Known stem breakers in the wild

The follow is a list of switches that are confirmed to damage GMK keycaps. Do what you will with this information. Each entry has been verified by a user of this forum, generally with accompanying photos for proof:

Known to cracked stems:

  • Cherry Clear (v2)
  • BBN Linear
  • Kailh Christmas Tree
  • Kailh FLCMMK Ice Mint
  • Kailh Midnight Pro (Tactile)
  • Realforce RGB

Suspected switches (caps stretched):

  • Kailh Box Mute Jade
  • Tecsee Blue Sky Tactile
  • Tecsee Carrot

If you know of any switches on the market that have wrecked your caps, leave a reply. I’ll add it to the list. Photography is welcomed for evidence.


I thought I would start a thread that keeps track of known switches that may break your GMK sets.

Long story short: I got some BBN Linears in the mail today. These will break GMK keycaps.

Longer explaination. I’m excited to try out these BBN linears. They are those weird ones with a PC bottom and Nylon top. You know… reverse of what you usually see. But I thought I would like them because I detest the high pitch noise on most switches top-out. They are really nice. Nothing ground-breaking, but a nice smooth linear with a decent sound profile out of the box.

So, I put them in my Frog TKL (hotswap) with a PC plate. Got a chance to use my new Geonworks plate fork. It works as intended and helped me get the switches in without issue.

Then I go to install keycaps. I have GMK Thai Tea sitting beside me, so that’s the one I went for. I was about 14 caps in. I kept hearing a sound like they were possibly breaking on about every other switch, but they didn’t feel overly tight. I thought… surely that’s the switches snapping into plate or something. Right? RIGHT??? Get out my iphone and turn on the 3x zoom with the flash on to inspect… yep. Broken stems.

So now it has an ePBT set on it. :slight_smile:

If you know of any switches on the market that have wrecked your caps, leave a reply. I’ll add it to the list.


I’d add any Kailh switch with the same shaped stem at least to a “sus” list; I haven’t confirmed it with actual GMK, but I have damaged some cheap cap stems with the FLCMMK Ice Mint and Christmas Tree switches. Great switches, by the way - but sus.

Here’s a close-up of a Christmas Tree by ThereminGoat, straight-on one of those stems:

Those nubs on either side of the horizontal cross bar are the culprit - not quite as bad as the old BOXes, even if they look worse.

Here's some blurry test photos from my phone:

Control; new cap, no damage

Damage from stock Midnight Pro tactile; look at the whitening at the horizontal ends of the cross shape. Here’s another angle:

Now here’s one after being mounted on the same switch, but after it’s been run through a specialized tool called the Geon Trimmer a few times (a couple links in the next summary):

Still some light stress marks, but nothing scary. You might be able to see the plastic forced out of the way by the tool at the base of the switch stem. (Caps aren’t likely to touch that; just to show the tool has in-fact moved some material out of the way.)

A fix - also a pain in the hands, but it works:

Cruciformers aren’t available anymore, but the Geon Trimmer is - and while processing a whole set of switches with it will make your hands hate you, it does work.

Geon Trimmer | KeebsForAll

Geon Trimmer – GEONWORKS

I processed a set of 104 old BOX Jades with this tool and I’m happy with the results. Felt it in my hands for a few days, but reclaimed what would have otherwise been for-parts / e-waste switches. I’m envisioning some kind of adjustable press for this thing…


I feel like this is a significant issue that doesn’t have enough discussions, for some reason manufacturers don’t stick to the Cherry MX standard they base their switches on, and it slmost feels like very new switch has an even thicker stem than the previous one.

Tecsee switches from what I’ve seen also tend to have thicker stems, I had a pack of Tecsee Carrots and they had a very tight grip and streched a set of keycaps I had, I’ll also add the JWK switches with the nubs to the suspect list, I haven’t used them but it can’t be good or in spec.

Also, is this an ABS thing or are PBT keycaps tend to break too?


What I’ve heard over the years is that PBT is harder than ABS and thus less flexible and thus more brittle so I’d think that it’d be more prone to stem cracking. Probably a mix of materials that go into ostensible PBT caps though that could offset the brittleness.

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Wow. Didn’t notice this bc I now only have one ABS keyset which I rarely use.


Kailh Mute Jades have definitely stretched my Tai-Hao ABS set. No cracks though yet.

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I’ll add it to the Sus list :slight_smile:

FWIF, I actually had my realforce RGB crack one of my stems (GMK Bento)

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Man I thought we were over this issue with the BOX stem debacle. I get that there is variances in plastics production, but you’d think they would air on the thinner side just to be safe.


Seems like a lot of the issues are specifically related to GMK caps. Perhaps GMK caps run slightly tighter and more brittle than others?

It’s not a huge deal to me. I’ve cracked caps a few times. They still work fine. But I know some people are very particular about what they spend money on. And it seems that people new to the hobby can often have exceptionally high expectations when it comes to value for the money.

I’d just hate to imagine someone saving up for their one and only GMK set and finding out it got cracked by one of the offending switches.


That’s correct, only the other way round.

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Everyone should get this, it’s an excellent tool for saving keycaps.


It can be used in any direction regardless of the direction

But IIRC the Cherry MX spec state different thickness to every axis, with measurements that confirm it, so this might have the potential of actually taking the stem out of spec rather than putting it in?

The caps fit snug and aren’t loose…so, I’m assuming it’s fine. When you use it, you can feel how much variance exists in the same batch of some switches.

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Can confirm, the Geon Trimmer is awesome. Doing 100+ switches with it will all but kill your hands, but it’s literally the only effective method I know to reclaim stem breaker switches - and it does work.

This is true - though I don’t think there’s much risk in the tool shaving the stem down too far. Instead of using a sharpened edge like the Cruciformer did, the Geon Trimmer essentially just uses force to mush the plastic out of the way.

On the down side, this means it might take three or four runs through the toolhead before the stem is good to go - on the upside, it lets you dial-in your adjustment.

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Official Cherry MX Ergo Clears cracked one of my GMK keycap stems and stretched a few others out. I put GMK Mitolet on Mekanisk Ultramarine Switches v1 without a problem, but as soon as I put them on Ergo Clears I heard cracking noises. I know original Clears have been known to crack keycap stems but I was surprised the new ones did as well. I did however put SA Oblivion v2 keycaps on the Ergo Clears and there did not seem to be an issue.


I’ll add the v2 clears to the list. I know many people were upset that Cherry didn’t address the tight stem issue on the new molds.


Tecsee Blue Sky tactiles for the sus list. They aren’t as bad as MX Clears, but they still have enough of a death grip that I’m not getting them near good caps.

Kind of a shame since they’re otherwise good tactiles with a nice feeling 2 stage spring.

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