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Voltage/current curves
Posted: Tue Jan 20, 2015 10:20 pm
by Bill Beauregard
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?
Re: Voltage/current curves
Posted: Tue Jan 20, 2015 10:51 pm
by GreinTime
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.
Re: Voltage/current curves
Posted: Tue Jan 20, 2015 11:25 pm
by Bill Beauregard
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?
Re: Voltage/current curves
Posted: Wed Jan 21, 2015 12:56 am
by GreinTime
Uhhhh dude if you can hit an OCV that high with a stick welder, I'd be impressed
Re: Voltage/current curves
Posted: Wed Jan 21, 2015 8:52 am
by Bill Beauregard
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.
Re: Voltage/current curves
Posted: Wed Jan 21, 2015 11:30 am
by Louie1961
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.
Re: Voltage/current curves
Posted: Wed Jan 21, 2015 4:27 pm
by GreinTime
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.
Re: Voltage/current curves
Posted: Wed Jan 21, 2015 6:31 pm
by WerkSpace
Re: Voltage/current curves
Posted: Wed Jan 21, 2015 9:35 pm
by Bill Beauregard
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!
Re: Voltage/current curves
Posted: Wed Jan 21, 2015 9:57 pm
by GreinTime
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.
Re: Voltage/current curves
Posted: Wed Jan 21, 2015 10:51 pm
by WerkSpace
I collect old aircraft generators and they can be set up similar to the earlier engine driven welders.
http://www.api-assembled.com/design/tec ... welder.htm
Bill Beauregard wrote: 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.
Re: Voltage/current curves
Posted: Thu Jan 22, 2015 5:18 am
by wheresmejumper
i think you are confusing OCV with working voltage
Open Circuit Voltage is whats present before an arc is struck,and only directly affects how easy a rod will strike up
crappy welders could be as low as 48v,good ones up to 115v ive seen
Working Voltage is whats present when actually welding.this is what gives the welder its characteristics with a particular rod.
20v with smaller welders which struggle with 6010 or 7018. 25v is average and lincoln pipeliners up to 40v
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![/quote]
Re: Voltage/current curves
Posted: Thu Jan 22, 2015 9:05 am
by Bill Beauregard
wheresmejumper wrote:i think you are confusing OCV with working voltage
Open Circuit Voltage is whats present before an arc is struck,and only directly affects how easy a rod will strike up
crappy welders could be as low as 48v,good ones up to 115v ive seen
Working Voltage is whats present when actually welding.this is what gives the welder its characteristics with a particular rod.
20v with smaller welders which struggle with 6010 or 7018. 25v is average and lincoln pipeliners up to 40v
Nope, crystal clear on OCV being different from welding voltage. I do know that in position welding you need watts. how they are provided is less critical. Higher voltage means lower amperage. Pipe welders aren't going to stop and readjust the machine as they move around the pipe. They need to prevent sag.
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!
[/quote]
Re: Voltage/current curves
Posted: Thu Jan 22, 2015 9:12 am
by Bill Beauregard
WerkSpace wrote:I collect old aircraft generators and they can be set up similar to the earlier engine driven welders.
http://www.api-assembled.com/design/tec ... welder.htm
Bill Beauregard wrote: 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.
I was referring to the Lincoln SA__ machines. I guess voltage is either controlled with the rheostat or engine throttle. Might amperage be a matter of varying inductance?
Re: Voltage/current curves
Posted: Thu Jan 22, 2015 10:00 am
by WerkSpace
The rheostat is controlling the current thru the stator, which controls the voltage output.
It functions as a sort of Magnetic Amplifier. The regulator on your car alternator works in a similar fashion.
The field terminals on a car alternator determine the output.
As your battery arrives at near full charge, the regulator will adjust the voltage on the field and the alternator will reduce its output substantially.
Just for fun, try this simple experiment. If you have a desk lamp that uses a small transformer to reduce the line voltage to the lamp's 12 volt bulb, place a permanent magnet next to the transformer. You will notice that you are able to control the 12 volt bulb's brightness by moving the magnet closer or farther away. This is because the transformer cannot reach magnetic saturation, so the secondary coil of the transformer has no way of producing current. Transformers can only function with expanding and collapsing magnetic fields. If the transformer is held fully or partially magnetized, the output of the secondary becomes limited.
Bill Beauregard wrote:WerkSpace wrote:I collect old aircraft generators and they can be set up similar to the earlier engine driven welders.
http://www.api-assembled.com/design/tec ... welder.htm
Bill Beauregard wrote: 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.
