304 or 410 for welded 14ga outdoor sculpture?

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I'm making an outdoor table base for a client and trying to decide onthe type of stainless to use. I'm currently mig welding 14 gauge 304 withAir Liquide Blueshield 8 Ar/CO2 mix and .035 308 wire. I'm spot welding toavoid distortion which is time consuming but ya gotta do what ya gotta do.The problems are mainly distortion, work hardening and flap disc glazing. The time spent grinding is getting out of hand due to the work hardening and glazing that's occurring.410 is more easily machined/worked so I'm wondering if that's the way to go orare the drawbacks worse than my current problems. I understand that weldscrack more easily.If I stick with 304 how do I avoid the glazing and work hardening thathappens with the flap discs? Different discs? less pressure? more cooling?Should I have a dedicated liner for the welding gun to avoidcontamination. I mostly weld mild steel.Any tips would be helpfulThanks.Last edited by orange4boy; 03-30-2011 at 07:56 PM.Reason: clarity
Reply:You are ok with the 304 stainless, and the 308 filler, but you should consider TIG as an option. If you are limited to wire feed, you could consider a smaller wire, pehaps dropping to .023". Blueshield 9 is a suitable gas for stainless, not #8 unless you are using flux cored wire. The Air Liquide supplier may also have Arcal 121 which is used for both short circuit and spray transfer and gives a better color match. If you are glazing the surface, you need tho use a coarser disc for metal removal, then the finer disc for polishing. Keeping a separate liner for your stainless welding is definitely advisable. The same goes for your discs, never use one that has been used on carbon steel.Last edited by Pro-Fab; 03-30-2011 at 08:57 PM.
Reply:Great. Thanks for the advice. Air liquide has an entry level 95A inverter tig for $460. 115V only. It's a good quality Japanese unit. I would be using it for sheet and thin wall tubing mainly so I don't need a lot of juice. No experience with tig though. I've been mig-ing for 10 years. I'm a quick study though. How's the learning curve on tig? Is there much difference between basic and good units? I think I know what the answer is there.For what I do tig would be better. Mainly furniture. I would like the idea of less grinding even if the welding takes longer.  I might sell my lincoln SP250 mig and get a good Lincoln tig instead if I knew I could pick it up fairly quick.I'll put in my Teflon liner tomorrow. I used it for a small aluminum job but never used it again.
Reply:For your application you would be better off cleaning out your liner, rather than ruining the teflon one used for aluminum. The entry level TIG will be sufficient for light gauge work on m/s and s/s. You will find that projects won't take any longer provided that you are good at fitting up your tubing. With practice, you should be able to practically eliminate clean up. Tacking your pieces together would be the only step that is slow, but perfect prep and fit up will solve that problem.You will be much more satisfied with the end result once you develop skill with the process. Good luck!
Reply:I would definitely use 304 if paint or Powder Coated finish, 316 if polish finish.Tig, 304L ,308, or 316 filler if using 316.100% Ar definitely.A few pics or more details would help.BrettA good guess is better than a bad measurement
Reply:The piece will be made with sections of plasma cut sheet. It will be a faceted, hollow core design. Welds will all be ground flush and the whole thing polished but not mirror. I am looking into gel passivation. Do you think that's necessary?I would definitely use 304 if paint or Powder Coated finish, 316 if polish finish.
Reply:Here is a pic of a small version tacked up to show you what I'm welding. This one is 18 gauge but the bigger one will be 14 gauge. I have since changed wire from 308LHS to .030 ER316L and I'm getting better results. Smaller, cleaner beads with less spatter.
Reply:Wrong wire, wrong gas, what else do I need to cover.For what you're doing, tig would save you time and money.  However, tig welding SS is NOT a process that's learned overnight.If I was doing that work in my shop, I'd be using .035/.045 308 filler, straight argon, and DC- tig.If I was "forced" into mig, I'd be using .023 308 filler, tri-mix, and a proper size liner for the mig gun.  Some (Ed Craig for instance) will recommend a 98%Ar/2%CO2 mix for this type work but I haven't used it so don't recommend it.  Straight argon will not wet out enough.Another factor that's been totally overlooked here is the need for a back purge or use of Solar Flux on the backside of the weld bead.  Without, one of the two, you're pretty much assured of early failure of your welds due to sugaring the back side.If you're "serious" about your SS work, you'll do a little more homework on the differences between welding mild steel and SS.  SS is great material, but it requires a different level of "attention".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:Originally Posted by SundownIIIIf you're "serious" about your SS work, you'll do a little more homework on the differences between welding mild steel and SS.  SS is great material, but it requires a different level of "attention".
