Mounting a PCB in a custom keyboard isn’t always straightforward. Top mount, gasket, and O-ring designs each assume the case gives them somewhere suitable to attach.
In my case, the Holy60-style keyboard I built with help from a community group presented a unique hurdle. The inner walls of the housing have an open lattice design, making standard mounting methods practically impossible. I had to insert about 12 snap-tights or PCB tights directly into the lattice just to make the board feel reasonably secure.
My soldered, plateless build made that harder. A normal O-ring mount relies on the gap between plate and PCB, and there was no plate here. I needed another way to remove the movement.
Company A specs: Internal width around 2.7mm, bottom clearance height around 1.2t
Company B specs: To match a bottom clearance height of around 2t, internal width needs to be 6–14mm
While considering the gap, I remembered silicone edge trim, the U-shaped channel used on sheet metal and glass. I searched for gaskets, edge protection, and rubber channel in different terms. There were plenty of products, but few sized for a keyboard PCB of 1.2T or 1.6T.
In the end, I went with a product from Company A featuring an inner thickness of 2T. The crucial factor here was the lip depth—a depth of exactly 2.7mm worked best. On a 60-size layout PCB, switches are placed right up against the outer edges. To avoid switch interference, I searched high and low for a product with a lip depth of 2T at most. If I had bought something with a depth over 4T, I would have had to manually cut down the depth by hand, which would have been brutal work.
Price-wise, it cost 9,000 KRW (about $6.7) for 10 meters. Considering that a VITON O-ring costs around 11,000 KRW (about $8.2) for 2 meters, this silicone trim is at least 5 times cheaper.
Wrapping the edge of the PCB with the silicone strip made the fit feel decisively more secure. Before that change, increasing the number of separate fixing pieces still hadn’t given me much confidence in the board. With the trim in place, I could turn the keyboard upside down and shake it without seeing the PCB shift. That result was more satisfying than I had expected from such an ordinary consumable. The improvement addressed the specific problem I was trying to solve, rather than simply adding another fastener to the lattice.
Of course, it wasn’t completely flawless. I ran into a few trial-and-error moments during the process:
- Corner Curvature: Due to the elasticity of the silicone, the corners tended to flare out. Instead of forcing it, I solved this by cleanly cutting the silicone at each corner.
- Slight Thickness Difference: Since the PCB is 1.6T and the packing inner width is 2T, the fit was slightly loose. For a 1.2T PCB, a 1T inner width packing would be ideal.
- Bottom Clearance: A lip width of 2T leaves about 1.2T of clearance underneath the PCB. If you want more space below, you would need to buy a 10T width strip and trim it manually.
The weak support in the plateless Holy60 build had led me to look beyond the usual keyboard mounting parts. Finding an answer in a strip intended for protecting glass or metal edges reminded me why the custom side of the hobby appeals to me. The material itself was familiar; the useful step was seeing another job it could perform. Cutting the corners and checking the fit added some work, and the thickness and clearance still required attention. That process also became part of the pleasure of the build. I had a problem in front of me, tried an unexpected consumable, and ended up with a much more convincing fit.