I was referring to the Lincoln SA__ machines. I guess voltage is either controlled with the rheostat or engine throttle. Might amperage be a matter of varying inductance?
Re: Voltage/current curves
Posted: Fri Jan 23, 2015 8:34 am
by Bill Beauregard
How then do they control amperage? With a MIG machine as voltage or electrical pressure rises more pressure pushes more current across the arc. I'm not sure I understand how it's done on a stick machine.
Re: Voltage/current curves
Posted: Fri Jan 23, 2015 1:04 pm
by WerkSpace
Re: Voltage/current curves
Posted: Fri Jan 23, 2015 3:18 pm
by p4nh4ndle
WerkSpace wrote:I collect old aircraft generators and they can be set up similar to the earlier engine driven welders.
http://www.api-assembled.com/design/tec ... welder.htm
Bill Beauregard wrote: 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.
That seems like a fun project if you have the parts on hand and some money/time to blow ;D
For the rest of us plebes, a used engine welder or an inverter is probably the way to go. Still, a good resource to demonstrate the function of those welders/parts.
Re: Voltage/current curves
Posted: Fri Jan 23, 2015 7:13 pm
by Bill Beauregard
I have a number to choose from, in my obsession to weld as good as Field Res, (Travis Field) I'll buy what I have to. At present I have a Dynasty 280DX, A Bobcat 250, A Twentieth Century 295A AC with three voltage taps, an AC/DC Twentieth Century beater 295A transformer welder, and I think I gave away the best welder in the world a 194_ Westinghouse monster 600 A.
Re: Voltage/current curves
Posted: Sat Jan 24, 2015 12:23 pm
by wheresmejumper
You dont need any more welders to be as good as good as travis
on a pipeline speed is king,then you need to adjust both amperage and voltage to get the sweet spot between you,the rod,and the machine.then you can put down metal both quick and clean.
To get good at pipe all you need is a half decent welder.
Re: Voltage/current curves
Posted: Sat Jan 24, 2015 10:22 pm
by Bill Beauregard
It would be very interesting to see a theory of operation for Bobcat and Trailblazer. If the old Lincoln pipeliner machines were so very sweet, what set them apart from newer machines. I do know a Bobcat does not weld as nice as a Trailblazer, but an expert can still do OK. Is the Bobcat missing something essential? or the old Lincolns overrated?
Re: Voltage/current curves
Posted: Sun Feb 15, 2015 9:52 pm
by WerkSpace
I bought an old Lincoln SA-200 on my way home today. This welder has been converted for propane.
I tried it out and liked it, so as with everything else, it followed me home.
Life is fun!
It will come in handy on the acreage, when I start messing around with shipping container garages.
Re: Voltage/current curves
Posted: Sun Feb 15, 2015 10:19 pm
by xwrench
WerkSpace wrote:I bought an old Lincoln SA-200 on my way home today. This welder has been converted for propane.
I tried it out and liked it, so as with everything else, it followed me home.
Life is fun!
It will come in handy on the acreage, when I start messing around with shipping container garages.
Score!
Re: Voltage/current curves
Posted: Mon Feb 16, 2015 8:22 pm
by Otto Nobedder
Sweet!
I've burned a good 500# of rod on one or another of those well-made machines. I regret I never owned one.
Steve S
Re: Voltage/current curves
Posted: Thu Feb 19, 2015 8:51 pm
by WerkSpace
I've been looking into how to adjust the 'auto idle down'
time limit for the SA-200 welder to idle sooner.
Reference:
http://www.lincolnelectric.com/Assets/U ... VM224A.pdf
The following diagram shows the electronic circuit board that controls the idle solenoid.
Note that there are two reed relays used as 'idle sensors'. The Auxiliary power idle sensor is on the board.
The DC generator idle sensor is mounted off the board. These are made with a magnetic coil and magnetic reed relay.
The idea is that when current is drawn via welding or via the auxiliary outlet, current passes thru a coil.
The coil creates a magnetic field and this field is used to activate a magnetic relay as a switch.
Resistors R1 and R2 are used to bias the transistor Q1 which turns on the power transistor Q2.
Q2 will have the current capacity to operate the idler solenoid which mechanically moves the throttle linkage on the engine.
The capacitor C1 is used as the delay mechanism. Lower its capacitance value and the engine will idle down sooner.