deskthority

Hey there,

I'm totally interested in a PCB as well! I passed up a cheap 'unsaver' awhile back, and it's biting me ever since. But an FSSK would be even better (my biggest problem with the larger F 'boards is that you either custom build your desk or you specifically buy one for the keyboard).

Here's what my plan would be... RIT dye a pearl white SSK entirely dark black (I'll have to see what tolerance of temp the plastics of the chassis tolerate, it feels like ABS to me but I could be wrong). Finding unused black badges would be a problem, I don't have any spares so that may have to custom printed. And then pop in some F-springs along with black keycaps and away we go.

Unfortunately I'm also out of black keycaps due to a recent keyboard mod, and it appears unicomp either stopped selling them or has them on a hiatus.

Well I got a bit excited and couldn't wait: so I took a spare SSK apart (don't worry, this SSK wasn't in perfect condition). I then took the buckling springs out of my failed F AT-- and what do you know, it has precisely the required amount that an SSK needs! Not a spring more, or less:


There is minor problem of some random tiny stems in the way of the bottom keys, seen here:


(iDollar may have mentioned it already, this is on the early iteration of the board, and not the later pearl one which poses other problems)

Thankfully they can be cut away without reprimand, and the springs go in nicely:


So how does it sound / feel? Exactly like a Model F as iDollar stated. I've hypothesized about it before-- and the Model F 'smoothness' comes from the extra winding in the springs, and the "crispness" is due to the fact there's no rubber at the bottom. Turns out that it must be true after all.

For everyone's viewing and listening pleasure, I took a video of the Model F spring in action on the Model M SSK. Since I am just holding it together with my thumb, this gave me the opportunity to go through different tensions-- the tightest tension is what you get from a proper Model F-- whereas the looser tension is the all-too-familiar problem of when we don't slide the Model F springboards back together properly: I've decided to paint the case black instead of RIT dye. If the case is ABS (or a plastic that doesn't take on dye well) it could be a disaster. I pulled off the white badge and was going to reuse it, but apparently engicoder might be doing a run of aluminium 'pill' badges. Totally awesome and would get some. The badge is at the bottom, and the brace is to fix some minor warping of the chassis:

Nice work micrex22! Good to see that someone else thinks that it feels like a real Model F, that's great to hear.
Now we only need that sweet PCB to complete the dream.

If everything goes well with the project, then I'm definitely interested in painting the case black.
Would be nice to see the results of your attempt.

Just to know, would it be possible to just swap the M flipper with F ones, but let everything else the same?
I mean, the bigger flipper should have contact with the membrane right?

That wouldn't be a "true" Model F, but maybe they are just as light as F ones then. Would be good to know, if anyone as experience with this.

As far as I know Model M flippers have a small nub that presses on the membranes to connect them. Since a Model F flipper doesn't have these it wouldn't work, I think.

This should not be a problem. The plan is to completely remove the membrane and use a PCB instead

The real problem is to find the time to design the PCB

Well, maybe I will try that today just to know how it feels, or if it improves the feeling.
The most thing I like about Model F's is that it's not as heavy to press down. Would be a nice transition until the real deal PCB is there.

The F flippers are too long. I guess that they will not hit the membrane in the correct place.
I need to find the time. I need to find the time ....

some progress today:

I decided to start again modeling the PCB
The previous work was somehow chaotic. I decided to start again, this time with the membrane, to then continue with the PCB.

This is the version 0.1
From the picture you can see that the membranes of the Model M Extended and the SSK have the same layout. Thus, I have decided to model a PCB for both keyboards. We will have the FSSK and the FEXM (F Model M).
The latest name reminds me to what happened to the "Mouseless commander", when mouse control was added
Feel free to propose a different name

Next is to add the holes

And here is the version 0.2

I have added layers and the bottom routes
I just realised that I will need to modify it. I have not added the holes for the screws. This is the next step

idollar wrote:And here is the version 0.2

I have added layers and the bottom routes
I just realised that I will need to modify it. I have not added the holes for the screws. This is the next step

FSSK v0.2.jpg

Is it just me or are the left and right alts not connected?

He said he added bottom routes. That means that there are probably traces on the PCB running to the controller on the other side, which are not on the graphic because it is 2D. Not 100% sure but it's what I figured.

