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Unread 09-03-2005, 03:33
Andy A. Andy A. is offline
Getting old
FRC #0095
Team Role: Coach
 
Join Date: Jun 2001
Rookie Year: 2001
Location: New Hampshire
Posts: 1,017
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Re: Drive Assembly Sprockets are Custom Bored

My team ran into this. We opted to run with the two wheel drive, but to drop the 21 toothed sprockets for 15's (we wanted to slow down a bit, rookie driver and all). I was in charge of ordering the new sprockets, and just as I was on my way out shop one night, I asked a student to measure the shaft for me so I could order them that night. He quickly grabbed a pair of calipers, and I guess 16mm was close enough to 5/8ths that he figured he had made a mistake and assumed it was 5/8ths (all our other drive train shaft is). I probably would have done the same.

So I ordered sprockets from McMaster with a finished bore for 5/8ths. Needles to say, I was confused when the sprockets just wouldn't go on!

After a while, we figured it out. 5/8ths of an inch does not equal 16mm's it seems. The solution was to ream out the bore and 'press' the sprocket on with a hammer. It was tighter then I would have liked, and I hope we never have to take that thing off, but it works. I probably spent more time trying to figure out why things didn't fit then I did fixing anything.

Moral of the story- Sometimes, that metric system will show up in the most unlikely of places. Read your manuals!

Although, now that I think of it, I probably still would have gotten the same sprockets. I'd rather have to take a few passes with a reamer then drill/bore out a unfinished sprocket. But I'm lazy.

My only critique of the kit trannys is that ours seem to run out lubrication real fast. That may have something to do with how we (mis)assembled them, but I notice that they need periodic lube jobs. If thats my only beef with them, I'm happy enough to go back to dealing with all my real problems on the bot, like where I'm going to find room for ballast.

-Andy A.