Evillemez - some data for you -
The most popular actuation force for keys is 55 grams.
MacBook Pro laptops and desktop keyboards use this standard, and it's widely regarded as the best level of feedback for your fingertips.
Higher forces in the range of 65 grams start to feel more like a pushbutton switch rather than a key, and are more work to operate.
Some coder keyboards like the Topre offer a choice of 55, 45, and 30 grams. Most buyers go for the 55 gram config.
TextBlade is engineered to deliver 55 grams. This can actually be set to any value we choose via the adjustable parameters in the design.
Unlike the rubber springs in most laptops, or the wire coil springs in many desktops, TextBlade provides its thrust entirely from a magnetic field.
WayTools patented this MagLever technology, which as the name implies, uses a combination of magnetic force and lever action to provide a very refined force curve.
A stainless steel magnetic core is molded into the butterfly LCP composite structure. This core magnetically laminates to the neodymium rare earth magnet that's recessed into the keyblade polycarbonate base.
As the core delaminates from the magnet, there is a nonlinear force reduction which results in a smooth yet over-center feel.
Now to the question of actuation force on the big vs.little keys -
As wmertens astutely observed, all of the cores and magnets are identical, so the source of thrust is very consistent, and never wears out. It is possible to mass-produce these parts with high precision as to the gross flux and permeability, so the performance is very stable.
Because the larger 6-station keys have a few grams more mass than the smaller 3-station counterparts, they load the magnetic thruster with slightly more gravitational force. Hence the net upward force on those keys is about 5 grams less.
It's easy for us to raise this, but through user testing, we found this slight offset to be desirable. The reason has to do with the kinematic properties of the keys.
When you strike the key, your finger is actually encountering two significant forces:
The magnetic lamination force
The reaction force from the inertial mass of the key
That second component of force is what's needed to accelerate the key mass from rest, up to strike velocity. It turns out to be meaningful to key-feel.
We found that by reducing the net rest force, we could "cloak" the added inertia. The result of this is that the keys feel very much the same to strike, despite the fact that their mass is different.
This "mass-tuning" technique proved very effective.
The most accute instance of this effect is the SpaceBlade. Just like a legacy keyboard, the spacebar is by far the largest key, and therefore the most massive. Although the thumbs are less sensitive than fingers, we wanted to match the feel there too.
To cloak the SpaceBlade mass, we were able to exploit this mass-tuning technique to an even greater degree. Here, we also reduced the magnetic lamination force to 40 grams of thrust. That, together with the higher inertia of the spacebar key, combine into a very satisfying feel.
To summarize -
55 gram nominal actuation force, with lower net static thrust on the larger keys and on the SpaceBlade, to optimize for lthe dynamic load and feel.