I Built a Keyboard Homage to ‘Tron’

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As you may know, the classic 1982 sci-fi movie Tron turned 35 years old in 2017, and it happens to be a film that I quite like. So, I’m celebrating in the most fitting way I know, with a Tron-themed keyboard. It wouldn’t do just to get some Tron keycaps and call it a day, though. I decided to build a keyboard straight out of the 1980s by restoring some parts that are more than 30 years old. Here’s how I did it.

Keycap Inspiration

I hatched this plan some months ago when a group buy started for a keyset called DSA Lightcycle. The set was run by The Van Keyboards, which has become known among keyboard enthusiasts for producing the popular 40-percent “Minivan” keyboard. A limited version of Lightcycle was made for that board previously, but most people use much larger keyboards. Thus, a full set was designed.

A group buy is a bit like a pre-order, except the buyers are taking on the risk instead of a retailer. You pay your money, and that goes directly toward funding the production of the keyset. A few months later, you’ll get your keycaps (or whatever you ordered) in the mail. Once the group buy is over, there’s no way to get the keyset without paying a premium to someone willing to sell theirs.

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I was intrigued by Lightcycle for two reasons. First, it’s a Tron-themed set with really cool novelties like an identity disc, a recognizer, and (of course) lightcycles. It’s also one of the few nice keysets you can get with support for Alps switches. They don’t have the standard cross-shaped stem you see on MX switches, so you have to get special keycaps.

Lightcycle is made in double-shot ABS by a company called Signature Plastics, which makes many of the nicer custom keysets. The wait was a few months longer than expected, which I actually should have expected. That always happens with Signature Plastics. Still, with the set finally delivered, I was ready to start building. Or at least to begin refurbishing some switches.

Retro Switches

Most of the mechanical keyboards you can get right now use Cherry switches or switches that are based on Cherry’s designs. You can do a lot of interesting things by changing up those components a little, but Cherry had not completely cornered the market in the 80s. Many keyboards came with Alps switches back then, and they have an entirely different design.

Alps are a type of mechanical keyboard switch manufactured by Alps Electronics. The company still exists, but it stopped making keyboard switches many years ago. There are a number of shortcomings in the Alps design that (in my opinion) eventually led to Cherry’s dominance, but they’re very interesting switches anyway. The Alps switches everyone thinks of as the real Alps are from the SKCL/SKCM series, sometimes known as “complicated Alps.” It’s a well-deserved name, too. Alps switches have around 10 parts, depending on the model. A Cherry switch usually has five, if you count the top and bottom housings as separate parts. Disassembling and reassembling a Cherry switch is a breeze, whereas an Alps switch can be hard to put back together the right way. The stem design also makes these switches prone to picking up dust and debris.

Some (dusty) Orange Alps.

For all the issues with Alps, they have a unique feel. Those who have experimented with a variety of Alps switches often contend the switches have much better tactility and a more consistent click (in those versions that make noise) compared with MX switches. The bottom-out on Alps is different as well — there’s less resistance after you hit the bump or click.

Since there are no production versions of the classic Alps switches (just some clones), the only way to get the genuine article is to find an old keyboard and harvest its switches. In my case, the donor was an Apple M0116, also known as the Apple Standard Keyboard. These were produced from the mid-late 80s until the early 90s, and came with a few different Alps switches. The board for this project had Orange Alps, which are moderately heavy tactile switches. There was also an Alps lock switch, which the Apple keyboard used for caps lock. That means that when pressed, it stays down to indicate that it’s on. When you press it again, it springs back up. I was happy to find this was still in full working order, as it’s not something you see on keyboards much anymore.

A disassembled Alps switch (left) compared with an MX-style Gateron switch (right).

I wasn’t done after the switches were desoldered — they were 30 years old, after all. As I mentioned earlier, Alps tend to pick up a lot of dust, so every switch had to be opened and cleaned. I used compressed air and rubbing alcohol to get them back into shape. While Alps switches are complicated inside, you get a good understanding of the inner working after you’ve taken 80 of them apart and reassembled them.

The key to the distinctiveness of Alps switches is that the metal leaf gives it its character. In MX switches, it’s the plastic stem. So, you need to make sure the metal leaf in each switch is in good condition and unbent to have a working tactile switch. It’s possible to warp the leaf, making a tactile switch into a linear one. That’s not what I was after, obviously.

Building a Keyboard

Finding keycaps for Alps switches is a challenge, but so too is finding a keyboard PCB for them. The location of the pins on the underside of an Alps switch is different, so the PCB needs a slightly tweaked layout. I settled on the Sentraq S65-X, which is a 65-percent keyboard. That’s my favorite form factor, which was a plus. It also has RGB underglow lighting, allowing me to really nail that Tron feel. While I like a lot of things about this board, the build process turned out to be more complicated than past ones.

Switches plugged into the plate and ready for soldering. Locking Alps visible on the left.

While the PCB fits Alps switches just fine, the plate that switches plug into could have used a bit more refinement. Alps housing are a bit more rectangular than MX, so the cut-outs need to be different. The switches fit fine in the 1-unit spaces for the alpha keys and numbers, but the size of the opening for larger keys and the bottom row offered little to no support for the switches. Thus, parts of the keyboard are basically what you’d call “PCB mount.” That means the only thing supporting the switches is the solder and mounting pins. Except… Alps switches don’t have mounting pins on the underside. So, it truly is just the solder holding them in place. I ended up overdoing the solder a bit to make sure they stay put.

Soldering. Note the elongated holes to accommodate Alps switches in addition to MX.

Each switch has two solder points, and Alps don’t support in-switch LEDs. So, that saved me two additional solder points for each switch even if I had wanted more LEDs. That’s a total of 136 solder points for the keyboard, some of which needed to be extremely precise to make certain the unsupported switches ended up straight (or at least close to it). It was extra important to use the keycaps to check spacing on the bottom row, which supports several different layouts. Soldering a switch in the wrong spot could prevent the keycaps from fitting at all.

Adding caps.

The Sentraq board’s case is what’s known as a sandwich design. There’s a top plate where the switches plug in, then a middle spacer, and a bottom cover. In this case, the upper and lower parts are aluminum, and the middle is frosted acrylic to diffuse the RGB LED light. Unfortunately, the spacer in my kit seems to have a minor defect. Some of the screw holes were drilled too large, so the screws just fall out. The board isn’t coming apart, but I’m still looking into ways to solidify it a bit.

Last-minute lubrication.

After assembling the board, I put on the keycaps and did a little typing. Unfortunately, the switches weren’t as smooth as I had hoped — they were probably used heavily. One of the nice things about Alps switches is they can be opened up after being soldered to a PCB regardless of plate design; only some MX plates support switch top removal. So, I was able to open each switch (yes, again) and add a tiny bit of PFPAE lubricant to the slider (the orange part) in each switch. That took an hour or two, but the feel is much improved.

Finishing Touches

Like all custom boards, this one is fully programmable. That means you can decide which key does what, and it’ll work the same way no matter what device it’s plugged into. There’s no desktop software needed to do things like change the underlighting. The Sentraq S65-X runs a keyboard firmware called QMK, which has been getting a lot of attention over the last year or so. QMK is an incredibly powerful firmware — you can do cool things like assign different functions to a long-press of a key and control the mouse cursor. However, it’s also a little complicated.

The firmware builder.

There’s an (unofficial) online visual editor for building a QMK layout, but it doesn’t have all the supported functions. If you want to do anything advanced, you need to dig into the QMK documentation and make manual edits to the layout file. I was able to get mouse cursor control and the locking caps key configured, as well as tweaking the key layout to my preference.

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At the end of this project, I’m thrilled with how the keyset turned out. It’s striking, and the legends are the same high quality I’ve come to expect from Signature Plastics. I’m reasonably pleased with the Orange Alps switches. It’s fun to use something that has different qualities after trying so many MX-style switches over the years. The Sentraq board itself is alright. I think the plate could have been a bit more Alps-friendly, and the sketchy spacer is disheartening. It’s staying together, but it feels like it could be more solid. I’m still chatting with the board designer about the defective part. I suppose this is just the sort of thing you risk when buying bespoke electronics.

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