Spacebar Jig; crazy idea?

Warped spacebars. Nobody likes them.

At worst they’re unusable, and at best they make stabs much harder to tune. There are various methods of straightening them; particularly with PBT bars which themselves probably compose the lion’s share of warpage - but none of those methods seem particularly… controlled… to me.

What’s more, many of them don’t work on or may damage ABS.

So, what do for someone like me, who wants a reliable way to straighten bars with no practice? Here’s my thought - this might be a big dumb, or it could possibly lead to a good thing - so I’d love some feedback about it:

I’m envisioning a machined jig with MX-style mounts in common spacebar positions - a hard metal thing to mount the spacebar on that will essentially hold it in the correct shape while heat is applied.

I could also see having some kind of straps or integrated weight thing to help with flatness as well, but my primary focus here is on straightening and lining-up out-of-spec spacebar stems.

Beyond that, I’m envisioning some kind of controlled heat application - and after some light research, I’m thinking water immersion is the way to go. At first I was thinking heat the jig itself, some other piece over it, maybe even a press-with-blanket type thing - but just immersing the whole thing in water at the right temperature seems a lot more simple. Maybe it could ship with a thermometer and a little chart of temperatures for different plastics.

The idea is to apply only as much heat is needed while the spacebar is being held to the desired shape - not just flat, but with the mounts all straight-up-and-down. The idea is also to de-couple the straightening process from skill as much as possible - I want this to be easy, approachable, and un-intimidating.

I love my ABS MT3, but about half my spacebars have just enough warp to make them into stab-nemeses. Totally gorgeous, excellent-feeling cap sets sounding worse than they should on my otherwise reasonably-tuned test keeb… surely there’s a better way. That’s what got me thinking; if only I had something to hold the stems in the right position while I apply a little heat…

So - more trouble than its worth, or might I be barking up a fruitful tree here? (Or has someone already done all of this barking and/or harvesting?)


Not crazy but I think it makes more sense as a service than a product. A few of us could get the device or implement their own and offer the service. Spacebar Doctors?

Alternatively, keycap vendors could offer No-Warp QA option for a few bucks per keyset, just a person who’d make sure there are no warps. They’d have the incentive to justify getting equipments needed to check and repair warps cost-effectively.


A good idea but a small detail I would comment on: make the mounts loose fitting. The first time I decided to straighten a space bar, I heated it and put it on an EnjoyPBT keycap tray (one with fairly tight mounts) to cool.

It worked well and straightened out the keycap, BUT the tight stems on the holder stretched out the mounting points.

So now this is now my only PBT space bar that I have to use plastic wrap shims on to keep tight.

But a diy Jig out of common parts…. Maybe Lego? That would be handy


I don’t know if it’s true, but I read that you can put the warped keycap on the 3d-printer heat bed and heat it up and then slowly lower the temp to fix it. :person_shrugging:


Hey, I had exactly the same idea !

They are things that made me think it does not look as simple as it is.

In the case of a banana warped space bar, the plastic may be bent so much that trying to force it in the MX mounts could break or fatigue the plastic.

I am also concerned about deforming the plastic around the MX stem insert when the whole keycap has been soften, that could result in a too loose fit with the stabilisers stems after the operation.

For 1 maybe have the MX stems as a separate machined piece that you could screw progressively during
keycap heating.

For 2 immerging in boiling water will heat all the keycap including the stems, so have to find a way to heat only the outside of the keycap and not heat the stems too much.


If you have a sous vide setup in your kitchen, the temperature chart (and jig) would be enough to make this a hands-off process. A quick bit of googling suggests PBT warps around 140F, which is definitely within the capabilities of the immersion circulators sold for home use. I imagine saving a recipe on my Anova (“poached PBT, 145F for 15 minutes”).


There is no problem putting PBT in water at 95° Celsius


Contemporary stone stew :upside_down_face:


It could be a machined mold with turn handles/knobs that allow you to slowly shape/stretch the key as the heat softens the plastic :thinking:


What a great idea, I wish I were inventive enough to contribute. My gmk Godspeed 7u would be thankful.


