I'm deep into a tranny build and working on cleaning up components and reducing stress risers. One concern are the sharp edges on some gear teeth, particularily around the root of the tooth. Kinda like this edge:



I started off on the front diff, and am now working over the input & intermediate shafts. I'm basically going over things I remember from reading Carroll Smiths books and from personal experience.

I started on the front diff spurs:








.. then to the bevel gears:







Question, does anyone have experience doing this, or know where I can find more information? Here are some of the links that I've gone over:


http://www.epi-eng.com/GBX-GearDesign.htm

Gear Design
http://www.tech.plymouth.ac.uk/sme/desnotes/gears/desgear1.htm

Elements of Gear Technology
http://www.qtcgears.com/Q410/Q410Cat.htm

Gear Industry Home Page
http://www.geartechnology.com/

Design of Machine Components
http://pasture.ecn.purdue.edu/~abe330/Spring2004.html

Gearology !
http://bostongear.com/training/gearology.asp

Bevel Gear Geometry
http://pergatory.mit.edu/2.007/handouts/gears/gearbox/bevelexplanation.htm

Gear Deburring With Power Brushes
http://www.weilercorp.com/gearbrochure.htm
Several pictures here showing different 'classes' of burrs. They seem to describe my concerns.

FAILURE ANALYSIS FOR GEARING
http://www.paperage.com/09_2000gearing.html

Standard Abrasives - DIY Guides (Engine Block & Cylinder Head)
http://www.sa-motorsports.com/diyguide.shtm
(not directly related to gears, but the grinding techniques and tools are described)

Found some good info here:

http://www.shotpeener.com/learning/tutor.htm
http://www.shotpeener.com/learning/gears.htm

...for starters:
Shot Peening Overview
http://www.shotpeener.com/learning/spo.pdf

From page 25.

"The fillets at the root of the gear are usually the areas of high stress and should be shot peened. However, it has also been shown that the tiny indentations produced by shot peening on the face of the gear act as very small oil reservoirs which help promote better lubrication, reduce fretting, noise, spalling, scoring and lower operating temperature by reducing friction. Gears which have to be held to very close tolerances may be lapped or honed after shot peening, provided the lapping or honing operation does not remove more than 10% of the depth of the compressive stress induced."

"It has been found that the life of a case hardened gear, stressed to 80,000 psi (56kg/mm2), increased from 2000,000 cycles before shot peening to 30,000,000 cycles after shot peening."

Guess I'm gunna need a shot-peening setup soon.


ps, if you search for peening... make sure you put the 'N' in there!