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DK2 Build Thread: Tenkeyless Cherry MX Modded Micosoft Natural Ergonomic 4000

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Update: I finished it thanks Jesus it works and everything wooooooooooo

. . . with a trackball!

The DK1 is a battleship with a trackpoint and scrroll wheel. That build thread is here:

User Lanx did something along this line but used the original inner frame as a PCB mount, which is interesting, instead of frame mounting the switches. Sadly many pictures are gone but the archive has a few of them, enough to get a good idea of what was done.

The DK1 board is for my use at work. Now I've started writing and I want one for the house.  Instead of having a giant trackball next to it, this will have a trackpad a meter-ish away. Instead of being on the desk it will probably be on my lap or on top of my laptop's keyboard area. The onboard pointing device will be used heavily on this board, I'm pretty sure. Having learned some lessons along the way with that build, I hope this one will go smoother.


* That sweet custom layout
* ...with MX switches
* ...on that sweet Microsoft Ergonomic platform with all the angles
* An integrated pointing device. It turns out I don't much like trackpoints and prefer trackballs over trackpads. So a trackball
* ...with at least right and left click buttons
* ...with a scroll function of some kind, probably a scroll wheel like on the DK1 but better positioned
* No major compromises on positioning of the mousing componentry, within reason
* Serviceability, meaning the ability to remove and replace/clean/repair switches. This likely means plate mounting, not PCB mounting, and probably individual wiring
* Internal tidiness. The DK1 is kindof a mess inside. I may be able to plan construction of the wiring so it's much (much) more tidy. We'll see. At least, hopefully, internal structure that doesn't prevent the thing from closing like happened (repeatedly) with DK1
* Quietness. This will be used in the still of the night and be the loudest thing. Blues are out. I'm leaning heavily toward o-ring'd Black stems.

Secondary goals:

* Plate cutouts to allow opening the switches without removal. This would be super duper duper helpful if I end up using a PCB here
* Maybe do something to have this sit on top of my laptop without hitting any keys?
* Use nicer switches for the right and left click if practicable
* Make the borders nicer, fill in the gaps around key areas. MAYBE make this actually nice enough to show off.
* Fill in the multimedia key area instead of leaving the stock silver keys in place
* Install the 'enter' key from the tenkey area in the main panel again. The carriage return key does different-enough things for this to be useful to me personally.
* Some kind of spill tolerance. Drain holes or liquid channels or something. I haven't needed this yet but my home environment involves children so God only knows.
* Possibly a 2U tall delete key instead of having an Insert key. This may require stabilization.
* Move left-control over to the left more. DK1 has it too far inboard
* Maybe a larger left shift key if it will fit
* Maybe (maybe) make the middle-enter key a 1.5U cap
* Some kind of way, make the cut-off right end of the frame not look horrible. This will be a challenge!
Lessons already learned/wisdom I bring to this show:

* Prepare and mount the switch frames, THEN do the paper layout of the switches
* Solder the switches AFTER the wiring is all done
* Tack the wiring in place with baby dabs of hotglue as it is being installed between switches
* Wear gloves for this part!
* No wiring around the extreme outside edge of anything if it can be avoided
* Many keys can be safely eliminated. I have never used the Insert, Pause/break, or Scroll Lock keys. The FLOCK key on the MS4K has to be retained in some vestigial form because I'm paranoid about actuating it by accident and not being able to un-do the actuation without a switch. This may be a tiny button hiding somewhere in the build, I'm not sure
* At work I sometimes use the left space key. At home the thumb hovers. This build will have no leftspace, and that area may be used for trackball works or custom copy and paste keys. I may also put the right and left click there, or just a thumbrest. We'll see.
* I breifly toyed with the idea of using a full-sized trackball like in my Expert Mouse but it would mean so much work to the MS4K's frame that I may as well just do a fully custom frame. I want to avoid that for this build.
* I started looking for a small trackpad to integrate after I realized it will be difficult to integrate a large trackball. I was shopping for pricing when I realized I don't especially like trackpads and want a trackball. So it's gonna be a trackball.
* Build threads are a lot of work and so are custom boards. Expect updates every few days at the oftenest. This will DEFINITELY not be updated nightly!
* Custom boards are a lot of work. DK1 has consumed at least 120 hours. I don't want to know how long this takes so I won't keep track.

If God so chooses to bless me I'll be able to accomplish this build for $0 as well  ;D

There will be many pictures coming soon, and lots of wordswordswords, as with the DK1 build. I hope you enjoy this process as much as I do!  If you have any ideas or constructive criticism, please feel free to chime in! I'm about to start digging through the archives to see if anyone has made a similar build in the interim. If you know of one here or on another site, please gimme a link!

I've got kind-of a handle on the keyboard side, I think, so I'm starting on the trackball part first.  TW: many pointing devices will be harmed in the making of this project!

