Saturday, November 21, 2015

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Friday, November 20, 2015

DIY Steel Casting Crucible

 I would probably use real arc welder handles not the stuff he used because he had no real protection against electrocution.


Published on Feb 12, 2015
A makeshift arc reaction chamber. Small enough to sit on the desktop, but powerful enough to melt steel, within minutes.

WARNING:

Electrical arc furnaces pose risks of electric shock, fire hazard, and toxic fumes depending on what material you're working. Dust from refractory brick should never be inhaled, as it can damage lungs and cause long term respiratory challenges. This project can reach temperatures in excess of 3,000ºF (1,648ºC) which is well beyond the melting point of hobbyists. Caution, care and expert planning are required to mitigate risks. Use of this video content is at your own risk.

Project History & More Info:

I made a homemade stick welder from old microwave parts (http://bit.ly/HomemadeStickWelder) and experimented with it's power by sparking an arc between two carbon electrodes I pulled out of a “heavy duty” lantern battery.

Although I haven't verified it, I believe any stick welder can be used to power the mini arc furnace, and for most hobbyists, that would definitely be the easier and safer way to go. I just don't own a welder, so I used the one I made instead.

You can get refractory brick from major hardware stores online, but to find something local, I did a Google search for “refractory materials” in my city. I called a couple of local companies and asked if they'd sell to the general public, and most did.

At their warehouse, I identified the 3” x 4.5” x 9” Alumina-Silica Bricks as the kind I needed, which are extremely lightweight, and capable of withstanding temperatures used in steel working.

Most local refractory suppliers will only sell the bricks in cases, but luckily they had an open case in the shop, and sold me a single brick for $6. However, I later went back and got a case of 10 for about $33, making the cost of each brick around $3.30.

I found the furnace can be powered off 120v mains power by center tapping the arc welder unit, however it performs tremendously better on 240v without any modifications. Impressively I didn't even need to use The “Scariac” (http://bit.ly/Scariac) to ballast it. In all my experimenting, it worked just fine on a 20 amp breaker by plugging it in and sparking the arc. A commercial welder should give your circuit breaker the same electrical protection because it will limit the current that can be drawn.

The longest I've run the unit continuously is around 3-4 minutes, and the electrodes get so hot at that point they can seriously burn your hands, or melt your gloves. I realize it would be easy to modify them to have insulating handles and run it longer, however I believe that's beyond the scope of this project, and there is good risk that the insulation on the cables would start melting and the system would self destruct.

I designed the furnace so you can easily make two of them from one brick, and you'll see how I made them in the project video, “How To Make The Mini Arc Furnace”.

CNC Router Project



 Belt and pinion linear guide and drive mechanism
Control Box using Arduino.  Still needs painting with flat black.

Greed