Ok! This has been quite some time now!
This weekend I finished a build of prototypes, using both MT3 (PBT dyesub) and GMK keycaps. The complete build is:
- TOFU case
- C3 stabs
- Holy Chicky switches (HALO stem inside Cherry MX housings)
- "Level 4" Lasgweloth (1.6mm PCB with bottom posts and central post removed)
- FR4 plate
I did the builds and the typing tests on stream. Links for the videos:
MT3 (please watch first as all the explanations are here):
https://www.youtube.com/watch?v=Q2_-qJvzRrcGMK:
https://www.youtube.com/watch?v=jJDqG2_j2iQMy thoughts are:
- The PCB works as a flex enhancer. I poop you not, the flex in this thing is marvelous to the point that if you press enough in some areas you can hear the PCB hit the bottom of the case
- It also works as a sound enhancer. As you guys can hear from the sound tests, a mere TOFU sounds like a top-mount keyboard. Except in two keys: TAB and ENTER. Nothing that can be done here, since they are exactly where the screws are. They don't sound bad -- in fact they sound like a top mount does when you have a fixing point right above a key -- but you can definitely hear a sound difference in these keys. The sound and feel is very uniform all throughout the rest of the keyboard.
- To be quite fair, this all just makes sense with a "level 4" Lasgweloth. Since the screw mounting points are removable, "level 4" is a 1.6mm version (it will be available in 1.2 and 1.0 too). If any other screws are included, specially bottom row ones, the case will make sound and there is no question about it. In this particular build, the PCB is held only by four screws -- the two lateral ones, below CAPS and ENTER, and the two ones next to those, below Q and P. Interestingly enough, these four points are almost simmetrical, meaning that when only these points are screwed, the pressure points on the PCB are uniform, which can explain the uniform sound.
- The only downside of all this is that the PCB being quite fragile and being held by only four points is quite prone to breaking on the pressure points when you are making extreme force and putting some keycaps in. So to remove and put keycaps I'd recommend unscrewing the PCB and plate, swapping the keycaps, and then screwing them back again, so as to avoid breaking anything.
In conclusion,
it works. I had never imagined a tray mount TOFU would sound amazing and feel flexy like this, and I'm quite proud of the results. There still are some things I want to do, though:
- Test the same build with rubber o-rings isolating the PCB from the screws. I am really curious as to how this will make the PCB sound. I am waiting for decent stabs to come in before I do this, as the ones I have here (R1 C3s) are not good to say the least and feel bad and sound rattly. I'm not the best luber in this world, but goddam I had a hard time making these work.
- Test the 1.2mm version. I refuse to test 1.0mm as it breaks quite easily. Then again, waiting for decent stabs to come in.
- Put a foam inside the case to damp some metal sounds and make the build sound less hollow.
As far as PCB development goes, it's done. I will make the release and order the final GB units soon to ship them to the GB participants. As always, I will update you guys and give insights here.
Godspeed,
You friendly neighborhood PCB designer
