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israelkk, You not only answered the questions but made me aware that older handbooks are worth keeping. Thanks! Tim

What is the "reference circle diameter" of worm (df) and same for wormgear? I am using Machinery's Handbook rev 22 to calculate strength of worm gearing and Df and df (f is subscript) are used in calculation and does not define these variables.

When blades are extruded what die and process steps are taken to ensure the edge is free of defects? A small defect would leave streaks on glass. As Compositepro mentioned, ideally to improve product life, the edge would be a very small radius. Does anyone know how small the radius is?

We are talking about cutting the surface that is in contact with glass, not method of cutting to length.

You are correct that a sharp edge is not what is desired. I should have said a very smooth, flash free edge, i.e.: minimal imperfections. Here is a link showing that Bosch makes blades with a cut edge. It is interesting that ad mentions cut is for smoother movement...

Some of the higher quality blades are cut and I assume this is after being molded or extruded. This will produce a cleaner edge.

What process is used to cut windshield wiper blades and produce a very sharp edge?

Thanks for the sources and I will get the AGMA paper. A paper can be seen on: http://rclsgi.eng.ohio-state.edu/~wu/REFERENCES/2001_kahraman_JMD.pdf

The two above posts will get me where I need to be and from different directions. I do a lot of FEA but have not used it for gears and comparing FEA results with real world results and hand calculations will work fine for my applications. Thanks!

How do I calculate the stress on ring gear? I know stress on planets and sun gear. I want to find out if 7075-T6 will work for ring gear? This is an extremely slow application and very low life is needed (a few hours at rated torque)

Go to Boltup.com to get calculated torque values for both standard flanges and special flanges.

One key factor in keeping fasteners from self loosening is lubrication. The lower the coefficient of friction the greater the tendency to self loosen. Also, machining fine thread in harder materials is easier and less likely to break taps with CNC machines then when machining coarse threads.

I really like the appearance of the PVD coatings. How do the costs compare to other processes?

Thanks for the useful and specific information.

I should have posted that the pinion and gear face widths would be .34"

How can I calculate the minimum spur gear thickness in the area away from the teeth? This gear is loaded on center with the gear. I would like to thin down the gear leaving a thicker web for teeth. Dp=20 Teeth number = 19/102 (.95/5.1" dia.) Possibly 1055 heat treated material .8 hp @ 7000...

With a through hardened (Rc48) 20 degree stub spur gear running very slow and with a 2 to 10 hour life, does contact safety rating matter? Bending strength safety calculates to over 6 but contact safety is about .75 . Is this OK if some surface damage is acceptable? Hours of use and speed were...

Thanks for the explanation to questions that I have wondered about for sometime.

Thanks for the useful information!

Thanks for the information! I assume the gear OD then is normally adjusted to keep the tooth height about the same. Does this mean the pitch diameter is different or considered to be unchanged?