Using top mount in a Freebird TKL with Durock Medium Tactiles using TX 62g Long springs, I’ve been alternating between the FR4 plate and the POM plate that I got with the keyboard. Feel is my primary concern here between the two.
Pros of the FR4:
- Springier feel from the stiffness
- Enough flex to not feel harsh but still a little bit stiff
- Vibration transfer between hands is controlled enough to give a pleasant bounce that isn’t uncontrollable
Pros of the POM:
- More dampened feel that suppresses a little more vibrations
- More flex than FR4 but not enough to affect the consistency
- Added flex makes tactiles feel a touch more tactile. (if anyone is wondering its because MX tactiles produce tactility as an axial load that’s applied to the side of the switch during travel, so added flex in the plate produces a larger difference from the vertical load force vs the axial load, making the tactility feel stronger)
I like both plate materials but I’d also like to hear from other people on what they liked about plate materials combined with top mount keyboards. What’s your preferred plate type for top mount?
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I was waiting for the replies cause I was interested too!
I don’t really have much experience in this area. Lately I have been really like POM and PC plates more than anything else. FR4 is a good middle ground. Currently I have a KBD8x with a FR4 half plate and I really enjoy it, but with the flex cuts in the PCB and the fact that the case has little room in the bottom, you can hit the bottom of the case with the switch legs if you press too hard.
I have been debating going to either a POM or FR4 full plate as a remedy. I haven’t pulled the trigger yet, but my gut is that while I may prefer the sound and feel of POM, it may not fix the specific issue I have with my particular board.
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I was originally using the POM plate when I typed that out but I recently switched to the FR4 plate and actually ended up switching back to the POM plate after an hour and a half of having the FR4 plate. I just found it more pleasant to type on in terms of comfort and the slight boost in tactility was a nice to have.
The PCB in the FBTKL is 1.6mm thick with no flex cuts so there’s some mild flex but nothing too uncontrollable where it affects consistency a huge amount. I think if bottoming out in the alphas is your main concern then I would go FR4, but in terms of feel I think POM is the way to go. FR4 to me now is what I would consider in the “stiff” but comfortable category, which is good for keyboards that use softer mounting styles like gasket/o-rings.
Maybe try for POM full plate with no flex cuts/relief cuts of any kind? JYMV didn’t seem to have any issues with bottoming out with a full PC plate from the original group buy keyboards. Most varieties of POM have a higher modulus of elasticity (measure of the resistance to deforming) compared to the average polycarbonate so I would expect the POM to flex less than PC.
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After trying many different plates in many different boards, I still find aluminum to be the best for top mount—and also the best starting point.
Depending on the board design, I might opt for a PC plate or (on TKL-sized or larger boards) a brass plate. This choice is based on how I want to tune the sound and feel of that particular board to my tastes.
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I really have to try Aluminum one of these days, I might end up cutting a plate at work (I have access to our IPG Phontonics laser cutter) to try.
I think it’ll still be too stiff for me, my preferences these days for typing seem to be best described as wanting to type on a thick slab of silicone - a little bit of localized give and a lot of vibration damping.
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Do 5000 series aluminum, and you can also try cutting a couple different thicknesses.1.5mm is standard, but there are also 1mm plates out there.
For me with top mount my absolute fav is POM or PC half plates, although you can get away pretty much every material other than steel for half plates. For full plates I’d go PC, POM, alum, FR4/CF (they tie IMO), brass/copper, steel (unless the plate is for ALPS, steel rates much higher for me there). You know the drill though, take this with a grain of salt as my preferences will be different from yours.
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Brass plates never fail me
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I got a PC plate in yesterday and typed on a separate build with it for a few hours to compare it more directly to the POM plate I’m still using.
In general I found that the PC plate flexed more if a lot more force was put into it, but somehow it also felt a little stiffer. The flexural modulus (measure of bending stiffness) of POM/Acetal Copolymer is a little bit higher than that of Polycarbonate but the compressive strength of Polycarbonate far outweighs that of Acetal, which is also evident in the toughness rating.
I think what I’m feeling here is that the POM feels softer on bottom out but it flexes less, compared to the PC which feels a little harder but it flexes more when pressure is put onto it. It seems to correspond with the debate that I see when PC is mentioned as the flexiest material but POM is also the softest material.
Right now I’m sticking with POM but I’ll keep testing, even with hard tactiles like T1s on the FR4 plate again.
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I’ve only had FR4 on a top mount (burger), but love the thwacky sound and feel on my board (Malicious Ergo). I’d be curious to get alternate plates made someday after reading this thread, but I’m enjoying it for now.
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It’s been a while since I’ve posted any updates and in the meantime I bought a Mode Sonnet and 4 of its plates (CF, POM, Alu, FR4). Switches for the Sonnet have been both Durock Medium Tactiles and T1s in multiple variants (Blue Lotus and JWICK).
Some impressions of all as follows with the board in its Isolated Top Mount config (Burger mount).
POM:
- Really flexy here, almost to the point of being too soft for my preferences. In the FBTKL it was a nice degree of movement but the POM blend they chose is even softer and it was just a little bit too uncontrolled feeling for my liking. My #4 pick.
CF:
- Stiff but also had some flex to it, more than aluminum but less than FR4. I did find it a little bit harsher than aluminum despite the added flex because it transferred more vibration/bounce to your hands than the aluminum did. My #3 pick.
Alu:
- Stiff and damped, but also felt pretty great overall despite the added stiffness compared to all other materials. The stiffness definitely paired better with higher spring weights since the lessened flex meant more of the force from my hands was directly applied to the switch actuation vs flexing the board. My #2 pick here.
FR4:
- I didn’t think I’d like it as much here but surprisingly I do. Its everything I liked about the aluminum but with 20% of the edge taken off in stiffness during typing. Its definitely flexier than CF and Alu but in practice I don’t notice that sort of flex you get when just bending the plates itself. The sound is a little bit deeper than Alu but I do hear that “muting/dead” effect that FR4 is described to have. That’s not a dealbreaker for me, so in the Sonnet FR4 is my #1 pick.
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I have used polycarbonate two times, once on a KBD67 Lite R1, and once on an HMKB.
The latter used a very high-quality aftermarket PC plate.
It worked well in both instances for tactiles. I can recommend polycarb together with top-mount for tactiles. I was using Ergo Clears, and tactiles similar to Durock Medium Tactile.
What I liked about it is that the bottom-out was not as harsh as a metal or CF plate. The KBD67 Lite R1 also had excellent sound, bringing out the best in a switch. You will be able to hear the switch, for better or for worse.
Often, lubed tactiles sound a little deeper but also louder or more insectile on PC.
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So after some continued use with the Sonnet and Freebird TKL, I’ve actually ended up gravitating towards the softest plates I have for both which are the plastics of POM and PC (POM in Sonnet, PC in Freebird TKL).
I ended up getting used to the subtle bounce and kind of liked it over the more “dead” setups that were full stuff like Alu. Interestingly I would consider CF in the Sonnet to have vaguely the same amount of bounce, I know from comparisons on CF vs Aluminum frames in bicycles that CF bikes tend to be more damped and stiff, but at least in the way CF is cut in the plate for the Sonnet I found it to be really undamped and it vibrated a lot like a tuning fork.
I do like POM over PC though because POM tends to be a little bit stiffer and I like how it sounds generally. But I think in general I like any sort of plastic plate on Top Mounts now.
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