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Unread 09-09-2006, 22:19
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Holtzman Holtzman is offline
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AKA: Tyler Holtzman
FRC #2056 (OP Robotics)
Team Role: Engineer
 
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Re: Fabricating Aluminum Sprockets

1114 has been machining our own aluminum sprockets for about a year now. We use a bench top CNC machine(like those found in many high schools) and a plain endmill. 1/8th for #25 and 3/16 for #35 sprockets.

We usually just use 6061 aluminum plate. Again 1/8th thick for #25 and 3/16's for #35 sprockets. We've never bothered heat treating them

After the milling is done, we put a slight chamfer on the teeth in the lathe. And a little deburing later and your done.

One of the really nice things of making your own sprockets is that you can put your own lightening pattern and bolt pattern in, and as long as it can all be completed without removing the piece, you don't need to worry about re-zeroing the machine. Everything comes out nice and concentric.

Due to the relatively small size of the milling machine we use, the biggest sprocket we can make is about 6.5" in diameter. That works out to something like 80 teeth for #25 or 53 teeth for #35.

We actually cut some out this afternoon for an off-season project we're working on. I've attached a jpeg of the inventor drawing. I don't have a descent camera with me, or I would post an actual photo of the finished product. It was 40 tooth #25.
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