For both Cherry MX and Futaba spacebars, use the screw-in PCB mounted stabilizers. The PCB is ready for these at the Spacebar and 2x SHIFT position.
For both Cherry MX and Futaba keys, there is no available pre-made 8x stabilizer rod. To make one, start with a stainless steel rod at least 6" or 150mm long, but that leave no room at all for error. I suggest at least 8" or 200 mm long and cut to fit.. The diameter can be 1.5mm or 1/16 inch. Bend/cut the rod so that it is 133mm long, with a 90 degree bend and an 11mm arm at either end. (see picture.) Measuring is nice, but it's best to eyeball the rod as you work.
For the Cherry MX, assemble according to instructions, using the 8u rod you made. The right-angled ends of the rod slide through the post and the rod snaps into the small detent at the front of the screw-in base. Since the cherry keyboard kits come with 2x stabilzer bars, and since the PCB can accomodate the stabilizers, you can also install the stabilizer for the 2x shift key.
For the Futaba keys, the cherry stabilizer posts are too short, so you will have to make your own from 1.5mm plastic sheet material.
- Cut two 4mm x 28mm strips, and drill a 1/16" (or 1.5mm) hole close (1-2mm) to one end of each strip. Make sure the holes are about the same distance from the end.
- 2. Insert the strips into the spacebar stabilizer slots, using pliers to push as far in as possible, so the holes are the same distance from the spacebar
install the spacebar, and then install the 8x stabilizer bar as for the cherry keys. - I found that the 2x shift key was plenty stable without a stabilizer. But if you want to install it, then follow the same procedure as for the spacebar. You should be able to use the 2x stabilizer bars that came with the cherry MX stabilizer kit.
Sources for materials:
Metal Rods:
McMaster-Carr: Tight-Tolerance Easy-to-Machine 303 Stainless Steel Rod
Ebay: 1.5MM STAINLESS STEEL ROD BAR SHAFT 300MM MODEL MAKER 316 MARINE GRADE ROUND
It looks like 1/16" TIG welding filler rod would work as well. Here's an example:
Ebay: ER308L 1/16" x 36" 1-Lb Stainless Steel TIG Welding Filler Rod 1-Lb
1.5mm sheet material
For the 1.5mm material, I recommend a plastic sheet with slippery surfaces. I've tested the following:
McMaster-Carr: Moisture-Resistant HDPE 4" Wide, 0.05" Thick
Ebay: US Stock 2pcs 1.5mm x 7.87" x 9.84" Black ABS Styrene Plastic Flat Sheet Plate