The Slab - 65% keyboard with wood case - News: PCB!

Matt_

31 Dec 2015, 20:41

This is a worklog for a custom 65% keyboard that I have been wanting to build for more than a year. I'll try to explain most relevant design choices in a concise manner.

• Basic ideas
- Layout
- Case
- PCB

• Build
- First prototype


Basic ideas

What I want is:
- a compact, low-profile board
- with a non-resonating case
- dedicated arrow keys
- the ability to replace keycaps easily
- backlit, possibly RGB (secondary)

Explanation: I have been using a Pure Pro for one year and a half and I love it, especially because of its size and dedicated arrows, but it has a few shortcomings: it is nearly impossible to replace all keycaps, and the bottom row is unnecessarily cramped. Also, the board sits too high on the desk for me, and the steel plate + case assembly gives each stroke a metallic sound which I find to become tiring after a short while.

So I modded the Pure Pro to solve the last two problems but the layout/keycap issue remains. The spoiler below contains details of the modded Pure Pro from which stemmed the basis of the 65% board's design.
Spoiler:
To prevent the noise of switches from resonating with the case (downstroke and upstroke), I just ditched the original case and replaced it with an acrylic bottom plate with rubber feet, fastened to the PCB through the original holes, with 2 mm rubber pads in-between to avoid crushing components:

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Kinda ghetto, but it did what I expected: there is a world of difference sound-wise. The stroke sound is now much quieter since the whole assembly absorbs sound/vibrations instead of reverberating it, so I can bottom out and enjoy the soft, matte "clack" sound (with thick PBT keycaps) without the annoying metallic echo. And it sits lower on the desk:

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The keyboard may look too flat in the first picture and way too angled inthe second one but it looks much better in person. There is only a 8° angle but the difference in comfort against the original case's 6° angle is huge. I have been typing on this board for more than a year and this is pretty much the perfect height and angle for me.

Despite its unfinished/barebones looks, I love the minimalistic appearance (low profile, no wide case edges) so I'll be aiming at something similar for the 65% board.

Layout

I settled on a 65% layout for the usual reasons: barely larger than a 60% board, dedicated arrows and almost-standard keycap sizes (safe for the 1.75 right shift, which is only a minor issue and a necessary compromise). The layout itself is fairly common for a 65%:

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I loved the Pure Pro's Fn instead of CapsLock setting and 1u top row so I'll be keeping that — CapsLock will be on Fn+Shift, and I'll try the HHKB's Backspace location.

I have no need for more than two mods on the right side of the spacebar so I'll keep 1.25 mods with a gap instead of filling the space with three 1u mods. It would be nice to have a PCB that allows for some permutations (ISO left shift, 2u backspace, 2.75u right shift with offset up arrow) but this is not a primary goal.


Case

The main idea is to keep the structure of the Pure Pro mod:

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From top to bottom: switches are placed on the plate, the PCB is installed, then a bottom plate is bolted to the PCB and feet are attached to the bottom plate.

For the 65% board, I want to try something different from the common "layered" look, so the plate itself will serve as the casing, with walls extending down to shroud the sides and form a thin, slab-like body. Here are two rough mockups of the upper casing:

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The casing will be made out of wood, because I am curious to see how it would feel. I will probably use maple, which is dense but easy enough to machine and to finish. Ideally, it would have to be CNC-cut, but we'll get back to that.

The "plate" section should be 4 mm thick to provide firmness and consistency. Additionally, the bottom plate may be aluminum or steel to add a bit more heft and stability. The "walls" will be 7 to 10 mm high. I'll spare you the ugly side mockups :mrgreen:

At first I didn't want the case/plate to be wider than the keycaps (see Apollos' 60% Mini design for instance, or the Pure Pro in its current state) but I may like a slight overhang on each side and a front lip (as shown on the renders) so I will make a few different prototypes to try design variations. Prototypes will be made out of balsa, which is much easier to work with than any other kind of hardwood.


PCB

I still have to decide what I will do here. First, hand-wiring the keyboard is not an option, since I need a PCB to attach the bottom plate and the feet.

Since I will use thick, non-backlit keycaps (either ABS or PBT) there may be no point in implementing backlighting, so I could just make a PCB without LEDs but I kinda like the glow under the keycaps. I am not certain that backlight implementation in popular firmwares (TMK, easyAVR) is as polished as the rest of the code, but perhaps trying to come up with a different implementation would amount to reinventing the wheel.

On the other hand, I have been toying with RGB stuff for a while, and although it won't be as polished as existing commercial solutions it could be fun to work out something like that in a custom keyboard. It will be imperfect, but it will be fun to do as well. RGB backlight tightens design rules though (much more traces and footprints on the board), which probably means either no pcb-mounted stabs or limited alternative locations for switches.

There is the middle way: a PCB with wide holes in LED locations, and a secondary PCB supporting backlight only (which I could add later), like Ducky's Shine 5 PCB. Flexible, but twice the cost and a few mm more in thickness.

Hopefully I'll make my mind before I finish building the case :D At some point I was hoping that it would be possible to buy the Whitefox PCB alone, but that would have been to easy, wouldn't it?

