Welding 2 pieces of different thickness

admin

How do you weld a piece of 1/8" plate to 1/4" thick square tubing? How do you keep from burning though the thin stuff?
Reply:Start the arc on the 1/4" square tube and allow the filler metal to wash or flow onto the 1/8" plate.  Spend more time with the arc on the 1/4" thick material.How you do this depends on the welding process and the joint position.  But that's the general idea.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Thanks.  Should the arc stay off the 1/8 then?
Reply:Why not set the maching to accomodate the thickness of the thinner of the two members?
Reply:Originally Posted by Tiger FishThanks.  Should the arc stay off the 1/8 then?
Reply:Originally Posted by PRattenburyWhy not set the machine to accommodate the thickness of the thinner of the two members?
Reply:I wouldnt worry about it, if you get the machine setup right for the 1/4" you should be fine on the 1/8", it will just be running a little hot.  If the fit-up is tight and you know how to weld I doubt you will even notice a difference.Have we all gone mad?
Reply:Originally Posted by PRattenburyWhy not set the maching to accomodate the thickness of the thinner of the two members?
Reply:Originally Posted by PRattenburyWhy not set the maching to accomodate the thickness of the thinner of the two members?
Reply:It's been a while (like 20 years) since I designed pipe hangers for submarines, but as I recall that's the way I would call out the welds when I did it. The best one can hope for is 100 percent penetration on the thinner of the 2 members.
Reply:Originally Posted by snappy101i aint an expert.. but i think that would be my limited guess.. youd only need penetration to the depth of the lesser thick metal so youd setup everything with that in mind, feel free to correct if im wrong, if you set it up for the thicker metal it wouldnt make sence, and youd probably burn through the thinner metal
Reply:Originally Posted by OldtimerOK, I'll correct you. If you set up for the correct heat on 1/8" material you won't have enought heat to get that amount of penetration on the 1/4" material. You will have a cold joint on the 1/4" side. Simply put, the weld will fail under load on the thicker material. Like stated, set up for a properly made weld on 1/4" material and concentrate most of your weld on the 1/4" material and let it flow into the 1/8". EXPERIENCE will teach you how to do this correctly. Same principal applies when welding expanded metal to solid.
Reply:Originally Posted by PookieThe weld shouldn't fail any sooner than the 1/8" material will fail.
Reply:Originally Posted by PookieThe weld shouldn't fail any sooner than the 1/8" material will fail.
Reply:Although 1/4 to 1/8 is no big deal, I'm with the camp that says set it for 1/4 and wash it into the 1/8.   If you set it for 1/8, you'll have to spend alot more time heating the 1/4 side and then you may warp the 1/8 side.When I was welding the school buildings, I welded alot of 14-18ga galv sheet metal stud and track to coated 1/4" wall tube and 3/16-1/4" @ edge channel and I-beam with self-shielded .035 fluxcore wire.   I set the machine HOT, for the thicker metal,  and carefully washed the puddle into the sheetmetal.  I got good penetrataion on the beams while not blowing through the sheet and was able to weld fast enough to avoid warping the sheet.  Setting the machine colder resulted in having to weld alot slower, spending more time heating the beams and dealing with warpage of the sheet and even some blow-through.  As the gap got wider, the weaves got bigger and messier.  Not good.  I find it's better to run it hot and med-fast on thick to thin rather than slow and cold.  Get a good puddle going on the beam and wash it into the sheet.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op