Follow-up Review of the BM40 Ortholinear Keyboard

Posted on October 22, 2021 by Richard Goulter

So I’ve had my BM40 for over a year now.

My initial impressions after getting the keyboard were:

Now that I’ve had more experience with the keyboard, I think those points still pretty much hit the mark.

Perhaps the most important point to add is that I’m still able to use a stock-standard row-staggered keyboard. I don’t lose that ability by using a small/weird keyboard.

Here are some more points for my updated impression:

Big Increase in Comfort

The biggest difference in usage between a BM40 and a standard row-staggered keyboard is the comfort.

I’d point out that the thumb is much stronger than the pinky.

On a standard keyboard, the thumb will press spacebar, and sometimes the left alt key.

On a standard keyboard, the pinkies will press the outermost letters (q, a, z), as well as ctrl, shift, the capslock key, tab, tilde, escape, and on the righthand side, the pinkies are responsible for the extra symbol keys ([], _, +, ), as well as the backspace, and enter keys. – Albeit.. you end up accessing many of these by moving your hand over, and using ring + pinky fingers; and these keys generally don’t need to be pressed very frequently. But this still leaves the pinky doing more work than the thumb.

By comparison, the BM40 does a much better job at utilising the thumbs (and reducing usage of the pinky).

Many layouts on the BM40 keep the two hands together on the inner 10 columns, leaving the outer columns for the pinkies. With the hands on home row, the thumb can reach the spacebar and each thumb can reach the key to the side.

– I think this leaves the lowermost, outer 4 keys in an awkward spot. You have to move your hands in an awkward way to use them. (Albeit, this is no worse than the Ctrl, Win, Alt, etc. of standard keyboards).

In general, better thumb/pinky usage would be to use the thumb more, and pinky even less. I also took a go at designing my own split keyboard (using a small development board to take care of the difficult parts of PCB design), and found this to be relatively comfortable.

With the BM40, you could also try and ‘split’ the hands; the left hand rests on the leftmost 5 columns, the right hand resting on the rightmost 5 columns, leaving a ‘gap’ of two columns in the middle. – I’ve been trying this layout out. I found it a bit difficult to adjust to, but otherwise appreciate it.

Customisable Firmware

The BM40 supports customising its keyboard firmware.

The QMK firmware documentation boasts a large number of features.

The features I’ve found most useful:

Pretty much all of this customisable functionality is accessible to regular keyboards using software like kmonad. – Although having it on the keyboard means you don’t need to fiddle with the OS settings for every computer you make use of.

Alternate Recommendation

I would also add a recommendation: Consider the BM40 is an ortholinear keyboard with a 4x12 grid of keys (with a 2-key wide spacebar in the middle), the lack of a number row limits its usablility for e.g. gaming.

Keyboards like the XD75 seem like they retain most of the advantages of the BM40, with fewer downsides. e.g. it’s a 5x15 grid of keys (so would be easier to use with gaming?), but also fits into a standard GH60-sized keyboard case. Since the size of the keyboard case is standard, this means there are more options.

Or taking another route: I’ve also seen a bunch of other interesting designs for “split”, two-handed keyboards. The ergodox was the first I saw. The ergodox’s key cluster for thumbs isn’t very good, though. The ergodox also needs a custom case 3D-printed, IIRC.

More recent designs often have a “sandwich style” case where the keyboard’s PCB is ‘sandwiched’ between two laser-cut metal plates. I think it’s easier to find places which will do lasercutting compared to getting access to a 3D printer.

Popular sandwich-style keyboard designs include the corne, the kyria or the lily58 or the sofle keyboard. These involve some very simple soldering. These are often sold in kits at various online stores. If the PCB design files are available, there’s also the option of getting the PCB fabricated & sourcing the other parts yourself.

Keyboard shouldn’t get in the way

– In my initial impressions post, I commented that you want a keyboard to be transparent between you and your computer, and not something you have to think about.

While getting used to it, the BM40 does indeed get in the way. And it also gets in the way if you make a significant change to your layout.

But once I got used to the BM40, the “not moving from home row” is wonderful.

In contrast, when I use a standard row-staggered keyboard now it feels like playing the piano. My fingers have to move all over the place, with all sorts of stretching or weird movements.

Downside: It’s your keyboard, others can’t use it

This will be familiar to those who use customisable text editors like Vim or Emacs. – Once your editor has been customised enough, others can’t use it. (And vice versa).

With small, customisable keyboards it’s the same.

Since the BM40 has fewer keys than the regular keyboard, there’s no obvious convention for where the keys can be expected to go.

If all you’ve got is this small keyboard and you’re ill-equiped to handle situations where someone else might need to type things in.

Downside: External Keyboards are Difficult to use with Laptops

Using a small keyboard is great when you’ve got a desktop setup. It means that much more desk space.

But if you’re using a laptop.. using an external keyboard means more desk space is used up by the keyboard.

One workaround I’ve seen people come up with involve disabling their laptop’s keyboard if using an external keyboard. The keyboard can then be placed on top of the laptop’s keyboard.

Another workaround I saw involved using a small tray that could be placed on top of the laptop keyboard.

This isn’t a downside of the BM40 itself. But, laptop keyboards aren’t ortholinear.

Downside: Mechanical Keyboards are expensive, or difficult to assemble

The BM40 is straightforward to assemble. And while it’s cheap relative to other non-standard mechanical keyboards, it’s also quite expensive.

(Standard mechanical keyboards themselves can end up being much cheaper than the BM40 keyboard. e.g. looks like an Anne Pro 2, which is a Bluetooth keyboard, is roughly about half the price of a BM40).

There are cheaper ways to try and assemble a small mechanical keyboard. I tried designing one which is relatively cheap to build. But custom keyboards which involve fabricating PCBs and doing some soldering work could be described as “difficult to assemble”.

This doesn’t really detract from how much I value having this keyboard, but it does make it harder to recommend to others.

Downside: Mechanical Keyboards are loud

All these weird/niche keyboards typically use mechanical key switches, since this makes the keyboard cheap enough to produce in low volumes.

In my own space, I consider loud clicky keys an upside. For work spaces, fortunately mechanical key switches don’t need to be clicky. However, I think they’re still louder than standard keyboards.

I worked beside someone who had a mechanical keyboard. His keyboard wasn’t a loud keyboard. I don’t remember being annoyed by the sound.

Though, even more typical keyboards can still be distracting. I once had a colleague who could type very quickly on his Bluetooth Mac keyboard. He said that when he visited one of the satellite offices, the colleagues he sat beside asked him to move away from them since his impressive typing speed was distracting.

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