Chiral - ambidextrous rgb numpad

[bakageta]

I made a post the other day about this on reddit, but I finally got around to throwing things on github so I thought I'd make a post here too. I've had too much time on my hands lately and decided to do a custom pcb instead of a handwire for my next keyboard, but I thought a full keyboard was a bit ambitious for my first custom pcb. I shelved that idea, and started in on something a bit smaller - a numpad. I've been considering a Helix build, and thought the design would make a great numpad with a few tweaks.

The result is (hopefully) a numpad that can be built either left or right handed, with or without an extra column of buttons, and has per-key RGB plus an OLED screen. You can see the layout here:



Because of the RGB cutouts, the only optional layout is to Dremel off the outermost row and solder 3 jumpers. Switch spacing is standard 19.05mm, changed from Helix's 19mm. I've ordered a small batch from JLCPCB that just shipped out today, mostly because I was too impatient to see what anyone had to say first. I used most of the Helix's footprints and referenced it heavily as I laid things out. I've got the kicad and gerber files up on github, as well as some pcb renders if anyone wants to take a look.

https://github.com/bakageta/Chiral

[suicidal_orange]

Looks great, assuming it works

The only improvement I can think of would be putting the screen in the middle but that's probably harder.  Also the switch holes look like the PCB works either way up but I'm pretty sure the [Teensy/pro-micro] has to go one way round, so if the board's upside-down the screen will be on the back?  This could be an example of not-quite-awake stupidity, sorry if it is!

[bakageta]

Like the Helix, there are two sets of pins for the pro micro, offset just slightly. You should be able to build this left or right handed and still put the pro micro on top. There are also 4 jumpers for the OLED pins to flip the orientation. Now I just hope it works, haha.

[katotaka]

hmmmm choc support, some extra keys for nav and stuff, perfect companion for the helix

[bakageta]

Prototypes are here!



Some closeups with my thoughts can be seen here.

[suicidal_orange]

Those staggered reversible pro micro pins are a great idea, for some reason I can see them much more clearly looking at a board rather than the schematics!

If the only problems with the prototype are cut LED lines you've done well, looking forward to the glowy fully built test pics.

[bakageta]

I can't take credit for the staggered pro micro, I saw it on the Helix and thought it was a great solution. Sadly I don't know if I'll be assembling the prototype in the next month or so. Poor planning on my part has left me waiting for pretty much everything other than the PCBs, all of which is just now leaving China. I started work on an acrylic case in the meantime, but I think I've slightly overdesigned it as it comes in around $40 from Ponoko.

It's a high profile case made up of six 3mm acrylic layers and a ~1.57mm delrin plate. There's a 3mm spacer plate that sits between the PCB and switch plate to give it extra reinforcement, while still keeping the plate thin enough for stabilizers and switches to clip in properly. The spacer plate should avoid all of the through-hole components, so there's no problem sitting it directly on the PCB. There's two 3mm layers above the switch plate, for higher profile than most acrylic cases. I'll be making a few quick changes like rounding out the interior corners before I order a test case, but then it's just the waiting game for China post.

I'll also be designing a case more like Helix uses for a cheaper option, mostly because my current design was made exclusively for MX-style switches. There's not enough room to get the spacer plate under the switch plate with Choc switches, but the thinner switch plate doesn't sit directly on the PCB like a 3mm plate would. Problems for later, though.

[Blitzschnitzel]

That looks great!
I am also designing a board right now. How much current would you say your LEDs will draw? The documentation of the SK6812MINI says 50mA per Led but that would be 1.5A for one numpad. I've seen 60%s with these LEDs so can't possibly be this much.

[bakageta]

They can definitely draw that much, unfortunately. I'll be limiting brightness in the firmware in an attempt to limit how bad the draw is, but really I need to get the prototype put together and take actual measurements on how much it's drawing. You might take a look at the qmk repo for the zeal60, also, to see if they did anything to control the current draw.

[ErgoMacros]

You could get a "USB power meter," to do the measurements. There are many out there.

Here's two I found at random (haven't used any, so am not endorsing these in particular)
     https://www.banggood.com/8-in1-QC2_0-3_0-4-30V-Electrical-Power-USB-Capacity-Voltage-Tester-Current-Meter-Monitor-p-1226594.html?rmmds=search&ID=224&cur_warehouse=CN
     https://www.amazon.com/MakerHawk-Voltage-Display-Multimeter-Voltmeter/dp/B07BRK7W7F/ref=sr_1_38_sspa

[bakageta]

I've already got something to check the power draw, no worries there, I just need to get the RGBs in and build it before I can.

(edit)
RGBs and diodes came in, now I'm just waiting on the pro micro. The cutouts came out perfect, better than I could've hoped. The LEDs fit the slot perfectly, and catch on a tiny lip to stop them from falling all the way through. I think they'll end up being easier to solder than the smd diodes I went with. Here's one sitting in the slot: