Pimp my MK14

[Slothie]

Well in between other things I've been upgrading my MK14, or at least making it a little more aesthetic. Not quite perfect yet, holes are the wrong size and the keys are a little strange, wonkey and horrific to print (still a newbie with my 3D printer) but the results are encouraging!

[SiriusHardware]

I'm in the market for one of the key bezel / surrounds but I would need it to be able to accommodate the clear capped switch tops rather than printed buttons (I just like them made that way). Maybe you've made your printed tops the same overall size as the clear capped tops, maybe not? Great effort, anyway. Oh, just realised you've made an undertray for it as well - that's definitely a first.

[Slothie]

Originally Posted by SiriusHardware

I'm in the market for one of the key bezel / surrounds but I would need it to be able to accommodate the clear capped switch tops rather than printed buttons (I just like them made that way). Maybe you've made your printed tops the same overall size as the clear capped tops, maybe not? Great effort, anyway.

I used the clear cap types to take measurements from, so it would probably work. I'm at this moment printing a new version that should be a better fit with holes actually large enough to get the right size screws in (!) so I'll check with the other buttons. I'm pretty sure they are 11mm square. I allowed 11.5mm and they are a bit loose, so I've reduced that a touch. Hopefully not too much. The idea is to keep the keys straight but still allow them to press!

[SiriusHardware]

I don't know if you have provided any kind of standoffs on the undertray but it might need cutaways to allow original edge connectors to fit onto the edge connectors - those connectors need a fair bit of height and depth both above and below the PCB.

If there are standoffs, then how about also including fixing holes in the undertray so that it can be screwed to a baseplate or chassis or the inside of a larger enclosure using screws with countersunk heads - one problem with both original MK14s and the issue VI is how to mount them onto any kind of backboard or chassis when the only screw holes provided on the PCB are those intended for the keypad.

[Slothie]

Originally Posted by SiriusHardware

I don't know if you have provided any kind of standoffs on the undertray but it might need cutaways to allow original edge connectors to fit onto the edge connectors - those connectors need a fair bit of height and depth both above and below the PCB.

If there are standoffs, then how about also including fixing holes in the undertray so that it can be screwed to a baseplate or chassis or the inside of a larger enclosure using screws with countersunk heads - one problem with both original MK14s and the issue VI is how to mount them onto any kind of backboard or chassis when the only screw holes provided on the PCB are those intended for the keypad.

Yep, got you covered on that. I do think a few extra supports around the edge might help, but I didn't want anything too close the the heatsink (PLA softens at 80 degrees....) and the main stress is on the keyboard area which is well supported.

I measured the size of my edge connector and left a generous margin. Its a a bit big now with dupont connectors but thats OK. The screw go through the keyboard holes and the back, and there are hexagonal recesses for the nuts at the back. By coincidence rather than careful planning with the keyboard surround 20mm bolts are exactly the right length! If only I had made the holes big enough for M3 nuts I wouldn't have had to use the M2.5 nylon bolt you see. So a Mk2 version is on the cards in future when I see if there are any other reasonable additions I can make.

I didn't make a top for the case, I kind of like seeing all the bits and bobs! The bottom just makes me less nervous about shorting things and putting it down on static-y surfaces. That said I might make a full case for my PIC14 so its more portable.

Edit: Some mounting holes on the bottom wouldn't be a problem.

[Mark1960]

Looks good. If you do make a top cover you probably need to include a cooling fan for the heatsink and the proms.

Probing the orton view I keep resting my wrist on the proms and thinking how hot it gets, so I’ve added a couple of clip on heatsinks that I’ve had floating around. Now I need to make sure I don’t rip open my wrist on the edges of the heatsinks.

[SiriusHardware]

Interesting that Slothie chose to include the PCB revision number (V1.2) as well as 'Issue VI' on the key bezel. I take it that's because the keypad geometry on rev 1.3 will exactly match that of original MK14s, especially issue V?

[Slothie]

Originally Posted by SiriusHardware

Interesting that Slothie chose to include the PCB revision number (V1.2) as well as 'Issue VI' on the key bezel. I take it that's because the keypad geometry on rev 1.3 will exactly match that of original MK14s, especially issue V?

Yes, I took the location of all the holes and the edge cuts from the mk14.keycad_pcb file. I was able to check it because I can use a plugin for FreeCAD to create 3D models of the PCB which I can convert to STL and import into OpenSCAD (which I used to model the keyboard cover and bottom tray) to check the alignment.

One correction in the hypothetical Rev1.3 will be to correct the location and size of the keyboard mounting holes. and to make them symmetrical so that the RH holes are the same distance from the edge of the keys as the LH side, as well as possibly making the PCB the same size..

That said, revision 1.3 is still in the pre-vapourware stage with only one other extra feature planned (bringing NENOUT and NBREQ out to the edge connector for completeness).