New Buckling Spring Design

[wcass]

nfc has been making 3d models of classic IBM for a while. I have one of his 1.75 "non-stepped" cap in "polished metallic plastic" (which is a decent match to Unicomp grey). My only complaint is that the layering of the plastic is quite visible on curved sections (like the top of the key cap).

http://www.shapeways.com/shops/nfc

I have put M hammers in F keyboards and also the other way around. The keyboards feel most like what the keyboards did before the hammer swap.

[idollar]

I have put M hammers in F keyboards and also the other way around. The keyboards feel most like what the keyboards did before the hammer swap.

This means that I was wrong

[RoastPotatoes]

Are there any updates?

[wcass]

I didn't win in the contest. :(
But i'm not going to let that slow me down. I'm finishing up PCB design and looking for quotes on laser cut acrylic sheet.

This is going to be using membrane type buckling spring switches. The bottom "membrane" will be a PCB (with integrated controller, microUSB connector, and 6 LEDs. The top membrane will be copper printed on thin, flexible plastic. I used this before and it worked well (for every key that i didn't screw up because my DIY PCB was so bad). I am happy with PCBWay who did the PCB for the XTant, so will likely use them again for this. The copper printed plastic is made in the UK. CIT Tech is the same as the InkJetFlex that i used last time. Quality was excellent.

The red lines are copper and the black lines are cuts. The USB connector will fit in the cutout at the top, left of center and the entire controller fits in that half square inch rectangle (under one barrel that is also used for a space bar stabilizer. Six screw holes and six LEDs are the larger circles; the smaller circles are for NKRO diode arrays. Z-conductive tape will electrically connect the 8 pads on the left to the PCB.

Top membrane.jpg (62.03 KiB) Viewed 12644 times

[Redmaus]

I didn't win in the contest.
But i'm not going to let that slow me down. I'm finishing up PCB design and looking for quotes on laser cut acrylic sheet.

This is going to be using membrane type buckling spring switches. The bottom "membrane" will be a PCB (with integrated controller, microUSB connector, and 6 LEDs. The top membrane will be copper printed on thin, flexible plastic. I used this before and it worked well (for every key that i didn't screw up because my DIY PCB was so bad). I am happy with PCBWay who did the PCB for the XTant, so will likely use them again for this. The copper printed plastic is made in the UK. CIT Tech is the same as the InkJetFlex that i used last time. Quality was excellent.

The red lines are copper and the black lines are cuts. The USB connector will fit in the cutout at the top, left of center and the entire controller fits in that half square inch rectangle (under one barrel that is also used for a space bar stabilizer. Six screw holes and six LEDs are the larger circles; the smaller circles are for NKRO diode arrays. Z-conductive tape will electrically connect the 8 pads on the left to the PCB.

Top membrane.jpg

I might get one of these if it it good as it looks. How much would it cost?
Also on the PCB way place, could you make a custom F122 PCB with all the pads connected? Like the ones in between ctrl and alt? How much would one cost?

[wcass]

I don't have enough data to estimate cost with any accuracy yet. I will let you all know when I do.

I've been asked for more info on F type PCBs for other keyboards. I promise to get back to that after this experiment.

[Redmaus]

Thanks.
I will be waiting for the info.

[wcass]

OK, i talked about the top membrane in an earlier post - now to talk about the bottom "membrane". Because it is actually a PCB, we can build our controller right on it and we can run traces on both sides. I'll start with a close-up of the controller itself - this is under the left thumb key (space, backspace, function, or whatever you want it to be).

PCB1.jpg (118.5 KiB) Viewed 12538 times

This controller is basically just a copy of Parak's design for the Infinity keyboard and will use HaaTa's firmware. At the heart is a Freescale MK20DX128VLF5. This is a great controller chip because it is small, cheap, and requires so few support components - just 6 capacitors and two resistors. I've compressed that to just 5 support chips by using resistor and capacitor arrays.

Entering the processor at the top-center of the image - the thicker trace and two traces to its right are from the USB plug; +5 and data lines (VSS is the fill on the back). Exiting the center bottom of the processor are two traces feeding a 2x current limiting resistor array and then off to the LEDs. The 2x3 header to the left is for "serial wire debug" and reset, and will not be populated with pins. I will use spring loaded "pogo pins" when needed.

