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Thread: Best approach on plastics restoration.

  1. #21
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    Quote Originally Posted by Chuck(G) View Post
    Most of the maker vids and articles involve casting keycaps. Seems to work pretty well. RTV rubber mold and casting resin.
    True, an RTV mold is easy to make, and cheap. A 3D scanned mesh of one however could also replicate the two-shot molding of having integrated lettering when done with a twin-head 3D printer.

  2. #22
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    I recall asking Unicomp some years back if their keys were double-shot--their response was that, no, nobody does it any more--too expensive.

  3. #23
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    Quote Originally Posted by Chuck(G) View Post
    I recall asking Unicomp some years back if their keys were double-shot--their response was that, no, nobody does it any more--too expensive.
    There isn't a big market for expensive keyboards these days. I think Companies like Northgate made good keyboards with double shot keys because they charged a decent price for them, and it helped sell expensive computers at the time.

    The expensive-ish keyboards I see today are low volume gamers keyboards and those people tend to like a good click and lights more then keycaps that last forever.

    I don't see mold marks on the inside of my Model M keycaps so they are just painted?
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  4. #24
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    You can make a modern double-shot keycap keyboard, but the quality of the molding isn't great (wobbly edges on the characters and inconsistent widths see 'N' and 'M' as examples)
    The bigger problem are the choices of font the kiddies are using. They are just butt-ugly. I am typing on a nixeus with $100 of keytops that (mostly) look
    like a classic san-serif font.

    kb.jpg

    of course, they didn't have Apple <cmd> keys, so I used the dye-subl keys that came with it, showing wear, and a slightly different height
    Last edited by Al Kossow; May 25th, 2018 at 07:03 AM.

  5. #25
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    Quote Originally Posted by Unknown_K View Post
    I don't see mold marks on the inside of my Model M keycaps so they are just painted?
    https://deskthority.net/wiki/Keycap_printing

  6. #26

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    Quote Originally Posted by Chuck(G) View Post
    Thanks for that link. I had no idea there were so many techniques.

  7. #27
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    ...and there is plenty of information at the various keyboard hacker forums, including some who have done DIY dye-sub keycaps.

  8. #28

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    I had a look into using thermosetting plastics like Urethane in silicon molds. It is doable, but there are all sorts of issues that keep making the process more time consuming/expensive. For example for anything that has thin walls you tend to get bubbles, which needs to be solved with a vacuum chamber. This ends up being quite expensive, as the size increases. Second silicon molds start to sag as they get bigger. For example consider making the bezel for something like an IBM AT case. Using just silicon, the top half of the mold would sag and touch the bottom half, leaving a hole in the from of the bezel. It can be fixed by supporting the top mold (or using huge amounts of silicon), but the complexity/cost of doing this on a one off, isn't really worth it in my opinion.

    Additionally if there's a market for a part because it's rare as it breaks all the time, then you have to find the part first, that's rare, a catch-22. Also urethane that can deal with heat, tend to be more expensive, increasing the cost. The whole process is going to be much cheaper than something like ABS for small runs. To give an idea of cost for something like the AT case bezel, the silicon, alone is going to be ~50-75.
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