Weld Copper to Stainless

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Hi Guys,I need to connect a 2" copper fitting to a flat piece of stainless. I have a Syncrowave 200. I have tested fusion welding the two together but the puddles don't want to mix, as I suspected.I thought for sure I could just use JB Weld but that didn't stick to the stainless.I want the joint to be pretty strong as a tall apparatus will be sticking out of the fitting.Is there any way to TIG this (PS I am brand new to TIG)?What about silver solder?PS Yes, this is to connect a copper still to a mash pot!
Reply:Silver solder is perfect for what you want to do.Have we all gone mad?
Reply:Good luck with your still...
Reply:Can be tiged with silicone bronze but not a job for a beginner tig welder.
Reply:What about a threaded fitting of the same metal welded on to each piece and then screwed together?HH 187Miller Bluestar1EAHP AlphaTig 200X
Reply:Originally Posted by GreyhorseWhat about a threaded fitting of the same metal welded on to each piece and then screwed together?
Reply:Braze the pieces together.Because short of some sort of 'solid-state' joining method (explosive welding and such), there is no real way to arc (or gas, or laser, or EB) weld two such dissimilar metals together.Pay attention to the brazing alloy and possible fluxes involved, as not all such may be food-safe.Maybe an alternative could be to weld or braze the appropriate flange-fitting halves to their similar metals and then make a bolted and gasketed flange joint between the two?  The best laid schemes ... Gang oft agley ...
Reply:Yes on the silver solder.  Keep most of your heat on the stainless.  Bob
Reply:Originally Posted by MoonRise...short of some sort of 'solid-state' joining method (explosive welding and such), there is no real way to arc (or gas, or laser, or EB) weld two such dissimilar metals together.
Reply:i have welded my copper template to a SS blade by accidentidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:doin some reading ( google search welding stainless to copper turn up some scrolled down found one    " welding-copper with intense heat localized heat input " 2/3 down article   PWL# 027 Weldability for weld repair,copper to stainless .welding-advisers.com/PRACTIAL_WELDING_LETTER-PracticalWeldingLetterNo.27 grrrrrrrrrrr  cant get link to workLast edited by prop-doctor; 09-19-2011 at 09:44 PM.idealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:I have TIG brazed, with a silicon bronze filler rod, lots of copper, brass, and bronze to stainless. Works fine. Copper is a lot easier than brass, especially if it has zinc and lead in it, like CDA 360 does.Copper takes a lot of amps, though. You will probably need to turn your welder up all the way.I would start the arc on the stainless, feed in silly bronze, and wash it down onto the copper.
Reply:So I went to get silver solder and talked to a buddy at the LWS. He had silver solder and some Bernzomatic "metal solder" So I bought both to try the metal solder stuff. It was $8.99 vs $54 for silver solder.I didn't realize that silver solder requires and OA torch. I only have Oxy Propane, but he figured I could use my TIG for the heat source.The TIG brazing sounds cool I will see if I can get some of that silicon bronze rod. Now in brazing you should be melting both host metals, right? Then add rod as filler?Anyway I attached it with the "metal solder" and did a test run with water, seemed to hold up OK. I need to patch a few leaks in my copper soldering now that I have run water through it. I will test the whole thing tonight on some apricot mash I have been fermenting for a couple of weeks. AND we have peaches and plums that are alomost ripe in the garden!
Reply:Umm, no.In brazing, you heat the 'parent' metals just enough to be able to have -them- melt the brazing filler.Just like soldering, except hotter.No melting the parent materials.  (that's called "welding"    )And if the low-cost Bernzomatic "metal solder" is the stuff I'm thinking of, it is a solder that is either solid wire (may be a lead-based alloy, which you really-really don't want to use for food stuff) or an acid-core lead-based solder (again, which you really-really don't want to use for food stuff).  So not the right stuff for your purposes either way.By me, TSC has (had?) some bare phosphor-bronze brazing rods (possible also some flux-coated ones too).  Lowes and HomeDepot also have (had?) similar.You probably do want brazing rods and not "solder" there.Last edited by MoonRise; 09-20-2011 at 05:35 PM.  The best laid schemes ... Gang oft agley ...
Reply:You're making this too hard. I used compression fittings and simple gaskets to fit up a SS part on my SS still and then a compression nut on the copper line. You could even use high temp silicone instead of gasket material.
Reply:I tried with a local plumbing wholesaleer for parts to do this and didn't have any luck. I guess if I researched and found the parts I wanted then just ask/order those it would work better. My whole still is copper, made of 2" copper pipe so that is what I need to connect to the SS pot. The "metal solder seems to work. It is actually around the outside of the connection too so there isn't really any interaction with the vapour going by.
Reply:with practice it can be done ----will be Hot and Fast  Tig set just like i weld SS ,didn"t have a big piece of copper or smaller SSwas running about 120 amps my SS was toooo thinguess in .020 ,copper .045needed both the same thickness and practice practice  but could be done sorry crappy cell pics Attached Imagesidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:I'll have to give this a try. I've accidentally welded aluminum to stainless with a very brittle but ok looking weld before.
Reply:Looks like a situation where high peak, low frequency pulse welding would be ideal.Something like:Peak 180-220ABackground 5%Hz .3-.5/secHave we all gone mad?
Reply:all the amps were needed to puddle the copper  but when it did you better be ready to movethe SS  was to thin just sucked right up, with same thickness materials could run a nice bead just didnt have enough scrap copper to play with any one got some test coupons to play with would like to see more testsidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Sounds like you already got it done but there is a method I will always try in those situations.Get both materials in a round form so it can be like a socket weld. In this case I would put the stainless as the smaller insert piece. Make the socket pretty deep, flux up the parts a ton and pour lead free solder about like lead'n up a drain line cast iron part. You should get something like a mechanical joint that is leak free. Should work as long as your application is below melting temp of solder. Could use lead if you did not have a booze application. Biggest trick is how to keep the pour from leaking, a preheat and hammered tight fit up works, inner part cold, outer hot is better yet before hammering her in. Can try the packing method used in plumbing pours too. Method does work when nothing else you try does. Or you ain't got the right equipment for something fancy.
Reply:silly question - why do you need to weld the copper to the stainless?  Why not weld a female threaded stainless part to the stainless, and then use a male threaded copper piece on the copper side.miller syncrowave 250hobart handler 140home made 400 amp engine driven in progress...