deskthority

Hi all, I want to share my build log of my new 60% keyboard, which uses Alps SKCM Brown switches and the unique layout of the IBM 5140. Hope you guys enjoy and I apologize in advance for the potato pics!



Introduction
Although this build took about a week to complete, I had been planning it for several months. I had originally envisioned the keyboard having SKCM Orange switches from an Apple Extended Keyboard and its keyset; this changed when I came across an IBM 5140 PC Convertible with SKCM Browns. My Oranges will have to wait a little longer to find a board to call home.

Layout
PBT Alps keysets tend to be few and far between and I wanted to make use of the entire IBM 5140 keyset instead of just the alphanumerics as others have done. This meant designing a custom plate and dealing with a Big-Ass Enter (BAE) layout. The 5140 layout is pretty eccentric, using a Focus-style split right shift and 1u backspace (my sole complaint with the layout). The plate would also need to be Winkeyless due to the lack of any bottom row 1u keys on the 5140.



Part List
+ 59 Alps SKCM Brown switches
+ IBM 5140 PBT Dyesub keyset + Additional Ctrl key cap + 7u space bar (Thanks alienman82 and Wingpad!)
+ Hasu's Alps64 60% PCB
+ 316 Stainless Steel plate cut by Lasergist
+ Harvested stabilizers and stab wires from various Alps keyboards
+ Cheap Aliexpress plastic case
+ Rust-Oleum Clean Metal Primer
+ Rust-Oleum Metallic Black Night Spray Paint

Anyhow, the main build log follows:

Plate Design
The layout of my 60% 5140 is largely the same as that of the original 5140 keyboard; however, I modified the bottom row to be a bit more standard: 7u space bar, 1.5u mods, and Winkeyless.

My biggest concern was the BAE key, which was stabilized in a manner that was unlike what I had seen with Focus or Northgate boards. I admit that I do not have calipers so I had to make do with rather imprecise measurements of the stab placement. Using Swill’s plate builder to generate a base plate and what measurements I could make, I threw together a design in Autocad:

IBM 5140 Plate




To deal with the inevitable errors, I like to test designs by making test printouts to tape onto thin cardboard and cutting certain cutouts with an X-Acto knife to test switch and stabilizer fittings:



After I had a design I liked, I ordered a plate from Lasergist. Their work is great, as is the price; This plate was done in AISI 316 stainless steel for about $40, shipping included.

Switch Preparation
While I waited for the plate to come in the mail, I worked on the switches next. The switches themselves, Alps SKCM Browns, also came from the same IBM 5140. They were pretty clean to begin with, but because a good bit of friction can come from contact between a switch’s housing and top housing, I wanted to be extra sure and so, I disassembled all of the switches and washed the top and bottom housings. I did not touch the switchplates, tactile leaves, or the sliders.

Disassembled switches


Cleaned switches, jar's a bit dusty on the outside though


Plate Painting
After the plate arrived, I gave its back side a good sanding. Lasergist offers a polishing service for this but I chose not to have it done.



The plan was to prime the front side and paint it. I had made several mistakes at this step in my previous 60% build, and I ultimately was not satisfied with the final result because of this. I took care not to repeat these same mistakes.

First, I scratched up the front side with a somewhat course grit sandpaper to help the primer adhere to the steel. I used Rust-Oleum white metal primer to prime the plate, letting it sit for a day to dry a bit.

Somewhat scratched plate


Primed


Afterwards, I used Rust-Oleum metallic Black Night spray paint on the paint. I think the final result was quite nice, definitely an improvement over my last attempt. There were minor imperfections, but this did not bother me. I also allowed this to cure for about a day.





Keyboard Assembly
At this point, soldering the diodes and switches to the Alps64 PCB was the only task remaining:

Diodes soldered


Switches attached to the plate






After everything was soldered, all that was left were the stabilizers and key caps. The final result:





Firmware Programming
Hasu’s Alps64 PCB makes use of the TMK firmware and I made use of it to add some additional layers to the board’s keymap.

Since the key caps had pad-printed keypad legends, I saw this is as a great opportunity to program a keypad layer. I also added the function row and nav cluster to IJKL on another layer.



Final Thoughts
Brown Alps are very tactile switches, apparently not unlike Topre switches but more mechanical-feeling. This was pretty apparent as I was getting used to typing on this keyboard: Indeed really tactile, perhaps somewhat overly so. The space bar also rattles a bit, but this is due to it lacking the typical ‘peg’ stabilizer. I might use some kind of lubricant to alleviate this in the future. Both issues are minor nitpicks; this is overall an excellent board, with pretty great tactility and that familiar Alps ‘clack’ from bottoming-out.

Thanks for reading!

Looks fantastic! Nice work, emdude. Those keycaps are exquisite, and I agree with your choice to use all of the keycaps, I really like that layout. 1u backspace might take a little bit to get used to though. As of right now, I think I will be on the lookout for any cheap IBM 5140s...

Thanks pyrelink! Yeah, the 1u backspace is definitely my least favorite part of this layout.. The ISO version of the 5140 actually came with a full-sized backspace (probably because ISO has a key to spare), wish that that was the case with the ANSI version. So far though, it's only been a minor annoyance, fortunately. Maybe it will encourage me to make less mistakes.

Great work! Ever since acquiring my first IBM 5140 convertible computer, I've thought that it would be good either to put the existing keyboard into a case and convert it to USB or to use the switches and at least the alphanumeric keycaps in a custom build.

