Current/voltage curves

[WillieB]

I watched a You Tube video by Travis Field, (FieldRes). He shows how to adjust an old Lincoln pipeliner's welder to best weld pipe. He doesn't address the subject of how this theory might be applied to other types of weld, or with other machines. He stresses the value of adjusting voltage low, and amperage high to preventing the arc from snuffing out, allowing the weldor to push the rod into the side of the joint, making the edge puddles penetrate deeper, and spread less. This prevents so much heat migrating to the center of the joint, allowing one side to solidify while on the other side, so when you return to that side you have a solidified place to pile more filler.


The question in my mind is, "might I use his info to make better vertical and overhead welds?" My Bobcat 250 has two dials I believe to be both amperage, I guess I can't adjust voltage? My Dynasty 280 has adjustable dig I guess to be voltage, but not adjustable over a wide range. My old Twentieth Century has three ranges I believe to be voltage choices. Are these machines adjustable only by arc length?

[Broccoli1]

Kinda answers the question

http://www.millerwelds.com/resources/communities/mboard/showthread.php?12098-Arc-Control-vs-Dig

[gnforge]

Current/voltage curves

I didn't watch video. Can u post link, I'd like to watch.
But I was taught or learned, I think was called droop ie curve maybe not just came to mind.
But on older welders as amp is increased volts increase. So if u adjust course setting low and fine setting high u run at higher volts compared to amp your welding at. Or if u set course setting higher and weld at bottom of amp range on fine setting you weld at lower volts for amps your welding at. Could be all wrong but that's what I was told many years ago.

[WillieB]

I didn't watch video. Can u post link, I'd like to watch.
But I was taught or learned, I think was called droop ie curve maybe not just came to mind.
But on older welders as amp is increased volts increase. So if u adjust course setting low and fine setting high u run at higher volts compared to amp your welding at. Or if u set course setting higher and weld at bottom of amp range on fine setting you weld at lower volts for amps your welding at. Could be all wrong but that's what I was told many years ago.

On You Tube, It is FieldRes, Amperage and Voltage on Welding.

[WillieB]

As I understand it, the dig function senses the arc is about to go out, and turns up the amperage to prevent sticking. I don't think it is a voltage control.

[gnforge]

Current/voltage curves

Yep you are correct as dig function is concerned
I was talking about pre dig welders as there curve or droop works.

[H80N]

Kinda answers the question

http://www.millerwelds.com/resources...Control-vs-Dig

Broc

That is a good thread on the subject...

[gnforge]

Current/voltage curves

Thanks WilleB. That was good. I normally weld that way with my engine driven welder. But that further explained and refreshed my mind.
This would apply to your bobcat.
The higher your course setting the higher the amps. And the higher your fine setting the higher your volts. As with 7018 try & run the higher course setting and a lower fine setting ie. Higher amps & lower volts.
I learned something else that 6010 doesn't like low volts and I was running them like I do 7018. Will try opposite next time out.
But like you ask does this apply to the wire I run in my 350-p. As in volt amp comparison? I might do some experimenting. Maybe someone smarter will jump in.

[WillieB]

A MIG allows you to control voltage, but that in turn controls amperage. I don't know if it relates to MIG. For me, a vertical up weave is easier with MIG anyway. I'm looking for an edge using stick. The monster Westinghouse DC pipeline machine I once used, then later owned, was amazing in the hands of an expert with it. With him setting it up, I could do well!

[WillieB]

The Bobcat manual is a disappointment. It gives little info about stick welding. Printed on the face it suggests a high right knob setting, with a low left knob setting, With only that clue I guessed left was voltage, or coarse amperage, and right was fine amperage.

The manual does give graphs showing both voltage and amperage lowest on the lowest left knob settings.

