13 January 2014

EtekChopper: Mechanical Odds and Ends and System Integration

Whew, it's BEEN A WHILE! Everything in this post happened in August 2013. 

While I've gotten a lot done in the past few months, I've been too busy being a MechE senior and doing the grad school application and getting A's in my classes thing to document it. Since I've been overhauling work on my motorcycle, and have actually written a couple of unpublished, more recent posts than this one, it's time to finish documenting everything that's happened since I got my Sevcon Gen4 working. 

Time to start making my modifications! First I want to replace the rear sprocket, which involves removing the rear wheel, remove the sprocket, and measuring the mounting holes to either order or waterjet my own. 

I was going to order a 56-tooth #50 sprocket for the rear sprocket, but turns out MITERS had one in the "Absurdly Large Round Things" drawer! SERENDIPITY! 

First came off the rear lights/fender assembly, and the black plastic fender (which seems to protect the engine/electronics from rocks and stuff coming off the rear wheel.)

next came off the rear wheel, but now I have this chain to deal with... I ordered a new chain of the proper size, so this one needs to come off. Thing is, there's no "master link" on standard motorcycle chain, and the only way to remove the chain is to remove the rear swingarm. 

I had a better idea...

Now to remove the original sprocket from the rear wheel for measurement. There is a pattern of 4 holes, each spaced 5.5mm from the center. 

The mounting holes of the 56-tooth sprocket I found are nothing like those of the CB750K rear wheel, though, so I used our mill+indexing head to make the proper mounting holes. 

Now came the challenge of mounting the batteries. 

Zipties should work just fine until I can design and weld steel tabs, right?! =]

Issue is the batteries come dangerously close to both the rear wheel...

... AND the front wheel/fender. I'll need to address this soon. 

I made a motor mount using everyone's favorite 2D H2O-based rapid manufacturing device.

And in came the motor and electronics! 

Time to test out the motor +throttle on the bike itself >:)

Now THAT's a motorcycle! 

More details on system integration coming soon...

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