Drill motor gear measurement

[George1902]

Originally Posted by Andy Baker

They are almost the same.

In fact, 32 dp is so close to .7 mod that we just used a 32 dp gear with the drill motor.

The pinion on the drill motor is hardened steel. You can take a 32 dp gear of a softer metal (we used brass) and run them in dry. Lube them up and you're good to go.

SPAM used this method on their 2000 and 2001 bots and we used it on our 2004 bot. Works great.

One word of advice: The number of teeth probably won't work right for calculating this ratio.

[Tristan Lall]

FYI, 0.7 module is exactly 25.4 * 1 / 0.7 = 36.2857 pitch. The 32 = 36.2857 thing has been used successfully, but it really isn't optimal, and will likely yield unpredictable wear on the large (softer) gear. Instead, I would try to predict an appropriate size of 0.7 module gear, and order it before the season starts. Once the kit of parts arrives, make any design decisions that need to be made, bearing in mind that you already have a proper gear, and won't have to wait 5 weeks for it. Only if you can't use what you preordered, should you consider using some sort of crude alternative. (And if your design can tolerate plastic 0.7 module gears, they can be had within a week from SDP/SI--even more reason not to go with 32 pitch, even when pressed for time.)

[Joe Johnson]

I too cringe when I hear folks using 32 DP gears with .7 module gears, but it is hard to argue with success. Apparently many teams do it (can the TechnoKats, WildStang and SPAM all be wrong? -- well, yes, but... ...how wrong can they be?).

Here is what I recommend, get the gears from PIC or have them burned from a wire EDM source (Lou Odin at Capital Tool & Die is a Detroit area source we use a lot -- he takes credit cards and will ship anywhere -- PM me if you want contact info). Failing that, press the gear off and press on whatever gear you can get easily. We've found the 5mm shaft is pretty easy to work with.


Joe J.

[Andy Baker]

Originally Posted by Joe Johnson

I too cringe when I hear folks using 32 DP gears with .7 module gears, but it is hard to argue with success. Apparently many teams do it (can the TechnoKats, WildStang and SPAM all be wrong? -- well, yes, but... ...how wrong can they be?).

Joe J.

Notice that I said we used a 36dp gear, NOT a 32 dp gear.

Andy B.

[Joe Johnson]

Originally Posted by Andy Baker

Notice that I said we used a 36dp gear, NOT a 32 dp gear.

Andy B.

Sorry, it was just a typo.

Joe J.