Aluminium TIG welding corner joint

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I'm welding an aluminium outside corner joint of 2 3mm sheet and using a 5356 filler.I'm looking to perfect my beed. Currently it looks quite high but i'm more concerned about the angle of which i'm welding.The 2 sheets are clamped in a way that one sheet overlaps the other. (ideally when doing SS corner joint it should not overlap but connected on corner) so as far as i see it, i need to weld from the overlap line.Is this the proper way?I hope i explained it enough, will try to have some pics of the setup soon.
Reply:I'd call it an open or a closed corner, and aluminum needs somewhere to put the filler, so an open corner is best, no overlap or just a little.SqWave 200Millermatic 190Airco 200 ACHypertherm PM45Boice-Crane Band SawVictor O/A
Reply:Originally Posted by RubberduckI'm welding an aluminium outside corner joint of 2 3mm sheet and using a 5356 filler.I'm looking to perfect my beed. Currently it looks quite high but i'm more concerned about the angle of which i'm welding.The 2 sheets are clamped in a way that one sheet overlaps the other. (ideally when doing SS corner joint it should not overlap but connected on corner) so as far as i see it, i need to weld from the overlap line.Is this the proper way?I hope i explained it enough, will try to have some pics of the setup soon.
Reply:Here are the pics.The initial setup/prep isn't mine, i was handed it that way and had to make do with what i have...The first 3 pics show different angle of the job and the last 2 show the weld in progress...As can be seen, that prep on the 4th photo, it's almost an outside corner...The inside panel is 3mm, outside panel is 2mm.Though i know my weld beed isn't that pretty, does it look OK?Is this how the weld beed taking into account the inside corner position should look? should i "eat" more of the 2mm panel? (angle the torch more downwards)
Reply:Hard to say with those picts. Some decent picts of the beads themselves showing the finsh on the bead would help vs those going away shots.Having a V to fill when the two edges just touch on the inside is the best/ When the two pieces touch fully and don't leave you any gap or V to fill, it makes it that much harder to do a decent joint. Biggest issues is if you got enough heat into the base material. When the joints but up tight like they do in most of those picts, you have no where for filler to go, and you need a lot more heat to melt into the base material. This makes getting a decent weld tough. Alum really needs filler for strength in the weld joint. With no where to go with filler, it makes it tough to add enough filler to get the correct alloying components in the bead. 2nd is with that tight joint, it will be very tough to pump enough heat in to get penetration to the back without making a giant mess of the corner.Many guys in an attempt to maintain a corner will go too cold. If for some reason they need to finish the edge and remove any reinforcement, you may not have enough material left if the base didn't get penetrated well and the bead is just sitting on top. Pump up the heat and burn it in and you may have issues with not enough filler in the weld to prevent cracking due to not having enough alloying elements mixed in with the base material. The base material will dilute the weld too much..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I'm no Tig hand, especially with aluminum, but I think you need to tack every couple inches. 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:Maybe these pics are better:
Reply:Honestly, if I am coming to a corner like the outside of a box, I tend to try and go straight thru the corner at least by 1/4" on the other side, then weld back to it or start fresh after the corner.Any time my welds die at the corner, there is going to be a small hump because that is where you concentrated some time and heat. If I am looking to lay a bead low in a corner like that, I will add a little pedal and work quickly on the weld, so I am in and out and the filler does not have a lot of time to build up excess height.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:If you are concerned with where the weld sits with respect to the joint, it is natural to get the weld to sit on the corner with a proper fit, corner to corner, as you have done in the last pic.With the tight fit and overlap, the weld will have to sit on the side where the seam is. Additionally, in that instance the weld will need to be a bit higher, with no place for the filler to go, and assuming the need for the same amount of filler for equal(or nearly) equal strength.I have, in the case of this kind of fit, emulated the outside corner fit by knocking the corner of the overlapping piece with a small bevel.This allows me to place the weld on the corner, and the newly tapered edge to give way for better penetration.A compromise, for sure, but where appearance is important, and strength, less so, it has worked for me.I have done this on aluminum gang boxes, and steel smokers.If it were for a customer, and a case where structural integrity were paramount, I'd have sent it back to the fitters.Otherwise, more and more welds will yield more and more consistent welds.
Reply:You want an open corner and the take extra care that the fit is as tight as possible. From my experience closed corners on aluminum weld like she it.I tack autogenously with quick high amp blasts. like in this video.This is a very fast method. I skip around tacking and tapping with a hammer (if necessary) until i have tacks every 1-2-3 inches. dont be discouraged if the tack doesn't work and it keyholes usually i will try next to the failed attempt or add the least amount of filler as you can to join the pieces. I see you have ground all over the joint. The key to very long consistent bead is a clean, straight cut with a tight fit and little to no filler tacks to run over. www.performancealuminumfabrication.com
Reply:Originally Posted by travisc454You want an open corner and the take extra care that the fit is as tight as possible. From my experience closed corners on aluminum weld like she it.I tack autogenously with quick high amp blasts. like in this video.This is a very fast method. I skip around tacking and tapping with a hammer (if necessary) until i have tacks every 1-2-3 inches. dont be discouraged if the tack doesn't work and it keyholes usually i will try next to the failed attempt or add the least amount of filler as you can to join the pieces. I see you have ground all over the joint. The key to very long consistent bead is a clean, straight cut with a tight fit and little to no filler tacks to run over.
