In June of 2019, when the first Zaunkoenig M1K prototype was revealed, its weight on the scale showed 23 grams. Henceforth, the M1K became known as «the 23 g mouse». Little did we know at that time if we would actually be able to reliably reproduce the weight of the M1K precisely to 23 grams. Especially the carbon fiber production was a big unknown. We also weren’t sure if we needed to do some minor design changes or not. Today, a couple hundred M1Ks into production, we have a better idea of how things come (weigh) together. For those who are curious as to what weighs what in the M1K, here we go.
Overall Weight distribution
First up: the overall weight. We weigh each and every M1K that leaves our production facility. After all, weight is what the M1K is all about. After 333 M1K we arrived at an average weight of 23.4 grams for an M1K with a regular bottom shell (the one without any holes). Most M1Ks with a regular bottom shell fall between 22.5 and 24.3 grams.
What weighs what precisely?
The heaviest component in the M1K is carbon fiber shell, followed closely by the PCB. Those two components make up roughly two thirds of the overall weight. The rest of the weight comes from the bottom shell, the nine screws, the cable and the Hyperglide mouse feet:
The PCB consists of many individual parts like the sensor (PixArt 3360), the switches (Omron D2F-01F) and various tiny surface mount parts (called SMD parts for short). This is how much the individual PCB components weigh:
These two weight distributions only tell half the story though. Some of the components in the M1K have quite a bit of weight fluctuation. In the following we will look at the weight fluctuation for the carbon fiber shell, the PCB as well as the bottom shell.
Weight fluctuation in the carbon fiber shell
The largest fluctuation in weight by far comes from the carbon fiber. We buy our carbon fiber in the form of prepregs. Such a prepreg consists of the actual carbon fibers plus an epoxy resin. And sometimes the prepreg we get has a little more epoxy resin in it than usual, and sometimes it is the other way round. So the raw material we use for our carbon fiber shells already has quite a bit of weight fluctuation to it.
It doesn’t stop here though: laminating the carbon fiber prepregs into the mould is a process that is done by hand, hence fluctuations are to be expected. Also, every time we bake carbon fiber shells in the oven, the epoxy resin will flow a little differently, resulting in varying amounts of epoxy resin exiting the mould.
All in all the first one hundred M1K carbon fiber shells we produced have been a little on the heavy side of things. With each shell we produced though, we managed to dial things in a bit better and thus over time our carbon fiber shells showed less and less variation in weight. This will always be a work in progress though: no two M1K carbon fiber shells will ever weigh exactly the same. In more than one way, each M1K is unique. Looking at our first production batch of 333 M1K carbon fiber shells the average weight of one shell was 7.5 grams. The overwhelming majority of shells weigh between 7.0 and 8.0 grams.
There are some extreme outliers though: some shells go below 7.0 grams, and some shells go above 8.0 grams. In these cases most likely we accidentally put in one carbon fiber prepreg layer too much or too little. We are only human, after all.
In the long run, we expect the weight of all our carbon fiber shells to be well between 7.0 and 8.0 grams.
Weight fluctuation in the M1K PCB
You might ask yourself how the PCB can have significant fluctuation in weight at all. And you are right to wonder: aren’t electrical circuits made to super tight tolerances in the realm of micrometers? Indeed they are, like for example the traces, the vias or the solder pads. However the thickness of a bare PCB (a PCB without anything soldered onto it) itself can vary quite a bit. And as a result of this variation in thickness you have fluctuation in weight as well.
The reason for this fluctuation may sound familiar: PCBs commonly consist of something called FR4, which is nothing else than glass fiber reinforced plastic. In other words: the PCB is very similar to the carbon fiber shell, in that it is a composite material: fibers plus a resin. Instead of carbon fibers though, which are electrically conductive, glass fibers are used for a PCB.
Just as we make the carbon fiber shell from prepregs, FR4 PCBs are made from prepregs as well. And as was the case for our carbon fiber prepregs, these FR4 prepregs have varying amounts of resin in them. So much so, that the weight difference of a PCB will be plus-minus ten percent. Hence a bare M1K PCB can weigh between 3.3 and 3.7 grams.
Weight fluctuation in the M1K bottom shell
On average, an M1K with a lightweight bottom shell is 1.7 grams lighter than an M1K with a regular bottom shell. This appears to be consistent when looking at the isolated weight of the regular bottom shell (5.6 to 5.9 grams) versus the lightweight bottom shell (4.0 to 4.2 grams).
Not much weight fluctuation here, but this is expected, as modern 3D printers are pretty accurate.
Looking ahead
At Zaunkoenig, we strongly believe that the optimal weight of a gaming mouse is zero grams. With 23 grams for the M1K we got pretty close, but there are still 23 grams to go. To get a little closer to zero grams, say, below 20 grams, attacking the heaviest component of the M1K would be an obvious weight optimization tactic. Ironically the heaviest component in the M1K is the carbon fiber shell itself.
So maybe we should drill some speed holes in the carbon fiber and call it a day?
That would be the easy way. But is it the best way? We thought a lot about this and we think the solution is not to remove carbon fiber from the equation, but to instead add more carbon fiber to it, while simultaneously making other M1K components lighter.
If you want to make the lightest gaming mouse in the world even lighter, you have to look past material properties. You have to look past speed holes. And you need to start looking at the mouse as a holistic weight optimization problem.