accurate involute gear tooth profile to model for SLA 1

[konduri]

I am working on four gears and trying to create 3D models for SLA and also for mold. I looked at several websites and Pro/E tips but none of them are giving accurate profiles. I appreciate anybody who can help me in creating a 3D model.

My gear parameters are:

1. PD = 1.7003
No. of teeth = 81
pressure angle =20
2. PD = 1.8892
No.of teeth = 90
pressure angle =20
3. PD =2.0691
No. of teeth = 91
Pressure angle =20
4. PD = 1.7947
No. of teeth = 79
Pressure angle =20

Again any help is appreciated

Thanks and regards,

Ramesh

 

[israelkk]

Can you explain the PD? Is it the Diametral Pitch (Module) or the Pitch Diameter?

 

[konduri]

Sorry, PD is Pitch Diameter. Thickness of the gear is .156" in all cases

 

[israelkk]

Something doesn't add up. What is the diametral pitch of the gears. When I calculate it I do not receive whole numbers, how did you came to those pitch diamters?

It seems that the gears are diametral pitch 48 and 44, if so what is the gear accuracy and how did you recieve the pitch diameters?

 

[konduri]

Yes, diametral pitches are not round numbers. I had use the pitch diameters since center distances and gear ratioes are controlled by other geometry which I cannot change. Since, I am planning to use molding to make plastic gears, I am thinking that it is OK to have these kind of diametral pitch numbers.

Gear accuracy AGMA 6.

 

[israelkk]

OK. If you want to get an accurate gear drawing you should get the free software GEARGN.ZIP which you can find in

http://www.mfgworld.com/fileid.html

. This is a DOS based program that export DXF files. I assume that you can import the DXF file to PRO/E and create a solid from it.

I have done this with Solidworks but since the DXF file is basically a bunch of large number of points the program had diffuclties to handle it and the process took a very long time and always succesfully. I hope PRO/E will do better.

If you intend to create molds then this program can create the G-CODE for wire EDM.

 

[gearguru]

konduri,
If you want "accurate" models, then you need to know more about the gears:
Major Dia
Root Dia
Tooth thickness (at known diameter, usually PD)
These data do not have to be standard (addendum does not have to be 1/DP etc.)
and also how the root fillet looks like.
The tooth profile and fillet root curve can be calculated using the data mentioned above, for a perfect involute.
Not a simple calculation, but it can be done.
Not that long ago there was a Lisp program (created by Diamonjim) published in this forum; if you have access to AutoCad, you can run it, save the 2D profile as a dxf and then you can import it to any CAD and extrude it to create the 3D model.
But think twice before you give the 3D model to somebody as a math model for machining actual gear. I personally would not do it - unless the gears quality is not very important.

 

[diamondjim]

I would use the .5 module gearing
and go with expanded center distance.
48 diametral pitch could also be used
and go with shortened center distance.
I think I posed answeres to this on
another forum as well or to your
e-mail to me. If you need the details
let me know.

 

[konduri]

Steve,

Gear 1 and Gear 2 mesh with each other. Center distance for these two gears is 1.79473

Gear 3 meshes with itself - center distance is 2.06912

Gear 4 meshes with itself - center distance is 1.79473

I downloaded your GEAR CAM program but it requires password to use it.

Thanks.

Ramesh

 

[israelkk]

konduri

Did you try the GEARGN.ZIP which you can find in

http://www.mfgworld.com/fileid.html?