We often take our “SoftwareSerial” libraries for granted, and don’t investigate what goes on under the hood — until they fail us, at least. Would you like to learn how to harness the power of interrupt-driven bitbanging? [Jim Mack] teaches us how to make our protocol implementations fly using the LTC protocol as a springboard.
LTC (Linear/[Longitudinal] TimeCode) is a widely-used and beautifully-crafted protocol that tends to fly under our radar, and is one that hackers could learn plenty from. It’s used for synchronization of audio/video devices during media production and playback. LTC’s signal is almost digital but not quite: it doesn’t need a clock, and it has no polarity. Additionally, it mimics an audio signal really well, you can decode it at any playback speed, and many other benefits and quirks that [Jim] outlines. You do need to maintain the timings, though, and [Jim]’s article shows us how to keep them right while not inconveniencing your primary tasks.
Would you believe the multi-tiered toolbox pictured here started its life as a piece of bog standard PVC pipe? It certainly wouldn’t be our first choice of building material, but as shown in the video after the break, it only takes a heat source and something suitably flat to convert a piece of PVC pipe into a versatile sheet material.
Flattening the heated PVC.
Unrolling the PVC pipe and getting it flat is covered in the first minute of the video, while the rest of the run time is dedicated to building the tool box. Each and every piece you see here, except for the screws and lid hinges, is carefully cut from the PVC sheet. Though we suspect a few more chunks of pipe went into this build than the video would have you believe.
Would we build such an elaborate box if we had to cut each piece of the thing out by hand? Probably not. But then, we can’t deny the final results here are pretty impressive. Incidentally, if you thought those hinges on the top looked a lot like links removed from a watch band…you’d be correct.
Admittedly we’re a bit late covering this one, and under normal circumstances we might have let it slip by given the several million views it’s amassed over the last year. But the central theme of reusing a common material to build something unexpected is solid Hackaday territory, and aligns closely with this year’s Hackaday Prize challenges.
Your [Bornhack] plans include leaving lemons in patterns as an info display. Your squirrel feeder needs to only dispense nuts when the squirrels deserve it. As promised last week, an intro to gating, feeding, and moving bulk material.
Gates
Bulk material flow needs control. Starting is easy, it’s stopping that’s hard.
Dump Gate, Slide Gate, Clamshell Gate
If your need is just to dump out the entire contents of the bin, a dump gate works – a trapdoor with a latch. If you need to stop before emptying the bin, you can use a slide valve – a flat piece of material in a box that slides in and out. Friction from material bearing down on them causes large open/close forces. Material can jam between the flap and the housing when closing.
A variation is the clam shell gate — a section of a cylinder on arms that swings aside, like a crane’s grab. They tend to leak, but with the material’s weight against the hinge pin, they are easier to close with a high force against them.
The upward bell gate, helps with in-bin flow pattern and seals well. Open by pulling from above or pushing from below, through the outlet. The material moving around the gate acts to improve the flow, and because the material at the lip is on an inclined surface, they tend to seal better. If it still has a leakage problem, a flexible lip can cure it.
A cone, suspended on a cable below the outlet of the hopper is a downward bell. Lowering the cable lets material flow between the outlet rim and the bell. When the cable is raised, if a lump sticks at one place the bell moves aside. The sealing surfaces are angles, so material rolls off. The bin is shallower and there’s no outlet pipe. This design ensures clearance so large particles don’t wedge against the wall as the bell closes.
Upward Bell, Downward Bell, Double Bell
Any of these gates would close just fine if not for the material in the bin. Double gates exploit this. The main bin has a normal gate and outlet. The outlet is below the lip of the much smaller, lower control bin. If the control bin fills, the main bin stops. The control bin has a gate larger than the main bin. Closing the main gate as far as it will go reduces flow through the control gate to a trickle. The control gate can now be fully closed, which fills the control bin and blocks the main outlet.
You might not want to share environments between bins. Maybe one has pressure, nasty chemicals, or hot gases. In that case, a rotary airlock gate is a paddle wheel apparatus in a close fitting housing. Material is metered out as it turns. A double gate also works (blast furnaces use double bells). If you need to meter a set amount, a sliding cavity like a grocery store bulk bin works. So does a rotary airlock.
Locomotive sander systems spread sand on the rails to increase traction. The sand is gated with a “sand trap”. A pipe supplies sand to a ‘valve’ with a sharp upward U bend. Of course this blocks. A compressed air line from a valve in the cab feeds into the upward end of the U bend. As long as air flows, the blockage is constantly cleared and sand flows. It’s collected and sent to the wheels.
Feeders
If you need a constant flow, independent of how much is in the bin, you need a feeder.
The rotary air lock can be a simple feeder. A conveyor feeder is a belt at the bottom of the bin. One side has a slight gap between bin and belt. Material covers the belt as high as the gap. A screw feeder is a helical screw at the bottom of the hopper, taking material off to the side. The screw needs a varying pitch, starting out slow and increasing, to let it fill gradually from all along the hopper. A vibratory feeder is a chute designed to arch, with a vibrator to make it flow anyway.
Any of these can have a poor pattern of feeding, taking from one place along it’s inlet. Fins and inserts in the bin can help – a doctor blade to regulate how deep the first couple inches of belt feed, or an anti-rathole type insert to keep mass flow going.
Conveyors
Unlike a feeder, a conveyor depends on whatever is feeding it to control the feed rate. Feeders are for controlling feed rate. Conveyors for moving stuff. A feeder will change it’s output when it’s speed changes. A conveyor may change how much is in each section (the ‘loading’) but the output is speed independent.
Screw conveyors should have a fixed pitch, and can be angled up to 45 degrees. Belts can be inclined up to the angle of repose of the material. These are best made with a slight ‘V’ in the belt so the material doesn’t roll off. Boards on the side also work, but introduce friction into the system as the material slides against them.
Don’t overlook skips — a bucket pulled up an incline. The front wheels run on tracks slightly narrower than the back wheels. Dip the inside tracks down at the end to dump.
Moving floors made of long strips will move a pile of material if actuated in the proper sequence. Picture the order as ‘123123123123’: shove 1 backwards suddenly, and the material above it will stay with the mass, do 2 and 3, then slowly move all forward. They also move solid objects, so many trucks have such floors.
Finally, you can always fluidize the material and blow it about with air or water, then remove the fluid at the other end. Think old time logging, with logs floated down the river.
Have fun hacking. We hope we’ve given you some options for dealing with walnuts.
Many of us have heard the name Archimedes’ screw — but not everyone knows the term screw conveyor. These folks (sadly, the videographer at [Breeze Media] doesn’t tell us their names, or the company name) has the process of building screw conveyors down to a fine art.
Screw conveyors are useful, but many folks shy away from them because they look hard to make. In this video, we see how it’s done. The crew in this video are doing it in metal for large equipment, but the same methods could be used in plastic sheet or paper on a small scale.
It starts with cutting washers and slitting radially. When they’re distorted into the final shape the hole will close up, so the hole is a bit larger than the pipe that forms the center. They’re then given a slight spiral (think a lock washer) by walloping with a sledgehammer. It works. The slit edges are welded together to make a ‘compressed’ spiral, and the end is welded to the pipe
Now for the ingenious bit. They have a tall gantry, just a couple of pipe poles with a crossbar, set up in the factory yard. Below it, they’ve drilled a well. The free end of the pipe goes down the well. The bottom of the spiral is clamped to a baseplate around the well. Next, the pipe is hoisted up to form the final shape. Finally, everything is welded in place.
In the video after the break, they’re making a screw feeder. It needs a lower pitch for the section under the hopper. So they clamp several turns, pull the main section out, weld it, then move the clamp and make the feeder section.
Hacks are partially art, and screws are visually interesting. This piggy bank has one. Put one in your next hack!
What’s the most important part of the keycap? The average user-who-cares might tell you it’s the look and feel, but a keyboard builder would probably say the mounting style. That’s where the rubber meets the road, after all. For anyone trying to make their own keycaps, ‘the mount itself’ is definitely the correct answer. Try printing your own keycaps, and you’ll learn a lot about tolerances when it comes to getting the mount right.
Conversely, you could use a subtractive process like a wood mill to make keycaps. Sounds easy enough, right? But what about all of us who don’t have access to one? [cbosdonnat], who has no CNC, has blazed a cellulose trail, combining hand-tooled wooden keycaps with 3D-printed mounts to create fully-customized keycaps. It’s a great project with concise how-to, especially when it comes to building the jigs needed to keep the keycaps consistently sized and shaped.
It makes a whole lot of sense to start by hollowing out the bottom instead of shaping the business side first or even cutting out the key shape, since the mount is mechanically vital. Why waste time on the look and feel if the foundation isn’t there yet?
Hardwood is a must for DIY keycaps, because the walls need to be thin enough to both fit over the switch and within the matrix, and be sturdy enough not to break with use. We love the look of the varnish-transferred laser-printed logo, and only wish there was a video so we could hear the clacking.
There are all kinds of ways to put legends on DIY keycaps, like waterslide decals for instance.
So you just built a super-mega robot project that you want to share with the world. Super! But now you’re faced with an entirely new and different problem: documenting the process for the world to see. It’s enough to drive you back down into the lab.
What software should I use to create my project site?
How deep down the rabbit hole should I go when it comes to documenting the project?
What toppings do I want on my something-to-eat-while-hacking pizza?
We’re not going to get into the age old “pineapple or no pineapple” debate, but it’s important to note that the topic of how to share a project with the world has as many choices as toppings, and just as many opinions. The answer will always be simple: Do what works best for you!
The purpose of this article is to give some options to somebody considering sharing their projects online. There isn’t enough room to talk about every single option available to a hacker, so be sure to fill in your favorite options in the comments below. Let’s dive in!
Plenty of potential, but a cozy hacking space it is not
To us hackers and makers, the tools of our trade are often as important and interesting as the details of the hacks themselves, but what about the most important tool of all — the very space you use to make your magic happen? That may be your bedroom, a nearby hackerspace, and if you have the resources, you may even own a place of your own, and get to build your perfect workspace.
The latter situation is what [MichD] and partner [Brittany] found themselves in, having moved into their first place. Many couples focus on getting a hot tub in the garden or sorting the nursery, but these two are proper electronics nerds, so they converted a free-standing double wide garage into the nerdhub, learning as they went along, and documenting it in excruciating detail for your viewing pleasure.
Door fitted, framed up, and insulation in place. All ready for plasterboarding.
The building structurally is a single-skinned brick-built box, with a raw concrete floor. Pretty typical stuff for the UK (we’ve seen much worse), but not ideal for spending an extended amount of time in due to our damp, cold climate, at least in winter.
The first order of business was partitioning the front section for bike storage, and screeding the floor. Once the floor was solid, the walls and ceiling joists could be framed up, ready for fitting insulation material and covering with plasterboard.
Electrics were next in order, with the wires clipped to the brickwork, well away from where the plasterboard would be, therefore making it less likely to accidentally drill into a live cable when adding external fixtures.
Since the front part of the room was to be partitioned off, another access door was needed. This involved cutting out the bricks to fit a concrete lintel. With that installed, and the bricks above supported, the area below was cut out to the required shape. A somewhat nerve-wracking experience, if you ask us!
As any self-respecting hacker will tell you — no room build is complete without a decent amount of RGB bling, so the whole room was decked out with APA102 addressable LED strips. Control of these was courtesy of WLED running on an ESP32 module, with LedFX used on a nearby PC to perform music visualisation, just because.
