Building Your Own Consensus

November 30, 2022 by 3 Comments

With billions of computers talking to each other daily, how do they decide anything? Even in a database or server deployment, how do the different computers that make up the database decide what values have been committed? How do they agree on what time it is? How do they come to a consensus?

But first, what is the concept of consensus in the context of computers? Boiled down, it is for all involved agents to agree on a single value. However, allowances for dissenting, incorrect, or faulting agents are designed into the protocol. Every correct agent must answer, and all proper agents must have the same answer. This is particularly important for data centers or mesh networks. What happens if the network becomes partitioned, some nodes go offline, or the software crashes weirdly, sending strange garbled data? One of the most common consensus algorithms is Raft. Continue reading “Building Your Own Consensus” →

Making 3D Print Time-lapses With Old Earphones And A Few Spare Parts

November 30, 2022 by 18 Comments

The trick to producing great 3D printing time-lapse animations is to ensure that the extruder has moved out of the frame each time a photo is taken — which usually requires OctoPrint to be controlling both the camera and printer. But [NirL] managed to bodge up a system to get the same result with a spare limit switch, a resistor, his mobile phone, and an old set of earbuds. Not bad for some spare parts and a little extra G-Code.

The print head hits a remote shutter button during a brief parking action after each layer.

Inserting custom G-Code to park the print head at regular intervals takes care of standardizing the printer’s movements; there’s even a post-processing extension in Cura that makes this easy. As for triggering the camera, [NirL] was inspired by the remote shutter button on a selfie stick. By positioning a physical switch in such a way that the print head pushes it every time it (briefly) parks, a photo gets taken for every layer. Essentially the same thing Octolapse does, just with fewer parts.

To create the DIY remote shutter button, [NirL] used a spare limit switch, resistor, and cannibalized an old set of earbuds for the cable and 4-conductor 3.5 mm audio plug. Most phones and camera apps trigger the shutter when they receive a Vol+ signal through the audio plug, which is done by connecting MIC and GND through a 240 Ohm resistor.

In this way a photo is snapped for every layer, giving [NirL] all that is needed to assemble a smooth animation. Sure, it ties up a mobile phone for the duration of the print, but for just a few spare parts it does the job. You can see the project in action in the video, embedded just under the page break.

As mentioned, the usual way to implement effortless time-lapses is by using the Octolapse plugin for OctoPrint, which creates silky smooth animations without the typical blur of time-lapses.

Continue reading “Making 3D Print Time-lapses With Old Earphones And A Few Spare Parts” →

Acrylic Light Puzzle Has A Point

November 30, 2022 by 4 Comments

[JBV Creative] recently became a proud owner of a laser cutter and, like most of us, started to think about what they could make with it. The answer was simple, a clever little piece of art or puzzle made of stacked acrylic.

He created some text and extruded it from a single point, but not every part intersected with every plate, giving each plate an indecipherable appearance. This allows a small light source (like the LED likely on the back of your phone) to cast a shadow on the wall. With some 3D printed brackets and spacers, it was mounted to a nice piece of cherry plywood. Overall, the technique is quite simple and easy to understand. [JBV Creative] didn’t include more detail on the process, which is a shame because it looks like a beautiful effect to recreate for some puzzles.

These glowing coasters are fantastic if you’re looking for engraved acrylic with a light source. Or this puzzle that lights up as the pieces are placed.

Continue reading “Acrylic Light Puzzle Has A Point” →

3d printed escalator, from side, showing mechanism

Tiny 3D Printed HO Scale Escalator That Works

November 29, 2022 by 25 Comments

[Luke Towan] has a cool HO scale Escalator mostly made of 3D printed parts, with some laser cut acrylic, for a station on his HO model railroad.

Escalators are mesmerizing to watch – there’s something magical about the stairs unfolding at the bottom and folding up at the top. But they’re very hard to model.

[Luke Towan] has done it – his 3D printed version closely resembles the real thing mechanically. Pins are carried around, cantilevered out from a 3D printed chain. A stair swivels on each pin – at the bottom each stair’s free end rests on a ‘bottom’ far enough down for the stairs to be level, while on the incline the ‘bottom’ is just below the pins. It’s a tricky build.

