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Voltage/current curves

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Voltage/current curves

Postby Bill Beauregard » Tue Jan 20, 2015 10:20 pm

Several days ago I was welding vertical, and overhead lap joints on 3/8 plate. I was outside, it was snowing/raining. I was using some very old Certanium mild steel welding rod. I was on a 12' ladder. My helmet was fogged inside, drizzling outside. Conditions were less than optimal. The resulting welds were not as ugly as I would have expected! That got me on the track of wondering if there was more I could do to improve.

Travis Field has a video on U tube showing how to adjust a 1959 Lincoln SA 200 for vertical up welding. He makes the point that a low voltage/high amperage setting will work much better for "stacking metal" The low volt/high amp setting allows the welder to push the rod deeply into the base metal at the left, making a deep, small diameter puddle. Then move across to the right, repeating the process there. By the time one moves back to the left it has frozen, as the depth leaves the molten puddle surrounded by steel, it cools quickly. The high volume of rod deposit melting serves further to cool the surrounding.

I don't have an old Lincoln Pipeliner's welder. Of several stick welders I own, only the two 1970s vintage Twentieth Century clunkers have voltage choices. Weather is too cold to go try them. Is there a way to influence voltage on say a Bobcat 250, or a Dynasty 280. I've thought of coiling lead cable around a steel object, I think that limits both voltage and current. Arc length won't work as higher voltage will stop the arc and stick without a long enough arc.

Is this what makes these old Lincolns so revered?
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Re: Voltage/current curves

Postby GreinTime » Tue Jan 20, 2015 10:51 pm

The only issue I'd say you have while coiling the lead around something like that is that you'd be basically creating an electromagnet out of whatever it is that you coil it around. Just something to think about. I have no input to offer on the volts/amps part though.
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Re: Voltage/current curves

Postby Bill Beauregard » Tue Jan 20, 2015 11:25 pm

GreinTime wrote:The only issue I'd say you have while coiling the lead around something like that is that you'd be basically creating an electromagnet out of whatever it is that you coil it around. Just something to think about. I have no input to offer on the volts/amps part though.


It is across the road from the airport. Might I bugger some compasses, thereby crashing planes?
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Re: Voltage/current curves

Postby GreinTime » Wed Jan 21, 2015 12:56 am

Uhhhh dude if you can hit an OCV that high with a stick welder, I'd be impressed :)
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Re: Voltage/current curves

Postby Bill Beauregard » Wed Jan 21, 2015 8:52 am

GreinTime wrote:Uhhhh dude if you can hit an OCV that high with a stick welder, I'd be impressed :)


I'm not a dude.

I was making a futile shot at humor. Miller, and other sources have addressed the subject of volt/amp curves in stick welders. It seems to be agreed among the experts that high current/ low voltage is the best power to make good vertical up welds. The Dynasty manual doesn't show a volt/amp curve. in some of the Miller literature posted they talk about cheap inverters having one curve, more expensive ones having a different curve in stick than in TIG.

Bobcat shows high OCV but under load, voltage drops precipitously. It seems to average 25 volts, which is much higher than the lowest an old Lincoln will go.
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Re: Voltage/current curves

Postby Louie1961 » Wed Jan 21, 2015 11:30 am

Bill I don't think you will be able to change or influence voltage on the dynasty. The microprocessor is probably working against you trying to keep to the factory set welding voltage.
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Re: Voltage/current curves

Postby GreinTime » Wed Jan 21, 2015 4:27 pm

Bill Beauregard wrote:
I'm not a dude.

I was making a futile shot at humor.

I see that now. My apologies. I was using dude as a generic salutation to address your question, after stating above that I had no input on the intrinsic relationship between volts and amps on either welder. I was not aware that voltage was an independently adjustable parameter when using any stick welder.

In regards to your statement about the OCV on the Lincoln vs the Dynasty, was voltage adjustable on the older machine? I thought Voltage was a direct relation to arc length vs amperage and as stated above didn't realize you could change the voltage. Also, by saying that it hovers around 25, I would assume that is at a stable, consistent arc length at which you can perform a satisfactory weld? What kind of voltage would make a better weld at a given amperage when making an uphill weld?

Please don't take the questions as confrontational, I'm asking because I'm curious.
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Re: Voltage/current curves

Postby Bill Beauregard » Wed Jan 21, 2015 9:35 pm

GreinTime wrote:
Bill Beauregard wrote:
I'm not a dude.

I was making a futile shot at humor.

I see that now. My apologies. I was using dude as a generic salutation to address your question, after stating above that I had no input on the intrinsic relationship between volts and amps on either welder. I was not aware that voltage was an independently adjustable parameter when using any stick welder.

In regards to your statement about the OCV on the Lincoln vs the Dynasty, was voltage adjustable on the older machine? I thought Voltage was a direct relation to arc length vs amperage and as stated above didn't realize you could change the voltage. Also, by saying that it hovers around 25, I would assume that is at a stable, consistent arc length at which you can perform a satisfactory weld? What kind of voltage would make a better weld at a given amperage when making an uphill weld?

Please don't take the questions as confrontational, I'm asking because I'm curious.


Some older welders have adjustable voltage. I've lost track of the exact model, Travis Field demonstrates setting a 1959 Lincoln SA200? As to how these machines change voltage I don't know. They have ranges of amperage, then fine control is done with voltage. At lower voltage arc length has more effect on voltage, therefore amperage. You are able to bury the electrode, melting lots of rod surrounded by cold steel preventing drips. As you used up substantial heat melting rod, less is dumped into the work piece. It freezes sooner.

As for Dynasty, I haven't found volt/amp curves.

Bobcat does show the graphs with varying voltage over a narrower range controlled by what, I don't know. These seem to average 25 volts. I once had a 1940s era Westinghouse 600 amp engine welder. OCV was 36 at highest voltage. You adjusted down from there. When I first used it, it was owned by my father's friend. He had hundreds of hours experience with it. With his settings, it was wonderful! It had a Chrysler industrial 236 flat head 25" engine. With no exhaust, the noise was life changing!
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Re: Voltage/current curves

Postby GreinTime » Wed Jan 21, 2015 9:57 pm

I can only imagine the noise that made man. We ran my buddy's Bobcat (or trailblazer) with no exhaust for shits and giggles while we were making a new one and it was LOUD.
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