Now on to building!

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Last edited by Matt_ on 04 Feb 2016, 17:24, edited 2 times in total.

Matt_

12 Jan 2016, 18:30

I did not have as much time as I hoped to work on this, but I managed to make a few steps forward:

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So no border, no front lip, and the top part is just tall enough to hide the PCB. Here is a shot of the underside of the top part:

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That's very rough, but they're just balsa mockups. I should start working with hardwood soon (maple first, perhaps walnut later), and I need to finish the PCB files and send them to a fab (probably itead or smart-prototyping, depending on which will handle multi-position switch footprints more conveniently). I'll keep things simple — single color backlight handled by TMK, and a Teensy 2.0 as the controller.

More progress in another fortnight, hopefully :D
Last edited by Matt_ on 04 Feb 2016, 18:02, edited 2 times in total.

mastermachetier

12 Jan 2016, 20:03

This is an interesting take on a 65% keyboard. Personally this would be my ideal layout for a keyboard. This combined with tmk software will be nice especially with the versatility it will have with fn layers and macros. I look forward to seeing what you do next and would love to go be involved if you were lets say placing a large order on switch plates , pcbs, and bottom plates. :)

Matt_

13 Jan 2016, 17:32

I could certainly order more pcbs if people are interested, but it may be more difficult for the case. Maybe I can find a way to have a small number manufactured — worst case, I could make them myself, but that would take more time. For now it is not a priority but if there is enough interest I may think about it seriously.

mastermachetier

14 Jan 2016, 21:44

Matt_ wrote: I could certainly order more pcbs if people are interested, but it may be more difficult for the case. Maybe I can find a way to have a small number manufactured — worst case, I could make them myself, but that would take more time. For now it is not a priority but if there is enough interest I may think about it seriously.
What would you think of a more "industrial design" Maybe no case leave parts of the pcb exposed and a cleaned up version of acrylic or a aluminum bottom plate. Very thin design kinda cool make it in a away that the pcb is not over hanging the corners so you don't touch it at all when maneuvering the keyboard.

mastermachetier

14 Jan 2016, 21:50

mastermachetier wrote:
Matt_ wrote: I could certainly order more pcbs if people are interested, but it may be more difficult for the case. Maybe I can find a way to have a small number manufactured — worst case, I could make them myself, but that would take more time. For now it is not a priority but if there is enough interest I may think about it seriously.
What would you think of a more "industrial design" Maybe no case leave parts of the pcb exposed and a cleaned up version of acrylic or a aluminum bottom plate. Very thin design kinda cool make it in a away that the pcb is not over hanging the corners so you don't touch it at all when maneuvering the keyboard.

Also there would be no resonating case if a case were not used. We could also use some kind of sound dampening or shock damping feet .

Matt_

18 Jan 2016, 17:51

mastermachetier wrote: What would you think of a more "industrial design" Maybe no case leave parts of the pcb exposed and a cleaned up version of acrylic or a aluminum bottom plate. Very thin design kinda cool make it in a away that the pcb is not over hanging the corners so you don't touch it at all when maneuvering the keyboard.
That could make for a workable design, but the point of this build is to do away with the barebones looks of my current keyboard, not to strip it further :D

Plus I really want to try to so something with wood. If that won't work, I'll revert to alu but keep the same structure. But your idea is valid, as long as you have a PCB to start with.

mastermachetier

21 Jan 2016, 05:47

Matt_ wrote:
mastermachetier wrote: What would you think of a more "industrial design" Maybe no case leave parts of the pcb exposed and a cleaned up version of acrylic or a aluminum bottom plate. Very thin design kinda cool make it in a away that the pcb is not over hanging the corners so you don't touch it at all when maneuvering the keyboard.
That could make for a workable design, but the point of this build is to do away with the barebones looks of my current keyboard, not to strip it further :D

Plus I really want to try to so something with wood. If that won't work, I'll revert to alu but keep the same structure. But your idea is valid, as long as you have a PCB to start with.
Makes senses haha , I might have to do my own build project . But I am very curious to see how yours turns out.

Matt_

04 Feb 2016, 16:59

Okay, this project needs a PCB to move forward so I made this:

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Which allows for those layouts:

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- partial 1.25u bottom row + arrows as initially planned
- 1.5u mods in case I come across a WKL set I really like
- 1u mods on the right, because that allows me to make this 60% layout:

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... which may actually suit me better than a slightly wider 65% layout. Not sure about that yet, but this PCB gives me the choice.

Also I don't plan on using ISO keysets but I was asked to add support for them, so there it is.

Here are the other characteristics:
- atmega32u4/Teensy 2.0-based (compatible with TMK, easyAVR and a few other firmwares)
- 16x5 matrix (15x5 was workable, but that extra column makes it easier to map in software)
- Through-hole diodes, SMT (0805) LED resistors
- Full backlight, LEDs on top except on Capslock (windowed cap-friendly)
- Stepped or full size Capslock
- Split Backspace
- Supports PCB-mounted Cherry stabs

Right now I am debating over these options:

- whether to use mini or micro USB. I'll probably go with micro because it's inherently better than mini and my only mini-USB board won't see much use when this is completed, but I'll try to find a footprint compatible with both just in case.