[gnforge]

Current/voltage curves

I'm opposite I still weld better very up with stick than mig but I'm guilty of welding hotter with mig. In mig have volt control and doesn't wire speed relate or control amps. So I might try dropping volts & increase wire speed ie amps. This might keep my puddle from being to fluid on vert up. Just a thought.
In his video the fine adj knob is reversed from miller. CC-CW. Low-high.
But you have it backwards, the higher the fine adjustment the higher the voltage. So to weld with lower volts & higher amps. Set course setting to highest possible ie high amps and fine adjustment in bottom of range ie low volts. But end result you can weld at same amps in either course setting as they overlap changing the volts your welding at.
I had learned this but But I didn't realize how much it affected puddle temp & snuff out. I might be able to jump up one more setting on the course side and weld at same amp but lower volts. I'm gona try.
Also that might be why I struggle with 6010 I d do fine with it just not great. I'm Gona try higher volts with it.

[Broccoli1]

Regardingin MIg process:
"The wire feed speed is in direct relation to the amperage at a given wire stickout (length of wire from the contact tip to the arc). The voltage is in the case of a CV (wire welder) the constant and is the length of the arc from the end of the wire to the weld pool, as you change the wire stick out the amperage changes to maintain the weld voltage. A normal wire stick out for short circuit mig welding is 1/4".

The following example may help you understand this with .035 ER70S-6 wire and C25 shield gas set at 20 SCFH flow.
1/4" wire stickout, volts 17 and wire feed speed 150 IPM = 100 amps
3/8" wire stickout, volts 17 and wire feed speed 150 IPM = 50-60 amps due to the resistive heating of the wire between the tip and the arc the weld current drops to the level required to maintain the set voltage.
If you were to reduce the stickout to 1/8" the weld current would increase to approximatly 150 amps to maintain the set voltage.

Typical min and max ranges of each wire diameter for ER70S-6

.024 minimum 30A 15V 105 IPM WFS, maximum 150A 21V 710 IPM WFS
optimum vert. setting 80A 18V 310 IPM WFS
optimum horiz. setting 110A 21V 465 IPM WFS

.030 minimum 50A 17V 95 IPM WFS, maximum 200A 23V 600 IPM WFS
optimum vert. setting 100A 18V 235 IPM WFS
optimum horiz. setting 150A 20V 385 IPM WFS

.035 minimum 50A 18V 75 IPM WFS, maximum 225A 25V 500 IPM WFS
optimum vert. setting 150A 18V 185 IPM WFS
optimum horiz. setting 215A 22V 415 IPM WFS

I hope this helps more than confuses you.
DrIQ"

http://www.hobartwelders.com/weldtalk/showthread.php?27631-Amps-Volts-amp-Wire-Feed-Speed

[Broccoli1]

The Bobcat manual is a disappointment. It gives little info about stick welding. Printed on the face it suggests a high right knob setting, with a low left knob setting, With only that clue I guessed left was voltage, or coarse amperage, and right was fine amperage.

The manual does give graphs showing both voltage and amperage lowest on the lowest left knob settings.

In Stick Mode the Fine and Course only refer to amperage- Not Voltage.

"For best performance, set the Coarse Range switch to the low- est range that covers the desired weld amperage. Use the Fine control to select the desired am- perage within the range se- lected. When properly set, the Fine control is normally set at 7 or higher."

[gnforge]

Current/voltage curves

Broccoli1
Not quite so. On engine drive welder the fine setting does affect voltage in CC mode.
Look at owners manual & study the curve. If u weld as you stated, low course & high fine you are welding at higher volts for same amps and you have very little rod manipulation avalible.
But you still need to consider which Rod your using. 7018 likes and works best with low volts for recommended amps. But 6010 likes and works best with higher volts per recommend amps. And we are talking about this same theory as it applys to mig within its recommended range.
Watch Video as willy stated above and see how this applies ands affects puddle heat, Rod snuff etc. It does make a difference.

[USMCPOP]

V/A curve and arc force info:

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

The attached pics are hard to read, but explain the phemenon. They are from a 1956 edition of the Lincoln handbook.