Compressed Air Jumping Shoes Are Not For The Faint-Hearted

March 3, 2022 by Dave Rowntree 30 Comments

[Ian Charnas] has taken a short break from building things that might injure himself, by building something that could injure somebody else instead. (Video, embedded below) Well, hopefully not anyway. After working with YouTuber [Tyler Csatari] on a few ideas, [Tyler] was insistent on getting some power-assisted jumping shoes, so [Ian] set to work mounting some compressed-air powered pistons to a pair of walking shoes. With a large backpack housing the 200 PSI air cylinder, control valves and timers. The whole affair looks solidly constructed, if a little ungainly, but does seem to work surprisingly well.

After some initial calculations of how much force each piston could exert before risking leg injury, he found that whilst it did work, to an extent, the pressure required was beyond the capability of the compressor they had on hand. After a shopping trip, a bigger compressor was located, but that still needed a modification to get anywhere near its maximum 200 psi rating. The thing is, that modification was to bypass the regulator and the safety valve, and this is definitely something you don’t want to be making a habit of. Compressed air systems like this can hold quite a bit of an explosion potential if pushed beyond reasonable limits, and care needs to be taken to keep things within safe bounds.

Cost-wise, [Ian] does mention a figure of around $3,000 USD making it a bit of a pricey project, but hey a YouTuber’s paying the bill, so it must just be a drop in the ocean for them?

Just to illustrate how useful compressed air is as a method of storing energy, here’s a compressed-air powered helicopter, and a 3D printed wankel rotary engine, which must’ve been tough to dial in and get working!

Continue reading “Compressed Air Jumping Shoes Are Not For The Faint-Hearted” →

Bend Your Vase Mode Prints By Hacking The GCode

February 22, 2022 by Dave Rowntree 3 Comments

[Stefan] from CNCKitchen wanted to make some bendy tubes for a window-mountable ball run, and rather than coming up with some bent tube models, it seemed there might be a different way to achieve the desired outcome. Starting with a simple tube model designed to be quickly printed in vase mode, he wrote a Python script which read in the G-Code, and modified it allow it to be bent along a spline path.

Vase mode works by slowly ramping up the Z-axis as the extruder follows the object outline, but the slicing process is still essentially the same, with the object sliced in a plane parallel to the bed. Whilst this non-planar method moves the Z-axis in sync with the horizontal motion (although currently limited to only one plane of distortion, which simplifies the maths a bit) it is we guess still technically a planar solution, but just an inclined plane. But we digress, non-planar in this context merely means not parallel to the bed, and we’ll roll with that.

[Stefan] explains that there are quite a few difficulties with this approach. The first issue is that on the inside of the bend, the material flow rate needed to be scaled back to compensate. But the main problem stems from the design of the extruder itself. Intended for operating parallel to the bed, there are often a few structures in the way of operating at an angle, such as fan mounts, and the hotend itself. By selecting an appropriate machine and tweaking it a bit, [Stefan] managed to get it to work at angles up to 30 degrees off the horizontal plane. One annoyance was that the stock nozzle shape of his E3D Volcano hotend didn’t lend itself to operating at such an inclination, so he needed to mount an older V6-style tip with an adapter. After a lot of tuning and fails, it did work and the final goal was achieved! If you want to try this for yourselves, the code for this can be found on the project GitHub.

If you want to learn more about non-planar printing, we’ve covered the process of non-planar slicing a while back, and if you think your 2.5D printer doesn’t quite have the range for really funky print paths, then you may want to look into a robot arm based printer instead.

Continue reading “Bend Your Vase Mode Prints By Hacking The GCode” →

Super Simple Camera Slider With A Neat Twist

February 22, 2022 by Dave Rowntree 5 Comments

When you get into making videos of products or your own cool hacks, at some point you’re going to start wondering how those neat panning and rotating shots are achieved. The answer is quite often some kind of mechanical slider which sends the camera along a predefined path. Buying one can be an expensive outlay, so many people opt to build one. [Rahel zahir Ali] was no different, and designed and built a very simple slide, but with a neat twist.

This design uses a geared DC motor, taken from a car windscreen wiper. That’s a cost effective way to get your hands on a nice high-torque motor with an integral reduction gearbox. The added twist is that the camera mount is pivoted and slides on a third, central smooth rod. The ends of this guide rod can be offset at either end, allowing the camera to rotate up to thirty degrees as the slide progresses from one end to the other. With a few tweaks, the slider can be vertically mounted, to give those up-and-over shots. Super simple, low tech and not an Arduino in sight.

