Lap Joint help...

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Any tips for making clean lap joints on thin material?I'm using 1/8" and it seems very difficult to make a clean bead without really cutting into the material edges. Im using the 2 steps forward one step back type of method.
Reply:Hello BrooklynBravest, you're not saying which process you're using and a little bit more information. SMAW, GTAW, GMAW, FCAW with or without gas, a little bit more information might help with responses and pictures also help immensely. Best regards, Allanaevald
Reply:Oops, feel stupid now.Using Mig.Il have to take pictures when I get back home.
Reply:Heres a picture.As much as I wish I could do that full bead instead of a bunch of 1" beads, I know I don't have the "stamina" to make a weld that long without stopping. But the ones I did, are they correct?
Reply:They look pretty good to me. You realize you're going to warp that box tube? Better start back stepping, and skipping around.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by CEPThey look pretty good to me. You realize you're going to warp that box tube? Better start back stepping, and skipping around.
Reply:What size wire?  Machine settings?In order to keep a smaller bead that will reduce the amount it "cuts in" you might need to go to a smaller wire.That being said I'd have to say IMHO (In My "Hobby" Opinion) that it doesn't look all that bad.  I do see the cut in on the back side and focusing the bead more on the main piece and letting the puddle wash up to the upper edge of the top piece should help.I might also suggest bring the bead around the angled corner to eliminate a potential stress point but then depending on the application it may be mute.Whatcha buildin'?MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Square tube is very reactive to heat. But easy to fix, reverse the process, put heat on the other side. Back stepping, and skipping around is a big help, but when all the weld is on one side it's gonna warp! That's where heat shrinking is a big help. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by duaneb55What size wire?  Machine settings?In order to keep a smaller bead that will reduce the amount it "cuts in" you might need to go to a smaller wire.That being said I'd have to say IMHO (In My "Hobby" Opinion) that it doesn't look all that bad.  I do see the cut in on the back side and focusing the bead more on the main piece and letting the puddle wash up to the upper edge of the top piece should help.As far as that corner, its just a spacer so it will receive no stress.I might also suggest bring the bead around the angled corner to eliminate a potential stress point but then depending on the application it may be mute.Whatcha buildin'?
Reply:Originally Posted by BrooklynBravestWhere were you 3 hours ago to tell me that before I warped it
Reply:Originally Posted by CEPSquare tube is very reactive to heat. But easy to fix, reverse the process, put heat on the other side. Back stepping, and skipping around is a big help, but when all the weld is on one side it's gonna warp! That's where heat shrinking is a big help.
Reply:I see CEP is waaaaaay ahead of me. I'll step back. MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Back stepping is when your direction of travel is the same, but each new weld stops at the start of a previous weld. What this does is break up the heat line. Like I said putting all the weld on one side of square tube, it's going to warp, no way around it!Yes use your torch to heat opposite side of each weld, take a spray bottle of water to cool each heated area. DO NOT re-heat until you can touch the metal with your bare hand and not feel any heat! Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by duaneb55I see CEP is waaaaaay ahead of me. I'll step back.
Reply:Originally Posted by CEPBack stepping is when your direction of travel is the same, but each new weld stops at the start of a previous weld. What this does is break up the heat line. Like I said putting all the weld on one side of square tube, it's going to warp, no way around it!Yes use your torch to heat opposite side of each weld, take a spray bottle of water to cool each heated area. DO NOT re-heat until you can touch the metal with your bare hand and not feel any heat!
Reply:Originally Posted by BrooklynBravestSo take a torch and make it red hot directly opposite the weld, and immediately spray it with water and leave it alone for a while?
Reply:Originally Posted by CEPI'll teach you how to heat shrink, if you teach me how to work on SA-200s
Reply:Originally Posted by BrooklynBravestWhere were you 3 hours ago to tell me that before I warped it Was pretty bummed, I am making 2 of these frame things and I am just gonna have to learn from my mistakes on the first attempt. It WAS a perfect square before I added those strips.How do I avoid warping it the next time around? And what is back stepping?
Reply:InterestingLast edited by B_C; 01-07-2014 at 04:22 PM.  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:that video was great! thanks for sharing
Reply:Great video but when it started I thought I was back in the 4th grade gym getting ready to watch the sex education film. MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:I loved that video. Thanks............Fireman BillHH 210 MVPMM 211 Spoolmate 100Lotas LTP5000D PlasmaOxy/Accet (Victor)Wards AC/DC buzz box30 ton old hyd pressA few brand name toolsA bunch of cheap toolsA wife to worry me and4 dogs to supervise me
Reply:Originally Posted by duaneb55Great video but when it started I thought I was back in the 4th grade gym getting ready to watch the sex education film.
