Intro/TLDR
I have been experimenting with various spacebar inserts since I’ve been into the hobby (about a year).
I like how sorbothane (aka sorbo) inserts work on spacebars.
I would like to share my experiences on the matter.
First encounter
The very first attempt was using a crudely hand-cut insert fit under an SA spacebar as shown:
I’ve used a 40 duro 0.10" sorbothane sheet from Amazon [link], scissors and office staples to cut the insert out of the sheet.
Keyboard setup was as follows:
- Tofu 60%
- Holy Pandas
- ZealPC stabs
- Maxkey SA set
Upon the insert installation, the effect on the spacebar sound had been evident immediately.
My personal textual description of the effect is that it became cleaner from noises and lower-pitched, but not silent.
I did not make any “scientific” sound recordings to demonstrate the difference, but here is the non-scientific, asmr’ish version: Tofu-0 - YouTube
Using similar inserts on other stabilized keys had no effect that I could notice in this setup.
Rationale and further attempts
After reading on the internet and experimenting I arrived to the following understandings:
- Spacebars and stabilizer are oftentimes (if not to say virtually always) crooked or warped, at least to a certain degree, which causes unwanted vibrations traveling on the spacebar as it moves
- A big enough sorbo insert, that has a good contact with the spacebar and is compressed just a bit will consume and dissipate those vibrations effectively.
- Sorbo spacebar insert won’t help with stab rattle, switch or plate sound, but only the spacebar itself.
Unfortunately, sorbo is hard to work with:
- It compresses readily upon pressure and does not lend itself to be cut with a knife easily
- If you cut it too small, there would not be a sufficient contact and compression for the vibrations to transfer to the insert effectively
- On the other hand, if you cut it too big, or unevenly, the insert would not sit in place over time and will not maintain contact or even fall out.
If I recall correctly, I have read that sorbo as a material, is known to have a resemblance to meat, in particular, it would deform, but not tear, and remember its original form to restore to.
The above issues are problematic with keycaps that are shallow and have ribs in them (i.e. Cherry profile)
Before proceeding to my attempts with the GMK spacebars, here is one more SA variant that works:
Closeup:
Here I’ve used a 30 duro 0.25" sorbothane sheet from Amazon [link] inserts, cut with scissors and a wire cutter.
It is a cleaner cut and sits tighter, and has about the same or better acoustic effect than the first variant.
Here is the spacebar from the Leopold keyboard (OEM profile):
Here I’ve used a similar 40 duro 0.10" sheet, but this time with a PSA for adhesion to the spacebar.
The 0.10" is thin enough to put it in under switch and stab areas (*).
Cutting was done using small scissors, and it was very difficult to do accurately. You can see that I have cut one of the sides too short and the other one too long, which prevents perfect contact and compression.
The effect on the spacebar sound is evident, but to a lesser degree than on the SA spacebars.
(*not entirely true because of the plate mount stabs which protrude higher and press against the sorbo)
GMK spacebars
So far I’ve tested three different variants for 6.25u GMK spacebar sorbo inserts, here they are:
Using 0.10" sheet with PSA, I’ve cut small pieces to fit in between the ribs.
The effect on the sound is barely noticeable. My explanation for it is that each of the small pieces is too small on its own and that the degree of contact I was able to achieve is poor.
Using the same 0.10" with PSA, I’ve resected some of the offending ribs to be able to insert more sorbo, and in bigger pieces.
Suprisingly, there was no big improvement with this one. My explanation is that I have cut the sorbo too wide of a piece, and thus it separated in a few spots because there was too much of the compression.
Also I think that the amount of the material could be just not enough.
Using the thick 0.25" sheet, I’ve cut two pieces using scissors and a wire cutter. Then I’ve made the cutouts for the ribs using a small wire cutter and dremel with the disk tool (which was not fun).
Using dremel on sorbothane is apparently suboptimal becase the sorbo is too soft, but I could not find a better way to do these cuts.
It can be seen from the above photo that the sorbo-to-plastic contact is not good around the ribs. However, the contact on the sides is good, compressed evenly and there is more sorbothane overall.
This variant showed the strongest effect on the sound.
Other stuff
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Since sorbo had been hard to work with, I tried to cast liquid silicone into the spacebar (see above), which yielded perfect space filling and contact. Alas, it had absolutely no effect on the sound of cherry profile spacebars. Nothing at all.
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Foam has different effect than sorbo. Foam traps some of the sound waves, silencing things a bit, including even rattle from the stabilizer itself. In my opinion, the effect of the sorbothane is more interesting.
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Sorbotane adds heft to the spacebar, so you might want to increase the spring weight by 5-10 gram:
My conclusions so far
Obviously I like this mod, but cutting sorbo accurately is hard, and I suspect that not being able to do so hinders the effectiveness.
As a next step I would I like to get some of the inserts cut using die-cutting and make sure it indeed produces an improvement.
As for the taller profile (SA, MT3) the effect of hand-cut sorbo insert is already quite satisfying, in my opinion, and I urge you to a sheet of 0.25" thickness and try!