First unfortunate victim: the Logitech TrackMan Wheel T-BB18

Four screws on the bottom and

It almost comes apart easily. The LOVELY thing about this mouse is that the circuit boards are all VERY small compared to what I've dealt with in the past. If it proves out that they can be separated by longish ribbon cables, my life just got a lot easier!

I have separate modules for the optical engine, the brains, and the switches and scroll wheel. Nice.

this is where the magic happens. A little optical filter window hides the sensing element from the world

The size of this gap between the ball and the scrotum is probably pretty important.

Yes I said it. You'll see why in a minute LOL

the scroll wheel mounting is looking a little complicated. I'll figure that out later. I don't like these plastic wheels anyway. I want to see if I can figure out how to get a metal wheel in there, and preferably a larger one. We'll see how that goes. Later.

While trying to pop out the optical engine, I broke a little clip somewhere and things went flying. The filter turns out to not be glued in position.

I've been able to swap out the red/dots balls with fancy metal-flake balls before, and I like 40mm better than 34mm a lot. I want to try to use this fancy gray/silver job:

It turns out I was able to just hamfist this all together with gravity holding the filter on the optics, plug the cable into a computer, and verify the thing still tracks with the little ball. Baby steps.

It did. But it didn't track properly with the silvery ball. So I hoped it would work with things spaced out properly.  I had to slice open the mouse's scrotum to get my big ball to fit. This was a job for tin snips.

aaaaaand it didn't work still. Happily I also have a red/dots 40mm ball so I tried that and it worked well:

which at least showed me the ball size is not the critical part and I can keep using the big ball.  If I had a 50mm red/dots one I might try to fit that, but the mechanics are looking pretty tight already under the hood of the microsoft keyboard, and I think full-on Expert Mouse size balls may require something much more drastic than I would be mostly able to fit in the Microsoft keyboard chassis.

Look at my balls.

Time for our next victim! Enter the T-BC21 Marble Mouse. One of these (don't ask why I have several in a bin) donated the red/dots 40mm ball. Note that the ball in the Marble Mouse is retained slightly even when held upside-down. This matters for ball-retention purposes in my final product. The hole is all of 0.1 or 0.2mm smaller than the ball. You push a little and the ball pops out. OR  if you're my children you drop the thing and the ball goes under the couch.

four screws later

Can you tell? There seems to be a family resemblance here!

Does the sensor of the one fit the other? Yes!

when taking the buttons off the top case, the scrotum fell off the mouse

The scrotum cups my ball properly on its three little bearings. As it was designed to do. I shouldn't have been surprised here.

Two little nubs poking out into the opening are all that effectively retains this ball. Simple, elegant. Nice.

The scrotum nestles nicely in the base plate, if a bit loose when it's not screwed up tight.

but to have the ball opening something like horizontal as I want it to be on the keyboard, I would need to have the baseplate at a drastic angle inside the chassis of the keyboard, which seems bad. So the baseplate goes in the recycle bin. The angles on top of the mouse are all funky too. I don't want laser rocketships here I just want a ball on my keyboard looking like it belongs.

But . . . hey, do you know who made a nice flat top opening for their trackball?

The Orbit has been a favorite of mine for a long time. This one may just have to die, unless I can sculpt a nice flat-topped ring opening for my trackball. Then again, I have some thick black plastic I may be able to roll into a top of my own. Hmm.

spare switches. You'll see why later if I end up using them.

The axle on this side of the scroll wheel is held on by a spring/clip. This is also a hinge, to allow the other side to be used as a switch operator. I don't like scroll wheel switches so I may dispense with this. Anyway, pull the spring off:

and the scroll wheel and switch operator both pop right out. The little slider is lubricated, which makes sense.

The axle only protrudes past the wheel on one side. The other side is supported inside the width of the wheel

The black plastic bracket protrudes into the wheel and supports the inner axle. The spring provides click detents. I want a smooth scrolling experience, so this is going away or at least being minimized.

The soft plastic on the scroll wheel pushes off from one side, and is retained by little tabs in slots on the other side. This came off easily, thanks God

The whole thing seems fairly weak, so maybe mounting that weak axle on a weak spring was a good idea IDK I'll have to consider whether I want to keep using this wheel or try to find something that seems sturdier. I am thinking about cutting a nice fat aluminum disc to make a new scroll wheel for this board. We'll see.

The sensing is via infrared optical interruption with this little sensor. So I'll have to mount that in pretty stinking close proximity to the wheel. 