- whether to use a Teensy (easier to build but more expensive, and less practical for a low-profile board because of that big "mini" USB on the Teensy) or to solder an atmega directly on the PCB (harder to solder, need to source all parts, but better integration).

Alternatively, I thought about making a hot-swappable custom controller based on the atmega32u4, so it would be as easy to install as a Teensy, could be fitted to other custom boards, but it would take less vertical space.

Also I need to make sure that the backlight implementation that I chose (one Teensy PWM pin -> transistor -> multiple (resistor + LED) in parallel) can be controlled with TMK or easyAVR.

I won't be ordering PCBs before Feb 15 (end of CNY), which leaves me a few days to make the final decisions and complete the design. Also, I saw that a few people on another forum may be interested in getting one of these PCBs, so if people around here are interested too I'm open to taking what suggestions you might have to make this PCB more suitable to your needs.

Caveat: it's a prototype, so it may not work as expected (unlikely, but you never know). Also, I am not taking orders — this is not a formal GB —, just gauging interest to see whether I shall order more of them (in which case I'll sell them for a reasonable price after testing, to fund the next steps of the project) or just get a small batch for myself.

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MrBishop

10 Feb 2016, 14:48

Wood cases FTW.

ive been CNC'ing my own.

looking forward to seeing how this one comes out!

Matt_

10 Feb 2016, 15:24

Nice to see you here! I've been fantasizing about getting a CNC but that won't be happening unless I move to a larger place. Until then, I'll keep hacking with files and a dremel.

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MrBishop

10 Feb 2016, 15:55

Matt_ wrote: Nice to see you here! I've been fantasizing about getting a CNC but that won't be happening unless I move to a larger place. Until then, I'll keep hacking with files and a dremel.
yeah i'm usually on GH but i'm not exclusive or what not ;)

CNC is awesome. i have a inventables x-carve. its not the most accurate thing in the world but for what i do its ok. been a real fun learning experience. once i get some more upgrades to the controller i'm going to start working on PCB milling ;) can't wait for that.

Matt_

10 Feb 2016, 16:45

If you can work with reasonable tolerances and make dual-sided PCBs, that will be great... no more ordering five PCBs and waiting two weeks when you just want one board!

mastermachetier

10 Feb 2016, 17:13

Matt_ wrote: If you can work with reasonable tolerances and make dual-sided PCBs, that will be great... no more ordering five PCBs and waiting two weeks when you just want one board!

Can you use a dremel to cut a plate?

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vivalarevolución
formerly prdlm2009

13 Feb 2016, 03:02

I shall ask the most important question: will the PCB be Alps/Matias compatible?

Matt_

13 Feb 2016, 13:48

mastermachetier wrote: Can you use a dremel to cut a plate?
A wood plate, yes. A Dremel is not the best tool to do that but if you're careful and know what you're doing, it can be done without too much trouble. I would never try to use one to cut a steel/aluminum/acrylic plate though. Better go with a lasercutting service.

vivalarevolución wrote: I shall ask the most important question: will the PCB be Alps/Matias compatible?
Short answer: probably not.

Long answer: not for the moment, as I am using Eagle which does not handle well those weird pad/drill shapes, and I have no idea if the fab house I will go with does too.

At some point I'll probably switch to KiCad for those keyboard projects, so if there is interest in adding Alps support I'd gladly add it. But Moz was talking about makig his TS65 design usable in a non-split configuration, so that may be a better choice right off the bat.

(I'm terrible at selling my own project, aren’t I? :D)

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vivalarevolución
formerly prdlm2009

13 Feb 2016, 14:52

Thanks, I know that adding Alps support is not as easy as 1, 2, 3...

Matt_

13 Feb 2016, 15:08

Honestly, this is not the most complicated thing to do, it's just the software I'm using that makes combined footprints quite unpractical. But replacing MX footprints with Alps would be quite easy (making it Alps-only). If I was more competent with Eagle, I'd gladly reproduce the design for combined MX/Alps switches and release the files so that anyone can have them fabbed, but with Moz's project (and Matt3o's apparently) that may not be necessary.

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David Parker

01 Mar 2016, 15:08

Matt_ wrote: Also, I am not taking orders — this is not a formal GB —, just gauging interest to see whether I shall order more of them (in which case I'll sell them for a reasonable price after testing, to fund the next steps of the project) or just get a small batch for myself.
I am very interested in the PCB design. Just wondering what the timeline for it will be? Is it still happening?

Matt_

02 Mar 2016, 13:14

It is! I let it sit for a while before making final decisions, but I'll finish the PCB files soon and hopefully ll get a first batch near the end of the month.

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David Parker

02 Mar 2016, 22:11

Matt_ wrote: It is! I let it sit for a while before making final decisions, but I'll finish the PCB files soon and hopefully ll get a first batch near the end of the month.
Cool! Thanks for the update.

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