Reply:You state the larger version will be 14 ga., polished afterwards.Experimenting with 18 ga. isn't a good a way to 'learn' SS welding.At your level of experience, simply butting edges together, tacking then welding---willproduce some to a lot of heat induced distortion on the sheet pieces and can warp theentire assembly.Finishing/polishing the facets will not hide this distortion. You may wish to consider creatinga form of framing from flat stock-with the edges serving as the bottom of square weld joint-for example; with the sheet edges butting to each side of the flat on edge.Water spray cooling with air blow off to suck 'sheet heat' back out-pronto-has worked well for me.Even with cool down--expect some bowing of the sheet stock--at least it's much more consistent.More and more with SS TIG--I've been using very slow 3-5 PPS pulsing, at a much higher than normal peak---to get minimum heat input on SS. This can create welds with only slight oxidation (blue coloring) on the opposite, non-purged side on 16 ga. Pulsing doesn't replace the ability to read the puddle and STOP--before the puddles drops flush-creating sugaring/melt-thru, etc. [I use solar flux B and back purging, BTW---as well. It just depends on the deal.]98/2 is supposed to work great with a high end MIG pulser (Miller 350P, etc.) As Sundown III sezit doesn't wet out well with convention MIG and 100% Argon is the same. Tri-Mix is the only wayto fly with conventional MIG--it won't be pretty and has it's own learning curve.Blackbird
Reply:Originally Posted by orange4boyThe piece will be made with sections of plasma cut sheet. It will be a faceted, hollow core design. Welds will all be ground flush and the whole thing polished but not mirror. I am looking into gel passivation. Do you think that's necessary?Brett,  What are the advantages to 316 over 304 in regards to polishing? I'm embarrassed to show you what my welding looks like right now. I have the wrong gas for starters and I'm using .035 on 18 gauge. If you want to cringe I'll post them anyway. Luckily It's not structural so as long as I can clean it up and there is no cracking or voids It's fine for this application.Pro-Fab, I'm wondering about the drive roller. Should that be stainless too or is that overkill?I'll probably pick up the Thermal Dynamics TIG unit and keep my big mig for my production mild steel jobs. For $439 it's hardly a big risk.I'll have to pick up some tri gas and argon. I'm assuming 100% argon for SS tig sheet.Thanks guys.
Reply:Originally Posted by Donald BranscomIF you have a 110V MIG and 14 ga. stainless is .074 thickness I do not think you will have enough heat.With a 220V MIG you would. I tried welding 20 gage stainless with a 110V MIG and had poor results.I was using all the right stuff. I had to have the setting turned up all the way.
Reply:I must add, working ss on a rusty ms table top will give no good results.. unless you want a rusty look on your ss sculpture --------------------------------------------------------------www.becmotors.nlyup, I quit welding.. joined welder anonymous
Reply:Unless your fit up is more accurate than what your mock up appears to be , your in for aworld of hurt dudeA good guess is better than a bad measurement
Reply:That was just a quick first shot at fabricating that type of shape. I will be spending more time on fit up on the bigger pieces. I just clamped the piece there to get a pic outside. I do have a clean work bench.
Reply:Originally Posted by orange4boyThat was just a quick first shot at fabricating that type of shape. I will be spending more time on fit up on the bigger pieces. I just clamped the piece there to get a pic outside. I do have a clean work bench.
Reply:You have recieved some good advise so far  mate and I agree with the others , it is a Tig job.If you have no alternative but to Mig your project ,distortion is going to be an issue you will have to address, heat sinks and backing plates may be a prerequisite.If its an outdoor application I would not hesitate to use 316 over 304 for its superior corrosion properties. There is not much difference between the two in welding characteristics.Have you considered welding a frame together out of angle and gluing the facets on? I know its heresy  to suggest things like that on a Welding site and I don't really know much of what the project has to do or look like , but the end result of Functionality and Aesthetics cannot be ignored.A good guess is better than a bad measurement
Reply:Originally Posted by orange4boyI have a Lincoln Idealarc SP250 MIG machine so I've got the amps for that. What would you recommend for a TIG machine to do up to 14 gage? The Miller Maxstar 150 can weld up to 3/16 mild but how does that translate to stainless?I got the 2B finish so I won't have to sand out the bush marks. I regularly polish out my woodwork finishes so I have all the equipment for that.Yeah, but I know how to swim.Added: Just read your addition. I was talking to a place that does stainless electropolishing when I was researching passivation. I will get back to them for a quote. It may save me a truck load of work and if it prevents rust as well then it's cheap insurance. I realize I will have to do a good job on the welding in any event.I will post some TIG pics when I get going. Probably not for a week or so at least.
Reply:Thanks. I have not been to the polishing operation yet. Will be interesting.Been looking locally for a good used unit. Found a  maxstar 150 STL with argon bottle and foot pedal for $1200 ( he tried to weld alum with it?!??!). There's a nice miller 330a/b/sp listed for $475 and a syncowave 180SD with pedal for $1450 obo.($1200 maybe)I don't really need the ac but would be handy sometimes. I will mainly be welding under 1/8" stainless but could use it for nice welds instead of the mig.Anyone care to chime in?
Reply:Going to look at a Miller syncrowave 180SD today. Guy wants $1000 for it. Has low hours and looks to be in very good shape. I don't have my van with me so it better fit in the Prius. Looks like I have an inch to spare.The guy with the other unit at $1450 is pretty firm on his price so I have to go a little further afield to get a deal. The maxstar unit is a bit overpriced as well and the 300a/b/sp has it's own gravitaional field.
Reply:Just picked my new welder. I found a great deal on a second hand brand new Lincoln Precision TIG 185. The guy bought it a few years ago but never even plugged it in because he bought a mig at the same time and so didn't get around to learning tig. It was still on it's pallet with all the original packaging. $1200. Had to drive a ways to get it but it was a nice drive. Now comes the hard part.
Reply:That's it...Took a lot of practice but got the hang of it. Made sure my fit ups were good and used heat sinks as much as possible. Didn't bother with purging the back because it's not going to be used for food. Didn't get any sugaring. Thanks for all the helpful posts. Especially Donald. Got me going in the right direction.Final dimensions: 30"H X 44"L X 16"W Last edited by orange4boy; 07-18-2011 at 10:51 PM.Reason: added pics