Rotary potentiometers, switches, and encoders all share a basic design: adjustment is done via a shaft onto which a knob is attached, and knobs are sold separately. That doesn’t mean one knob fits all; there are actually a few different standards. But just because knobs are inexpensive and easily obtained doesn’t mean it’s not worth making your own.
Why bother 3D printing your own knobs instead of buying them? For one thing, making them means one can rest assured that every knob matches aesthetically. The ability to add custom or nonstandard markings are another bonus. Finally, there’s no need to re-invent the wheel, because [Tommy]’s guide to making your own knobs has it all figured out, with the OpenSCAD script to match.
By default, [Tommy]’s script will generate a knob with three shims (for interfacing to a splined shaft) when pot_knob(); is called. The number of shims can be adjusted by modifying potKnobDefaultShimCount. To give the knob a flat side (to interface with D-shafts), change flatted = false to flatted = true. And for adding a screw insert suitable for a set screw? Change tightenerDiameter = 0 from zero to the diameter desired.
[Dennis] aims to make robotic control a more intuitive affair by ditching joysticks and buttons, and using wireless gesture controls in their place. What’s curious is that there isn’t an accelerometer or gyro anywhere to be seen in his Palm Power! project.
The gesture sensing consists not of a fancy IMU, but of two potentiometers (one for each axis) with offset weights attached to the shafts. When the hand tilts, the weights turn the shafts of the pots, and the resulting readings are turned into motion commands and sent over Bluetooth. The design certainly has a what-you-see-is-what-you-get aspect to it, and as a whole it works much like an inverted, weighted joystick hanging from one’s palm.
It’s an economical way to play with the idea of motion sensing, and when it comes to prototyping, being able to test a concept while keeping costs to a minimum is a good skill to have.
Food-grade 3D printing filament is on the rise and it is nice to have a custom coffee mug in the office to instill a little envy in the locals. [Stefan] took it upon himself to create a Mocha Machine that he would 3D print and test the boundaries of his filament.
[Stefan] used Fusion 360 to replicate the famous Bialetti Moka Express pot in it true octagonal shape. Since the pot brews coffee under pressure, he tested tolerances in Fusion 360 to make sure all the thicknesses were right. While the design was being printed, a steel washer was added to facilitate induction heating since you can’t really put a plastic pot over a flame. The print uses Formfutura Volcano PLA which is annealed for an hour at 110 degrees Celsius.
Below is a video of the whole process and though the material may not be food grade, the project is definitely a step in the right direction. Since the printed parts can withstand temperatures of up to 160 degrees Celsius, projects that involve boiling water or experiments with crystallization can benefit from a custom design.
We really hope to see more projects that use this technique, however, for those looking at their coffee machine right now, take a look at more coffee machine hacks as well as alarm clock hacks to get the coffee brewing in the morning.
[This Old Tony] was cleaning up his metal shop after his yearly flirtation with woodworking when he found himself hankering for a nice coffee. He was, however, completely without a coffee making apparatus. We imagine there was a hasty round of consulting with his inanimate friends [Optimus Prime] and [Stefan Gotteswinter Brush] before he decided the only logical option was to make his own.
So, he brought out two chunks of aluminum from somewhere in his shop, modeled up his plan in SolidWorks, and got to work. It was designed to be a moka style espresso pot sized around both the size of stock he had, and three purchased parts: the gasket, funnel, and filter. The base and top were cut on a combination of lathe and mill. He had some good tips on working with deep thin walled parts. He also used his CNC to cut out some parts, like the lid and handle. The spout was interesting, as it was made by building up a glob of metal using a welder and then shaped afterward.
As usual the video is of [This Old Tony]’s exceptional quality. After quite a lot of work he rinsed out most of the metal chips and WD40, packed it with coffee, and put it on the stove. Success! It wasn’t long before the black stuff was bubbling into the top chamber ready for consumption.
Those twisty knobs connected to potentiometers aren’t necessarily a strict linear progression from one resistance to another. Potentiometers have a taper. Yes, sometimes it’s a linear taper that’s a straight line from one resistance to another, but you can find log (audio) taper pots, and anti-log taper pots. It’s been this way for a hundred years, and now we have a pot with a digitally controllable taper thanks to a guitar pedal that fits in your shoe.
For the last few years, [John] has been hard at work creating the SoulPedal, a shoe insert that’s the wireless, wearable alternative to expression pedals, wah pedals, and every other guitar effects pedal that uses an ankle. [John] got the idea by replacing the light-sensitive resistor in a wah pedal with a force sensitive resistor in his shoe. It worked, but there were wires. Now the SoulPedal is based on a TI SoC +Radio with all the niceties you would expect.
When designing the ‘base station pedal’, [John] realized he had a digital pot with two channels, and the entire device only uses one of these channels. Instead of letting that little bit of silicon go to waste, [John] wired these two digital pots in parallel, allowing the user to customize the taper of a digital pot. If you’re asking yourself, ‘why’, the answer is, ‘because he could.’
It’s an interesting application for sure, and while this digitally controllable pot can replicate the linear, log, and anti-log tapers, the really interesting thing will be to see what non-standard tapers sound and feel like.
Lets just take a second to be completely honest here. There’s no point in suggesting that this is possibly for smoking tobacco. Medical marijuana is legal (well, not federally), in several states, and we’re sure there are hackers there that would really enjoy making something of their own instead of just buying something.
We’ve covered a few below and they always seemed to have something in common. They use soldering irons for heat. Inevitably someone points out what a bad idea this is.