Chief Delphi - gear mod

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- - gear mod (http://www.chiefdelphi.com/forums/showthread.php?t=28155)

some one is likely to come along with a better sounding answer, but the pitch diameter is the diameter where proper meshing should be. So when using gears that "mesh", but doesn't have the expected pitch diameter, the true pd is not being achieved in one, the other, or both gears. In that case, it's hard to say what ratio they're running at. Perhaps it's somewhere between the ratios using the dp of the correct gear and the substitute.

Quote:

Originally Posted by Nuson

This is not true. While it IS true you cannot calculate what the true operating pitch diameter you CAN calculate the ratio exactly.

Unless the mesh is so bad that the gear teeth pass each other the ratio is the [Nteeth-on-Gear1 / Nteeth-on-Gear2].

Joe J.

P.S. Knowing the ratio tells you the ratio of speeds exactly, but it does not allow you to know the ratio of the torques. Don't forget that the ratio of the torques is [the gear ratio X efficeincy]. This efficiency is going to drop considerably when you loose "conjugate action" (by mating involute gears with different DP's or Pressure Angles for example). Lapping or running the gears in will help in this regard, but it is no substitute for using properly matched gears to begin with. JJ

Personally, I think the 32 pitch and .7 mod meshing is awsome. In the sense that, if someone can do it well, more power to them. They have learned what few can do, defy engineering rules. We gotta get together and talk about how to send a banana back in time :D

haha sorry for the randomness.. onto real suffs.
I would buy .7 mod gears off PIC design, you can get them in steel with a .1875" face width up to about 128 teeth. I have bought a lot of gears off PIC, and I always get them in EXACLY 14 days. Very strange...

By the way, wire EDM shops have gotten very cheap. While I would never get gears done there, (you can always buy better ones) I always go to EDM to get precision work done. I am working on a 3 speed shifter, and I got the intricate shifter cut into the gears for VERY cheap. 12 gears total (I made a spare set) for about 200 bucks. It was really cheap because it was the same cut. The guy even offered to harden them before they were cut for 50 bucks. Of course I could not resist.