The CAD modelling was done with Fusion 360, with all the models downloadable with source, in case someone needs to adapt the design further. We were just expecting a pile of STLs, so seeing the full source was a nice surprise, given how many open source projects like this (especially on Thingiverse) do often seem to neglect this.

Electronics consist of a simple DC motor controller (although [Rahel] doesn’t mention a specific product, it should not be hard to source) which deals with the speed control, and a DPDT latching rocker switch handles the motor direction. A pair of microswitches are used to stop the motor at the end of its travel. Other than a 3D printer, there is nothing at all special needed to make yourself quite a useful little slider!

We’ve seen a few slider designs, since this is a common problem for content creators. Here’s a more complicated one, and another one.

Continue reading “Super Simple Camera Slider With A Neat Twist” →

Dummy The Robot Arm Is Not So Dumb

February 21, 2022 by Dave Rowntree 30 Comments

[Zhihui Jun] is a name you’re going to want to remember because this Chinese maker has created quite probably one of the most complete open-source robot arms (video in Chinese with subtitles, embedded below) we’ve ever seen. This project has to be seen to be believed. Every aspect of the design from concept, mechanical CAD, electronics design and software covering embedded, 3D GUI, and so on, is the work of one maker, in just their spare time! Sound like we’re talking it up too much? Just watch the video and try to keep up!

After an initial review of toy robots versus more industrial units, it was quickly decided that servos weren’t going to cut it – too little torque and lacking in precision. BLDC motors offer great precision and torque when paired with a good controller, but they are tricky to make small enough, so an off-the-shelf compact harmonic drive was selected and paired with a stepper motor to get the required performance. This was multiplied by six and dropped into some slick CNC machined aluminum parts to complete the mechanics. A custom closed-loop stepper controller mounts directly to the rear of each motor. That’s really nice too.

Stepper controller mounts on the motor rear – smart!

Control electronics are based around the STM32 using an ESP32 for Wi-Fi connectivity, but the pace of the video is so fast it’s hard to keep up with how much of the design operates. There is a brief mention that the controller runs the LiteOS kernel for Harmony OS, but no details we can find. The project GitHub has many of the gory details to pore over perhaps a bit light in places but the promise is made to expand that. For remote control, there’s a BLE-connected teaching device (called ‘Peak’) with a touch screen, again details pending. Oh, did we mention there’s a force-feedback (a PS5 Adaptive Trigger had to die for the cause) remote control unit that uses binocular cameras to track motion, with an AHRS setup giving orientation and that all this is powered by a Huawei Atlas edge AI processing system? This was greatly glossed over in the video like it was just some side-note not worth talking about. We hope details of that get made public soon!

Threading a needle through a grape by remote control

The dedicated GUI, written in what looks like Unity, allows robot programming and motion planning, but since those harmonic drives are back-drivable, the robot can be moved by hand and record movements for replaying later. Some work with AR has been started, but that looks like early in the process, the features just keep on coming!

Quite frankly there is so much happening that it’s hard to summarise here and do the project any sort of justice, so to that end we suggest popping over to YT and taking a look for yourselves.

We love robots ’round these parts, especially robot arms, here’s a big one by [Jeremy Fielding], and if you think stepper motors aren’t necessary, because servo motors can be made to work just fine, you may be right.

Continue reading “Dummy The Robot Arm Is Not So Dumb” →

All About Dichroic Optical Filters

February 20, 2022 by Dave Rowntree 7 Comments

[IMSAI Guy] presents for your viewing pleasure, a nice video on the topic of optical filters and mirrors. (Video, embedded below) The first optical device is a simple absorption filter, where incoming light is absorbed in a wavelength-selective manner. Much more interesting however is the subject of interference or dichroic filters. These devices are constructed from many thin layers of a partially reflective material, and operate on the principle of interference. This means that photons hitting the filter stack will interfere either constructively or destructively giving the filter a pass or stop response for a particular wavelength.

As [IMSAI Guy] demonstrates, this makes the filters direction-specific, as photons hitting the stack at a different angle will travel slightly further. Longer travel means the interference effect will be different, and so will the filtering response. You can see this by playing around with one in your hands and seeing the color change as your rotate it. Dichroic filter films can also make for some stunning optical effects. Very cool stuff.

