Help with a split hand (MS Natural style) case design?

[TD22057]

My last keyboard build was a matrix style split hand.  It turned out really nice but after using it for awhile, I've decided that I don't really like the matrix layout.  So my next project is to design a Microsoft Natural style split hand board.  I haven't finalized the exact layout yet, but there are several possibilities which will probably all work fine.  A full size version and a more compact version which I both like are shown below.  A big advantage of these designs over my matrix split hand is that standard keycaps can be used for everything except the space bar.  I've shown 2u space bars below because I'm planning on using caps from the GMK Carbon drop w/ the 2u keys from the ErgoDox companion drop.  Using 2.25u and/or 2.75u space bars would allow shift keys from other sets to be used as spaces but I don't particularly like that idea since I don't think it will ever look as nice as at should (especially given how much it will cost to build).

The biggest problem I'm having is whether the hands should be tented or not and the case design.  If everything is done in a single plane, it's easy.  A single PCB can be created and a standard laser cut plastic layer case will work just fine.  However, I really like the light (~8 deg) tenting that's in the MS Natural keyboard and would love to duplicate that.  That adds a lot of complexity though: 1 PCB turns into 3 separate PCB's that will have to be connected together, and the case becomes much more complicated.  Maybe even too complicated for me to attempt.

So here's a few questions I'd like help with.  Any ideas you have would be great to hear.

1) How would the 3 separate PCB's be connected together?  Assumes they're connected inside a single case so nice, external connectors aren't required.

2) How can a case be designed to hold a series of tilted planes (see attachment below) that would be as easy and cheap to build as possible while still looking nice?  For starters, assume that the 3 planes (left hand, right hand, num pad) are only tilted in one plane.  I'm assuming any front to back tilting can be handled some blocks under the back of the case.  Obviously 3D printing would work, but that's a big thing to 3D print, I'm not sure how nice it will look, and doing the design work is beyond my current experience.

One advantage of my split hand board was that the switch plate was plastic (i.e. cheap) but that only worked because it was supported by the bottom of the case.  I could duplicate that kind of sandwich design and make 3 separate keyboards, connect them with external cables, and then build a stand or base of some kind to hold them together in the arrangement I want.  That might be my best option at this point, I'm just not sure it will look as nice as a good custom case.

[kurplop]

I'm sorry to hear that the matrix style didn't work well for you.

Assuming that you like the tenting, I think it's a feature worth the effort. I think that by making an 18º bend between alpha's and a reverse 9º at the number pad in the top plate is doable if the arrow cluster was modified. The remaining plates could be flat, independent units with a flat single bottom plate to finish off the bottom. Carefully fitted triangular pieces could be solvent welded to the top plate to create a finished look.

When I bent plates for my first custom keyboard ( I used aluminum),I found 2-9º bends made in an inverted 'V' better oriented the alpha planes to my hands. It would be necessary to increase the split slightly to do that however. Beware however that it makes the keyboard much higher.

Connecting the pcb sections is easily done with a few jumper wires.

I'm looking forward to see what you come up with. 

[Findecanor]

1: There are multiple ways of doing it.
The one that involves the least hardware would be to use ribbon cables soldered between the PCBs.
To minimize the number of leads in a cable, design the logical matrix to be as close to a square as possible.
Place the controller in the middle part to avoid long cables.

Another way is to use an I/O expander in each part (except one) and have them connected over a I2C bus. Then you would need only four leads from the controller board to each keyboard part. This could require some custom programming. ErgoDox does this, and there are a couple of firmwares available for it that you could cut and paste from.

2. There are lots of ways. Some ideas pulled out of my behind:

2A: Because you are using a regular staggered layout, get hold of two cheap old keyboards with steel plates. Cut those up and weld them together in the shape you want. Might need extra steel here and there and of some switch positions cut in the bottom row. Because you will also be using PCBs then all holes don't have to be perfect. Then that will be your chassis that everything else attaches to.

