1/8" fillet on 1/2" aluminum

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Just following the prints. Though I'm relatively new to aluminum, what's the best way to get a good penetrating weld with only an 1/8" fillet on something that thick? I've got a 210amp MIG W/ Spoolgun or a 230amp AC/DC "Scratch" TIG with a high frequency unit. Should I pre-heat it? Joining a 1/2" wall thickness tubing to a 1-1/4" solid aluminum square bar.John 3:16(2) Miller Pheonix 456(2) Millermertic 252Dynasty 210DXHobart 210MVPDoringer D350 SA Cold SawScotchman 350LT Cold SawWebb 10x50 MillWebb 15x40 LatheGeka Bendicrop Ironworker
Reply:I should also mention the whole assembly is about 10" round, x 10" high and will bolt together as well. Welds are NOT critical, just used to position the pieces for assembly and dis-assembly.John 3:16(2) Miller Pheonix 456(2) Millermertic 252Dynasty 210DXHobart 210MVPDoringer D350 SA Cold SawScotchman 350LT Cold SawWebb 10x50 MillWebb 15x40 LatheGeka Bendicrop Ironworker
Reply:Scratch start tig with an HF box doesn't sound like the best setup to tig alum with. It certainly wouldn't be at the top of my preferred list of alum welding methods. Given the two choices, I'd have to say I'd opt for mig. However a small 1/8" alum mig weld isn't going to be the easiest thing to do either. My guess is the weld will be bigger.A dedicated Ac tig with pedal would be my 1st choice to do such a small weld. You'd have to have the amps up pretty high to get the puddle going and the small weld and large heat sink isn't going to make life easy. An inverter unit that would allow you to crank up the hertz might make life easier.You might check and see how "critical" that 1/8" weld has to be. If you can get away with a bigger weld, life becomes a lot easier on you. However if they are calling for an 1/8" weld to avoid issues with interference when assembling, you might have no choice but to look at having the welds machined so things will fit..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:It doesn't leave the cleanest looking weld but it works. I haven't even taken the job yet. I'll see how critical the weld size needs to be.John 3:16(2) Miller Pheonix 456(2) Millermertic 252Dynasty 210DXHobart 210MVPDoringer D350 SA Cold SawScotchman 350LT Cold SawWebb 10x50 MillWebb 15x40 LatheGeka Bendicrop Ironworker
Reply:Remember that 1/8" is minimum, so you can result in a slightly larger weld. It could be 3/16" and be within spec. Only if there is an interferece issue would the size be a problem, but some blending by the customer would be in order.Best way to go for you is DC straight tig, 4043 or 4943 filler. Preheat will help immensely to about 250 to 300 degrees. Your weld can be driven into the root with a smallish size if you can get an arc started. 3/32 diameter filler would be my choice. Good cleaning is in order for quick wetting as well.Last edited by shovelon; 06-11-2014 at 12:51 PM.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:Originally Posted by shovelonRemember that 1/8" is minimum, so you can result in a slightly larger weld. It could be 3/16" and be within spec. Only if there is an interferece issue would the size be a problem, but some blending by the customer would be in order.Best way to go for you is DC straight tig, 4043 or 4943 filler. Preheat will help immensely to about 250 to 300 degrees. Your weld can be driven into the root with a smallish size if you can get an arc started. 3/32 diameter filler would be my choice. Good cleaning is in order for quick wetting as well.
Reply:Originally Posted by EcondronIs there a secret to welding aluminum on DC? I've never tried it, but I've only been told you can't do it. One person said you can do it if you use ultra pure helium or something like that for the gas.
Reply:I concur with shovelons advice. if you want the best penetration and narrowest beads on thick aluminum use DCEN and helium.I've done a little myself.Two turn tables and a microphone.
Reply:It would seem with the 4943 that cover passes would be unnecessary. The helium I got said "high purity" but anything more expensive would not be appreciated at my level. I will say the root passes looked great. Nobody ever seems to mention that you need a flow meter graduated for helium or that the actual flow of helium through an argon meter is about twice whatever the ball reads. Just get one of those torch end flow meters recommended by shovelon.
