An Affordable Force Curve Meter Kit for MX switches

Hi everyone -

This is more of a pre-IC, and at least several months away as I’m still working on other projects that I need to wrap up (such as my 120% keeb which has been in IC forever), but I’ve been thinking about this and would like some thoughts/input in terms of determining a direction to design things towards. The page will be updated as things progress.

Back in April I built a cheap force curve meter for MX switches, the design of which is open-source. Measurements are published here. This cost me about $200 to build, uses a cheap $11 load cell paired with a $0.50 load cell amplifier to measure force, and seems to generate usable force curves.




Some example force curve measurements:



There are also similar projects that other people have independently worked on, which use similarly inexpensive parts. For example, Ruddy of Geekboard.ru independently developed a similar open-source force curve meter using similar components. There’s also someone in Japan working on a force curve meter.

I was thinking of doing some design work on an inexpensive force curve meter that would be user-friendly enough to be available to the community should people want to own one.

The scope of this would involve:

• An inexpensive force curve meter kit, most likely priced between $150 and $250.
  • This would only measure discrete MX switches, and possibly other discrete switches (e.g. Choc, Alps). It will not be able to measure a whole keyboard like HaaTa’s force curve meter. This lowers the cost and size of the device significantly.
  • It should be easy to offer both a free-standing stand and something to clamp it to the edge of your table like my current one. My current meter takes up about 250x100mm clamped to an edge of table, and a stable table stand can probably done within a 250x250mm footprint, and probably about 200-250mm tall,
• Software for calibrating the force sensor, and for processing the data into a chart.
  
  • My current force curve meter is calibrated with a 100g weight, an Arduino script, and a spreadsheet, run using Arduino and Arduino Serial Monitor, and the data is processed using a spreadsheet. Labels are added in MS Paint. This is fairly manual and time consuming, and I would like to sit down and automate a lot of these tasks (e.g. with a Python script or application). This would also go a long way towards making the device more user friendly.

I would like to make this all open-source.

There has been talk and some work on a website to display and compare force curves between various people with force curve meters (including me), though that is mostly separate from this project and a ways off.

Right now there’s a couple of different routes to go down for the hardware design, with tradeoffs between price and performance. If you’re interested in this project, would you mind filling out this form? This would be very helpful in choosing a direction. Thanks!

> IC Form Here <