Would a rotary encoder fit in a keyboard not designed for one?

[MechKeys122]

Hi. I've seen keyboards like the Satisfaction75 which has been designed from the beginning to have a rotary encoder. Is it possible to add a rotary encoder to a keyboard that wasn't designed for a rotary encoder, in terms of the case, plate, and switch spacing? If i replace a keyboard's pcb with a pcb that can use a rotary encoder, will a plate and case designed for mx switches allow it? Will i need to change the plate as well? Would a rotary encoder fit next to other mx switches in the space a single mx switch would take up? Would there be any clearance issues with the knob and the other switches?

Thanks for any help.

[Findecanor]

Even if you'd manage to mount one securely, you would still have to interface it to the microcontroller.
Rotary encoders usually require two dedicated GPIO pins.

(Theoretically you could substitute two switch positions for it (two rows, common column or the other way around) but I not yet seen support for such an arrangement in any firmware)

[nevin]

you can see physical spacing and example of using an encoder in a switch position here
keeb.io's BDN9
in this example, they are just held in place by the solder pads on the pcb. another way you can mount one of these encoders is just to drill a hole in the case and put a washer & nut on the shaft. after all, these are just panel mount encoders.

but yes, you would either need a pcb that supports an encoder or wiring it into a board/controller that supports QMK firmware and enabling the encoder in the firmware.

[MechKeys122]

Thanks for the advice guys. Like i said I'd be replacing the PCB with one that can use a rotary encoder so i understand that part. I'm just wondering if that's enough.

I looked at the BDN9 and it appears that the plate cutouts are all the same size unless i missed something. Although maybe on that plate all the cutouts are a bit bigger then regular mx switch cutouts? If not then maybe adding a rotary encoder in place of an mx switch won't be a problem in terms of clearance.

The reason i originally made the post is because i was looking at the satisfaction75 plate and noticed that the cutout for the rotary encoder was longer vertically than the cutouts for the mx switches. So i was wondering if that was necessary for it to fit or if anyone had experience using a rotary encoder with a plate in the place of a regular mx switch cutout. Would flipping the rotary encoder footprint 90 degrees on the pcb make a difference in terms of getting it to fit in a regular mx plate cutout?

Here are pictures of the S75 plate:




So for instance i was wondering if i took a keyboard like this:




and replaced the pcb with one that would allow me to put a rotary encoder in place of the Prt Sc button

or a keyboard like this:



and replaced the pcb with one that would allow me to use one of the 4 extra media keys on top of the numpad with a rotary encoder

Would the encoder fit without any changes to the plate and case next to the other switches without any clearance issues? Has anyone tried anything like this who might have experience with whether this would work or not?

[Findecanor]

The reason i originally made the post is because i was looking at the satisfaction75 plate and noticed that the cutout for the rotary encoder was longer vertically than the cutouts for the mx switches.

I did some tests with an encoder and in CAD: Yes, a rotary encoder would be a tight fit inside a standard 14×14 mm mounting hole: The pins touch the plate.
That would work if the plate is made of a non-conductive material such as acrylic, PC or FR4.

Some mounting holes are widened a little bit anyway to also be able to fit Alps switches or to allow switches to be opened in place -- in which case an encoder might fit in one orientation.
Footprints that support two kinds of components can also have issues. On the Iris, the encoder's stabilising pins have to be clipped before installation, and on the BDN9, the encoder's button looks like it shares switch position with the switch.

[abstractkb]

I just tested it with an encoder, pcb, and spare 1.5mm aluminum plate, and it does fit in a standard switch cutout.  Your mileage may vary but for me, the switches hold the plate just high enough to not touch the pins of the encoder, and the surface of the encoder body is flush with the top of the plate.

[nevin]

if you needed a little extra room in the plate opening, and this would not be switched back to a key/switch position, you could file the opening a little larger to make a little more room for anything that's too close for comfort....

[MechKeys122]

Thanks a lot guys. If i ever get around to trying this I'll try to remember to come back and update this thread with how it went in case someone else wants to try something similar.

[MechKeys122]

Update:

So if anyone else is looking to try in the future, I'm confirming what abstractkb said. The rotary encoder (at least the one i used) fits perfectly fine in one of the switch openings in the regular oem steel plate that came with my keyboard (IKBC MF108). I didn't have my own plate made or anything. You do need to put the encoder into the pcb first and then put the plate on top of it. It won't fit through the plate from the top.

After putting in switches, the encoder doesn't look like it's touching the plate at all either. It seems to be a standard 1.5mm steel plate.

Edit: Although unlike abstractkb's post, on mines i don't think the encoder's body is touching the plate either.

[suicidal_orange]

Thanks for the update

If you've found an encoder that fits perfectly a make and model number could save future searchers from having to read datasheets to find the dimensions, if that info is available.

[MechKeys122]

Thanks for the update

If you've found an encoder that fits perfectly a make and model number could save future searchers from having to read datasheets to find the dimensions, if that info is available.

The encoder i tested was an old one i had lying around. Not sure what model it is. I am planning on ordering a different one soon that I'm going to be using. If it also fits the same as the one i tested, I'll come back and update with the exact model number of that encoder.