Six switch matrix columns enter the processor from the right and four columns enter from the left. Each trace is connected to a (looks like a spider) diode array; eight diodes combined into one very small chip. This prevents back-flow through the switch matrix when any key is pressed and will allow NKRO. The eight pins at the bottom-right of the processor go to the back side of the PCB, route to the far-left side of the keyboard, come back to the top of the PCB, and connect to the top membrane trough "Z-conductive" tape.

PCB2.jpg (136.3 KiB) Viewed 12538 times

Some links ...
The Infinity keyboard PCB https://github.com/kiibohd/pcb
pogo pins https://www.youtube.com/watch?v=MwjQuXaowDg
Z axis tape https://www.youtube.com/watch?v=K3SPijvXtew

[Redmaus]

Good to know the controller is being made!

On the backlighting do you mean the clear acrylic on the board is lit so the board itself lights up? Or is it per key backlighting with transparent legends I assume?

Oh, and I think I have a good name for the board the "buckling mini" Let me know what you think!

[andrewjoy]

chip on film ? aint that going to be unreliable ?


forget that bottom layer is a PCB , very cool

[wcass]

Not per-key lighting. The LEDs will be in the frame of the case and my hope is that the case will funnel the light to the barrel frame (under the key caps) and the case edge around the key caps. I will be using just a few bright LEDs so it is quite possible that the light will not be evenly distributed. The only way for me to know for sure is to test. Just for this test i will be using adhesive vinyl to make temporary reflectors to try to channel the light where i want it to go. Once/if i find something that I like, i can replace the vinyl with thin acrylic for a more professional look.

To illustrate what i am going for, consider this side view of the front edge of the keyboard. Grey lines are clear acrylic, blue lines represent a thin reflective covering. A red LED on the PCB shines up in a 120 arch. The top and front edge of the case (top and left side in this view) reflect the light so that the only place light can escape is under the key caps.

LEDs.jpg (126.86 KiB) Viewed 12482 times

[__red__]

Great project here wcass - I'm excited to see how it goes.

Random questions if I may:
i) Gold plated or copper?
ii) Do you have a "punched" acrylic sheet or something between your top layer and your PCB so that gravity doesn't activate all the keys for you?

As you're making your board out of acrylic I'll mention this - I've managed to make F barrels which are low friction by using additives to cast urethane. Unfortunately the additives make the barrels opaque (and i've been working on a transparent Model F design).

I'm also working on a proper working F foot which will work with the capacitance pads but that's for another thread.

I can't wait to see your final product!



Red

[wcass]

PCB will have a red mask with ENIG (gold) pads. The top membrane will be copper with ... i don't remember how they treat the copper, but do recall that it doesn't tarnish like untreated copper on a PCB would. I expect that I will need a punched membrane sheet between the PCB and top membrane. Other M use 5 mil between top and bottom membranes, but my membranes will be flatter than the conductive silk screen on an M, so i expect 3 mil will work best. . LEDs and the foam pad will be red. I will probably go with red caps too.

I'm very interested in your barrels.

[Redmaus]

PCB will have a red mask with ENIG (gold) pads. The top membrane will be copper with ... i don't remember how they treat the copper, but do recall that it doesn't tarnish like untreated copper on a PCB would. I expect that I will need a punched membrane sheet between the PCB and top membrane. Other M use 5 mil between top and bottom membranes, but my membranes will be flatter than the conductive silk screen on an M, so i expect 3 mil will work best. . LEDs and the foam pad will be red. I will probably go with red caps too.

I'm very interested in your barrels.

Do you have an estimate as to when the board will be available?

The idea of a backlit 75% buckling spring keyboard intrigues me...

