Detecting S.U.piston lift

Whilst talking on the turbominis forum I had a brainfart and it turned into the Piston lift indicator. The Idea was to use a stack of optical slot sensors with a vane that sits on the piston to drive LED's to display the position of the HIF piston at any point of drive. The parts cost under $30 and it worked.

However once that was OK I realised that simplicity was better and I converted it to an "Analog" version. To make it I drilled a small hole in an old dashpot piston which lined up with the top of the pistonshaft so that an aluminium wire "pin" will drop through the hole and rest on the shaft. I glued a small nylon spacer over the top of the hole to give it some stability added a ring of Aluminium painted red to the pin as an indicator and encased the whole thing with a syringe, sealing up the end as well. I then taped a modified 16 station needle chart to the tube, offsetting it slightly to account for the jet position in the bridge. This works even better, I can see the piston lift at any point of drive and polishing is much easier now the guesswork is eliminated.

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