Inductance/dig control

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I have a Miller XMT 304 CC/CV machine and it has a inductance/dig control. From my manual I can concern that dig is for stick and inductance relates to mig. I am currently using just the stick process and monkeyed with the control, but am not really discerning any difference. Can somebody give me an explanation of what, dig control, provides? Thanks in advance, jwr2200.
Reply:I asked the same question a long time ago.  "Arc Force" is the name of the control for stick on most machines.  It makes for a smooth or crisp arc.  Using different rods, it changes the characteristics of the arc.  Probably left for smooth and right for more forceful digging arc.  With 7018, turn it towards smooth and weld.  If the rod sticks to the work, turn it up some until it doesn't.   Set it in the middle.  Get your machine to weld a nice bead. Turn to the left.  The puddle cools slower and the bead profile will be wider and flatter.  Turn it to the right and the bead will be taller and narrower.  Turning it towards crisp makes the puddle cool faster and MAY help in out of position welding.  Too far and your welds won't look as nice.  With the knob all the way to smooth I find  the arc becomes less stable and can wander.  Way up seems to make a lot of spatter.For inductance with wire, way up high makes Co2 run like C/25.  If you are running c/25, go for the middle or to the left.  What ever makes the machine feel best for you.  Always start in the middle and adjust from there.Take some time burn some rod and get a feel for what it does.  After a while it will become your friend.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:The Dig/Inductance control on an XMT does two things. When set in CC mode such as when stick welding, the Dig feature is active. What this will do is when the machine senses voltage is dropping below 19 volts, it will give an additional boost of amperage to make sure that any shorting is cleared. When this knob is all the way to the left you are at minimum dig, all the way to the right is Max. When running rods such as 7018 a softer arc is wanted. In this case you want less short circuit current, which will give you a nice soft arc with less spatter and unloading from the rod. If you weld a 7018 at minimum, then weld at max you will see alot of large sticking spatter at max. This is due to large amounts of short circuit current on Max. I like about 10-20% on the knob for 7018. When welding with a rod that gives a stiffer arc such as a 6010 then the knob is usually set higher. This gives plenty of current to clear any shorts, and the spatter will not be large and sticking as a 7018 because the 6010 does not transfer the filler across the arc in the same manner as a 7018. Guys who use XMT's on tack rigs while welding cross country pipe like this feature because during the root pass (bead pass) they can use a very short arc length without ever sticking to the pipe.When in CV mode that knob now controls inductance. Inductance is the rate of current response to a change in current. What this means is that when MIG welding with a short arc you can adjust how fast current is applied to the shorts. The less inductance you have the criper the arc will appear and the wires will start easier. This will also make the bead taller and narrower. More inductance will make the arc appear "softer" with a flatter wider appearance and if too much is used, wires will stumble during starts. Typically when short arcing steel only a little inductance is used in order to get a crisp arc. Low thermal conductivity materials such as stainless need more inductance to get acceptable wetting when short arcing.Arguing with a Welding Engineer is like wrestling with a pig... after a while you realize the pig likes it
Reply:I had the same ?
Reply:redddoggoose,nice description of what Dig and Inductance controls do to the arc and how they do it.   For practicle purposes, it may be enough to know "turn the knob left for a soft arc and right to prevent sticking", but knowing the mechanism that is causing the arc change is the really valuable knowledge.  Can't think how to describe why it is so valuable, but for example consider that you are trying to figure why one CO2 short arc setup is running hot and harsh with excessive spatter and another similar setup is cooler, smoother, with less spatter.  Knowing the effect of inductance, you discover the difference is that the smoother arc setup happened to have a longer work (ground) cable that was coiled up, many times around a big I-beam, creating a crude inductor.Anyway, thanks for the detailed description in layman's terms.
Reply:I called Lincoln a few times about that screwy knob on my Ranger 250.  No one could answer me except the gas engine drive guy I think his name is Bob Crow.  I read all I could find and redogoose did a great job of explaining it.  Once I got the V350, I had an inkling what it did.  For the inductance using CV wire, I just welded and turned the knob till it was what I wanted.  It makes the welder do some nice things. Welds smoooth with wire no matter what gas I am using.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:I saw "Inductance".I never saw "Dig"!How about "Pinch effect"? I swear, that control did nothing!There's another mystery knob or two, can't think of 'em right now.
Reply:good info52, 59 & 66 Lincoln SA200, Tombstone Idealarc 250, Thermal Dynamics Cutmaster 50, Marquette 250 amp mig, Miller 330 A/BP
Reply:Originally Posted by denrep(snip)I never saw "Dig"!How about "Pinch effect"? I swear, that control did nothing!There's another mystery knob or two, can't think of 'em right now.