Monday, December 28, 2015

Working on a repair to the cracked ceramic feed wheel on the 1442 card reader punch


I decided to use my UV hardening material, Bondic, to build up the broken section of the wheel that moves cards through the punch station. Once I get the material up close to level, I will have to invent a method to establish an accurate radius for the new section. I intend to spinkle grit onto the top layer as a way of establishing a similar grip to the remaining section and other wheel.

It was a very slow and careful process to build up layers and harden them, approaching but not exceeding the height I need. If I overshoot I will need to find a way to file this surface down, something I don't relish. Still, it is likely I will need to do this and the maker of Bondic says that this is feasible with various standard methods.

I ran out of my first vial of the material, ordered more, but need to wait a few days for it to arrive.


Unfortunately, while it looked like it might be correct and was advertised as an IBM mainframe key, the key I received is probably for a cash register or other non-mainframe instead. I will continue to seek out the key which lets me switch the between CE mode and customer mode meters.


  1. Is the wheel radius exact, so that the machine depends on a certain amount of rotation to move a card a known distance? (turn X degrees to move the card one column) Or is there an axle adjustment allowing for some small difference in diameter, with card motion being gauged in some other way?

    Obviously you'd have a lot more freedom in the second case. You could look at building up the entire rim of the wheel, ending up with a uniform thin "tire" of Bondic.

    In either case, I would think you could bring the built-up part into round by chucking the wheel into a drill and spinning it against a file or an abrasive. However, that technique would likely not work after you glued abrasive to it. How to get a uniform abrasive layer? I don't suppose it would work to just super-glue a strip of wet/dry sandpaper around it? No, it's probably under heavy spring pressure against the card.

  2. There is a common axle with two wheels on it set up so that the wheels grip the top and bottom of a punched card to move it forward. There are pressure rollers that pinch from the bottom of the card to hold it against the wheel when the card is being moved forward column by column.

    While I can adjust the pressure of the rollers, the position of the wheels above the cards is fixed by the metal frame in which the axle is held. That means that the diameter is relatively exact - if the diameter is too far off, the card will 'cock' to one side or the other while moving through the punch station.

    The requirements aren't machinist-accuracy, which is the only reason I can get away with this. Still, I have been worried about the ability to forge a good enough repair to this wheel. I don't think I can add Bondic over the unbroken arc of the wheel, instead I need to build up the missing arc to match the ceramic original portions.

    I don't want to abrade down the 220 degrees of intact wheel, so the method of spinning the wheel won't work. Whatever I use to abrade down any high points has to be accomplished at right angles to the rotation, applied only to the Bondic portion.

    The ceramic surface has a low density of relatively high grains, fortunately, not a very uniform dense field, so that I believe I can recreate the 'grit' by sprinkling similar sized objects into the bondic, pressing them into position and then hardening everything.

    There are three possibilities after my repair. First, I might have repaired it sufficiently to accurately punch cards with the 1442. Second, I might have repaired it enough to allow reading cards, with them registering correctly and moving properly through the punch station. Third, it might not be able to successfully read or punch. Since I am assured of the third case with it broken, I have to take the gamble.

  3. The pressure rollers are rubber and the section of the card bed where the rollers meet the wheels have rectangular open sections. This would allow the card to be slightly lower on one side, if my wheel is a bit too large in diameter. I think the other guiding rollers and pressure adjustments will let me compensate for small variations in diameter, but frankly this is an assumption.