Reply:Side note here as far as the warping of the pipes, I mis-drilled two 1/2" holes (dead center) on either pipe and I filled them in and redrilled. Is the warpage more likely from the lap joint beads or from filling in those half in holes? The warping is an even bow to the center of the tube on each side. I probably should have included that little tidbit.When I make the 2nd one, should I just leave those spacer pieces out and let it have the 1/8" gap? I don't have real access to a torch that I can use at home to pre-heat it.Last edited by BrooklynBravest; 01-07-2014 at 09:46 PM.
Reply:Brooklyn,CEP and duaneb55 gave you the way to straighten out your tubing.  Search "heat shrinking" on the forum and you will find several examples of it being done.I'd take Duane up on the coffee offer! ...probably a LOT warmer where he is!Originally Posted by shortfuseBrooklyn,CEP and duaneb55 gave you the way to straighten out your tubing.  Search "heat shrinking" on the forum and you will find several examples of it being done.I'd take Duane up on the coffee offer! ...probably a LOT warmer where he is!
Reply:Originally Posted by BrooklynBravestJust watched that video. Pretty cool something so old still holds true.So essentially I just need to clamp the tubing down, with some form of shim directly opposite the weld site to pre-stress it?
Reply:Originally Posted by BrooklynBravestJust watched that video. Pretty cool something so old still holds true.So essentially I just need to clamp the tubing down, with some form of shim directly opposite the weld site to pre-stress it?
Reply:Hey Brooklyn, welds look pretty good to me.  Very interesting topic and I've learned from it.  Thanks all!
Reply:Ok so for the sake of not starting a new thread, this is what I am building. It is essential a window frame used for firefighter training that I designed and hope I am good enough to build.This picture shows what is the lap jointed pieces. That piece of 1" flat stock is basically only being put on as a spacer so the window sash lines up with the outside frame. It will receive no stress and probably could be held on by much less than I did on it.So, heres my question. Knowing what I learned in the heatsinking video, would this balance everything out. Notice in the first picture above that the frame has 2" brackets for bolting it on all around it. If I put those welds, which are 2" welds on 1/8" flat stock opposite the welds for the spacer piece, it should theoretically balance out the warping? Is this a correct statement?
Reply:I'm not sure I understand. Are you saying you want to use bolts, and bolt the brackets on instead of welding?Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by CEPI'm not sure I understand. Are you saying you want to use bolts, and bolt the brackets on instead of welding?
Reply:OK now I under stand. It might work, but aren't you going to have more welds on the inside than brackets on the outside?Here I took your drawing and drew on it. This should make it clearer on how I would heat shrink this frame. I'm just guessing where the welds will be, But as you can see everywhere there is a weld, I'd apply heat opposite. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:I can just make a weld there for the sake of applying opposite heat and grind it off as well right?The spacers can honestly be held on by 3 small welds I would imagine instead of 10, 1" welds like I did.Does the opposing weld need to be made immediately while the first one is still warm or does timeframe not matter?
Reply:A lot of people will use a weld as heat to heat shrink, and grind it off latter.You can heat shrink at any time. I would wait until the frame is cold from welding. Place a straight edge on the outside / opposite of weld, and mark where the bow is. Heat / weld to correct the bow. Make sure each heat shrink / weld is dead cold before moving on!Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by CEPA lot of people will use a weld as heat to heat shrink, and grind it off latter.
Reply:Originally Posted by MinnesotaDaveI was young and it looked like magic.
Reply:Originally Posted by CEPWhat do you mean, was young?
Reply:Originally Posted by MinnesotaDaveYoung(er), young-ish, young at heart ?Waaay younger than you?
Reply:Originally Posted by CEPYou know, I get a kick out of picking on you! Your almost as fun as weldermike to pick on!
Reply:Originally Posted by MinnesotaDaveThat's ok, us young'ins feel bad if we make fun of the elderly too much...I feel bad when they get over excited and the tennis balls slip off the walker
Reply:Originally Posted by CEPOh you must of missed my point, I get a kick out of me picking on you! Not you picking on me!
Reply:Originally Posted by MinnesotaDavePlus, your voices get quiet really fast as we leave you in the park sitting on a bench swearing at pigeons...
Reply:Originally Posted by MinnesotaDaveNo problem, we never listen anyway Plus, your voices get quiet really fast as we leave you in the park sitting on a bench swearing at pigeons..."Honest, I'm just going to get you more popcorn and I'll be right back..."
Reply:Got it to bend back with about 4, 3" beads dead center and a few other short 1" ones across the length of it. Its within 1/16" of where it should be.Wish I knew working with metal was so much more interesting than wood. Woulda gone to school for welding over carpentry.
Reply:Originally Posted by BrooklynBravestGot it to bend back with about 4, 3" beads dead center and a few other short 1" ones across the length of it. Its within 1/16" of where it should be.Wish I knew working with metal was so much more interesting than wood. Woulda gone to school for welding over carpentry.