Filling a hole on aluminum with Tig

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I want to practice filling a hole on an 3/8 aluminum plate, hole is 1/4". I was told to use a copper backing plate. Will the copper cause problems and introduce contaminants while filling the hole? Thanks for the feedback
Reply:you can use carbon or copper and no it will be fineMiller Xmt 350Lincoln Ln-25Ahp 200xSmith Gas Mixer AR/HTig is my Kung FuThrowing down dimes and weaving aboutInstagram http://instagram.com/[email protected]
Reply:Great! Thanks for the info!
Reply:Why would u need a backing to fill a 1/4" hole is my question.I forgot how to change this.
Reply:if you can't access the back to weld that side and are inexperienced in doing it from one side. I have the technique down pat with mig from filling over a hundred holes in the back of a guys boat that bought all new gadgets every year and filled the old holes with silicone.Dynasty 200DXPassport plus w/ spoolmate 100victor 315c oxy/(act and prop)Miller digital elitemilwaukee power tools
Reply:I am repositioning the spark plug location on a small gas engine. I am hoping not to do any machining inside of the cylinder so I want to prevent the filler from going into the combustion chamber. I can lathe myself a brass plug, similar size as the piston and have a similar dome shaped area to back up the current spark plug hole. I will practice on a plate with holes and hopefully learn from it, then maybe I will try it on the actually part. The cylinder itself is new but since it aluminum casting it might give me some problems.Last edited by vicrc; 12-11-2012 at 03:20 AM.
Reply:Originally Posted by vicrcThe cylinder itself is new but since it aluminum casting it might give me some problems.
Reply:Hey Zap, its okay its only a spare cylinder head, around $30 a mess. I fully understand it might not go so well but I can make more holes on the sacrificial one before deciding to do try it on another spare. Its worth the try and the rewards outweighs the cost and the experience whether good or bad result is still an experience.
Reply:Cast aluminum sucks. I don't have balance settings on my machine, but the time I had to weld a piece of cast aluminum and got awesome results. I wire brushed it, hit it with a propane torch, then threw in my powder coating oven at 375-400* for about 20-30minutes. Then wire brushed it again. Did a light pass with no filler, more wire brush then welded with filler. Zap did 2 small holes on a manifold IIRC. After cleaning he dropped some filler around the holes until they got smaller and smaller. Maybe try that.A pic would really help.Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Copper backer would work well.  Stainless backer is another option.  Aluminum won't "stick" to either.  Welding from both sides is also an option.  If you are skilled enough with torch control, you can make the inside surface very close to flush (or so it requires a mininum post-weld work.)  If you are welding with a backer, I'd extend the tungsten down pretty deep into the hole.  Also, let the pre-flow run for kind of a long time to get a good purge going down into the hole before the arc starts.  You will probably need to use a lot of amps.  A helium mix may be good.  You may need to bevel (e.g., cone shape) the top of the hole to allow slipping filler rod by the tungsten to reach the initial puddle at the bottom of the hole.  Once you get a puddle started properly, it should be cake.  Welding from both sides may be easier.