GMAW/FCAW setup ?

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Most of my experience is SMAW, but I am currently using a miller shopmate 300 with 22-A wire feeder and would like to be more sure of my setup. I am working on heavy plate steel with deep bevels, multipass, and have had best results with .045 flux core , 75/25 gas, 30CFH, at 24-25 volts and wire speed set by sound to run smooth without too much spatter(more fast than slow). Slag peels off in one piece real pretty. Sorry, I can't provide actual speed. I've searched here, and the big 3 for info, and have some questions.(1)Can someone link me to a parameter chart for basic starting points? If so, is this machine specific, or wire specific or???(2)Polarity?   How do you change it on this machine, and what is correct for solid,fluxcore, and fluxcore with gas ?(3)Voltage? Set first, or wire speed? Where to start for different wire?(4)Wire speed. I think I have this one figured out, but any input is appreciated.This machine also has inductance control which seems to be nice for fine tuning the wetness/profile of the puddle.I've been able to get nice strong welds with the flux core and gas that have put up with lots of abuse, but my setup was all trial and error.I tried some solid .035 and was not able to get a satisfactory bead. Lots of spatter and did not wet out well, or appear to have adequate penetration.I have a setup for this particular job, but I want to know what to do with different wires and applications.I realize this is a fairly broad group of questions, but I think it is a topic that will help quite a few people.Thanks in advance.
Reply:Fluxcore with gas, do you mean dualshield?  What exactly wire are you using?USUALLY self shielded wire is electrode - and dualshield is electrode +Set wire speed first, that will be your amps, then fine tune for a good arc with the volts.TRY the inductance at 75%.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:David, it's hobart wire,Excel ARC-71 I think.There are rolls of solid and flux that seem to have the same label.There is a new spool coming monday so no guessing...I also used a high tensile-110,000 psi., that worked very much the same. I spent about a month with it last winter and the machine was new to the shop then. The salesman made recommendations and helped with setup to some degree.I think that is how I ended up running the gas.I did find the higher side on the inductance made me happier with the welds.
Reply:Your parameters look pretty good, and I'm betting that your wire speed is around 250 ipm.  Turn up your shielding gas flow to 40-50 cfh if you're having any sponge porosity or if you're doing any out of position welding.  Your electrode extension is important, should be 1"; 3/4" stickout and 1/4" from contact tip to nozzle mouth.1 - parameters are based on base metal thickness, and filler wire diameter; moreso on filler wire diameter.  Check Miller's website for a table of parameters, I bet there's one there.3 - I'll quibble with Dave a bit here.  Set your voltage first.  With no idea where to start, turn volts down until electrode is stubbing out.  Note this number.  Then turn volts up until the arc becomes erratic and the bead contour looks really crappy.  If you get burn back, and weld the electrode to the contact tip, you've definitely gone to the upper voltage limit.  Knowing nothing else, about half way between these two extremes is a good starting voltage.  Next set amps. A good setting is one that keeps the arc smooth, with minimal spatter; which you've already found.Miller's documentation should have more specific ranges for each type of electrode filler wire.For ideal performance, your 0.035" solid wire requires more precise settings for voltage, wire speed, and the stickout has to be much shorter(1/4"~3/8").  If voltage and wire speed aren't well matched to one another, you get just what you described.  If you're game to try again, maybe try something like 21 volts and 170 ipm wire feed speed.  But this is from memory, and I make no promises that it will work.  When it's right, you'll know, just like you did for the gas shielded flux core wire.
Reply:A_DAB_will_do, Thanks for the response. I did search miller's site for what seemed like an eternity, and lots of mention of parameter charts, but I could not seem to find one. I guess alot of smaller machines have 'em right on the case. Maybe with the shopmate you are supposed to know betterIf you set voltage first, what wire speed do you start with?
Reply:Go to Hobart Brothers website and get the parameters for the Excel Arc 71. They have the optimum voltages and wire speeds listed. Dual shield can be pretty voltage sensitive at times. I agree with starting with the voltage and dialing in the WS. That is SOP.
Reply:Where is welderwomn?  We could use her.  Here ya go.http://www.hobartbrothers.com/pdf/da...xcel_Arc71.pdfThe reason I set wire speed first is because you know how many amps needed for the thickness of the plate.  Then adjust voltage for the best arc.  edit:  Here is where I found to set amps (wire feed speed) first.http://www.millerwelds.com/interests...rs/pdf/MIG.pdfDavidLast edited by David R; 03-24-2008 at 06:29 AM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:i would agree you need to set volts first, then adjust your amps/wire feed. your gas is fine no need to go up to 40. .045" flat with 75/25 should run at 250A, 26V, 500 imp, and 1/2" stick out + or- 1/4".
Reply:Many thanks for the responses guys.The new spool of wire was not delivered, so I had to run out to get it. This proved to be a good thing as the lws had a Hobart Bros. handout booklet with everything they make and all applications, properties,impact values,recommended procedures,gas,polarity, etc....Exactly as you found, DDA52,and David. Thanks for digging. So now I have at least a good starting point for the Hobart stuff.My settings today were 25.5 volts and 7 out of 10 on wire feed, and I was very happy with the results.I'm definitely getting enough heat now. The display was showing an avg of 250 amps if i had to guess.I also changed the polarity to DCEP. I'm betting that was one of my biggest problems with the .035 solid I tried to use the other day.Guys had it set DCEN. Is the polarity based on gas or no gas?While I was at the lws, I did see charts on the cases of several machines. Hobart and Miller. Are they just for their brand of wire, or what? I imagine that brands of wire are as different as stick electrodes can be in the same spec.
Reply:Daddy, The AWS # tells you everything you need to know about that wire. E71T1 is DCEP with gas and E71T11 is DCEN without gas, solid wires are DCEP, with gas.  There must be 15 or 20 AWS books on this subject.  JohnSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :