[IC] The Bullet Train - a Low Profile Wireless V4N4G0N layout board

[upas]

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I’d like to introduce the Bullet Train keyboard. Like most of my designs, the idea for this board came from a personal desire of mine. I wanted to have a small portable keyboard for myself that is suitable for gaming, but also works as a daily driver for normal tasks. I’m not the best at typing on ortholinear or columnar staggered boards, but 40% staggered boards fit the bill. With the additional requirement of gaming, it made sense to use the 12.75U wide V4N4G0N layout featuring a number row with numbers 1 to 6.


Ultimate Portability

When I think of ultimate portability, I typically don’t think about MX based keyboards. While I would consider some MX keyboards light and portable (for example - Bakeneko Go or Photon), sometimes if you’re trying to pack light or travel with a single bag, it can be hard to justify using your limited space on a full height MX keyboard. So for this keyboard, I also wanted to use low profile switches.

To the best of my knowledge, there are no other low profile V4N4G0N variants that exist already, except for one that maybe uses Kailh Choc v1 switches - but I personally don’t like the reduced travel on choc v1. Recently, some new low profile options have come to market which really improve the acoustics and type feel - so I decided to base this on my preferred new low profile switches - the Gateron KS-33 series. With this in mind, I decided to design a new keyboard from scratch.






Wireless and Latency

For me, most of the games I play are single player ones where keyboard latency doesn’t make a huge difference, and as such, I also thought that wireless would be a nice quality of life feature to add. The V4N4G0N layout is also well suited for this purpose - since it has the 1-6 keys in the numrow which are often useful in games, and the rest of the empty numrow space can be used to house a sizeable battery, so the keyboard shouldn’t need to be charged much. For games where latency is a focus, the keyboard can still be plugged in via USB. Its 40% layout and low profile nature still make it a great candidate for a travel gaming keyboard.



Layouts

Starting from a 6.25U bar gaming layout (big spacebar is quite useful for gaming) - we went with the traditional V4N4G0N layout.

With low profile switches, stabilizer clearance needs cutouts on the PCB, limiting the potential split space options - but we were able to allow for a 2.25/1.25/2.75 split spacebar. While not as optimal as a 2.75/2.25/1.25 split, there is a split space option.

Each of the layout options will need a different plate, since low profile stabilizers are plate mounted.




Aesthetics

The Bullet Train looks quite simple at first glance - but has a few aesthetic features I wanted to bring attention to. The board is flat - 0 degrees - in order to keep it as low as possible. But, we wanted high-profile bezels, so the gaps between switch and keycaps will not be visible. The bezels are pretty thin - again in an effort to keep it sleek and portable. The top left of the board features a PC diffuser for RGB status indicators.




The top right of the board has a triangular cutout so you can add charms, a carabiner, or a strap to the keyboard for easy carrying.

And There’s a bullet train shaped indent across the 7-0 section of the num row. This indent will have a bullet train sticker in it - the design is being finalized.



The bottom of the board features AKB feet.



There is also a Cannon logo on the back of the board.



Mounting

The V4N layout has a unique challenge - the num row only has 6 keys - so unless you’re careful about mounting, you could end up with an inconsistent feeling board. Some other designs use side-of-case mounts to tadpole mount or top mount the plate. But since this is low profile, I chose to use a PCB gasket mount. The PCB basically sits on gaskets that touch the bottom plate of the keyboard. As the bottom plate is installed, the gaskets compress. The gasket placement is optimized to ensure consistency across the alphas.

There are tabs on the PCB which ensure that the PCB/plate assembly can’t move higher than it should as well. Ultimately, this gives a nice comfy feeling board without being too stiff or too bouncy.





Acoustics

The Bullet Train is also planned to ship with a 1.2mm poron + PET plate foam layer as well. The purpose of this is twofold.

First - I think it helps with acoustics. With the Poron foam, the sound of the board is a little cleaner.

Second - it makes the build process way easier. With a 1.2mm plate and low profile switches, it's way easier to install switches with the foam included. You can use a 1.2mm plate fork as well - but those are hard to find.

As usual, most of this comes down to personal preference, but in my opinion, the foam is worth using. I would encourage people to try building with and without the plate foam and making their own decision, though.


Keycaps

Right now, legend accurate low profile keycaps are a bit tough to find for the V4N4G0N layout. Luckily, matt3o is working on PFF profile. It’s basically a low profile compatible version of PBS. I’m a huge fan of PBS profile, and I’ve been able to try early versions of PFF. I love PFF profile as well. I hope to sell a Bullet Train specific PFF profile keycap set with this keyboard.

All the images of Bullet Train here are using some early version of PFF, with Akuko Lab's Aperture Priority design printed on them. The final ones are not ready, and the final keyset will be something different, but this should give you a sense of what the profile will look like.




Options and Addons

I hope to offer the Bullet Train in a number of colors. The colors we offer will almost entirely depend on IC results. The prototype is a forest green which I quite like.

For plate materials, we’re using an FR4 plate as default, in order to make sure wireless signals can get through (an aluminum plate would compromise signal strength). With that in mind - we’re still going to try to offer an aluminum plate and a PC plate as addons as well to offer extra customization.

The stock PCB is wireless / Gateron KS-33 hotswap, but I also made a wired QMK KS-33 hotswap and solderable version too. I’m going to try to add Kailh Choc V2 support to the solderable version as well. All 3 of these PCBs will be available for purchase as well.


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Pricing

I don’t know what pricing is going to end up like, but I think it should be pretty affordable. It’s a 3 piece case (high profile aluminum frame, bottom cover, PC diffuser). My goal is to be able to sell this under $200 in group buy, including wireless and a battery, and a bit less for a wired QMK-only version.

To meet this goal, we'll likely offer 4 colors max, and have an MOQ of 100. We'll also price it out at an MOQ of 50 just to see what that might look like. Depending on IC results, maybe we can initially price at 50 MOQ and refund to the 100 MOQ price if we reach it.



Next Steps

We’re hoping we can run this GB in January, but it’s contingent on a few things.

I already have a fully working wired prototype, but need to finish firmware and testing for the wireless PCB. That is underway already.

We need to figure out what colors we want to run - this IC should help with that.

Finally - we need to design the bullet train sticker and the PFF keycap set to pair with bullet train.

The most difficult parts of making this board are already done, luckily, so I think a January group buy is realistic.


More images are available here

Alternative image host for those in the UK


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[upas]

Reserved

[paperassgasket]

Guess it's big bar for me.
I'm personally not a fan of the middle bar between mini split bars.

[AerosolFNTM]

This is a very Interesting! I love the design and the spot for the carabiner, and while I don't know I feel about the use of low profile switches, I see the reasoning and may end up enjoying it, Sign me up!

[OrinNYC]

take my $

[BossKeebs]

Nice 40% keyboard.

[Matt3o]

I approve

[warhopper]

I love the concept for this, but 0 degree angle I fear may be a mistake for actually using it. Could you consider possibly adding larger feet for the rear or possibly some kind of flip out feet if that was at all possible?

[Dingo_Seven]

This is really cool!

I'm curious if that PCB could possibly work with regular MX switches and 3d-printed V4N4G0N cases to get a wireless board up and going?
Oop I didn't read well enough, I'd love to see a ZMK V4N PCB with conventional MX support tho, filled out feedback on the form. I'd also use a wired one for playing games as well.

I think a version of this with a typing angle and a would be a perfect board to be playing games with and I've been entertaining the idea quite a bit these past few weeks.
I've been tempted to use V4N to play games but need to get around to getting a PCB and 3D printed case made.

[VaporKeebs]

Oooooh down for this. And January is my birthday month so Id love to order this as a bday gift to myself.

I suggested a beige option but Ill be happy with silver if we dont get beige.

I also second the suggestion above with an MX compatible switch PCB but if you stick with what youve got Ill try my first low profile switches.

[GrumioThaSpoonGod]

Will wireless be bluetooth or 2.4ghz

[NihonCK]

bluetooth since zmk doesnt offer 2.4 and nothing mentioning a reciever which would be needed if they developed their own 2.4

im assuming zmk since there is very little space for a battery and most of their recent wireless has been zmk

[tacahiroy]

This is nice. It would be great to have a PC case option for a lighter build. GLWIC

[Livid]

I love the concept for this, but 0 degree angle I fear may be a mistake for actually using it. Could you consider possibly adding larger feet for the rear or possibly some kind of flip out feet if that was at all possible?

Agree with this, not so sure about 0 degree