DIY Sandwich case for a 6 keys macropad

[aubreemaxime]

Hello guys, i need some help.

My project is to make a sandwich case for my mini macropad(6 keys), i only have the PCB and its a hotswap one.

I already do the keyboard layout editor and swillkb thing

How can i mount the pcb to the layer around it ?
What type of screws, standoffs and inserts do i need ? And where i can find them ?

[suicidal_orange]

Does the PCB have mounting holes?  Did you add matching holes to the bottom of the case?  If both yes you'll need to get standoffs that match your chosen hole size.  If there are holes in the PCB but not the plate you can drill some.

You can find standoffs in bulk packs on ebay or aliexpress, or you can get just the ones you need in different materials and finishes from an electronic component supplier, such as Mouser

If there are no mounting holes in the PCB you could use a non-conductive thermal pad to stick the PCB to the bottom plate but you will probably need to file the corner standoffs to the perfect length.

The standard height is 10mm standoffs for the corners but you'll need to measure how far the hot swap sockets stick out from the PCB to check that's enough.

Or maybe you're using layers of acrylic in the sandwich?  If so you could make the middle layer tight to the sides of the PCB and no attachment will be needed...


Sorry for all the ifs but there just isn't enough to go on - feel free to give more details or add pictures

[aubreemaxime]

No too much "ifs" its perfect, you ask the good questions, i wasnt sure what i have to told you and precise.

So
- yes the pcb have 4 (mounting) holes
- yeah i was matching the holes to the bottom of the case, on every layer, but i can change it
- in my sandwich type i want to cover all the sides/front/back not only the top and bottom like QLAVIER did with some macropad and keeb (https://www.instagram.com/p/B9-3kmBn-FS/?utm_source=ig_web_copy_link and https://www.instagram.com/p/B-RzotcHSkS/?utm_source=ig_web_copy_link)

- layers of acrylic and maybe stainless steel when im satisfied with the design

for the pcb its just the rama m6-b hotswap (https://ramaworks.store/products/m6-b-pcb)

thanks a lot Suicidal_orange

edit: if possible i want to include some type of screws i have from rama(M2-4 M3-5 M3-6 M4-6)



 

[suicidal_orange]

Great - details.

Looking at the pics of the PCB the mounting holes are very small (smaller than the 4mm centre hole of a keyswitch), a round M3 standoff is 5mm outside diameter and an M2 is around 4.3 so the only thing going through that hole is a screw.  Do any of the screws fit those holes nicely?  If you want to use them that would be a good place to start   Also are the numbers after the - the length of the screws?

The other option is to ignore the holes and hold the PCB using the layers.  As you're using hotswap you probably want to use a 1.5mm layer for the plate so the switches clip on and don't fall out easily.  With 1.5mm for the plate and assuming the PCB is 1.5mm thick a 5mm case layer would go down to level with the bottom of the PCB so if the next layer had a smaller hole so the edges touch all round  the PCB it couldn't drop any lower.  That layer can be 5mm as well, and if the hotswap sockets don't stick out more than 5mm you just need a bottom layer.

So 5mm holes in the case layers and 4x5mm layers means you can use a standard '20mm M3 round standoff' - like these which will leave you 1.5mm of exposed screw but if you put that at the bottom it shouldn't be noticeable.  Or you could use 2x3mm middle layers below the PCB for a slightly taller and more expensive option with less screw showing.  Or if you want it really chunky you could use 2x5mm layers below the PCB and use a 25mm standoff...

M3 is a standard size screw so you should be able to use the screws you have, assuming they are just different lengths.

The only worry is that 1.5mm acrylic plates can be fragile.  The PCB will be taking some of the load when you use the pad but I guess you're planning to swap the switches often which might not be ideal.

[aubreemaxime]

Yeah very small, only an M3 screw can fit.
yeah the number is the length, so two types of M3 screws.

yeah this is a good option i gonna go with this one.

for aesthetic i will choose the same thickness for all the layers, more layers but it will be perfect ... i hope

thanks a lot mate, its very clear

goodbye

i will show you the result here