Multiple Passes?

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Hey all,I was told that anything above 1/4" is typically welded in multiple passes? Is this an accurate statement?  I am looking at a thermal arc 185 but am concerned about its maximum welding thickness of 1/4".  It seems as if everything my dad has around the farm he would like to weld is 3/16" or 1/4" steel.  I guess I could just switch to the stick setting but would much rather tig for the puddle control.  We also have a AC/DC 225 lincoln tombstone stick welder.  I understand in tig you can do multiple passes without worrying about cleaning slag but do you let it "cool" before you start again or once you have freeze at the end of the bead do you ease the pedal back and go back the other direction immediately? I know I will probably run into torch cooling issues like this but plan to build a water cooler as one of my first projects.  The invertig 205 and dynastys go to 200+ amps but for 15-20 amps they are about 1-2 grand more.  I am pretty much sold on inverters though so maybe this is how I am limited?Thanks!Andrew
Reply:Anyone?
Reply:It all depends on your machine's amprage and what size electrode/rod you use. how thick is the material your are going to weld? If you are going to welding outdoors, I would definately break out the sticks. You have to be real careful with your shielding gas with tig. You should be able to get about 1/4" weld with 3/32' or 1/8" fill rod. If you are going to use stick go for 1/8" stick. Again it all depends on your material to be welded.
Reply:Farm equipment and Tig??Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Originally Posted by hpfiendHey all,I was told that anything above 1/4" is typically welded in multiple passes? Is this an accurate statement?  I am looking at a thermal arc 185 but am concerned about its maximum welding thickness of 1/4".  It seems as if everything my dad has around the farm he would like to weld is 3/16" or 1/4" steel.  I guess I could just switch to the stick setting but would much rather tig for the puddle control.  We also have a AC/DC 225 lincoln tombstone stick welder.  I understand in tig you can do multiple passes without worrying about cleaning slag but do you let it "cool" before you start again or once you have freeze at the end of the bead do you ease the pedal back and go back the other direction immediately? I know I will probably run into torch cooling issues like this but plan to build a water cooler as one of my first projects.  The invertig 205 and dynastys go to 200+ amps but for 15-20 amps they are about 1-2 grand more.  I am pretty much sold on inverters though so maybe this is how I am limited?Thanks!Andrew
Reply:Originally Posted by Broccoli1Farm equipment and Tig??
Reply:Tig is good and great for the small stuff.  If you have 22 feet of 1/4" weld, good luck!Yes you can do multipass and should for bigger stuff.A general rule of thumb is one pass for every 1/8" thickness.  This can be changed with lots of amps and the correct process, but on a farm.....I have an arcmaster 185.  The stick machine you already have is better in my opinion.  The arcmaster is a great tig machine, but for stick its just OK.  It runs 6013 or 6011/10 just fine.  For me it leaves some to be desired for 7018.  The arc force is not adjustable and a little too crisp for me.With an air cooled tig torch, I find I can run ONE length of filler before the torch gets too hot to hang on to.  I use my Arcmaster a lot, but when the big stuff comes around, its something else.  Usually wire.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:If you're building a stainless steel tank or counter top, TIG might make economical sense; if you're welding diamond plate for the inside of a utility trailer, stick welding should do just fine. With TIG it's not just the time, but the cost of the gas too.
Reply:Thanks for all of the replies-  It is tough to understand the real world applicability of a process when in class all you do is weld on clean 1/8" mild, aluminum, and stainless flat plate all day for a week running puddles and lap welds with water cooled torches.  I would really like to get a machine to practice what I have learned in class and figured a tig would be a nice addition to our big stick welder and with the high entry-level cost of tig I want to make sure I will be able to use it.
Reply:In answer to this question I will say Inter pass  temperatures need to be kept within the acceptable limits of the procedure.
Reply:If you get a TIG, you will use it.  It has some really good applications.   Its just not for putting a new bottom in a manure spreader.Go for it and learn how to use it.  Learn all process you can.Yes, interpass temp is important.  Look in books like the Procedure for Arc welding handbook by Lincoln electric.David David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:go for it! IMHO those rtatigs are highly subject to joint design. most could weld 1" plate with 125 amps if the they had to and the joint was set up for that.
Reply:I have a Thermal Arc 190, and lately been doing some thicker stuff with 0.30 and find that way before you ever will run out of power with these migs the wire size being the conductor becomes self defeating. And the only way to change this is to keep larger rolls .45 or .35 and change them out and/or go back to stick.With stick your penetration is better, and so much less prep.
Reply:i have a ta 185, as david r says it may have some limits but guess what everything does. i burn rod with it , just welded some 1"  thick boiler plate,,6010 root, 7018 stringer over the top and a bigass weave i just love doing... i also tig steel, similar procedure, a fgew stringers and a weave and 1/2 steel aint comin apart. have  fun..