Kailh Box Switch Stem Measurements and Possible Problems


We now have people reporting in that XDA Keycaps have started to stretch and crash from BOX switches: https://www.reddit.com/r/MechanicalKeyboards/comments/93jwkq/psa_xda_caps_will_break_on_box_switches/

I have also heard that cheap keycaps should be having issues. (I have destroyed some from a old AJAZZ keyboard by putting the keycaps on BOX Jade switches.)


This is some sad news. I have both navies and jades for 3 builds, but will most likely go with something else now. Wonder if the ones with updated stems will be available in Europe too? I would even be okay with changing just the stems if that would be a possibility.


This weekend I will start measuring my GMK keycaps to find out GMK’s mean & median for their keycaps receptacle thickness as well as try to establish their level of tolerance.

I wish GMK would publicly release their stem receptacle measurements like PMK/SP has, but at this point all I can do is measure.


I’ve sent today GMK about 40 Hako switches (which are one of the batches that has caused fractures on GMK keycaps), so they’ll have “pre-retooled” box switches to compare with once the new ones are made.


I have received the tolerance amount from SP/PMK:

“Measurements provided are after shrinkage - the tolerance is +/- .005 inches. These have been the standard specs for our mounts since the company inception in the 70’s and we don’t have any plans to change our tooling. Note that we have NEVER had complaints about the mount size for the Cherry switches, unless there was a defective issue with the tooling.”


Decided to poke at some more of my caps that I’ve got on Jades at the moment since discussion was still active. Checking my G20 Semiotic set I’m not seeing stress marks or cracking, but putting them onto some Gat greens(200g+) the fit is such that they almost want to stay on for normal use, but if I try to get them to pop off they actually pop up high enough to catch them. So while amusing, it does show that even PBT caps can be affected by the Box switches.


so don’t buy bad quality keycaps


Kind of ~offtopic buuut… are Hako switches in any way connected to Hako soldering irons? Probably not, but I have to ask. FX888D is very popular among keyboard enthusiast for switch soldering.


Apparently Hako means “Box” in Japanese, and that’s why they are named that. Forget where I heard that, maybe Top Clack

(also the soldering iron brand has two K’s)


Yeah, that makes sense. I thought it has to do something with japanese origins.


For those looking to meme on this matter: Shitpost General



Something just occurred to me: Has anyone compared the dimensions of the Kailh Box with Cherry MX Clear? I’m curious how different they are considering MX Clears have had some stem issues - but clearly [audience laughter] doesn’t seem as serious as the Box switches.


I measure one row of my Race 3 (for sale!) which has mx clears. I did not measure y axis length because i could not get an accurate number due to the notch cherry has in their stems.

MX Clear Stem x-axis length x-axis thickness y-axis thickness
1 3.95 1.31 1.11
2 3.96 1.32 1.14
3 3.97 1.31 1.14
4 3.97 1.3 1.12
5 3.96 1.26 1.12
6 3.97 1.29 1.16
7 3.95 1.31 1.13
8 3.96 1.3 1.11
9 3.95 1.31 1.11
10 3.95 1.31 1.12
11 3.96 1.29 1.13
12 3.98 1.3 1.12
13 3.97 1.28 1.1
14 3.97 1.3 1.13
15 3.97 1.28 1.15
MEAN 3.963 1.298 1.126
MEDIAN 3.960 1.300 1.120
STDEV 0.010 0.016 0.016
CV 0.24% 1.21% 1.46%


I managed to get a box jade x axis from 1.31 mm to 1.28 mm by using a metal keycap, which i modified by using a file to roughen up the prongs that contact the x axis and then bent them in slightly for a tighter fit. I then forced the keycap onto the stem, and rocked it along the x axis for a few minutes, slowing taking it off with a similar motion. It is a lot of effort for a single cap, but it kind of worked. I will try to find some keycaps to test on modified stem

Metal keycaps used: https://www.amazon.com/gp/product/B07F9XRB7S/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1


Which metal keycap did you use? This would be a great fix!


It addition to the modification, I am testing fit with a GMK cap, and SA and DAS from SP.

Brief testing consisting of inserting and removing cap 20+ times and several hundred actuations.

So far no caps have cracked, and I have also tested fit on an Aliaz switch and everything still seems like it fits, it is noticeably less tight on the Aliaz, but by no means looser than before being mounted on the box stem.

These results are by no means definitive, and so far I have only tested a single stem on three individual keycaps. I will see if I feel up to spending a few days to get a larger number of stems modified and using them in a hot swap board with a grabbag set of keycaps (dsa or sa)


Edited info post with link to keycaps used

I have also ordered a 1.5mm Chisel to attempt the unthinkable - I am going to attempt to manually shave the sides of the x axis


This is what I’ve been trying on my BOX blacks, except with a needle file. It is working surprisingly well; the force to mount the keycaps are comparable to my MX browns, and the force to remove the keycap is significantly less than a stock BOX black. However the process is very long and tiring.


I have 4 boards with box switches (burnt orange, blacks, royals and navies) and haven’t found any cracks or stretch marks on the keycaps.

If I ever moved them to another keyboard and they were loose I suppose a plastic food wrap mod would make them tight again. That always seems to fix loose stabilizer mounts.


So I feel like an ass, but I still don’t got my measurements for you guys (give me hell I deserve it… :frowning_face:). I got the caliper from my buddy at work but the read out screen is broken on it. Then I was just gonna buy a new one this weekend, but I injured my knee at work last week & had to go to the ER which sucked up a good bit of my extra cash. Hopefully gonna be getting a new caliper in the next few days & will have some numbers to add here, sorry guys! :flushed: