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I Forge Iron

Electrical resitance heating


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With the high cost of propane lately, and the high initial cost of an induction; heater electrical resistance heating may be a good alternative.

 

In the past I have seen people heating rivets with a spot welder when a user here (andrewwillis) posted a method to make a power supply to make a spot welder It got me thinking.

 

It uses a rewound transformer from a microwave oven, they can be ganged in parallel to produce more current and, thus, greater capacity. It cost me nothing to build and was completed in about twenty minutes.

 

They produce heat between the power attachments so they can be very local. Maybe for upseting or twisting, etc.

 

In the video I am heating a piece of 1/4 rod about 4" long.

 

I have been looking for a larger transformer to scale up the abilities.

 

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Yes, propane has gone up this winter but with spring around the corner it should be going down. I will stick with my coal and propane for forge work (customer is paying anyways). Induction would be nice but no matter what heat source there is a trade out of the final cost wich in most cases is a wash from one to the other (initial investment, accessibility, cleanliness, ease of use, pros/cons of working with, etc,etc,etc.) Tried and true works from me.

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It would get hot......but I'm wondering how much wattage is running. Also you've got issues like how long does it take to SAFELY disconnect your leads and go back and forth to the anvil.

 

I have seen at least one case where someone built a small arc furnace using microwave transformers. Don't know how effecient it was though.

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Hum I think it could be great. Maybe a commercial unit that has two fixed clamps that can be spread apart. Step on some foot pedal to open clamps put in bar, step on pedal again take out heated bar place next bar in clamps and forge the hot bar. Good production posabilitys.

Have one that can heat up at least 1/2" SQ and make it clean and user friendly and there would be a real market.

Keep up the good work

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Hmmm I was not suggesting that one use vice grips as a method of making the electrical connection. To make this a viable heating method there would need to be a good clamping system and a switch that would initiate the heating process, perhaps with a  timer, or current sensor, etc. Obviously there needs to be some work on something like this. I like to see how others may run with it or share their ideas and opinions. I have often found myself starting a gas forge or a torch to take a short heat on the end of a bar(s) I think there is potential for this heating method here.

 

brad

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ISTR reading about this in an old industrial usage; but didn't see it in my 1948 Metals Handbook, ASM when I briefly looked at it.

 

In modern usage you would probably need a special power line installed *and* a commercial meter and pay commercial rates unless you were doing only the smallest stock which I would experiment with an old arc welder.

 

It can be done but I'd bet that it would n ot be cheaper then other fuels until a lot of expensive work had been covered.

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LastRonin: That is a little presumptuous. Are you sure that I have no experience? I am not sure that we have met. I measured ~400amps at 2 volts. While the current potential is high there is not enough voltage to overcome a humans (normally)high resistance if that were the case two D sized batteries would be lethal.

 

Thomas: I have not worked out the cost but where I live electricity is reasonably cheap at least it is cheaper than propane. I have several old welders I was going to look at the transformers but so far I have been looking at a transformer from a large industrial battery charger they are simpler and easier to rewind. I think that induction heaters use a lot of power as well and they seem to be cost effective.

 

One final note about safety: I had an old Lepel 1.5kw Induction heater, it was not like modern self tuning solid state systems, when the setting did not match the coil a VERY large spark would jump between the coil leads. I would guess that it was many thousands of volts I feel that would be a shocking experience if you were placing a piece of stock into the coil at the wrong time.

 

 

I have since found this video

 

 

This guy has a much larger transformer.

 

brad

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NeatGuy: I regret the misunderstanding there and apologize that you felt I was targeting you. I was not at all presuming anything about you or your experience level. I was referring to the general danger to ANYONE attempting this sort of thing that didn't have the knowledge and experience needed to approach it safely. You are absolutely correct that I don't know you. As my statement was intended as a general condition statement, if you do have the experience/knowledge, then by all means share the results. But as my post was intended as a warning to the reader(s) who did not have the aforementioned prerequisites but thought "Neat. I'm going to try it."

 

Your voltage and current readings are based on the transformer you have and it's windings. I know that the voltage output of a transformer is dependent on the ratio of turns on the in and out sides, i.e. if you have a 4:1 ratio transformer and apply 120 VAC at 10 Amps to one side, the voltage on the other side would be 30 volts at 40 Amps, assuming the windings could withstand that current load. Transversely, if the transformer was hooked up the opposite side, the output with the same input would be 480VAC at 2.5 Amps. 

 

So if someone else had a transformer that was wound differently than yours, they could easily end up with a voltage/amperage setup that could very easily be lethal.

 

Once again, I apologize that my post was not clearly enough perceived as the generic warning it was intended to be.

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Greetings All,

 

I am going to take the hard line on this one...  I think it is stupid...  Energy is energy be it coal .. propane .. or electrical   ...  No advantage  .... Ease of working .. Not so much....   Danger..  Mistakes will be made that has no reverse..    My big question  WHY ?????   This old boys 2c

 

Forge on and make beautiful things

Jim

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