By creating a filter stack with a wide enough range of inter-layer thicknesses, it’s possible to construct a mirror that covers the full spectrum with excellent reflectivity. Since you can tune the layers, you can make it reflect any range of wavelengths you like. One thing we’ve not seen before is a wedge-like optical filter device, where the layer thicknesses progressively increase lengthways, creating a variable optical frequency response along the length. We guess this would be useful for diagnostics in the field, or perhaps for manually tuning a beam path?

We like the applications for dichroic films – here’s an Infinity Mirror ‘Hypercrystal’. If you don’t want to buy off-the-shelf films, perhaps you could sputter yourself something pretty?

Continue reading “All About Dichroic Optical Filters” →

Open Source LXI Tools Free Us From Vendor Bloat

February 18, 2022 by Dave Rowntree 8 Comments

LXI, or LAN eXtensions for Instrumentation is a modern control standard for connecting electronics instrumentation which supports ethernet. It replaces the older GPIB standard, giving much better performance and lower cost of implementation. This is a good thing. [Martin Lund] has created the open source lxi-tools project which enables us to detach ourselves from the often bloated vendor tools usually required for talking LXI to your bench equipment. This is a partial rewrite of an earlier version of the tool, and now sports some rather nice features such as mDNS for instrument discovery, support for screen grabbing, and a LUA-based scripting backend. (API Link)

SCPI or Standard Commands for Programmable Instruments is the text-based language spoken by many instruments, allowing control and querying of an instrument. Just to be clear, SCPI is not at all a new thing, and older instruments that have GPIB or RS232 connectors, still could talk SCPI. lxi-tools is not for those. Some instruments can also be very picky about the formatting of commands, especially if they’re buggy, so the ability to interactively debug commands is very desirable. It is quite possible to make poor use of SCPI commands in your test script and end up with tests that just take far longer to execute that they need to. lxi-tools has a benchmarking tool too, which helps you to dig in and find out where all the time is going and make suitable adjustments.

We’ve not seen much about LXI on Hackaday, but we did cover using PyVISA for dealing with SCPI-over-GPIB in python. If you have an older instrument with GPIB and you don’t want to sell a internal organ to pay for a USB adaptor, here’s one you can make yourself.

FPGA Starter Videos To Help Soften That Learning Curve

February 17, 2022 by Dave Rowntree 8 Comments

Digi-Key have been producing YouTube videos for a number of years now, and if you weren’t aware, they’re definitely worthy of some viewing time. The playlist we’re highlighting here is a pretty good introduction to FPGAs, specifically those supported by open source tools, with low cost hardware. If you’ve always wanted to get into hacking FPGA platforms, but don’t know where to start, this is going to be a big help. After first covering what an FPGA is and is not, and why you want to use one, [Shawn Hymel] dives in to the toolchain.

We’re really lucky that the bitstream for the Lattice iCE40 was reverse engineered by the super talented Claire (née Clifford) Wolf (AMP hour interview) which enabled the project ICEstorm toolchain to be created. Leveraging Yosys for synthesis and logic mapping, Icarus verilog coupled with GTKwave for simulation, netpnr for place and route and finally the project ICEstorm bitstream tools for packing into iCE40 format and loading onto the hardware. The whole toolchain flow is managed by APIO for simplicity, that is, provided your FPGA board is supported!

Of course, [Shawn] is using the low cost (for an FPGA) ICEStick by Lattice for this tutorial series, and they’re currently hard to get (you know why by now!) but, there are many other boards you could use. If you want to play with applications coupling a ARM micro to an FPGA, then the excellent BlackIce Mx is an option, but there are many other boards now with an decent micro nestled next to an FPGA and a few peripherals for convenience.

We should mention here, that project ICEstorm and the iCE40 is not the only show in town. Project Trellis has had our eye for a while, which targets the more complex Lattice ECP5 device. Yosys and friends do support more architectures, but the available flows usually require at least some vendor tool support at this time (looking straight at you, Xilinx) but as more devices get decoded, the open source tools will grow, and we will bring you that news!

What’s nice about this Digi-Key YT series, is that it doesn’t just cover the basic toolchain flow, then drop you in at the deep end of a big learning curve. There are videos covering subjects such as finite state machines (FSMs), test-benching and simulation, using embedded (block) memories, PLLs, harder subjects like dealing with metastability and clock-domain crossing (OK, he covers one technique – there’s more than one way to skin that particular cat) before finally looking at soft cores like the RISC-V. Lots to learn, and pretty well executed if you ask us! A Github version is available, for those who can’t stand watching the videos!

Continue reading “FPGA Starter Videos To Help Soften That Learning Curve” →