Current Limiter For A MOT Welder

August 3, 2013 by Mike Szczys 14 Comments

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[Mike Worth] wanted the option to run his Microwave Oven Transformer welding rig at less that full power. After being inspired by some of the other MOT hacks we’ve featured he figured there must be a lot of ways to do this. But his searches on the topic didn’t turn up anything. So he just designed and built his own adjustable current limiter for the welder.

At the beginning of his write-up he details what we would call a bootstrap procedure for the welder. Go back and check out his original build post to see that he had been holding the framework for the cores together using clamps. To make the setup more robust he needed to weld them, but this is the only welder he has access to. So he taped some wood shielding over the coils and fired it up.

The current limiter itself is built from a third MOT. Adjustment is made to the cores by changing out the E and I shaped pieces. This allows for current limiting without altering the windings. [Mike] holds it all in place with a couple of bicycle wheel quick connect skewers.

It just goes to show that you should never get rid of a microwave without pulling the transformer. Even if you don’t need a welder wouldn’t you love a high-voltage bug zapper?

Tools And Talent For Custom Platinum Jewelry

July 30, 2013 by Mike Szczys No comments

The diamond engagement ring is arguably the most universally adopted of all jewelry. It’s artwork that even the most common men and women appreciate, and it’s creation calls for skills that go back centuries. [Jerome Kelty] crafts custom jewelry from platinum. Here’s an in-depth look at his process.

The first step of his Instructable post is so long you might be fooled into thinking it’s the whole post. He shows off the equipment that he used in taking this ring from design to reality — we thought the use of beeswax to pick up small stones is an interesting technique.

Click through the steps to see that he starts with a cad drawing. This model is sent offsite for casting and arrives back as an oversized blank which he then begins to clean up. A range of differend files bring it to its finished shape. He preps the areas where stones will be set. A trip to the buffing wheel gives it the shine it needs before the diamonds are put in place.

Regular Hackaday readers may recognize his name. When [Jerome] isn’t making jewelry he’s building animatronics, like Predator or Stargate replicas.

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PCBs With Powder Coat

July 29, 2013 by Brian Benchoff 48 Comments

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The toner transfer method of PCB production should be a staple in every maker’s bag of tricks. That being said, it’s a far from ideal solution with a lot of things that can go wrong, ruining hours of work. [Ryan] thinks he has a better solution up his sleeve, still using heat activated toner, but replacing the laser printer with a powder coating gun and a laser engraver.

[Ryan] is using a powder coating gun he picked up from Amazon for about $100. The theory behind it is simple: particles of toner coming out of the gun are statically charged, and bonded to the grounded copper clad board. In real powder coat shops, this coating is baked, resulting in a perfectly hard, mirror-like finish. [Ryan] skipped the baking step and instead through the powder coated board into a laser engraver where the PCB design is melted onto the copper. After that, wash the board off, etch it, and Bob’s your uncle.

What’s really interesting about this method of PCB production is that it doesn’t require a very high power laser. [Ryan] was actually having a problem with the toner burning with his laser engraver, so it might be possible to fab PCBs with a high power handheld laser, or even a Blu Ray laser diode.

Propane Forge Built From A Soup Can

July 28, 2013 by Mike Szczys 19 Comments

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It doesn’t look like much, but this easy to build propane forge is just what you need to try your hand at blacksmithing. [Code Cowboy] took on the build after watching this how-to video which shows the fabrication of a small knife after completing the forge build.

The first step is to eat all of the soup (or beans if you prefer). With an empty can in hand the stand — made of two angle brackets — and inlet are attached. Next comes the heat proofing for the walls of the forge. At first glance we thought that cat litter was one of the ingredients, but that’s just an empty container used to haul playground sand. The sand is mixed with equal parts of plaster of paris before adding water to achieve a clay-like consistency. This is packed into the can, with a small opening to receive the metal to be heated.

The torch itself can be used to cure the heat shield. After letting the mixture harden a 30 minute burn will force the rest of the water out of the heat proofing.

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Make Your Own Fume-extracting Glove Box

July 27, 2013 by Mike Szczys 25 Comments

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Here’s an easy to follow guide for building your own glove box. It’s a lab tool that contains the project you’re working on to keep things in or out. For instance, we could have used this a few years back when we tried to add an acrylic window to a hard drive. Instead, we ended up putting several hours of work into a cool-looking paperweight. But it will also come in handy for chemistry experiments that generate harmful or dangerous byproducts.

The picture above tells most of the story, but [Jason Poel Smith] does include several good tips about the construction in his video. He uses weather stripping along the edges of the clear container to ensure a seal. The hose is used to provide negative pressure so that no fumes leak out. We figure adding a smaller hole on the opposite side with a charcoal filter will help air pass into the chamber to serve as a fume extractor.

We’ve already seen a similar setup for a reflow oven. Perhaps this is the perfect solution to protect yourself from 3D printing fumes. We’re sure you saw the headlines about 3D printing being as bad as smoking cigarettes.

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Geometry Class Just Got Augmented

July 26, 2013 by Brian Benchoff 26 Comments

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Just about every engineer needs to take a drawing class, but until now we surprisingly haven’t seen electronics thrown into rulers, t-squares, and lead holders. [Anirudh] decided to change that with Glassified. It’s a transparent display embedded in a ruler that is able to capture hand drawn lines. These physical lines can be interacted with or measured, turning a ruler into a bridge between a paper drawing and a digital environment.

For the display, [Anirudh] mounted a transparent TOLED display with a digitizer input into a ruler. The digitizer captures the pen strokes underneath the ruler, and is able to interact with the physical lines, either to calculate the length and angle of lines, or just to bounce a digital ball inside a hand-drawn polygon.

There’s no word on how this display is being driven, or what kind of code is running on it. [Anirudh] said he will have some schematics and code available up on his website soon (it’s a 404 right now).

A Keygen For The Rigol 2000-series Scopes

July 24, 2013 by Brian Benchoff 111 Comments

A few weeks ago it came to our attention that Rigol’s DS2000-series oscilloscopes were easily unlocked with a few USB commands. We had expected a small microcontroller device would be developed to send these bits to a scope automatically, and we never imagined the final version of this tool hack would be so elegant. Now it’s possible to unlock a DS2072 o’scope using just a serial number and a great encryption hack.

The engineers over a Rigol (bless their hearts) used the same hardware for the $800, 70MHz DS2072 and the $1600, 200MHz DS2202. The only difference between the two are a few bits in the scope’s memory that are easily unlocked if you have the right key. A few folks over on the EEV Blog forum figured out the private key for the scope’s encryption and the user [cybernet] wrote a keygen.

The upgrade process is extremely simple: get the serial number of your DS2072, put it in the keygen, and enter the resulting key into the scope. Reboot, and you have a $1600 scope you bought for half price.