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Voltage/current curves

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Re: Voltage/current curves

Postby Bill Beauregard » Sat Jan 24, 2015 10:22 pm



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?
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Re: Voltage/current curves

Postby WerkSpace » Sun Feb 15, 2015 9:52 pm

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. 8-) Life is fun!
It will come in handy on the acreage, when I start messing around with shipping container garages.
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Re: Voltage/current curves

Postby xwrench » Sun Feb 15, 2015 10:19 pm

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. 8-) Life is fun!
It will come in handy on the acreage, when I start messing around with shipping container garages.

Score!
We are not lawyers nor physicians, but welders do it in all positions!

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Re: Voltage/current curves

Postby Otto Nobedder » Mon Feb 16, 2015 8:22 pm

Sweet!

I've burned a good 500# of rod on one or another of those well-made machines. I regret I never owned one.

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Re: Voltage/current curves

Postby WerkSpace » Thu Feb 19, 2015 8:51 pm

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/US/EN/ServiceNavigator2/LINCOLN2/SVM224A.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.
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Re: Voltage/current curves

Postby WerkSpace » Sun Feb 22, 2015 6:08 pm

SA-200 Faceplate.jpg
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I recently bought a Lincoln SA-200 welder, so I got more interested in this topic.
My welder has the propane conversion and uses a Continental engine (with magneto).
The generator is DC, so it provides a very smooth arc. No rectification or filtering required.

The welder has 5 amperage ranges that overlap and a fine amperage control.
The advantage of this setup is that the fine amperage control can be used to alter the characteristic of the weld.
The fine amperage control is used to adjust the percentage of one of the 5 amperage ranges.
It's also used to set the voltage, which is very important to the characteristic of the weld.

Example:
175 amps can be achieved on 2 of the 5 ranges. (240-160) and (190-120).
Use the fine amperage control to set your 175 amps (and voltage).
Remember, as the voltage goes down, the amperage goes up.
Voltage controls the height and width of the weld bead, while amperage controls penetration.

If you want a hard (arc force/dig) type of weld used on vertical or overhead
select 240-160 and set the fine amperage control setting for a lower voltage.
Increasing amperage while lowering voltage creates a narrower weld bead,
deeper penetration and a more fluid (hotter) weld puddle.


If you want a soft (buttery) type of weld used for normal horizontal position
select 190-120 and set the fine amperage control setting for a higher voltage.
Increasing voltage while lowering amperage creates a flat, wide bead with shallow penetration.
Long arcing also causes the weld puddle to freeze faster because it lowers the total amount of energy available.


Reference: http://www.millerwelds.com/resources/articles/constant-current-CC-welder-training/


Bill Beauregard wrote: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?
Last edited by WerkSpace on Sun Feb 22, 2015 6:49 pm, edited 2 times in total.
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Re: Voltage/current curves

Postby weldin mike 27 » Sun Feb 22, 2015 6:19 pm

If you set a Lincoln welder the way Miller suggests, would the world end?
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Re: Voltage/current curves

Postby xwrench » Sun Feb 22, 2015 6:25 pm

weldin mike 27 wrote:If you set a Lincoln welder the way Miller suggests, would the world end?


Apparently not :lol:
I have a machine that has the engine and frame of a miller big 40 with the generator from a lincoln sa-200. No rips in the fabric of space-time seem to have occurred. :ugeek:
We are not lawyers nor physicians, but welders do it in all positions!

Miller Dynasty 280DX
Lincoln 210 MP
Miller 625 X-Treme
Hobart Handler 150
Victor Oxygen-acetylene torch
Miller/Lincoln Big 40-SA200 hybrid
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Re: Voltage/current curves

Postby weldin mike 27 » Sun Feb 22, 2015 9:18 pm

Good to know. Just don't use 6013s and 7018s on the same job or we are all doomed. Doomed, I tells ya.
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Re: Voltage/current curves

Postby WerkSpace » Tue Feb 24, 2015 7:02 pm

Miller and Lincoln play very well together.

Today, I bought a Miller X-treme 12VS for my SA-200.
My engine driven welder now has Stick, TIG and MIG capability. Very cool...

https://www.youtube.com/watch?v=Ar1TxSYEg38
https://www.youtube.com/watch?v=aueqgwqZg08
weldin mike 27 wrote:If you set a Lincoln welder the way Miller suggests, would the world end?
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