Now that I have an idea of what I'm going to be putting in here, it's time to open a keyboard frame to do some actual physical comparisons & whatnot

There are 3 different-length screws out here

There are 3 different lengths of screws under  the palmrests and space bar:

Relative positions of screws in the cap mounting plates:

and I can finally compare ball sizes. Look how much deeper into the frame the larger ball protrudes! I don't know what I was expecting, but for a system with a captive ball, this big one is not going to make my life easy. So I've settled on using the smaller ball.  If it's not a 50mm ball it may as well be small.  I found a 50mm ball by the way but it's just too big, unless I wanted to make a big bulbous protrusion thingy and I don't.  Looking at these pictures made me realize I will have to be careful to not mount the scroll wheel so high up that it activates by accident when I am using the trackball (!) so I guess I'll have to do the trackball mounting bits first, then figure out the scroll wheel later. This should be tricky but do-able.

Okay so that's decided.  On to the scroll wheel.  Here's the stripped-down wheel inside the Zoom slot on the keyboard top frame:

It's too small. IF I wanted to keep the original size and material, it would have worked. I don't. I want an awesome big aluminum knob here, not a reused plastic dial.  I really think I'll stand firm on this point. If I just can NOT make it happen, I have a backup mouse I can use the scroll wheel from. Mounting would be simpler too, I think. But for now, I want to go bigger.  The gap in the frame is about 9 to 10 mm wide depending where you measure. So I can have a nice FAT wheel with big rounded edges and chunky texture for my fingertip to grip.  Also, There's room for a larger wheel. After some experimentation, I came up with "about" 30 mm as a good diameter to shoot for. I used some foam scrap for prototyping purposes LOL and there's plenty of room (I hope) for mounting under there.

The next step may take a while: I have to come up with a suitable scrap of aluminum (or maybe copper?) and cut a wheel.

I've been working in two locations on this project. Here's a report from the second, for the last few weeks' work. It's a long, image-heavy post!

A reference photo, for use later:

Showing the back side. Note the board is flat across the bottom, but there is a big swell in the middle; this goes flat well before the cable exits the back of the board

The feet on the back corners really kick this board up in the back. I don't like 'em kicked up in the back. This will be going away.

Reference photo of the bottom.  You can better see how the swell in the middle goes flat toward the tenkey end of the board. Note also: the very large protruding feet in the rear

I really like the layout of this model. Too bad the switches are regular membrane switches and they fail because [reasons], and the keys don't all have a very nice feel when pressed.

After taking out the screws on the bottom case, there are a bunch of screws holding the top case to the middle, and holding the angled key plates in position.

Please excuse the filthy mess from whoever used to use this board and look carefully at the shape of the keycaps. This is one of the main reasons the MS4K will never be a *really* good candidate for a straight switch modification. Look at the shape of the 6 and F5 keys, for example. Look at the Z, it's subtle but still not square. They also played tricks with cap heights to get the gentle curves on the final product.

Also: look at the spacing for the G and T keys. Crazy. They did that a lot, on this board!

note: there are screws holding the top frame to the middle frame hiding under key caps! The central bridge also has a clip holding the frames together

The back feet stick out like a lot

Look at the fasteners for the wrist wrest. Then look at how much of it needs to be altered to fit a tenkeyless format:

THREE sets of top frames died for this project (so far). You can see the different paint colours on two, that I knew I was going to be sacrificing, on this test cut fitup. It looks do-able to reuse the right end of the frame, but the nice little "microsoft logo" area is going to be troublesome. There is a little sliver of black plastic between the shiny silver and the main frame area that needs to be dealt with, to fill the gap neatly.

but it looks like a TKL frame mod is going to be possible AND possibly look really nice!

On the "final" frame, I glued that sliver of black plastic to the edge of the frame.  I didn't want to get ABS funk all over the finished parts, so I used liberal amounts of masking tape before applying ABS slurry and clamping the parts together.

And by "glue" I mean "ABS shavings left over from 5 years ago when I made the last keyboard, dissolved in acetone until they become goo"

Very handy tools for very very fine adjustments during fit-up: a dremel vibratory tool and a razor knife

After the glue had cured and the tape was off, I had one solid piece of plastic to grind down to size. This was WAY easier to work with than when the black sliver was loose and jumping all over the place!

The fit-up was slow going but this WIP shot shows it coming along pretty nicely!

I realized after I glued the ends of the frame together to eliminate the tenkey area, the top and middle frames were going to be permanently bonded. So I thought it may be a good idea to sand the insides of the joints between frames, in case I would want to inject acetone in the gaps later, to turn the loose-fitting parts into one part. We'll see how it goes but I did this anyway:

The glue-up was done in two stages. The top was left open so I could adjust it. First stage done:

It's a focus miss but you get the idea: there was a difference in angle on the frames from the arrow area to the TK area. I'll have to deal with this later.

I was pretty happy with the way I was able to get the big ridge on bottom of the frame lined up pretty straight. I think that will help me later.

The top corner was left open so I could do the fine adjustments without having to fight the frames moving against each other. I want this joint especially tight. Adjustments were made with a razor knife. It was tricky.