Other than that, awesome i$, always great to see progress!

neverused wrote:

idollar wrote:And here is the version 0.2

I have added layers and the bottom routes
I just realised that I will need to modify it. I have not added the holes for the screws. This is the next step

FSSK v0.2.jpg

Is it just me or are the left and right alts not connected?

Yes, these are errors. Thanks
I am reporting while doing.

And here is the version 3, with the bottom layer complete for the Extended M and the holes
Next the top layer (just for reference, in the case that some one wants to use these files)

And here is the top layer: Version 0.5
Next the PCB, which was the goal, actually

Here both layers together.

This is to be an FSSK, right? So all the traces will all be changed. The M needs traces to be disorganized to minimize ghosting; the F will not have that problem. It's pads will be MUCH larger (so much less room to route traces) and traces will need to be organized to avoid crossing.

The only thing you need from the membrane is the outline (minus the tails), the rivet hole size and positions, and the contact point of each switch. You also need to know the relative difference between the M contact point and the F pad placement.

wcass wrote: This is to be an FSSK, right? So all the traces will all be changed. The M needs traces to be disorganized to minimize ghosting; the F will not have that problem. It's pads will be MUCH larger (so much less room to route traces) and traces will need to be organized to avoid crossing.

The only thing you need from the membrane is the outline (minus the tails), the rivet hole size and positions, and the contact point of each switch. You also need to know the relative difference between the M contact point and the F pad placement.

Hello,

You are right. I only modeled the traced on the original membrane for documentation purposes. I thought that having a single file with all the contours, the membrane layers, the holes and the PCBs of the FSSK would be useful.

Here is where I am now with the modeling (work in progress as you can see):

The top layer (incomplete work): The bottom layer (incomplete work): Both layers of the PCB (incomplete work): All the layers in the file together
I am using your work a lot. Without your help this would have been much more complicated. THANKS !!!!

Is there provision for calibration pads?
They are present in the AT for sure, and I think on the others too. xwhatsit's controller uses them to auto-set the threshold.

And thank you for putting time into this! It's going to be great!

Yes, there will be calibration pads
Thanks for the comment

The Challenge will be the holes.

I have printed the CAD drawing, with a calibration line at 10cms that has shown that the printer scale is correct.
It seems that the holes layer has some problems that I shall correct. A drawing with the challenges and hand painted solutions follows:
Note that the holes are very exaggerated (big) in the membrane that I have been used.
The pencil traces are from the holes on this membrane.

If the same exercise is done with the little holes on the plastic foam of the keyboard it looks better.

Have you tried printing on dimensionally stable transparency film? Plain paper can change in size quite a bit when printing, and on a 40cm long print it adds up.

Hello,

I do not think that it is the printing scale. I have made a test rule in the paper of 10cm. It looks fine.
(apology for the picture. It is made with the telephone)
I will check the printout anyhow against the file.

Here my next quality check:

I have screwed the printout to the SSK and using a bollpen push the centre of the barrels.
I could also check the alignment of the flippers.

Once more, telephone-quality pictures

I really appreciate all the work you are putting into this, idollar! My SSK will definitely become my go-to keyboard once I turn it into an FSSK!

idollar out of curiosity what CAD software are you using for this project? KiCad? Something else?

XMIT wrote: idollar out of curiosity what CAD software are you using for this project? KiCad? Something else?

wcass recommended to use DeltaCad, and as I said before, I normally listen to people with experience
It runs on windows or Mac natively. I execute it on top of wine on a debian box.

This is the DeltaCad home page

The software is VERY easy to use. It comes with a manual that shows, in few pages who to draw a calculator:
On top, I have found a summary with shortcut keys which resulted to be very useful

DeltaCad costs some 40 dollars. For the time being I use a demo version, that should expire in some days.

I have to repeat that the research and recommendation merits shall go to wcass

I have created the following spreadsheet to collect the interest in this project.

Click here

Please write down your interest/preferences.

First in, first served

Cheers

Count me in for prototype testing, I'm on mobile now, can't edit spreadsheet.

Okay, great, thanks. Picking a software package is always the hardest part. I pick free/open source software when possible. In this case that means the KiCad suite. However the tiny amount of experience I do have - and the community of folks in this area - are EagleCAD users.

I'd love to help but also need to be realistic about the number of projects I'm taking on. I'll check in after a few days to see who else signs up.