stainless,need some advice?


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Old 07-22-06, 08:07 AM
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Question stainless,need some advice?

hi, i want to do some welding on stainless.mostly the type you would find in comercial resturant sinks and equipment.i have no clue where to start. i have a millermatic 210 with a spoolgun that we use for alum.do they make a flux core for stainless?what type of gas would i need? will i beable to grind and polish to a uniform color or will it be differant then the rest.most of the work will be on finishing the corners. like welding up the corners of a box a made on a box brake.i am looking for cosmetic more then structual this wil be used as a top for a cart that will have a frame and support under it. long but wanted to give as much info as possible thanks for any help or comments
 
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Old 07-23-06, 07:31 AM
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Im not positive but I believe most sinks are 304 stainless. You might be able to find this out from the manufacturer? Its a shame you dont have access to a tig machine but if using MIG i would look into using pure argon, otherwise I believe the weld will will turn a dark grey. If youre worried about appearance i would stick with the gas shielded 308L wire or better if you can find it. If youre not set up to use MIG yet it might get expensive (bottle, reg/flowmeter whip liner etc.)
hope this helps somewhat
 

Last edited by thePlumber; 07-23-06 at 08:25 AM.
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Old 07-23-06, 08:21 AM
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also i forgot to mention welding stainless is very different than welding mild steel. Stainless expands/contracts to an incredible degree, so if youre not careful the material may get to hot and warp on you after in cools. On thin material it may be tricky if youre not experienced. If you have some scap pieces left over maybe practice for a bit to get a feel for how it will react? Im not a professional welder by any means, most of my experiance comes from pipefitting so maybe one of the moderators maybe be able to explain this a little better.
 
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Old 07-23-06, 08:31 AM
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If you want a pretty weld I would go with TIG. For the best result the joint should be as tight as possible so you don't have gaps to fill, though you may still need filler rod. The TIG can produce a very tiny spot of heat so you discolor and warp the metal much less than with MIG.

If you MIG or TIG the stainless will discolor (with TIG it's actually a bit pretty with pinks, blues & grays). Whichever way you weld it can be cleaned up by grinding, filing, sanding and polishing.

Be carefull when using a power grinder or sander. It is very easy to get the metal too hot which will create black/gray areas that are very difficult to remove. A power sander (disk and belt) seems to be the worst for making the black/gray spots. Usually there one spot that just needs a bit more work so you hold the sander in one place for a few seconds too long and then there is a blob of gray. Make sure to keep your tool moving over a broad area. If you must work on one spot. Sand for a few seconds and let the part cool. Stainless cools slowly so be a bit patient. If you do get the black/gray spots give up on power tools. Once the material has been heated too much it is extremely sensitive. Get out the file, sand paper and Scotch Brite pads and remove the discoloration old school.

I just did a custom vent hood for my house and had to form several box structures with a lot of exposed welds. With TIG is is not too hard to make your welds totally disappear and get a totally seamless/jointless look.
 
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Old 07-27-06, 10:45 AM
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stainless need some advice

wow sounds way more complicated then i might want to get into right now. cpl more ? would the heat sink putty help with the distortion? i would mostly be welding 1.5" long corners of a box.5ft by 30" broke to form a 1.5 " deep pan and need to finish the corners i belieave the thickness is .037? wondering if silver soder would work? there would not be any strenth issues as this will be a top of a cart and supported and backed all the way around. sorta like a lamanet.and thanks for all the good info
 
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Old 08-02-06, 04:09 PM
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If you plan on using your Mig welder you will need to use a sheilding gas normally called stainsheild it is 43% argon 2% CO2 and 55% helium if you are using 304 or 304L stainless base materials you will need a roll of 308 or 308L wire. Tig is so much better I would look at goin that route. Use pure argon for sheilding gas on the Tig
 
 

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