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Discussion Starter #1
I'm trying to get this engine up and running for a friend of mine. The locomotive is in great shape for the most part, except that the main idler gear is disintegrated due to zinc rot. It's got a patent number on (1-685-691) it and was utilized in several American Flyer O gauge locomotives of the era. Northwest Short Lines is open to the idea of making a gear for it, but they need an accurate count of the number of teeth on the gear which I unfortunately can't cipher from the remnants of the gear I have. Does anybody have a Prewar American Flyer locomotive in their collections that utilizes this gear that they could count the teeth on for me?

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A quick peak at Northwest Short Lines' web site seems that one of their specialties is gears. Maybe you could just send them the gear and they can take it from there. There likely experienced with measuring critical dimensions, gear pitch, etc.

Can't hurt to ask them ...
 

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Discussion Starter #5
A quick peak at Northwest Short Lines' web site seems that one of their specialties is gears. Maybe you could just send them the gear and they can take it from there. There likely experienced with measuring critical dimensions, gear pitch, etc.

Can't hurt to ask them ...
I'm actually already in contact with them prior to making this post. I was able to give them all specifications except for the number of teeth which he'd need to make the part. He's ready and waiting, just needs that number to go from.
 

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How was it done? Count visible teeth in given degrees of arc and multiply by appropriate no. to equal 360 degrees, perhaps. Digital calipers to measure diameter from which circumference is calculated and teeth counted for that dimension?
 

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Discussion Starter #9
The first time I counted based on what’s left of the missing teeth I counted 40. The second time I got 35. Confirmation from somebody with a good gear showed that I was correct with my first count. It is indeed 40.
 
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