Drill Motor Gear Specs?

[Ryan Curry]

Well the experiment has taken place, and with much success. While I agree that a press is a much safer bet, I had a very hard time fitting a plate between the pinion and the motor, so to the dremel I went. I first masking taped the ENTIRE motor, so that shavings would be reduced to a minimum. Instead of using a cutting wheel though, I used a grinding stone to grind away 2 semi-flat places of the gear without going all the way to the shaft. After this, I put the motor is a vice and tightened untill..crack went the pinion down one side. After this it popped right off with a piece of brass as a punch and a ball peen. I cannot be happier with the outcome and had no bad experience using the dremel to do this. Some teams that have a hard time trying to press the pinion off should look into this as a fast and easy alternative, in my opinion.

-Rc

[Rob Colatutto]

Originally Posted by Ryan Curry

Well the experiment has taken place, and with much success.... Some teams that have a hard time trying to press the pinion off should look into this as a fast and easy alternative, in my opinion.

Are you sure it was a success? Did you try to run the motor yet? Better make sure you didn't bend that output shaft when you...dremeled... it off. Also, when you agree with Paul saying the correct method of using a press is much safer, don't turn around and recommend other teams go to and attempt what you did. Even if your motor did not get damaged in the process, other teams might not get the same outcome.
Out of curiosity, what and how do you plan to attach another gear to the Bosch with its very small metric output shaft?

[Veselin Kolev]

Never underestimate the strength of those small motors. If you really wanted to, you could do anything with the pinions. For example, my team had many left over fischer price motors, so one day I took one home and swapped out pinions. I first used a diamond dremel cutoff wheel to cut a slot into the gear, almost to the shaft. Then, I ground off the teeth of the gear (of course with the motor covered so shavings dont get in it). Then I put the gear into a vice, put a hardened steel pin to the shaft and yes, smacked it with a hammer until the motor popped free. The motor and shaft were in perfect-looking condition, so I commenced in "pressing" the new gear on. This was a little more tricky to do... First I determined the diameter of the hole in the new gear, drilled it, and prepped for "pressing". This was the hard part; I first put the motor in a vice. Then, I took a .5" peice of aluminum, and drilled into it a hole with the diameter of the outer diameter of the gear. This way, you put the gear in the plate, put the gear onto to motor, and smack away with a hammer, yet again. The end result was pretty good, but I wouldn't ever use it on a robot. Don't be ghetto. Do it the real way. To test this gear, I rigged it up so that the shaft was clamped down, and I got some huge vice-grip clamps around the gear and twisted as hard as I could. That was like a 15 inch lever, and it took a lot of force, I'm guessing 50 foot pounds to make the thing twist a little. So... the moral of the story is that you can do this for small projects, but not robotics. If I made a drive train that used this method of pinion removal, every match we played, I would be praying. Yea... as Andy Baker and Paul Copioli do, just use an arbor press. Makes life a lot more secure. As well as your drive train.

[Robb Gerber]

I was just looking at

http://www2.usfirst.org/2004comp/Spe...inion_Gear.pdf

It shows 13 teeth NOT 15 like everyone is reporting?

What's the verdict? Is it 13 or 15?

ARGH!!!

[Paul Copioli]

No doubt about it. The gear IS 15 teeth. The drawing has been wrong since last year. If you are unsure, then count the number of teeth on the motor that came with your kit. I have our motor in my hand and it is definitely 15 teeth (same as last year).

-Paul

[Robb Gerber]

Whew...what a relief!
I was just working out our gear ratio's - 2 less teeth makes a BIG difference.

Thanks for confirming Paul.

[Paul Copioli]

Please look at this thread if you are designing your own gearbox for the drill motor:

http://www.chiefdelphi.com/forums/sh...ad.php?t=24181


The bottom line is that I have designed my gearbox with a 0.006" increase in the center distance due to the oversized pinion, but please read the thread for details.

I am using a 56 tooth gear to mate with the 15 tooth gear. My standard center distance would be 24.85mm and I am using 25.00mm (0.015mm ~ 0.006").

Also,

If you plan on using the gear from the drill motor then you need to get your mating gear at www.pic-design.com. Beware that these gears take at least 2 weeks for delivery. I ordered mine on 1/15 and still have not received them.

I hope this helps.

-Paul

[Stu Bloom]

Originally Posted by Paul Copioli

... I ordered mine on 1/15 and still have not received them...

... maybe its the accent ... ??

sorry ... I just couldn't help myself ...