission-ratios. (e.g..: 3:1)
mafer78
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Re: Bevel gear - module/script/tutorial

Postby mafer78 » Tue Oct 20, 2015 8:27 pm

Hi expert, honest very good feedback and contribution of this thread.....and welcome to looo, the image is really interesting because is more detailed comparing with mine.For the value of the parameters present in the image there is some standardization that I can take into account?

I create on freecad a bevel gear 3:1 type, which is the best approach for create the bevel gear rightly?

looo, for production scenario, can I use your gear wb?or there is the possibility that something is wrong?

br
//Mafer
mafer78
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Re: Bevel gear - module/script/tutorial

Postby mafer78 » Thu Oct 22, 2015 9:44 pm

no any answer?
do you know I can retrieve the pitch angle value?

BR
//mafer