help with 14g stainless

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tig welding counters (14g butt welds) and getting some warping and concave even though  we are cooling with wet rags and staggering welds.Using a dynasty 200 dx with a water cooler, 1/16 tungsten and 1/16 filler rod I am setting the machine at 55 volts. Keeping joints tight and am even fusing with half pedal whenever possible.There is a backup strip at the joints tacked on only one side, seems to work better when I dont tack the other side of back up strip? Interested in going to mig any detailed pointers , have never done it and dont even know what machine, wire, gun, etc would be good. Any help would be appreciated
Reply:Same basic question you posted under MIG, TIG, etc, see comments there.Here you say,  " I am setting the machine at 55 volts", I think you mean amps.
Reply:need more argon flow around the weld area less heat with a real sharp clean  2%ceriated tungsten.
Reply:I agree with cmartman46. Your tungsten should be ground to a sharp tip that is at least 2 1/2 times as long as the diameter. Hold as close an arc as possible, and try to use as little amps as possible. Stainless has about 1/3 less themal conductivity than mild steel; heat will travel less. Did I get that right? You are doing butt welds on counters, as in kitchen counters? I would be tempted to fuse the joints without any filler metal; but start each weld with just a dab of filler. (this tends to prevent suck down and cratering. Backstep or scatter the welds in 2 inch increments, and allow slow cooling, as in only doing say 1/3 or 1/2 of the welds at a time. I think cooling with wet rags may be working against you, and actually increasing distortion by shocking the metal. I think you could benefit from using a heat sinks. Get pieces of 1/4 or thicker copper or aluminum, 6 or more inches wide and as long as the weld; clamp it to the backside of the weld zone. You could go one step further and place heat sinks to both sides of the face of the weld zone, allowing only a one inch gap between the heat sink strips. Restrain the stainless with the heat sinks and clamps in place, and allow it to cool slowly.Last edited by maarty; 07-24-2009 at 11:32 AM.
Reply:Maarty,If you can't control the heat with tig, you can forget about the mig.You won't be making countertops, you'll be making washboards.14 Ga is actually a pretty thick countertop.  Are you sure.A while back there was an article posted up on the steps a company (H.L. Lyons) used to prevent warpage and minimize post weld operations in the fabrication of SS refrigerator enclosures.  Basically, it dealt with high speed pulsing of the arc to minimize total heat to the weld. I'd suggest doing a search to find the article.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Sundownll,   I never suggested using mig. Did you read my post?  Tig is my choice for welding light stainless since there is a high degree of precision and control possible. I didn't suggest anything unproven or what I haven't experienced first hand myself. I therefor also feel no need to quote other posts. I would be very surprised if TJFXG employed my advice and didn't experience a radical improvement of his product.  Now that I am back into this and since TJFXG is talking about a backing strip it may be possible that he is talking about a butt weld with a gap; in which case he is adding filler metal and pumping in a lot of heat. Butt welds on a countertop need to be tight fusion welds, with no gap, moderate penetration, and just a slight crown on the weld. A half dozen half inch long fusion welds on the backside of the joint will be enough to keep the assembly strong with the face fully welded.   A countertop has little to no tensile or zero point load stress. The process I am recommending takes this into account. Stainless is incredibly strong and if the welds only penetrate a third of the thickness that will be enough to have a very respectable result, and a minimum of cleanup with the flap wheel and scotchbrite pads (of which I can make another post to describe a method of cleanup and finishing which will leave no discernible divots or defects)Last edited by maarty; 07-24-2009 at 06:02 PM.
Reply:Using a 3/32 tungsten might also improve things since the travel speed will be much faster.
Reply:Originally Posted by maartyUsing a 3/32 tungsten might also improve things since the travel speed will be much faster.
Reply:Stainless is stainless doesn't matter what u do it will shrink and warp
Reply:marrty,I am sorry.  My post was directed at the OP, not you.  He was the one who questioned using MIG.There's been considerable discussion here on the boards about using hi speed pulsing when welding thin gauge SS steel.If you'd like to read more, to include the link to the HL Lyons article, an easy way would be to go back to some of my previous posts (about a month ago) and you will find it.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Sudownlll,Thank you for that. And Snowboarder88, if the tungsten is brought to a long fine point two and a half to three times the diameter of the tungsten, and given a final slight bevel at the very tip, a very tight and constricted arc can be had; especially if it is held close. Remember the variables of melting point, puddle size, arc distance, angle of torch etc. 14 gauge isnt that light. I think a 1/16 tungsten is too small. Controlled more slowly, but not necessarily putting in less heat. Putting in the least amount of heat and as fast as possible is whats called for here.
Reply:Ok I see your point, but I dont understand how with that reasoning you think going to 3/32 will offer a faster travel speed and less heat input?  Going with a long tapered point will give a concentrated arc, but the same if not better can also be had with 1/16 tungsten ground in the same fashion.1/16 tungsten is rated for 150 amps, well more than what is needed for this application.  So assuming they are ground the same, why do you think a 3/32 inputs less heat than a 1/16 tungsten?Have we all gone mad?
Reply:snoOborder88         Ok, the thing is this; the 3/32 will run hotter. Knowing this the travel speed will have to be significantly faster. Put it together; the same penetration, but with the weld executed much quicker: because of the faster travel speed less heat will have had a chance to migrate into the surrounding metal. This is much the same reason that a jetrod (7024) will have less distrortion than a similare size weld produced by a similar sized low hydrogen (7018) Stainless is a lousy thermal conductor; heat will not travel away from the weld as fast as with steel, copper or aluminum. The faster the weld takes place the less distortion there will be.
Reply:Thanks everyone
Reply:I pulse at 170/180 peak amp 40@75% backgnd 20% back stepping in short intervals to stop warping 20 cfh's . that is what works for me! "inverter"