Building a Keyboard: Part 2
blog.fsck.com
blog.fsck.com
- Twisted-pair cable either requires either grounding one wire in the pair (in 100baseT) or fancy differential-signalling tricks. (in 1000baseT or HDMI)
- Sounds like the biggest problem was solder joint failure as a result of inadequate strain relief. In satellite design, where repair is, of course, impossible; the rule is to never use a solder joint as a mechanical connection. The component is secured to the frame, and the wire coming off the component is separately secured.
If you're not building a satellite, the method of accomplishing this is usually hot-glue, copious amounts of it, on everything. (As seen in cheap hand-assembled electronics. Expensive electronics are robot-assembled and use SMD components, which usually don't need strain relief unless you're doing something really exciting.)
In a bunch of the cases, the problem was "hysterically bad solder joints." It wasn't so much that the joints would fail when put under pressure as that they'd fail when you looked at them funny.
There is a massive argument in the 3d printing community about whether Nylon is safe to print with. I would use it only in an industrial/laboratory setting with decent fume extraction and filtering and safety procedures (like Shapeways has). There is a dangerous asshole who is actually selling nylon filament for printing and telling people it's safe. He has performed some tests with an HCN detector with very questionable methodology and is now making a lot of noise about how safe it is. This is why I felt compelled to make some noise about how incredibly dangerous it can be to process it in a home setting. Note that unless you subject it to very high temperatures it's not going to decompose.
OT: Related from yesterday, a USC doctoral student has proven that a "strain or stress gradient" is key to tin whisker growth
For keyboards, having to sometimes use other people's machines as well as frequently switching between my desktop and laptop means that, while tempting, this level of customization is too far for me. The sweet spot for me is a high quality mechanical switch (-style) keyboard: Topre's Realforce.
The W-S-Z fingering leads to a nice curve that mostly follows the movement of your finger, just like what you get on the right side of the keyboard (U-J-M, etc).
I don't know how folks type Q-A-Z with their little finger. It causes immediate hand pain to curl my fingers inward/perpendicular to hit Z, X, C, and V.
I imagine this method was only taught in the first place thanks to clueless typing teachers who thought "first keys on the left = first left finger", ergonomics be damned. Does anyone else type "Z" with their ring finger?
For the shells, yes, those will cost a bit of money. Or you could make friends at your local hackerspace.
Edit: But yeah, the project looks really cool, something that each one of us uses every day and yet is so complicated internally. Well done.
Flying out of DCA a week later, the TSA agent was astonished that I wasn't _selling_ keyboards -- "People will buy anything. You should make some money on that shit."
Transiting Narita and flying out of Taipei a week after that, I just put it through the X-Ray. Nobody said a thing.