Back in January 2015, copter posted a project he started to convert the IBM 5140:

workshop-f7/ibm-5140-convertible-conversion-t9666.html

Did you consider expanding the layout in order to use the half-size F-keys, Fn, and arrow keys with the compact green swtiches? How do you like the BAE and 1.0x BS? These would be stumbling blocks for me. I need a standard US ANSI Return/Enter (although it could be as short as 1.25x and still be comfortable; in fact, I use a 1.00x Return on my IBM XT, which is not entirely comfortable, but doable). However, I really need my Backspace key immediately above and to the right of Return like it is on the HHKB. On a standard US ANSI board, I remap the Backslash as Backspace.

Do you find the brown Alps rather heavy? I was able to purchase a custom 60% with brown Alps, and I was surprised by how stiff the switches felt. The board is great fun to type on, but fatiguing for long sessions.

What I'd like to do when I eventually get around to building my own custom 60% is to use a lighter Alps switch, probably SKCM white, blue, or undamped tactile cream, HHKB layout, just the alphanumerics from an IBM 5140, and blank black mods and spacebar from Matias. Yes, I am in a rut -- this is essentially the same pattern I've used in several other keyboards, but after lots of experimenting with other layouts and keycaps, I've settled on what I like best.

If Matias ever starts selling PBT keycaps, I would use them as a source eventually to replace all those blank black ABS mods with PBT. I wonder if Matias will have PBT spacebars as well?

Thanks Hypersphere, as I mentioned over at GH, SKCM Browns do feel a little stiff, but less so now that I have swapped in Cream Damped sliders.

I came across copter's project to convert the 5140 keyboard as well during my research into the IBM 5140. I briefly considered attempting to do the same thing, but I chose to put together a 60% keyboard, mostly because I did not have the time to tackle such a project. I also quite like the 60% form factor and wanted to take on the challenge with designing a plate with the 5140 layout in mind.

Also, the green SKCL Compact switches seem to ping like their larger relatives and this was very noticeable while trying the IBM 5140 keyboard, which I didn't care much for. I don't mind just holding on to the loose switches for parts in case I need to replace a grey switchplate. This is what E3E does as well.

For your future 60% build, may I also recommend SKCM Oranges? Those are probably the lightest tactile SKCMs you can get (barring spring swaps). You might also consider SKCL Greens, which are very light as well.

I think I would be interested in another 60% (or perhaps TKL) build myself, I still have SKCM Oranges to use. I will probably go for the layout that accommodates Matias' PBT key sets. I am also hoping he will make PBT space bars; no other Alps key set has them, so it would be a major improvement.

@emdude: Thanks for the recommendations. I'm not particularly looking for a light switch. Among my favorites are IBM capacitive buckling spring (Model F) and SKCM white Alps. In fact, the exalted SCKM blue Alps might be a bit too light for me. I think that the thing I like about Model F switches is the precipitous drop in force at actuation when the spring undergoes its catastrophic collapse into the buckled state. At the other extreme are mx clears -- the force-displacement curve continues to increase at a high slope after actuation all the way to bottoming out. Because my typing style entails bottoming out every keystroke, I don't want to fight the switch after actuation.

I am not too interested in MX myself either because I prefer to bottom out my keystrokes too.

I do agree that SKCM Blues are kinda light, coming from buckling springs, but you are the only person that I'm aware of on either DT or GH who expresses a preference for SKCM Whites over Blues.

@Hypershphere if you like a sharp drop in force, you should definitely try ambers then. Still _very_ different from BS, but closest of all the alps switches to it.

Really nice build, I have still two ALPS64 pcb's over. Painting the plate is a very good idea, I also likethe pattern on your plate. Maybe I find some day some green or brown alps, I have allready a plate (AEKII) which I also want to paint and modify to a standard layout.
I also like to bottom out my switches I must say I cant type without bottom out the whole time.
@Hypersphere I have the same feeling I push at the switch and it activates (and clicks), increasing force after this is just annoying.

emdude wrote: ↑I am not too interested in MX myself either because I prefer to bottom out my keystrokes too.

I do agree that SKCM Blues are kinda light, coming from buckling springs, but you are the only person that I'm aware of on either DT or GH who expresses a preference for SKCM Whites over Blues.

Looks like I created a misconception about my preferences. At this point, I do not have enough direct experience with SKCM blue Alps switches to have a definite preference. My only board with blue Alps is a LE DC-2014, and I am trying to compare that with a Northgate Omnikey 101 with SKCM white Alps that are in excellent condition. Between the two, I prefer typing on the Northgate, but there are too many variables to isolate a preference for one switch over another.

Hypersphere wrote: ↑

emdude wrote: ↑I am not too interested in MX myself either because I prefer to bottom out my keystrokes too.

I do agree that SKCM Blues are kinda light, coming from buckling springs, but you are the only person that I'm aware of on either DT or GH who expresses a preference for SKCM Whites over Blues.

Looks like I created a misconception about my preferences. At this point, I do not have enough direct experience with SKCM blue Alps switches to have a definite preference. My only board with blue Alps is a LE DC-2014, and I am trying to compare that with a Northgate Omnikey 101 with SKCM white Alps that are in excellent condition. Between the two, I prefer typing on the Northgate, but there are too many variables to isolate a preference for one switch over another.

That's true, it probably helps that the Omnikey is much better built in comparison.

This is one of the finest projects I've seen in a while! Thanks for posting, loved reading through this!

I just procured an IBM 5140 and have been wanting to replicate this for some time. Thanks for the contribution emdude! (I also sent you a PM to ask you a favor...)

If any readers would have a 7u Alps spacebar and stabilizer(s) lying around from an SGI Focus set or similar, please let me know.