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Slipring episode 1: FAIL

So we started our slipring adventures this weekend after a $50 trip to radioshack.  The slipring is one of the most crucial parts of the project.  It is essentially a disc with concentric copper channels on it mounted at the hub of the bike, so we can transfer power from the frame to the moving bike wheel.  We need a 4 channel slip ring, 1 to supply the +12v to the leds, and then the LEDs have three color channels, which in total will give us the option of producing 7 different colors.

We had previously contacted an industrial supplier of sliprings to ask about ordering two, and we were quoted over $200 per ring, obviously way out of our budjet, so we’re making them ourselves.  The process to make them is the same as making a circuit borad, but we have never done that, so our baseline knowledge on this was zero.  The process entails transferring a pattern of the slipring onto a copper plated board (more on this later), then soaking the board in etchent solution which is an acid that eats through the exposed copper, leaving only the copper which was covered by the pattern. 

The first way we tried transferring the pattern to the board, and the one which is the most popular for homemade circuit boards is to laserjet the pattern onto a glossy paper, then ironing the print onto the board while applying a lot of pressure.  the heat in theory melts the plastic based toner onto the board.  

We are mounting the sliprings to the hubs using the 6 bolt pattern usually used to mount brake rotors for disc brake bikes

The paper mock up on our rear hub:

The supplies:

Jon diligently battled with the studio copy machine and we finally got a good print onto glossy (we used magazine paper)

Ironing the first board:

After ironing you wait for it too cool, then soak it in water to peel away all the paper, theoretically leaving only the toner transfer, but of course nothing is ever that easy

it failed:

The second one failed too.  This was how we ended slipring adventure day one, the next day we tried a different technique, more on that in the next post.