Rubber Sheet

ARD, one idea for your platen might be to use some suitable solid material (steel, nylon, not sure) as a central core and pull a rubber tube (such as an inner tube) over it. The thinness of the rubber might give it just the amount of movement you need to make a nice print of each letter.


  • I am sure this is going to confuse everyone, as I have not mentioned the device here. Quite why the comment wasn't sent to me by e-mail is beyond me... But as it has been made public, I had better explain.

    The device in question is a Kent Chromalog 2, an integrator for a chromatograph or similar instrument. It dates from about 1970. There are some photos in my flickr account, tony_duell.

    The unit has a very odd printer consisting of banks of electromechanical counters (accumulating the time from start of run and integral of the current peak). There are a pair of flat platens. One in front of each bank, operated by a large solenoid in the unt. The idea is that when it detects the top of a peak it fires the time platen solenoid, when it detects the start of the next peak it fires the integral platen solenoid, printing the area of the last peak, and then resets that counter to zero.

    The integral platen solenoid also advances the paper by driving a couple of rollers.

    As HP calculator people will know, rubber/elastomers decay with time. In this case there are 3 areas that have failed, the 2 platens, the feed roller and a damper strip for the solenoid return.

    I have bought some rubber sheet from the excellent 4D Model Shop in London. A couple of strips of that will replace the damper. I will have to experiment with the platens to get the thickness right (either 3mm or 2 thicknesses of 2mm). For the roller I intend to use O-rings as tyres (it doesn't have to be continuous across the paper). I have some in stock. I will have to turn some new aluminium rollers for the O-rings to go on, that is not going to be too hard.

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