Failed pinion gear install: AM-2195 to BaneBots P60

[MrRoboSteve]

We were installing the BaneBots 15T 3.2mm pinion gear on the AndyMark AM-2194 motor this weekend. We install them by carefully placing the pinion on the end of the motor shaft, placing the unit in a vice, and slowly closing it.

The first pinion we installed works fine. The second one was loose on the shaft. It looks like, rather than deforming around the shaft of the motor, the inside of the hole was peeled away by the motor shaft. I checked the shaft and it's fine dimensionally and otherwise, reading right at .125.

I'm going to order more pinions, but am wondering whether there is something additional we should be doing during the install to prevent this from happening.

[cfair]

I would try heating the pinion before you put it on. And if you have an arbor press, that's what you should be using. But I've done exactly what you described before without trouble. Crappy pinion?

[MrRoboSteve]

Heating is a good idea -- will get out the hot air gun and give it a shot.

[Jpatterson1710]

We like to use a torch to heat pinion gears, we'll set the gear on the steel base of our hydraulic press and heat it until she's cherry red. Then press motor into gear and allow ample cooing time. Just be careful! That pinion wouldn't be too comfortable to touch.

[Ether]

Originally Posted by Jpatterson1710

We like to use a torch to heat pinion gears, we'll set the gear on the steel base of our hydraulic press and heat it until she's cherry red...and allow ample cooing time.

I take it the pinion gears you use are not heat treated?

[mentorDon]

For a light press fit, a little light machine oil should be used. This helps to prevent galling between the surfaces as they slide together. Heating them until red hot and letting them cool down without quenching would soften/normalize any previous heat treatment. There are 'air hardening' tool steels, but it properties wouldn't be useful for gears.

Also make sure you are pressing against the opposite end of the motor shaft and not the motor body.