ALPS double action switches [SKCPKB and SKCLKB]

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zrrion

04 Jun 2021, 05:06

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Here we have some double action switches from a Cannon AP350. Not sure why alps used both kinds of double action switches in the same typewriter but whatever, just means I don't have to buy 2 machines to get these. They're both neat switches too. SKCPKB is the long one and is platespring, while SKCLKB is the SKCL-looking one. I don't know why there are so little pictures of these things, maybe folks loose some of the smaller parts and are too embarased to post pics of their mishaps. Whatever the reason I've corrected that oversight. Maybe I'll even get around to adding them to the wiki some day. For now feel free to use these pics anywhere you want I guess. All keyboard pics I post on DT are public domain or however close you can get where you are.

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look at this mess. someone got paid to design this and other folks got paid to make it. wild

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Here we have the parts laid out, as you can see there's a brown switchplate. There is also a dummy blister switch in the bottom that serves as a source of tactility and extra resistance got the brown switchplate. The small -shaped spring just kinda sits in the slider so you have to be super careful not to drop it. Some older SKCC-like switches from alps called SCK used this same sort of spring to actuate their contacts, although that version had a longer track in the slider to allow for hysteresis. Snacksthecat has a partial examble of one such switch and I'm sure other folks do as well. would love any leads on where to get some of those.

these feel a lot like the idea ALPS was chasing with SKCC double action but almost perfected. I think instead of a metal spring they might have been able to build that into the plastic of the slider but if it works it works

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But I have no idea why alps made these. Who wanted these? they use 2 different spring+pusher setups to actuate 2 different sets of contacts, and because of how horizontal each contact is there's no way to do it in a 1u space so you end up with this really weird 1.5u-ish switch that you can only use for large keys. the AP350 uses them on the space bar, return key, and backspace. No idea why since there's already SKCLKB to match the SKCMAF the rest of the thing uses. Maybe ALPS didn't want to pair linears and tactiles together like that, but they did for capslock despite having the option to put SKCPFB which would have given them a tactile LED switch. No idea really, Cannon likely made the call as opposed to ALPS and there's no telling what was up with those guys.

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ZedTheMan

04 Jun 2021, 07:00

Very interesting! I've never seen the SKCLKB before, I've seen the platespring one though. Some real oddities, here.

Johnbo

04 Jun 2021, 20:45

Thanks for the teardown. I actually just got some of these SKCPKB switches and am trying to think of some uses for them

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soyuz

04 Jun 2021, 22:35

SKCPKB is so uniquely horrid. It is my most hated switch. It feels like pressing a key through lumpy old pudding.

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zrrion

04 Jun 2021, 22:52

soyuz wrote:
04 Jun 2021, 22:35
SKCPKB is so uniquely horrid. It is my most hated switch. It feels like pressing a key through lumpy old pudding.
This is a problem with SKCP's design, it bottoms out on the plate spring, which can result in the plate spring becoming deformed. SKFF doesn't have this issue as the bottom out doesn't directly interact with the plate spring. They can still wear out the plate spring from use, but it only effects the tactility in SKFF and not the bottom out. For these typewriters they likely went to secretaries and are very well loved so plate spring starts feeling like that. The 3 of these double actions that I have all feel and sound very different. Return sounds the best and I bet that's because it was used way less than space or backspace.

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