Reply:It would be cool if those gas saver hoses came with a smaller orifice for helium, but even the argon orifice ones seem to save lots of helium in part because the hose is smaller diameter.
Reply:The problem even if I try it and it works great, I've still only got about 140 amps of DC. I don't think that would be enough, would it?John 3:16(2) Miller Pheonix 456(2) Millermertic 252Dynasty 210DXHobart 210MVPDoringer D350 SA Cold SawScotchman 350LT Cold SawWebb 10x50 MillWebb 15x40 LatheGeka Bendicrop Ironworker
Reply:Originally Posted by EcondronThe problem even if I try it and it works great, I've still only got about 140 amps of DC. I don't think that would be enough, would it?
Reply:Originally Posted by shovelonI thought you had a 230 amp AC/DC scratch start tig?
Reply:Originally Posted by shovelonI just use weld grade helium(not party balloon grade for sure). It is a tad dirtier, but I find that the base metal cleanliness is much more important, which is why I send my parts out to a plater for chemical etch for weld. But if you can get a deal on Grade 5 helium, do it. I use a gas lens and a #7 cup with about 30cfh of helium or more. I did find that keeping the electrode nearly vertical helps me. When you strike an arc, the puddle will have somewhat of a skin on it. Poke that skin with the rod and it will open up. Keep on welding.
Reply:Originally Posted by 4956shovelon,Have you ever tried adding just a little Argon to your Helium when using DCEN on Aluminum?   I usually set my Helium flow around 30 to 35 and my Argon so the ball is just coming up off the bottom of the tube.   I  use a Wye fitting to connect the hoses coming from the flow meters together before it goes to the machine (the poor man's gas mixer).   I find that the arc in straight Helium is just a little erratic and unstable.  I've found that adding a little bit of Argon to the mix makes a significant improvement.
Reply:Originally Posted by EcondronIt's a transformer. 230 amps AC but it's only rated at 140 DC.
Reply:Doesn't even a bit of argon take a lot of heat out of the arc? PS - What is everyone paying for a big tank of helium these days?
Reply:Question ,who wrote that specification?You may want to preheat that weldment.Argon stabilizes the arc.AWS certified welding inspectorAWS certified welder
Reply:No secrets. Just information and education.AWS certified welding inspectorAWS certified welder
Reply:Originally Posted by atgDoesn't even a bit of argon take a lot of heat out of the arc? PS - What is everyone paying for a big tank of helium these days?
Reply:Originally Posted by EcondronIt doesn't leave the cleanest looking weld but it works. I haven't even taken the job yet. I'll see how critical the weld size needs to be.
Reply:Originally Posted by DSWScratch start tig with an HF box doesn't sound like the best setup to tig alum with. It certainly wouldn't be at the top of my preferred list of alum welding methods. Given the two choices, I'd have to say I'd opt for mig. However a small 1/8" alum mig weld isn't going to be the easiest thing to do either. My guess is the weld will be bigger.A dedicated Ac tig with pedal would be my 1st choice to do such a small weld. You'd have to have the amps up pretty high to get the puddle going and the small weld and large heat sink isn't going to make life easy. An inverter unit that would allow you to crank up the hertz might make life easier.You might check and see how "critical" that 1/8" weld has to be. If you can get away with a bigger weld, life becomes a lot easier on you. However if they are calling for an 1/8" weld to avoid issues with interference when assembling, you might have no choice but to look at having the welds machined so things will fit.
Reply:@ Econdron - you want an 1/8" fillet (leg) to fuse 1-1/4" Al to 1/2" wall Al?   You're 140Amp machine on DC won't cut it, even with Helium.  As Shovelon mentioned, you should baseline the AC TIG Scratch and apply pre-heat.  Now if you had 250+ Amps of DC that would be a horse of a different color.  Then, applying Helium might be appropriate.Recently fabricated some custom floorboards for a CanAm Spyder.  The floorboards required welding 3/8" thick to 1/2" thick sections of 6061-T6 Al.  Used 185A, TIG AC (60Hz, 72% Balance) with 3/32" 4943 filler.   PreHeat'd the assembly to 300deg F using MAPP.   1st test shot of 1/2" to 1/8" shown below. Attached Images"Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi