Kailh Box Switch Stem Measurements and Possible Problems


Yeah, I think there needs to be more clarity around these specs especially as I feel like we’re seeing more and more keycap profiles from different vendors. It’s important that everyone is working on the same page in terms of tolerances and design specs.


I’m not sure that I can really agree with saying the problem is ‘not widespread’ given the number of affected people across 4 forums (here, geekhack, /r/rmk, deskthority). Also blaming it on the keycaps we haven’t seen a corresponding set of damaged/stretched keycaps on normal Cherry boards seems logically incorrect as well.

The as-measured stem size of Cherry switches people have been reporting don’t match up with 1.31 +/- .02 mm. The seem to be in the range of 1.27-1.29.

That drawing references a bunch of DIN specs, has anyone gone and read all the DIN specs to make sure none of them have a note like ‘dimensions apply before shrinkage due to cooling’ or something like that?


So a potential confounding problem with that argument is that there is a pretty large selection and confirmation bias going on here with cracking. Only the people who are having issues are posting, and from what I’ve seen when they post only a handful of the switches are having issues (for instance I haven’t had any issues with mine other than maybe one keycap, which still sucks). This does suggest that this is an edge of tolerances issue. If box switches were systematically too large you most expect a large fraction of the switches on every board to crack (like upwards of 50% not 5%).

Also I am not too sure I trust the measurements of a lot of people, like every person has a pretty large shift in measurements. There have been some people who have measured cherry to 1.3 or 1.31 and as small as 1.24.

The 1.32 box has seemed to be a major component of the issue though, I am not saying it isn’t, but 0.02mm is a ridiculously tiny change. And if what Seth says about TTC, Kailh’s non-box, Greentech, and cherry, then the swtich to 1.3±0.02 should fix the problem.


Oh my dolch :frowning:


I’ve just noticed that on the KBDFans website that they now say “NEW VERSION” for all BOX switches on offer. Example:


Can somebody confirm or deny that these are the new retooled versions with the 1.3±0.02 stems? If so, does this fix the keycaps cracking problem?


They are the new re-tooled versions. KBDfans posted these two images on their Discord server earlier today.


I got 100+ new box royals in this afternoon, quickly measured 20 samples and found the vast majority of them were right at 1.28 mm with the largest measurement at 1.29 and smallest at 1.27. The stems seemed to be very consistent.


Have there been any discussions around selling new re-tooled stems? I’d much rather stem swap than mod existing stems or buy a whole new switch.


It’s disappointing that Kalih and vendors do not appear to be serious about addressing the old stems.
I’m not going to buy Kalih products unless they do something about this mess. Is it so hard to sell re-tooled stems a la carte for limited time?


TBH - sounds like the kinds or responses someone would give when they’re trying to ensure they don’t end up in a lawsuit.

(Full disclosure, I do not and have never owned box switches so I am unaffected. Just a 3rd party observer to the discussion)


More measurements! Mike gave me a handful of 3 different kinds of retooled box switches and here are the results:

Retooled Box Jades Retooled Royals Retooled Navy Switches
X-axis thickness Y-axis thickness X-axis thickness y-axis thickness x-axis thickness y-axis thickness
1 1.29 1.09 1 1.29 1.1 1 1.28 1.09
2 1.29 1.1 2 1.28 1.09 2 1.28 1.1
3 1.28 1.1 3 1.28 1.1 3 1.28 1.11
4 1.28 1.09 4 1.28 1.1 4 1.28 1.1
5 1.29 1.09 5 1.29 1.1 5 1.29 1.1
6 1.29 1.09 6 1.29 1.1 6 1.28 1.1
7 1.29 1.1 7 1.29 1.1 7 1.28 1.1
8 1.3 1.1
9 1.28 1.1

These all seem pretty consistent with the changes Kailh has mentioned they would made. I know of at least 1 report of someone reporting stem stress (not cracks), so I’m not sure if the issue has been 100% solved yet. I have a lot of Novelias I can measure in the near future as well.


I’d be interested to see how some new switches would measure with some more precise instrumentation. With temperature compensation set on a CMM I have access to, I measured an old box white at 1.1275 on the y-axis and 1.3356 on the x-axis. Unfortunately I don’t have any Cherry switches or retooled box switches for comparison (yet).

Also, I never had any cracking issues with my box whites, though they were definitely tight fitting (EPBT BoW Hiragana caps).


I think it’s pretty safe to say that PBT caps endure the stresses of old box switches than ABS. I have a set of Box Navies paired with round one /dev/tty and there are no stem issues at all. I’m going to build a board for my brother-in-law once Espectro lands which will have round two /dev/tty and OG box navy. I’m not worried at all.


To anyone who bought BOX switches through CandyKeys, they’re offering replacements free of charge. I bought my old BOX Navies from them back in March and wasn’t sure if they were willing to replace them, so I contacted them and asked - and they promptly told me they’ll happily replace them too. We won’t even have to send back the old switches. :ok_hand:

So that’s pretty sweet. Now I just hope that the retooled version have actually been fixed. :face_with_raised_eyebrow:


If you’re able to measure much more accurately, I can send you some switches if you’d like :slight_smile:

I can send some retooled cherry, retooled box, preretooled cherry, and preretooled box switches. Just let me know!


My big question is if the nubs are completely gone or not, more than the thickness.


according to this post, retooled are stressing caps, but at least not breaking them – https://geekhack.org/index.php?topic=96323.msg2664777#msg2664777


Cherry may not be perfect but they never ran a train on my caps.


This is very disappointing. I was eyeing Box navies or jades for a Tada68 build, but I’m not sure I want to do that now. I don’t have a lot of keycaps that would be affected by this, but I feel like this could kill resale value on the board if I decide to sell it.

I’m already wondering what I am going to do with the non-RGB Pok3r I have with r1 Box Yellows. Not sure I want to switch swap that again.


right now I am running box jades on a HHKB Tofu with a set of Maxkey Lime to assess for damage after an extended period of use. I will update after next week.