Monday, September 22, 2008

Pot Mounts and Actuators

No, this has nothing to do with either cooking or weed.

The throttle and clutch pedals work by operating a potentiometer, which is a variable resistor. Each of these will be connected by a couple of wires to the Leo Bodnar load cell controller, which has circuitry to deal with switches and pots as well as the load cell.

The little bracket that mounts the pot to the top of the pedal platform is made from a 3/4" long piece of 1" angle aluminum. The pot is the black plastic box with the little solder tabs sticking out to the left.

The pot actuator arm is made from a piece of gray square plastic rod we ordered from McMaster. The minimum was three feet and we only need about six inches to do both pedals on both my and Amos' (yet to be built) pedal sets, so we have a lot left over! Fortunately this stuff cost about a dollar.

It's also very easy to work. Which is lucky because I drilled the hole for the pot shaft a little bit oversize in the first one I made, so I had to make two more. This took about ten minutes each.

Once we'd cut some 6-32 threaded rod for the pot pushrods we were able to assemble them together with the little R/C aircraft rod ends and 4-40 screws, nuts, and washers, and figure out exactly where we wanted to mount the pot mounting brackets to make sure we got free motion throughout the range of travel of the pedals.

We were also hoping for linearity of operation of the pot, but given the geometry that's pretty much impossible. However, we think that the nonlinearity will be advantageous, with slower ratio at the beginning of the pedal travel and higher ratio at the end of travel.

I think this is wicked cool!

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