We’ve been told that standing at a desk is good for you, but unless you’re some kind of highly advanced automaton you’re going to have to sit down eventually no matter what all those lifestyle magazines say. That’s where desks like the IKEA SKARSTA come in; they use a crank on the front to raise and lower the desk to whatever height your rapidly aging corporeal form is still capable of maintaining. All the health benefits of a standing desk, without that stinging sense of defeat when you later discover you hate it.
But who wants to turn a crank with their hand in 2019? Certainly not [iLLiac4], who’s spent the last few months working in conjunction with [Martin Mihálek] to add some very impressive features to IKEA’s adjustable table. Replacing the hand crank with a motorized system which can do the raising and lifting was only part of it, the project also includes a slick control panel with a digital display that shows the current table height and even allows the user to set and recall specific positions. The project is still in active development and has a few kinks to work out, but it looks exceptionally promising if you’re looking to get a very capable adjustable desk without breaking the bank.
The heart of the project is a 3D printable device which uses a low-RPM DC gear motor to turn the hex shaft where the crank would normally go. A rotary encoder is linked to the shaft of the motor by way of printed GT2 pulleys and a short length of belt, which gives the system positional information and avoids the complexity of adding limit switches to the table itself.
For controlling the motor the user is given the option between using relays or an H-Bridge PWM driver board, but in either event an Arduino Nano will be running the show. In addition to controlling the motor and reading the output of the rotary encoder, the Arduino also handles the front panel controls. This consists of a TM1637 four digit LED display originally intended for clocks, as well as six momentary contact tactile switches complete with 3D printed caps. The front panel’s simple user interface not only allows for setting and recalling three preset desk heights, but can even be used to perform the calibration routine without having to go in and hack the source code to change minimum and maximum positions.
Electric bikes are getting a lot of attention lately. Pretty much anyone can buy a kit online and get a perfectly street legal ride with plenty of range. But if you don’t want to take the kit route, and you’d rather take a tack that will get you noticed more around these parts, take some notes from [Jule553648]’s recent build that definitely isn’t using any parts from a kit.
The motor from the build is an electric power steering pump from a junkyard car. This gets mounted on a one-off rear bike rack and drives the rear tire with help from some gears from a pocket bike gearbox from eBay. A lot of the parts in this build were designed and built using CAD and a machine shop, and the parts for the battery and the power controller were sourced via China to save on cost.
The whole build has a homemade vibe that we find irresistible. The bike can go 35 km/h on level ground without breaking a sweat and has about 40 km of range which is nothing to scoff at. It might even be street legal depending on the wattage of the motor and whether or not you live in Europe (where throttles are generally not allowed on electric bikes). If you’re lacking a machine shop, though, we featured a very well-built kit ebike a while back that you could use as a model to get your feet wet.
No microcontroller, no display, and not even an LED in sight. That’s how [Made in Poland] decided to roll with this motorized linear plasma cutter, and despite the simplicity it really gets the job done when there’s metal to be cut.
Plasma cutting makes slicing and dicing heavy stock a quick job, but it’s easy to go off course with the torch or to vary the speed and end up with a poor edge. This tool takes the shakes out of the equation with a completely homebrew linear slide fabricated from square tubing. A carriage to hold the plasma cutter torch moves on a length of threaded rod chucked into the remains of an old cordless drill. The original clutch of the drill removes the need for limit switches when the carriage hits either end of the slide, which we thought was a great touch. Simple speed and direction controls are provided, as is a connection in parallel with the torch’s trigger. One nice feature of the carriage is the ability to swivel the torch at an angle, making V-groove welds in thick stock a snap. No need for a complicated bed with sacrificial supports and a water bath, either — just hang the stock over the edge of a table and let the sparks fall where they may.
Simple is better sometimes, but a CNC plasma table may still be your heart’s desire. We understand.
Artist Pe Lang uses linear polarization filters to create an unusual effect in his piece polarization | nº 1. The piece consists of a large number of discs made from polarizing film that partially overlap each other at the edges. Motors turn these discs slowly, and in the process the overlapping portions go from clear to opaque black and back again.
The disc rotation speed may be low but the individual transitions occur quite abruptly. Seeing a large number of the individual discs transitioning in a chaotic pattern — but at a steady rate — is a strange visual effect. About 30 seconds into the video there is a close up, and you can see for yourself that the motors and discs are all moving at a constant rate. Even so, it’s hard to shake the feeling of that one is watching a time-lapse. See for yourself in the video, embedded below.
[Tim] needed very small, motorized joints for a robot. Unable to find anything to fit the bill, he designed his own tiny, robotic joints. Not only are these articulated and motorized, they are designed to be independent – each containing their own driver and microcontroller.
None of the photos or video really give a good sense of just how small [Tim]’s design is. The motor (purple in the 3D render above, and pictured to the left) is a sub-micro planetary geared motor with a D shaped shaft. It is 6mm in diameter and 19mm long. One of these motors is almost entirely encapsulated within the screw it drives (green), forming a type of worm gear. As the motor turns the screw, a threaded ring moves up or down – which in turn moves the articulated shaft attached to the joint. A video is embedded below that shows the joint in action.
[Tim] originally tried 3D printing the pieces on his Lulzbot but it wasn’t up to the task. He’s currently using a Form 2 with white resin, which is able to make the tiny pieces just the way he needs them.
The base has been outfitted with cogs and a chain from an old bicycle. The gear reduction lets a power drill rotate the platform. This worked well enough but [Gary] found that making fine adjustments was rather difficult and more often than not he ended up moving the binoculars to avoid overshooting when adjusting the platform with the drill. Luckily he didn’t give up on the idea. On the eighth and final page of his build log he refines the rotating setup with the help of an ice cream maker. It’s gear box is used as a speed reducer so that a very slow drill speed results in an extremely small heading correction. Now he can view the stars in peace, freed from frustration by a well-refined hack.
You’re certainly not going to sneak up on anyone if using this LEGO motorized wheelchair. The high-pitched whine of all those tiny motors sounds like an army of robotic mosquitoes out for blood.
Six of the LEGO Mindstorm bricks are used to drive the motors, with a seventh acting as the master. It’s not pictured above, but there is a joystick on the right hand side which allows the rider to navigate. The master brick monitors the four sensors on that joystick. It then uses a pair of motors to actuate switches monitored by the slave bricks. Each slave has one switch for forward, and another for backward and drives two motors. To get around problems with angular velocities dues to turning, all of the wheels are multidirectional.
The plan is to add Bluetooth control in the near future. The master/slave setup should make that relatively easy as it only affects one of the bricks. The idea is to facilitate Android control to the chair like we’ve seen in other Mindstorm builds.