Technique vs Current

HasBean · Nov 9, 2008

Now this is probably a very daft question but.......

for those of you who have been bored enough to read my seemingly never ending posts about my stick welding shenanigans I've found that to acheive the (relatively :laughing:

) same results as my instructor I have to use totaly different current settings :confused:

For a root in 6mm plate he uses 60A, I find I need to use about 80.
Is this just me being a silly bugger or are these things subjective? :dontknow:

rusty69bus · Nov 9, 2008

maybe it's down to speed?

matt1978 · Nov 9, 2008

A lot will depend on travel speed............also are you both using the same exact machine? If you are using different types of machines and one of or neither have been calibrated, then you don't know if he is really using 60amps or if your really using 80amps.......both machines could actually be really welding at 70 amps for example.

Paul. · Nov 9, 2008

Hi Paul
Thats probably because he's experienced and able to control and vary the arc length accurately, an open arc will increase the arc volts and therefore the heat, and a tight arc will lower the heat, so he's using it like a valve to vary the heat input in the pool, learning to maintain an arc at low amps is very useful for open root welds,

HasBean · Nov 9, 2008

Thanks guys, must say I've decreased my travel speed which has helped a lot. Matt, I find using my IFL at home easier than the Cebora at classes, I find my electrode holder is easier to use, much heavier, don't need to rest my elbow on the deck so much.
Paul, I'm following what you told me before and trying to keep the arc tight to the pool, also turning my mask from 11 to 10 1/2 has made all the difference, I can nearly see where I'm going :laughing:

For some weird reason my welding this morning was better than it has ever been (must've been the cider last night

must drink more :whistle:

)

scarecrow · Nov 10, 2008

HasBean said:
Thanks guys, must say I've decreased my travel speed which has helped a lot. Matt, I find using my IFL at home easier than the Cebora at classes, I find my electrode holder is easier to use, much heavier, don't need to rest my elbow on the deck so much.
Paul, I'm following what you told me before and trying to keep the arc tight to the pool, also turning my mask from 11 to 10 1/2 has made all the difference, I can nearly see where I'm going
For some weird reason my welding this morning was better than it has ever been (must've been the cider last night must drink more )

It's know as a steady shake :laughing:

dutchman · Dec 23, 2008

Here is something that had me thinking for a while now....

The power dissipitated over a resistor P=V*I right?
Now why does everybody only mention amps (I)? Surely the voltage makes a difference as well.
I know that with a bit of substitution you get P=Isquare*R but I think R will be larger if V is larger because you can maintain a somewhat larger arc gap and arc gap is the most influential factor for R, right?
Errr anyone still following my somewhat unclear explanation

Note:
P=power (in Watt)
V=voltage (in Volts)
I=current (in Ampere)
R=resistance (in Ohm)

Don't shoot me if I talk nonsense, I am just a nutter that regrets not having more expert knowledge of technology

Drains · Dec 23, 2008

Everybody only mentions amps cos you can't do a lot about the volts. Welding (as opposed to open circuit) voltage is dictated by the rod/flux type, and, as you say, the arc length. Lengthen the arc, the voltage goes up, so more power/heat into the weld.

Don't ask me for the maths.

dutchman · Dec 23, 2008

I phrased it somewhat badly I think. My comment is more of a remark toward the welding industry than to the people reading what the manufactures printed on the machine.
As I remember it, the little knobby that says to adjust the amps actually adjusts the voltage, and thereby creates a higher current, and current times voltage is power. So why don't they call it power?
And since some machines have a higher voltage at a given current than others, this could be an explanation for Harengs question couldn't it?

(Just to suck eggs a bit, I think the more scientific word for voltage is potential difference)

shenion · Dec 23, 2008

The knob adjusts the current slope on lager machines. The OCV stays the same.

malcolm · Dec 23, 2008

Arc welding sets supply constant amps. The knob adjusts amps. You might be thinking of MIG sets that supply constant volts and where the knob doesn't really have a direct bearing on amps.

Amps would seem a fairly good way of specifying an arc set. They are a poor way of specifying a MIG set as there are many other variables involved there. Though for migs open circuit volts aren't much use.

I'm sure there are other variables. And I might be wrong, but that's potentially the difference.

dutchman · Dec 23, 2008

OCV is the starting current right? and with the knob you set the point at which the current stabilizes, right?
Hmmm, I think I see what you guys are getting at.
My reasoning that for a given current the power output at the arc is different for a more powerful machine that uses a higher voltage at that setting would still be correct, right?
Would be fair if producers would inform people about the actual power output of their welder than, not just the amps I guess...

For example, at 200A tig, my Lincoln welds with 28V and kicks out 560Watt
A similar Miller maxstar at 200A tig, welds with 18V and kicks out 360Watt

shenion · Dec 23, 2008

OCV is the starting voltage for no current.

The welding voltage has to do with rod size and arc length. The current setting on the machine are just an estimate; it can vary with technque: One use may use a higher current setting with a shorter arc length or another may use a lower current with a higher arc length. The power would be the same.

When I started dragging smaller 6013's as needed for tight welds, I found I had to increase the current to get the same heat input.

dutchman · Dec 23, 2008

OCV is the starting voltage for no current.

Thats what I meant, but didn't say correctly :ashamed:

Getting a bit sleepy here, sorry. :laughing:

dutchman · Dec 23, 2008

And then, logically, you have the increase in voltage when arc length increases so that the amps stay in the same range.... :whistle:

So, P is not a very stable value either and therefore the amps indication makes a bit of sense... :laughing:

Drains · Dec 23, 2008

dutchman said:
For example, at 200A tig, my Lincoln welds with 28V and kicks out 560Watt
A similar Miller maxstar at 200A tig, welds with 18V and kicks out 360Watt

I think they'll use the same wattage Dutchman. The 18v/28v will apply to the OCV, not the welding/arc voltage, which probably end up being similar on both machines .

dutchman · Dec 23, 2008

Just checked the manual, OCV is 80V
28V is at given current....

shenion · Dec 23, 2008

Yes, that's why arc welders are called constant-current machines although they do vary a bit with load.

aero · Dec 23, 2008

All good stuff. If you hold the current constant then the voltage WILL alter.

I've noticed that holding the arc tight to the job produces different welds to letting off a loose one. So to speak.

Arc welding is very subject to feel, technique amps and rods, which is why it's good practise. For brain and eye to hand control.

beats trying to refill a beer can at six feet after a few :rolleyes:

Technique vs Current

HasBean

Member

rusty69bus

moving to the goldcoast

matt1978

www.lorch.eu

Paul.

Moderator

HasBean

Member

scarecrow

Outstanding in his field

dutchman

t(r)igger happy

Drains

Yeah, nah.

dutchman

t(r)igger happy

shenion

Tool Pack Rat

malcolm

& Clementine the Cat

dutchman

t(r)igger happy

shenion

Tool Pack Rat

dutchman

t(r)igger happy

dutchman

t(r)igger happy

Drains

Yeah, nah.

dutchman

t(r)igger happy

shenion

Tool Pack Rat

aero

Member