You know who should be investing time and money into fixing the warped spacebar issue…the manufacturers who make them. :microphone: drop.


It’s wild to think how many problems enthusiast have to end up solving on our own sometimes. The things we do for the pursuit of the betterment of this hobby!

I think making a jig and demonstrating it would probably be great at helping influence others to try it themselves. The more people who get this idea means more people will make better iterations we can all learn from. Maybe eventually this knowledge will trickle through to manufacturers.

Like think of prelubed switches. They wouldn’t exist unless enthusiasts lubed switches and you know what? Before enthusiasts lubed switches, one of the main reasons we didn’t see that many (or any) prelubed switches was also because manufactures didn’t know where to lube and how much lube to use. Now they have thousands of example to reference and integrate into their production methods.

I’d love to take a look at your spacebar jig and try one myself :thinking:


and i could finally un-banana some kbdfans EC bars. though i guess most people stick to official Topre and don’t have these issues


Fortunately I do not have a lot of experience with bent spacebars so please forgive my ignorance. If most of the bending would be curving up due to shrinkage, so one warpage only in one plane.
2 metal plates clamped together on the top and bottom of the spacebar then apply heat via Sous Vide machine (which is a fantastic idea @jshufelt).

Quick mockup I only had one metal ruler but you can get the idea. Dunk something like this in sous vide pot of water at a certain temp depending on plastic for x minutes. The clamps don’t need to be super tight just enough for the bar to be flat.

Would be cool if something like these wood clamps came in all metal (heating wood could lead to warpage)


I wonder if there is a worry about creating a new “flat” spot on the top of the spacebar when using a ruler up there. Obviously it would be better than deformations due to the clamps, but I wonder how much that could change the geometry of the spacebar.

I guess in theory it should straighten before it creates a new flat surface on the curve of the spacebar


I know some heat/pressure processes use a sort of heat-resistant blanket to prevent flat spots and/or sticking; I wonder if something like that would work here. Basically something that can transmit the heat while being physically malleable to a point.


Going wild here,
A mold the spacebar fits in that has heat applied to straighten the spacebar… This would be so troublesome for such a minor inconvenience lol


Fair point regarding flat spots. A mold of the top of the bar so the contours remain in something like concrete then sandwich that against something flat with just enough force to flatten the spacebar. Or multiple runs if it is really bad. Just a thought though.

Edit just saw your reply we are thinking the same way lol


At the end of the day it’s the keycap manufacturer that really should be making and using these straightening jigs in their factories (if they can’t mold a straight spacebar in the first place), rather than expecting end users to shell out substantial sums of money for a specialty straightening jig. A fancy $2000 straightening jig with custom-machined parts, integrated heaters, a fancy temperature controller that can do custom temperature profiles, etc. would be very feasible for a manufacturer to afford since they can spread that cost out over thousands of keysets, but it would be completely unreasonable for end users to own one that’s 1/10th the cost.

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Totally agreed, and I know I’ve seen the question asked before; “why don’t they just straighten them after cooling if they know the bars will warp?”

The question remains. :stuck_out_tongue:

Still. There are folks running switch break-in services with switch break-in machines you can buy on AliExpress; mostly 3d-printed stuff attached to a chunky motor. It makes me wonder how cheaply this could be done with reliable results. Sure, machined steel would be ideal, especially for doing this in a factory setting - but what about ceramic? Forged carbon?

Ideally those in the best position to be doing this would be doing it - and I think they will be, eventually - once it becomes a marketable thing, once the masses (relatively speaking) know it’s good.

I’m trying to imagine someone marketing lubed keyboard switches named after marsupials to teenage PC gamers in 1992…

I don’t think we’re all that far-off, though; who knows, we could be one really good YouTube video from lighting the fire under some manufacturer’s ass to have bragging rights to the first machine-straightened, verified-to-spec space bars.

Perhaps more likely is that some creative and passionate folks will figure out how to get it right, and then some other differently creative folks will figure out how to make that cheap and efficient.



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