More masking tape for the second glue-up

The backside is a lot uglier:

With the tape off, here's the result of the second glue-up. Note that several of the key locations have been ground down so c-clamps could be fitted in the depressions in the keyboard for glueing time.

Another focus miss :( but the shiny and dark place at the corner of the joint is a gap that I accidentally left during the fit-up. I filled it with ABS slurry LOL

I like the gap between the light and dark frame areas, but not the one between the dark plastics. I filled that, as well as adding a glom of plastic for the big offset by the bottom/right and top edge:

I've been considering how to cut the top frame to fit all the switches I want to fit. The DK1 has kindof an awkward set of curves. I'm thinking maybe something like this could be better. We'll see how she ends up!

I put the bottom frame back on loosely to check clearance. I found kindof a problem.  To have the keys kinda normally "about even with the top of the frame" like this

The mounting plate needs to be 'way up high in the frame. Just setting a switch on the bottom plate got me a good height. This puts  the mounting plane of the switch several millimeters higher than the plane of the stock mounting plates. 

I put the switch mounting plates in the DK1 at the level of the Microsoft mounting plates on the MS4K. It has the key caps *really* low in the board, sometimes the lower-height caps are lightly under the edge of the frame!  I am pretty sure I'll trim the frame up on the DK2, so the caps can be a more ordinary height, protruding from the body of the keyboard.

Okay on to the bottom case. I had to do a lot of eyeball measurements and ended up with some pretty big gaps on this, unhappily. Oh well. I'll weld it up later.

Look at the big jump on the bottom corner. That's gonna be tricky to fix!

In order  to get the top and bottom frames to mate on the end, I had to grind down this one screw mounting boss that's no longer used. It was hitting a screw mounting boss and the bottom of the media keys.

Taped and clamped for the first glue-up of the bottom case:

I left the bottom edge untaped because I knew it would need to be trimmed and bent to match the edges on the front of the board. But I clamped the area together because I am trying to have the bottom of the board reasonably flat.

After the tape came off, I noticed the little ridge around the label is preventing said flat-bottomness. The ridges around labels shave off pretty easily thanks God!

There was a big gap at this corner and I filled that in a separate glue-up:

The front edge of the frame was cut a bit to allow the plastic to bend. I jammed a bit of plastic in the end of the gap to get the edges lined up properly, and welded that in place with a hot knife. Then I put another little tack weld in the middle of the open space to keep the gaps about right on that end too. The clamp shown here is holding the various open/cut ends on a plane. Since the sheet of plastic was twisted into shape, they wanted to point their own directions several degrees from flat. CLAMP and they were flat. Tape to keep the ABS good from running out the giant gaps during glue-up.

Here's the glue-up for that

There were some pretty big gaps left.

Another fill of ABS slurry

And a bit of filing. This may be close enough to a "flat" surface for this project. I'm not sure.

I briefly toyed with the idea of adding the cut-off rear foot back to the now-shorter end of the board. I decided I want the feet gone instead and ground off most of the remaining foot. I didn't cut it off altogether because I want to reuse as many case screws as possible and here's a screw boss I may want to use later. So I fixed this gap in a two-stage glue-up.


and then a bit of plastic removal:

after the second filling:

The level of the foot area is depressed relative to the surrounding plastic. I'll have to fill that in. So I put a coat of ABS slurry on the whole area except for the screw boss, let it cure, then filed it down. Most of the depression is filled. This will take at least one more round of filling with fresh (recycled) plastic then more filing to shape, but this is looking good for now, I think!

I realized the screw holes in the middle with little protruding cylinders of plastic around them, were not going to be used. They're right in the middle of nowhere now and I don't know that I'll want those screw holes on my soon-to-be switch plates:

So I trimmed off their cylinders from the bottom of the case. I didn't cut the screw hole out entirely because it's offset and I think it will leave a hole. Plus I might want that screw location later. I also shaved the ridge from around the rest of the labels


The scroll wheel was giving me difficulty. I didn't know what I wanted to make it from, until I saw this:

a big chunk of plastic just a bit larger than the 30mm initial diameter estimate!  Here's a circle about 32mm diameter. I'll cut it out large, then fit to size!

some quality time on the bandsaw to cut off the end, then a rough taping to give a guide line at "about" 1cm thickness and that was cut off too.

The initial fit is . . . not great

and the rough cut part is not exactly round LOL

So I drilled a hole on the central mark left by the point of my compass and put a screw in there and chucked her up in my drill press! The file took it to close-enough to round at about the right diameter, with a rough profile shape on the edge, fairly quick and easy. Nice!

The fit was much better at this reduced diameter thanks God!

But my fingers have seen lots of use and are not super sensitive. I like big chonky grippy textures on things like this. So I chucked up a baby little ball mill and . . .

Now THAT's what I'm talking about!

To be continued!


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