If you like pushing the envelope of what 3D printing can do this is an interesting project, even if you’re not planning to build an escalator. There are lots of tips for making small mechanisms with 3D printing, and for making small mechanisms that work reliably without stuttering.

He’s not the first to build an escalator. Back in 2015 we covered this wooden escalator for slinkies,  and just recently this 3D printed version from [AlexY].

Prototyping The Prototype

November 29, 2022 by 28 Comments

For basic prototyping, the go-to tool to piece together a functioning circuit is the breadboard. It’s a great way to prove a concept works before spending money and time on a PCB. For more complex tasks we can make use of simulation software such as SPICE. But there hasn’t really been a tool to blend these two concepts together. That’s what CRUMB is hoping to solve as a tool that allows simulating breadboard circuits.

Currently, most basic circuit functions are working for version 1.0. This includes passive components like resistors, capacitors, switches, some LEDs, and potentiometers, as well as some active components like transistors and diodes. There are some logic chips available such as 74XX series chips and 555 timers, which opens up a vast array of circuit building. There’s even an oscilloscope feature, plus audio output to incorporate buzzers into the circuit simulation. Currently in development is an LCD display module and improvements to the oscilloscope.

Besides prototyping, this could be useful for anyone, students included, who is learning about circuits without the need to purchase any hardware. The major downside to this project is that it there doesn’t seem to have a free or trial version, the source is not available, and it’s only for sale on Steam, Apple Store, and Google Play. That being said, there is a forum available for users to discuss problems and needs for future versions, so it’s possible that a community could build up around it. We’ve seen previously non-free versions of circuit simulation software become more open after some time, so it’s not out of the realm of possibility.

Thanks to [Thomas] for the tip!

Interfacing An Old Engine Cowl Flaps Indicator To USB

November 29, 2022 by 9 Comments

[Glen Akins] had a WW2-era aircraft engine cowl flap indicator lying around (as you do) and thought it would make a jolly fine USB-attached indicator. The model in question is a General Electric model 8DJ4PBV DC Selsyn, which was intended for four-engined aircraft. For those not familiar with the purpose [Glen] explains in his detailed writeup, that piston-engine aircraft of that era were air-cooled, and during conditions of maximum engine power — such as during take-off — flaps on the side of the engine cowling could be opened to admit additional cooling airflow. These indicator dials were connected to a sender unit on each of the flap actuators, providing the pilots an indication of the flaps’ positions. Continue reading “Interfacing An Old Engine Cowl Flaps Indicator To USB” →

This Electric Outboard Conversion Makes For A Quiet Day On The Water

November 29, 2022 by 21 Comments

Nothing beats a day on the lake in a little boat with an outboard motor putt-putting along behind you. It’s great fun, if perhaps a little noisy with all that putting going on. And maybe that oily sheen on the water in your wake is not so nice. it could be that the fish are a little annoyed with your putting, too. Come to think of it, outboard motors are a bit of a problem.

Fortunately there’s a better way, like converting an old outboard motor to electric. It comes to us by way of [Anton], who happened upon the perfect donor platform — a 5-hp outboard by Crescent, sporting a glorious 1970s color scheme and a motor housing shell perfect for modding. He started by ripping the old engine and drivetrain out of the housing to make room for the BLDC motor and its driver. The motor was a project in itself; [Anton] rewound the original stator with much thicker wire and changed the coil configuration to milk as much torque as possible out of it. What started as a 180-kv motor ended up at 77 kv with much more copper and new Hall sensors for the controller. He also put a ton of effort into waterproofing the motor with epoxy resin. With a 3D-printed prop and a streamlined fairing, the new motor looks quite at home on the outboard. In fact, the whole thing barely looks customized at all — the speed control is even right on the tiller where you’d expect it.

The video below shows the build and a test run, plus an analysis of the problems encountered, chief of which is water intrusion. But as [Anton] rightly points out, that’s easily solved by reusing the original driveshaft and mounting the motor above the waterline, like this. Still, we like the look of this, and the idea of knocking around on the water nearly silently seems wonderful.

Continue reading “This Electric Outboard Conversion Makes For A Quiet Day On The Water” →