Click to view our Accessibility Statement or contact us with accessibility-related questions

Where Force Curves Don't Quite Measure Up

more_vert
search
Figure 1: No, this is not a mistake. This is actually a real force curve I collected...
I’ll be the first person in line to swear up and down that force curves are and should be the absolute gold standard of information to have about any mechanical keyboard switch prior to buying them. Even those questionable, hacked together diagrams from manufacturers provide more of an idea about how a switch could or should feel than any sort of buzzword or marketing fluff about them. If you’re serious about buying switches, weird onomatopoeic descriptions or comparisons drawn to other switches just shouldn’t cut it – unless they’re in a longform switch review from your favorite switch reviewer, that is. While many of you probably already have a half decent familiarity with force curves as a result of my introductory article to them here on Drop, as well as my over 1,200 different switches that I’ve collected force curves on to date also thanks to Drop, not many of you probably realize that there are actually some limitations to these graphs. Obviously force curves can’t describe the sound or switch wobble of any given switch, but there are even blindsides within how switches feel in terms of force and bottom out that simply can’t be captured or cleanly read in force curve diagrams. To expand your minds a little bit about the power (and limitations) of what force curves have, let’s go through a few of the rare instances where these graphs fall just a bit short… - The Effect of Heavy Lubing
search
Figure 2: If you've ever tried a particularly generously lubed Gateron Oil King switch, you know what I mean.
Whether it’s from an accidental over-application during your first modding session, or just a really unlucky purchase of pre-lubed switches from a factory, all of us have tried an overlubed switch at least once in our lives. Gummy, squishy, and even sluggish – it practically feels as if you have to snowplow lube out of the way of the stems in order to push the switch all the way in to bottom out. In my experiences measuring force curves for these kinds of less than great feeling switches, this ‘sluggish’ feeling isn’t something that I ever actually see come up in force curve diagrams. (In fact, I can’t recall having really ever seen a difference between the force curves of switches that are lubed versus unlubed at all!) This is likely because of the fact that any increased force that is felt pushing back on you from the lube is uniformly distributed throughout the downstrokes of switches or simply isn’t variable enough in its force to be registered by a machine. In order to even potentially see some differences in how much force you have to apply to push a switch stem through lube in a single force curve, you’d have to have super overlubed regions of a switch immediately next to bone dry, scratchy regions – something which simply isn’t realistically possible. Despite all of our advances in technology, and the fact that Drop was kind enough to gift me a fairly high end lab grade force curve machine, our fingers will always be more sensitive to these micro-scale differences in force than them.  - Force Curve Machines Can't Measure Scratch Speaking further of things that both can’t be measured by force curve machines and can also definitely be felt in hand when testing out switches, scratch is not something that is capable of being measured by even high-end force curve machines. No, despite whatever some well-intentioned, math loving keyboard enthusiast out there has tried to convince you of once upon a time, we cannot actually separate the scratch of a switch from its underlying spring-only force in a force curve. This is not for a lack of trying, either. While the noise present in any force curve may lead you to believe that there is some tracking of scratch going on in the data, consider that fluctuations in force on the order of tenths of a gram are significantly heavier than what scratch actually feels like in hand. These fluctuations, in all reality, are something that is present in all measurement devices and is due to some combination of resolution of the machine as well as its sensor’s sensitivity. In ultra-high end, million dollar measurement devices used in things like academic chemistry and physics research, being able to isolate real data from the background ‘noise’ of these sensitive machines is half of the battle because of just how sensitive their sensors are to the most random of conditions. As well, since scratch is not uniform nor consistent in its ‘grain’ or feeling, the likelihood that it is contributing to the force so substantially in singular directions that causes a switch to feel heavier or lighter at any given point is close to nothing. In order for a switch to actually have a scratch that registered as noticeable on a force curve machine, you’d almost certainly have to glue sandpaper into the slider rails of a switch. 
search
Figure 3: Believe it or not, those little jagged lines you see are not actually from scratch in this switch as it felt smooth to the touch.


- 'Bottoming Out' is Really Complicated... One of the areas where force curves are actually the weakest at capturing information related to the physical push feeling of switches is in the not so niche case where switches have aggressively sharp or soft, dampened bottom outs. In the case of switches with harsh, sharp, and pointed feeling bottom outs, this is often due to an elongated stem pole which collides with the housings early and prevents a switch from traveling a full 4.00 mm, as is traditional in the MX footprint. While it is more than possible to see when a switch bottoms out early using a force curve diagram, there’s not really any good way to tell how abrupt or sharp feeling that bottom out is. Some of the more creative among you may be inclined to think that the difference in slope of the steep bottom out region of a force curve might be a way that we could discern this information, but it’s unfortunately a function of too many variable for that to be the case. Namely, this slope appears to be affected by the stem pole length, housing material, and physical housing thickness too. Speaking on that latter point further, switches which have mechanically thicker or materially different housings such as those made of nylon, polycarbonate, POM, etc. all have different hardness values to how they bottom out as well – something that simply can’t be measured on a force curve meter. Force curve machines are really only good at reading the force of springs and how that spring force changes based on the shape of the stem of the switch and how it interacts with the leaves of a switch and not much else. When you stop to think about it, bottom housings are surprisingly absent in force curve diagrams, except where they start the bottom out!
search
Figure 4: Can you see a noticeable difference in how steeply these famous switches deflect at bottom out? I sure can’t see a pattern…


Despite these few and somewhat far in between shortcomings of force curve diagrams, there’s more than enough reasons to seek them out and try and consult them when looking up your next switches to buy. Quantitative, objective measurement of tactile bumps and empirical results showing you bottom out weights and distances are incredibly useful to have and often can show where manufacturers and/or vendors have been less than accurate in their marketing. But, if the switches you’re seeking out have a bit more of a… something special… to their push feeling – such as heavy factory lubing, unique housing materials, or weirdly long/short stems – you may need a bit more information outside of just those force curves to know if those switches really are for you! If you’re wanting to pick up some more information about switches in general before making your next purchase, consider checking out some of my other articles here on Drop such as ‘A Few Obscure Keyboard Switch Modifications’ or ‘The Secret Beginner’s Guide to Switch Lube’
(Edited)
8
1
remove_red_eye
998

search
close
Related Posts
Trending Posts in Mechanical Keyboards