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Voltage/current curves

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Re: Voltage/current curves

Postby Otto Nobedder » Tue Feb 24, 2015 9:07 pm

I've used the 12VS with a Lincoln Invertec 275 as the power source.

Seemed to be a peaceful marriage.

Steve S
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Re: Voltage/current curves

Postby WerkSpace » Wed Feb 25, 2015 10:23 am

I like the fact that the drive rollers are interchangeable with my Millermatic 210 shop machines. It came with .045" flux core rollers and I typically use .035" solid core rollers on my shop machines. So, I borrowed the rollers from one of my Millermatic 210s to fit the suitcase machine. That Millermatic machine is setup with a spool gun anyway, so it won't miss those rollers as they are never used.

The only thing remaining to do was purchase some .035" contact tips for the Bernard 400 amp gun. $16 for ten tips on eBay including shipping and they are already on their way.

One thing that I noticed is that this suitcase weighs 35 lbs empty and about 80 lbs when you fit 12" spool of wire in it. I might figure out a way to put some wheels on this case. Afterall, who wants to lug 80 lbs around, plus all the extension cables.
Otto Nobedder wrote:I've used the 12VS with a Lincoln Invertec 275 as the power source. Seemed to be a peaceful marriage. Steve S
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Re: Voltage/current curves

Postby weldin mike 27 » Wed Feb 25, 2015 1:43 pm

Fabulous to see the kids playing together. Now we need to get the parents more friendly. Baby steps eh?
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Re: Voltage/current curves

Postby ryan.k.mcdaniel » Sat Apr 22, 2017 1:49 am

WerkSpace wrote:
SA-200 Faceplate.jpg

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?



So I have a question about finding the setting for amperage on this face plate. I weld daily with an SA200 on pipe.

For my example I'll use the selection that I was using just today capping a 6" schedule 40 with a 5/32 70+ (8010) rod in the 3rd gear (190-120) with the rheostat at about 65.

My mathematical reasoning says that gear has a range of 70 amps which I divide 9 time to give me the increment value of 7.77 amps per every 10 units on the fine current adjustment.
7.77×6.5=50.55
50.55+120=170.5 amps sitting on 190 and 65

To achieve 170 amps in the 240 gear with this reasoning would be described as

240-160= 80
80÷9= 8.88
8.88×1.5= 13.33
13.33+160=173

This would mean that to get the same amperage in 240 gear as in my normal operation I would have to have my rheostat set in between bottoming out (10) and 15.

I can with out a doubt promise that if I tried to fire up with a 5/32 on 240 and 15 I would have a very difficult time maintaining my arc and would not be putting a decent cap on with the rod due to it. I figure that I would be closer to around 30 on the rheostat.

Similarly when running the 3/16 70+ rod I am capping on 190 and 75/80 or 240 and about 50/55 or 178/182 & 204.4/226.6 respectively.

If the rheostat dial is supposed to be a percentage of the range selector and that the same amperage can be obtained, why is either my mathematics or my amperage selection so far off.

I am ignoring travel speed in the equation as well as the possibility of arc length variation due to the open current voltage being set at 93 at 100 on the rheostat in either gear.

Any clarification?
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Re: Voltage/current curves

Postby MinnesotaDave » Sat Apr 22, 2017 11:06 am

ryan.k.mcdaniel wrote:So I have a question about finding the setting for amperage on this face plate. I weld daily with an SA200 on pipe.

For my example I'll use the selection that I was using just today capping a 6" schedule 40 with a 5/32 70+ (8010) rod in the 3rd gear (190-120) with the rheostat at about 65.

My mathematical reasoning says that gear has a range of 70 amps which I divide 9 time to give me the increment value of 7.77 amps per every 10 units on the fine current adjustment.
7.77×6.5=50.55
50.55+120=170.5 amps sitting on 190 and 65

To achieve 170 amps in the 240 gear with this reasoning would be described as

240-160= 80
80÷9= 8.88
8.88×1.5= 13.33
13.33+160=173

This would mean that to get the same amperage in 240 gear as in my normal operation I would have to have my rheostat set in between bottoming out (10) and 15.

I can with out a doubt promise that if I tried to fire up with a 5/32 on 240 and 15 I would have a very difficult time maintaining my arc and would not be putting a decent cap on with the rod due to it. I figure that I would be closer to around 30 on the rheostat.

Similarly when running the 3/16 70+ rod I am capping on 190 and 75/80 or 240 and about 50/55 or 178/182 & 204.4/226.6 respectively.

If the rheostat dial is supposed to be a percentage of the range selector and that the same amperage can be obtained, why is either my mathematics or my amperage selection so far off.

I am ignoring travel speed in the equation as well as the possibility of arc length variation due to the open current voltage being set at 93 at 100 on the rheostat in either gear.

Any clarification?


I don't weld pipe and am strictly part-time.

I divide by 10 because the math is easy.
Lowest (0) corresponds to lowest in coarse range (120).
Highest (10) corresponds to highest in coarse range (190).
Add or subtract 7 between (in this case).

Just because the amp ranges overlap doesn't mean a particular rod runs well in both theoretical math equivalent settings.

"Adjust recipe to taste." :)
Dave J.

Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

Airco 300 - Syncro 350
Invertec v250-s
Thermal Arc 161 and 300
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Dialarc
Tried being normal once, didn't take....I think it was a Tuesday.
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