Will this work as a "copper backing" for welding?

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I need to fill in some holes in 1/2" mild steel.  I need some copper at the bottom of the hole to keep any weld metal from sticking onto my weld table.  It would also be used to keep the initial molten puddle from falling on through the hole.  I've never done it before but I heard a piece of copper will work.  Finding a nice thick piece of copper is pricy.  So, as an alternative, could I take a scrape piece of 2" diameter copper pipe (typical thin walled stuff used in most plumbing applications) and pound down the end with a hammer making flat?  Then I thought I could maybe use that pounded flat piece of pipe as a backer for my holes that need to be welded solid. Will that pipe work?  Or do I need to go buy some thick copper plate?Thanks. "Hey I didn't come to look and learn, I came to turn and burn.... If I can't light up, I'm gonna light out!"-JodyIdealarc 250 "Fatman"MM 252MM 211 "Little boy" Victor Torches
Reply:Don't know what diameter hole you have. I don't see why it won't work as long as you keep the puddle moving so the arc won't burn thru the copper. Fill the bottom w/ 6011, then stand the plate on edge if possible and switch to 7018 and work from the lower edge of the hole to the top letting the slag(flux) run out away from the puddle. This makes it easier to clean slag out of each pass and prevents slag intrusion.                                  JMHO,                                            MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Originally Posted by mla2ofusDon't know what diameter hole you have. I don't see why it won't work as long as you keep the puddle moving so the arc won't burn thru the copper. Fill the bottom w/ 6011, then stand the plate on edge if possible and switch to 7018 and work from the lower edge of the hole to the top letting the slag(flux) run out away from the puddle. This makes it easier to clean slag out of each pass and prevents slag intrusion.                                  JMHO,                                            Mike
Reply:That's OK. I knew what you meant. What irritates me is when some folks decide to use "texting" language on forums, etc.                                 Mike  ps: I lke your signature, LOL!!Ol' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Okay, thanks Mike. The slag issue was also a question I had. The holes I have are the diameter of a quarter and about a 1/2" deep. These were old tractor tread plates that I'm using for another project but I need to fill in and grind flat the holes. I will try to 6011 then 7018 route as suggested.
Reply:use a copper  or brass pipe will work just flatten it and stab a piece of pvc to use as a handleLincoln Power Arc 4000 Thermal Arc Fabricator 252 iThermal arc 186Thermal Arc 26 tigTweeko 200 amp spool gunHobart AirForce 400WP-17V-12R
Reply:an old ceramic insulator will work just as well,  they make tiles just for this but $$$$$.  The insulators from larger heaters work great - as do the flat connectors from Roper or Americana electric stoves.When any government, or any church for that matter, undertakes to say to its subjects, "This you may not read, this you must not see, this you are forbidden to know," the end result is tyranny and oppression, no matter how holy the motives.
Reply:A 1/4" piece of Aluminum will work also.
Reply:I 2nd the aluminum recommendation..We do this at work sometimes..
Reply:I use a small slab of 1/2" aluminum for filling holes. I usually end up grinding down the backside a bit after I remove the plate, then putting a quick cover pass and re-grinding. I almost always get some cold lap in the bottom edge of the hole.
Reply:Maybe some copper bottom cookware from a 2nd hand store?
Reply:Buss bar from the scrap yard.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Sorta like these ?  They had 1/2 a 55gal drum of these...I  bought 4 pieces for $3 a pound...$21 total... They are 3/16" thick. (pretty ain't they?)I use bent & shaped pieces of copper pipe as backers for odd shapes & curves though. Attached Images
Reply:At one time, I used a spot welding tip as a backing pad (a 1" by about 5" or so cylinder of copper).  Aluminum also seemed to work well, but copper flatbar did the trick better than the latter.  Brass also works.Last edited by mb_welder; 01-05-2012 at 02:34 AM.
Reply:Originally Posted by David RBuss bar from the scrap yard.David