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spot welder made from a microwave transformer

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lilshawn:
it's really not a big deal. you are making a weld using the materials you are attaching together. the tiny spot between the electrodes heats up red hot. the pressure you apply squishes the red hot metal together forming the weld.

The reason you get arc with other forms of welding is because you use high voltage. because this is so low voltage (2.2 volts AC) the voltage doesn't have enough "omph" to jump a gap. there is no arc (or next to none) it's perfectly safe to use. In fact, it's safe enough that if you accidentally touched both ends of the output, no harm would come to you. there isn't enough "omph" to push through the great resistance that is the human body.


--- Quote ---SHOCK HAZARD: As defined in American National Standard, C39.5, Safety Requirements for Electrical & Electronic Measuring & Controlling Instrumentation: A shock hazard shall be considered to exist at any part involving a potential in excess of 30 volts RMS (sine wave) or 42.4 volts DC or peak and where a leakage current from that part to ground exceeds 0.5 milliampere, when measured with an appropriate measuring instrument defined in Section 11.6.1 of ANSI C39.5.
--- End quote ---

because this project's output is under 30 volts RMS AC, the output is not considered a shock hazard.

If the skin is wet or damaged, the resistance through the body will be greatly reduced, and a much lower voltage may be lethal.

so really, it's POWER not either amperage or voltage that can kill you. it depends highly on excessive amounts of both to get to the point of lethality. It also depends of the path of conductivity. a lethal power isn't likely to be lethal if it's conducted only through your hand. but would be if it went from one hand to the other. (across the heart) or through your head.

Any electrical device is capable of killing you under the right (wrong?) circumstances, and as always, precautions should be taken when operating them. This goes especially with items that are home made, or retail items that are modified.

You can't see in the photos I posted, but the core of the transformer is  grounded and the input is fused. Should the insulation on the transformer primary short out, the ground and fuse will help prevent serious injury or death. The output, because of it's ridiculously high output current, is un-fused. Failure of the secondary would likely be plainly obvious. The likelihood of coming into contact with 110v AC from the input on the output side of the transformer is highly unlikely.

yaksplat:
This scares the crap out of me.  I love it.


lilshawn:

--- Quote from: Nephasth on February 12, 2013, 11:44:05 am ---Clean up that workbench! :soapbox: :lol

Looking forward to the results! :applaud:

--- End quote ---

yeah no doubt  :lol

it's even worse now.  ;D  i'm currently procrastinating cleaning it as I type this.

yaksplat:
I'm guessing that won't do aluminum welding  >:D

lilshawn:

--- Quote from: yaksplat on February 12, 2013, 12:28:02 pm ---I'm guessing that won't do aluminum welding  >:D

--- End quote ---

I haven't tried, but  the resistivity of aluminium is 65% higher than that of copper. (much much higher than steel) It could in theory work... but you'd probably need in the area of 15 or 20,000 amps to do it. you'd need a bigger transformer though.

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