2B: Make a base plate with blocks on top lifting each keyboard part. Each keyboard part would be a sandwich of bottom plate, PCB and (optionally) a switch plate with spacers between the top and bottom in the sandwich, screwed together. Have the bottom screwed onto the lifting blocks and base plate.

[MajorKoos]

I've been thinking of doing the same thing, but TKL.
I purchased a Phantom PCB from mechanicalkeyboards.com ($32) that I intent to cut into 3 pieces.
I'll be using hookup wire to jump any traces that get cut in the process.

[Findecanor]

BTW, If you cut a PCB be very careful that you are not able to breathe in fibreglass dust. That causes cancer.
Make sure you do it in an area where it does not spread, and can be collected. I use a vacuum cleaner right next to the dremel tool.

[TD22057]

Thanks for the ideas everyone - you've given me some things to think about.

Here's another one I came up w/ this morning:  Build each of the three pieces as a laser cut sandwich case and have "fingers" on the ends that interlock w/ the next case.  Then run a rod (threaded?) through the fingers to connect the cases together.  Assuming it can be tightened enough and there is enough friction, that could make a case w/ adjustable tenting angles without too much effort.  I may try and start throwing some prototype ideas together in sketchup to see what they look like.

[TD22057]

Another idea:  make 3 separate layer cases and screw 2 strips (1" wide?) of aluminum bent to hold the cases in the proper angles into the bottom of the cases (one at the front and one at the back).  Cover the transitions with extra top plates to hide the metal and the ribbon cables connecting the pieces. 

Another idea: Create a single bottom plate from plastic.  Then carefully design triangular (or trapezoidal really) edge pieces which would get glued to the top plate and hold them at the proper tenting angles.  The edges would have to be drilled and tapped at an angle for the bottom plate and the edges on the ends would have to be beveled which might be difficult to make look nice.

Here's an initial sketchup rendering of a full size, Microsoft Natural style keyboard in 3 pieces.  Total width is basically the same as the Microsoft (~505 mm).  I stole the keycap model from the 3d warehouse and built up my layout with it.  This isn't my final design but being able to rotate it around really helps visualize how the 3 pieces can be fit together and where things like the cpu can be placed.  If anyone wants the sketchup file, let me know and I'll attach it here.

[FrostyToast]

This might be of interest if the numpad isn't absolutely necessary.

[TD22057]

I think that's interesting but it's single plane - no tenting. I think that would be pretty easy to do with a layer case but I really want to try and get a tented case going.

Sent from my SM-G935T using Tapatalk

[TD22057]

Here's a rough rendering of the hinge idea.  I think this looks really cool and it would allow a flat keyboard or a tented one with variable angles.  It does make things wider - especially when adding the numpad on the right.  The hinges also reduce the area where a CPU can be placed though perhaps with custom PCB's this can be worked around by soldering the CPU on the PCB instead of using a pre-made teensy.  Wiring is also more complicated - a "window" would have to be made in the lower 1/2 of each hinge piece for wires to pass through between the sides.  But it does look very cool...

[Findecanor]

I would not worry about the extra space. I think that of all the features (tenting, angling, etc.) of ergonomic keyboards, it is hand-separation that is the single most important feature.
Look at how ErgoDox and µTron have extra keys in-between the keyboard halves, and the space between halves on Kinesis' and Maltron's contoured keyboards is immense.
If there is more space then maybe only the angle between halves should be smaller, but you will find out about that when you have your first mock-up.

[bifrost1107]

Hello, I am new to the forum. Was thinking on doing custom keyboard, so I guess registrating here was logic step xD.

Using this http://www.keyboard-layout-editor.com/#/gists/a9070ceb5254324371ea8a72a792f68a and this http://builder.swillkb.com/ . I got *.dfx, and edit it a bit.



Those space bar stabilizers needs to be deal with, but here is *.dfx so far https://github.com/bifrost1107/split-key-keyboard. I am thinking to hot gun space bar to get curves and to be one peace, then deal with that stabilizers place. If not possible 2x space bar is probably way to go.

Maybe that *.dfx will be helpful to you.

https://skfb.ly/SpFM