Under desk/table holder for 3x1 USB mini keyboard

I got myself mini keyboard with three keys and rotating encoder. Idea was to use it to control sound volume and media player on my PC without need to open applications. Keyboard was supposed to be mounted under desk table within hand reach.

So I had to do mount for it.

Keyboard has USB-C connector on the top which is awkward for connecting cable. I had one angled USB-C male to female adapter so I used it to redirect cable connection.

As keyboard has double glue tape on the bottom it can be simply glued to the mount but I decided to use screws instead. I like when things can be easily disassembled if necessary. Glue does not fit in that perspective.

I met another issue. Idea was to replace screws used in keyboard assembly to mount it on the holder but those screws were to short. I had some longer screws but they were M2.5. Original screws were M1.8.

So i had to use drill to widen holes on the plexiglass elements forming keyboard housing and also on PCB. Luckily, diameter difference was very small to it was easy and harmful procedure.

As longest screw I had was 16mm long I decided to get rid of the back plate of the keyboard. Holder acts like back plate anyways.

I used M2.5x3.3.5 brass insert as a nut. It is inserted on the back of the holder. No heating is necessary. I just used screw to pull brass insert into the hole.

On the back of the holder there are holes for two zip ties. They are optional and can be used to attach USB cable to the holder to have tidy cabling under table. I used 2.3mm wide zip ties, but 3mm should fit to. Channels for zip ties is curved so if you push it through one hole it would come out on the other. If it clogs inside just bend tip of the zip tie a bit to make it easier to pass through.

=== Mounting

Holder is attached to the table with two 3.5mm wood screws (there is hole for the third screw but that is not necessary).

Top edge of the holder server as alignment tool. Just keep it flushed it with the edge of the table and everything will be aligned properly.

There is some planning needed for mounting keyboard.

First attach holder under the table plate with no keyboard mounted. When keyboard is mounted it overs screw holes so screws are then not reachable.

USB-C adapter cannot be inserted into keyboard if it is already mounted in holder. So, insert adapter through the slot, attach it to the keyboard and then fix keyboard to the holder. It goes really easy.

Do not forget that you should remove back plate of the keyboard if you use 16 mm long screws.

However if you do have longer screws, or you want to use glue table instead of screws, try it. I am not certain but there is some clearance in a model and it is probably possible to fit keyboard with back plate too.