[wcass]

I got the case in the mail today - i'm surprised at the size. It is noticeably smaller than my Kishsaver despite having one more key column.
Kishsaver = 14" x 7", 98 square inches, 64 barrels, 61 (typical) keys
this = 13" x 5.1", 66 square inches, 74 barrels, 70 (typical) keys

I'm hoping to have the first one built in time to debut at KeyCon Chicago (May 16). I've ordered almost everything i need, so should be able to give you guys an idea on how much one of these little guys are going to cost; under $100 for the PCB, membranes, case and electronics. This does not include the cost for buttons, stabilizer inserts, pivot plate/springs, and rubber mat (about $50 new from Unicomp or donor board) or barrels (donor board only, sadly). It also doesn't include the cost for time and tools to assemble - a Bus Pirate and pogo pin header for programming, acrylic weld/glue, tap, and soldering equipment.

I can't keep calling it "my new design" so it needs a name. Please feel free to make a suggestion.

[scottc]

That's fantastic news. I'm really excited to see the progress. Pictures would be very much appreciated!

[Muirium]

Aye. And for name suggestions: what does the (suggested) layout look like?

[vsev]

M 70 or 74 ?

[Redmaus]

I would like one reserved for me since I can't go to Chicago. Could we get some pictures if the frame and case? Oh, and will the LEDs come with the initial order?

[wcass]

Aye. And for name suggestions: what does the (suggested) layout look like?

Mine will look like this:

layout.jpg (50.85 KiB) Viewed 12274 times

Left "space bar" = backspace; Fn + right shift = Caps Lock; Fn + P = Print Screen; Fn + Del = Ins

It will use HaaTa's kiibohd controller software (same as the Infinity keyboard), so any key can have any value or function. I like the Fn in the "Caps Lock" position, but I know many of you will want to move the Fn key to one of the "space bars". It also uses IBM's common barrel spacing, so you can substitute ISO Enter and left shift if you prefer or you could substitute a 2x (backspace) key for any two adjacent 1x keys.

[snoopy]

Aye. And for name suggestions: what does the (suggested) layout look like?

Mine will look like this:

layout.jpg

Left "space bar" = backspace; Fn + right shift = Caps Lock; Fn + P = Print Screen; Fn + Del = Ins

It will use HaaTa's kiibohd controller software (same as the Infinity keyboard), so any key can have any value or function. I like the Fn in the "Caps Lock" position, but I know many of you will want to move the Fn key to one of the "space bars". It also uses IBM's common barrel spacing, so you can substitute ISO Enter and left shift if you prefer or you could substitute a 2x (backspace) key for any two adjacent 1x keys.

Very nice! Want!

[eldorange]

Is this keyboard for mass production release or exclusive per order basis in the future?

[wcass]

I am not interested in any part of sales (hoping someone else will take that up). But i do have extras of almost every part of this keyboard - polycarbonate screws available in packs of 100; capacitors that cost .10 each for <10, but .01 each at >9; PCB cost $100 for one, but $171 for ten; membrane cost $50 for one, but $152 for ten. Also, my soldering skills are not great (actually, i suck). My strengths are ideas and a willingness to spend money to see the ideas come to life.

I'll release all design files under CC0. Actually i should post everything now.

[scottc]

I'll definitely take a complete kit, wcass. I'd be willing to spend a reasonable amount on it too.

Edit: I'm sorry if this is a stupid question but I can't figure it out. Will this take Model F barrels, or should we cut up Model M barrel plates for it?

[XMIT]

I may be interested as well. I certainly won't be able to make it to Chicago.

[Madhias]

I can't keep calling it "my new design" so it needs a name. Please feel free to make a suggestion.

I would propose "Model W" to remember its creator wcass somehow! But then the 'W' is not good when pronounced (in German and English)? Then my next idea would be "Model C" for custom.

[scottc]

I like the W because it's an upside-down M!

[macmakkara]

Im interested in one kit also!

[Mal-2]

I can't keep calling it "my new design" so it needs a name. Please feel free to make a suggestion.

I would propose "Model W" to remember its creator wcass somehow! But then the 'W' is not good when pronounced (in German and English)? Then my next idea would be "Model C" for custom.

Model μ. Just to piss off all the people with boring, English-only keyboards.

[Redmaus]

Model W seems like a good idea to me. The initial order will also include the Lights for the case correct? Also, I would recommend asking Unicomp to print a custom set for the model W. Maybe they could sponsor it or something. :/