The Surprisingly Manual Process Of Building Automotive Wire Harnesses

July 27, 2022 by 115 Comments

Even from the very earliest days of the automobile age, cars and trucks have been hybrids of mechanical and electrical design. For every piston sliding up and down in a cylinder, there’s a spark plug that needs to be fired at just the right time to make the engine work, and stepping on the brake pedal had better cause the brake lights to come on at the same time hydraulic pressure pinches the wheel rotors between the brake pads.

Without electrical connections, a useful motor vehicle is a practical impossibility. Even long before electricity started becoming the fuel of choice for vehicles, the wires that connect the computers, sensors, actuators, and indicators needed to run a vehicle’s systems were getting more and more complicated by the year. After the engine and the frame, a car’s wiring and electronics are its third most expensive component, and it’s estimated that by 2030, fully half of the average vehicle’s cost will be locked in its electrical system, up from 30% in 2010.

Making sure all those signals get where they’re going, and doing so in a safe and reliable way is the job of a vehicle’s wire harnesses, the bundles of wires that seemingly occupy every possible area of a modern car. The design and manufacturing of wire harnesses is a complex process that relies on specialized software, a degree of automation, and a surprising amount of people-power.

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Move Over Silicon, A New Semiconductor Is In Town

July 27, 2022 by 28 Comments

Silicon has had a long run as the king of semiconductors, and why not? It’s plentiful and works well. However, working well and working ideally are two different things. In particular, electrons flow better than holes through the material. Silicon also is a poor heat conductor as we’ve all noticed when working with high-speed or high-power electronics. Researchers at MIT, the University of Houston, and other institutions are proposing cubic boron arsenide to overcome these limitations.

According to researchers, this material is a superior semiconductor and, possibly, the best possible semiconductor. Unfortunately, the material isn’t nearly as common as silicon. Labs have created small amounts of the material and there is still a problem with fabricating uniform samples.

Early experiments show the material has very high mobility for electrons and holes along with thermal conductivity almost ten times greater than that of silicon. It also has a good bandgap, making it very attractive as a semiconductor material. In fact, only diamond and isotopically enriched cubic boron nitride have better thermal conductivity.

However, there are still unknowns about how to use the material in practical devices. Long-term stability tests are as lacking. So maybe it will wipe out silicon or maybe it won’t. Time will tell.

We are always on the lookout for the next big semiconductor material. However, we suspect this tech will be out of reach to the home semiconductor fab, at least for a little while.

Large Format 3D Printer Is A Serious Engineering Challenge

July 27, 2022 by 14 Comments

When you want to build a large format 3D printer, you can’t just scale up the design of a desktop machine. In an excellent four-part build series (videos after the break), [Dr. D-Flo] takes us through all the engineering challenges he had to contend with when building a 3D printer with a 4x4x4 ft (1.2 m cube) print volume.

For such a large print volume you won’t be printing with a 0.4 mm nozzle. The heart of the printer is a commercial Massive Dimension MDPH2 pellet extruder, capable of extruding ~1 kg of plastic per hour through 1.5 mm to 5 mm nozzles. To feed the extruder, [Dr. D-Flo] used a Venturi vacuum system to periodically suck pellets from a large hopper. The system is driven by compressed air, which can introduce moisture back into the carefully dried pellets. To reduce the humidity levels, the compressed air passes through a series of vertical aluminum tubes to allow moisture to condense and drain out the bottom.

At 8.4 kg, it needs a powerful motion platform to move it. [Dr. D-Flo] went with a stationary bed design, with the extruder pushed around by seven high torque NEMA23 motors on a large gantry built from C-beam aluminum extrusions. A machine this size needs to be very rigid with well-fitting parts, so [Dr. D-Flo] made heavy use of CNC machined aluminum parts.

To allow dynamic bed leveling, [Dr. D-Flow] made use of a Quad Gantry Leveling (GQL) scheme. This means that each of the four Z-actuators will dynamically adjust its position based on inputs from the leveling probe. The avoid stressing the corner mountings that hold the X-Y gantry to the Z carriage plates, he used radial spherical bearings at the mounting points to allow a few degrees of play.

The build plate consists of an aluminum plate bolted onto the base in 25 positions with springs for adjustability. A massive 6000 watt 220 V heating pad sticks to the bottom, while the actual printing surface is a large sheet of borosilicate glass. One major concern was the deflection of the build plate when heated to working temperature, but with all the adjustment options [Dr. D-Flo] was able to get height variation down to about 0.25 mm. This is within the acceptable range when printing with layer heights of 1 mm or more.

We’ve featured large scale 3D printers in the past, but none are quite as big the University of Maine’s building-sized 3D printer that can print a motorboat in one piece.

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Mini Falcon 9 Uses NASA Software

July 26, 2022 by 17 Comments

[T-Zero Systems] has been working on his model Falcon 9 rocket for a while now. It’s an impressive model, complete with thrust vectoring, a microcontroller which follows a predetermined flight plan, a working launch pad, and even legs to attempt vertical landings. During his first tests of his model, though, there were some issues with the control system software that he wrote so he’s back with a new system that borrows software from the Space Shuttle.

The first problem to solve is gimbal lock, a problem that arises when two axes of rotation line up during flight, causing erratic motion. This is especially difficult because this model has no ability to control roll. Solving this using quaternion instead of Euler angles involves a lot of math, provided by libraries developed for use on the Space Shuttle, but with the extra efficiency improvements the new software runs at a much faster rate than it did previously. Unfortunately, the new software had a bug which prevented the parachute from opening, which wasn’t discovered until after launch.

There’s a lot going on in this build behind-the-scenes, too, like the test rocket motor used for testing the control system, which is actually two counter-rotating propellers that can be used to model the thrust of a motor without actually lighting anything on fire. There’s also a separate video describing a test method which validates new hardware with data from prior launches. And, if you want to take your model rocketry further in a different direction, it’s always possible to make your own fuel as well.

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Omnidirectional Walker With Wheeled Feet

July 26, 2022 by 4 Comments

[James Bruton] is on a quest to explore all the weird and wonderful methods of robot locomotion, and in his latest project created an omnidirectional walker that can move in any direction instantaneously.

The walker actually makes use of three independent four-legged Strider mechanisms, connected in a triangle at 120deg. Wheels are attached to the bottom of each leg, oriented at a right angle to the leg’s plane of motion to allow the foot to slide. Varying the relative speed and direction of each of the mechanisms lets the robot move in any direction, similar to his ball-wheeled robot. Each strider mechanism uses a single motor and looks similar to Strandbeest walkers, but it lifts its feet to traverse rougher terrain. [James] demonstrates this with some obstacles, and found that moving in such an orientation that all three sets of legs provide the best results.

[James] planes to build a larger rideable version, but we think he should mount a chest of Sapient Pearwood to carry all his stuff and name it The Luggage.

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A New Way To Produce PCBs With Your 3D Printer

July 26, 2022 by 50 Comments

With the low-cost PCB fabrication services available to hackers and makers these days, we’ll admit that making your own boards at home doesn’t hold quite the appeal that it did in the past. But even if getting your boards professionally made is cheaper and easier than it ever has been before, at-home production still can’t be beat when you absolutely must have a usable board before the end of the day.

If you find yourself in such a situation, this new method of DIY PCB production detailed by [Adalbert] might be just what you need. This unique approach uses a desktop fused deposition modeling (FDM) 3D printer throughout all of its phases, from creating a stencil based on the exported board design, to warming the UV soldermask to accelerate the curing process. It may not be an ideal choice for densely packed boards with fine-pitch components, but could definitely see it being useful for many prototypes.

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