Reply:Originally Posted by geezerbillIf you are concerned with where the weld sits with respect to the joint, it is natural to get the weld to sit on the corner with a proper fit, corner to corner, as you have done in the last pic.With the tight fit and overlap, the weld will have to sit on the side where the seam is. Additionally, in that instance the weld will need to be a bit higher, with no place for the filler to go, and assuming the need for the same amount of filler for equal(or nearly) equal strength.I have, in the case of this kind of fit, emulated the outside corner fit by knocking the corner of the overlapping piece with a small bevel.This allows me to place the weld on the corner, and the newly tapered edge to give way for better penetration.A compromise, for sure, but where appearance is important, and strength, less so, it has worked for me.I have done this on aluminum gang boxes, and steel smokers.If it were for a customer, and a case where structural integrity were paramount, I'd have sent it back to the fitters.Otherwise, more and more welds will yield more and more consistent welds.
Reply:Originally Posted by RubberduckMaybe these pics are better:
Reply:R'duck, I think you may have already described the main problem with this weld seam?"The initial setup/prep isn't mine, i was handed it that way and had to make do with what i have..." (R'duck)The sheet edges are not prepped correctly for either a lap joint OR an outside corner which is much better if the two panels are edge to edge along their inside material 'knife edges' and a small gap between them is not unwelcome depending on the thickness.So by accepting someone else's errors you kind of corner yourself into poor working conditions.  If I were to accept the work I'd have to #1 take the joints apart to reassemble them correctly or (if not possible) #2 make some very careful removal of some of the joint material, in aVERY specific order, or #3 refuse the job as below my standards.My first advise is #3.  My second recommendation is #1; but if I were willing to accept the 'junk' that will likely result of someone else's poor work (I'm not) I'd make plans to re-cut the seams to b e welded so they can be welded correctly as an outside fillet.By leaving the huge, out of scale tack, and ignoring the very over-sized grinding marks that did not dress the tack correctly, I'd put a 4" saw or 3Hp router along the edges (with roller guide and carbide bit) and remove one thickness of the overlapping side so the resulting cut joint is inside edge to edge.Then by skipping the huge lumps in the tacked up areas, I'd re-weld the entire seam(s) and come back when completely done, and cut out the tacks AND the overlapping sheet edges and weld this final 3-4" seam 'tie-in' area so that A) the seams were set up to give good penetration, B) I could put in a proportional weld that had decent parent metal fusion C) the work, even if it were a save from someone without adequate goals for their aluminum work, would hold up in use.A lapped joint may be used if the overlapping material is entirely V'd and the lapped over material is also V'd to match but then; in thin material that overlapping pieces edge is slumped into the weld and therefore the weld seam is very irregular by comparison to a 'full shoulder' of the inside edge to edge fit.here is how I'm hoping to describe a better joint for an outside corner weld in thin aluminum.  The sheets' edges can be sawn or sheared but they should have Vixen filed edges so the metal is clean shiny and base parent metal not contaminated by band saw or jig saw or plasma irregularities- or shear tear marks if avoidable.I like the control of the puddle that comes from uniform inside edge fits. By adding just a very small increase or decrease in the overall wattage/power/amperage of the weld a keyhole will form indicating that a back weld is happening (mainly in aluminum this is more 'slump' of the molten metal puddle than a 'back weld') and I think this is the best outside corner weld I can put down.Colors are used to separate parts of the illustration for clarity.In practice this 0.160" tank is being welded using the bead shown in the illustration above. Doesn't look like I've followed my own advice to Vixen file the edges ! But the keyhole is kind of visible, the weld proportion to the parent metal is shown, and the tanks made this way always hold 3-4 psi when tested.So, IMO, (refuse the job; but if you're already committed......) I'd cut the edges so they approximate the joints shown here and on the other posts with the starts and stops cut out, although in tank work like this a small tipped carbide burr can be used to dress the tacks into small cupped fusion points that can be weld over without distorting the final bead.  A saw can do this work but a router is more suited to dress the seams as its more controllable. Then a fine tip carbide burr more controllable for the end dressing shown above in another post.My few cents.cheers,Kevin MorinKenai, AK
Reply:Thanks Kevin for one of the most comprehensive answer on this subject.I will try your suggestion as well.
Reply:What is the piece you are trying to build suppose to be used for rubberduck?
Reply:I have had plenty of customers bring me overlapping joints tacked like the ones shown your photos. I file a deep notch to retack, then pull out my disc sander, grind a diagonal flat  across the seam to take material away and leave a land, take grind surface off with my alum file, and drive a good weld in. The inside should show indications of penetration. Should look like Mr. Travisc454's welds with a tighter bead spacing.Have fun.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Some kind of a holding tank. No pressure or neat welds. just strong enough to hold. Size of about 1600X400X400mm.
Reply:I normally set up an edge to edge joint for tanks and run a pretty good size bead I have seen guys sand the sides for whatever reason but I like as much consistency through the joint as far as thickness as possible... http://im1.shutterfly.com/media/47b8...D550/ry%3D400/  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock