Not Just Your Average DIY Spot Welder

Microwave oven transformer spot welder builds are about as common as Nixie tube clocks around here. But this spot welder is anything but common, and it has some great lessons about manufacturing techniques and how to achieve a next level look.

Far warning that [Mark Presling] has devoted no fewer than five videos to this build. You can find a playlist on his YouTube channel, and every one of them is well worth the time. The videos covering the meat of what went into this thing of beauty are below. The guts are pretty much what you expect from a spot welder — rewound MOT and a pulse timer — but the real treat is the metalwork. All the very robust parts for the jaws of the welder were sand cast in aluminum using 3D-printed patterns, machined to final dimensions, and powder coated. [Mark] gives an excellent primer on creating patterns in CAD, including how to compensate for shrinkage and make allowance for draft. There are tons of tips to glean from these videos, and plenty of inspiration for anyone looking to achieve a professional fit and finish.

In the category of Best Appearing Spot Welder, we’ll give this one the nod. Runners-up from recent years include this plastic case model and this free-standing semi-lethal unit.

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Homemade EDM Can Cut Through Difficult Materials Like Magnets With Ease

Many years ago [ScorchWorks] built an electrical-discharge machining tool (EDM) and recently decided to write about it. And there’s a video embedded after the break.

The build is based on the designs described in the book “Build an EDM” by Robert Langolois. An EDM works by creating lots of little electrical discharges between an electrode in the desired shape and a material underneath a dielectric solvent bath. This dissolves the material exactly where the operator would like it dissolved. It is one of the most precise and gentle machining operations possible.

His EDM is built mostly out of found parts. The power supply is a microwave oven transformer rewired with 18 gauge wire to drop the voltage to sixty volts instead of the oven’s original boost to 1.5kV.  The power resistor comes from a dryer element robbed from a unit sitting beside the road. The control board was etched using a hand traced schematic on the copper with a Sharpie.

The linear motion element are two square brass tubes, one sliding inside the other. A stepper motor slowly drives the electrode into the part. Coolant is pumped through the electrode which is held by a little 3D printed part.

The EDM works well, and he has a few example parts showing its ability to perform difficult cuts. Things such as a hole through a razor blade., a small hole through a very small piece of thick steel, and even a hole through a magnet.

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Retrotechtacular: So You Want to Be a Weldor

Welding is one of those things that takes minutes to learn and years to master. It requires coordination, strength, and a good pair of eyes. This vocational guidance video from the early 1940s touches on these points and more for those considering careers in welding. The narrator jumps right in, discussing welding types, equipment operation, and employment opportunities in both the welding field itself and other fields that use welding techniques.

Oxy-acetylene welding is one of the oldest methods of fusing metal. A flame fueled by a specific mixture of pure oxygen and acetylene gas heats the metal welding rod and the work piece to plasticity, which allows them to join together. An oxy-acetylene setup can also be used to cut metal, though a special cutting torch with a kind of oxygen turbo boost lever is required. The work piece is heated to red-hot at the point along the edge where the cut will start. The oxygen-rich flame will cut right through the piece.

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Wireless Water Level Sensor from PVC Pipe

[Bob] was having trouble keeping up with his water troughs. He had to constantly check them to make sure they weren’t empty, and he always found that the water level was lower than he thought. He decided it was time to build his own solution to this problem. What he ended up with was a water level sensor made from PVC pipe and a few other components.

The physical assembly is pretty simple. The whole structure is made from 1/2″ PVC pipe and fittings and is broken into four nearly identical sensor modules. The sensors have an electrode on either side. The electrodes are made from PVC end caps, sanded down flat at the tip. A hole is then drilled through the cap to accommodate a small machine screw. The screw threads are coated in joint compound before the screw is driven into the hole, creating its own threads. These caps are placed onto small sections of PVC pipe, which in turn connect to a four-way PVC cross connector. 

On the inside of the electrode cap, two washers are placed onto the screw. A stranded wire is placed between the washers and then clamped in place with a nut. All of the modules are connected together with a few inches of pipe. [Bob] measured this out so it would fit appropriately into his trough, but the measurements can easily be altered to fit just about any size container. The wires all route up through the pipe. The PVC pipe is cemented together to keep the water out. The joint compound prevents any leaks at the electrodes.

A piece of CAT 5 cable connects the electrodes to the electronics inside of the waterproof controller box. The electronics are simple. It’s just a simple piece of perfboard with an XBee and a few transistors. The XBee can detect the water level by testing for a closed circuit between the two electrodes of any sensor module. The water acts as a sort of switch that closes the circuit. When the water gets too low, the circuit opens and [Bob] knows that the water level has lowered. The XBee is connected to a directional 2.4GHz antenna to ensure the signal reaches the laptop several acres away. Continue reading “Wireless Water Level Sensor from PVC Pipe”

A Digital Condom a Reality Thanks to Arduino

[Bill Gates]’ foundation is currently offering up a ton of prizes for anyone who can improve the condom. It’s a laudable goal, and somewhat difficult; one of the main reasons why male condoms aren’t used as often as they should is the,  “male perspective… that condoms decrease pleasure as compared to no condom.”

While most of the work inspired by the [Gates] foundation is work investigating a change in the geometry of the condom, [Firaz Peer] and [Andrew Quitmeyer] of Georgia Tech managed to solve this problem with an Arduino.

The basic idea of the Electric Eel – yes, that’s the name – is to deliver short electric impulses, “along the underside of the shaft for increased stimulation”. These impulses are delivered in response to different sensor inputs – in the video example (surprisingly safe for work) they’re using a force resistor wrapped around the chest for an electrical stimulation with every breath.

Although this is only a prototype, the hope is the conductors in the condom can eventually be implanted along the inside surface of a condom during manufacturing.

Video after the break.

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Electrodes turn your eyelids into 3D shutter glasses

[Jonathan Post] has a way to watch 3D video without wearing shutter glasses but it might be kind of a hard product to break into the market. As you can see above, a pair of electrodes are stuck on a viewer’s eyelids, using electricity to alternately close each eye. The video after the break shows a demonstration of this technology. Obviously a camera can’t capture the image that the viewer sees, but this man describes a perfect 3D image. This reminds us of those ab exercisers that use electrodes to stimulate the muscles. Do you think a 3 hour epic would leave your eyelids tired and sore, eventually resulting and a steroid-esque muscle-ridden face?

Edit from [Caleb]: Judging from the comments, some people believe this to be an absolute impossibility. While we concur that this example is pretty silly (what’s powering those electrodes?), we invite you to watch [Daito Manabe]’s facial electrodes fun.

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Rat propulsion via brain-machine interface

Our little red-eyed friend can drive this vehicle around with his mind. WITH HIS MIND, MAN!

This is the product of research into adaptive technologies. The process is pretty invasive, implanting neural electrodes in the motor cortex of the brain. The hope is that some day this will be a safe and reliable prospect for returning mobility to paralysis victims.

We found it interesting that the vehicle was trained to react to the rats’ movements. They were allowed to move around a test space under their own power while brain signals were monitored by the electrodes. Video tracking was used to correlate their movements with those signals, and that data is used to command the motors for what the Japanese researchers are calling RatCar.

We can see the possibilities opening up for a mechanized cockroach v. RatCar free-for-all. Something of a battlebots with a live tilt. But we kid, this is actually quite creepy.

[via Neatorama and PopSci]