spot welding questions.

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hi needed to fab up sheetmetal  this weekend and bought an expensive 240v resistance welder with just an on/off switch.  it works pretty well but i am not sure of the right technique to use.  i get that  the  idea is to  clamp the pieces together and send high current through it to melt the metal together. but  how much clamping pressure do i want?   if i am using 2 pieces of 18 ga material do i want to set the  tongs up so that when they are clamped together  (with out the material to be welded) i have a small gap?  it seems to me the dimpling i am getting on  my test pieces is from excessive tong pressure. why wouldn't i want to be able to move half of the material to be welded in and out of the tongs almost like a feeler gauge with spark plugs?  so i guess i am asking is there a rule of thumb for setting the distance open of the tongs for the thickness of the material you weld?  thks bobbobs77vet/37ford4drEastwood digital TIG200HH190Lincoln Invertec 155sLincoln weldpak 100sears/craftsman (lincoln) 50a 240v buzz boxO/A rig Harris gaugesnexion cut 50 dxchicago electric (HF) 240v spot welder
Reply:the dimpling is normal and expected. dont set a gap. if you want one side of the weld to not show a dimple,put a piece of copper on that side between the metal and the electrode.miller thunderbolt 250vlincoln square wave tig 175 prolincoln idealarc mig sp250everlast tig 210EXTeverlast power plasma 50chicago electric (hf) 130 tig/90 arcchicago electric 90 amp flux wire3 sets oxy/acet
Reply:thks i will try that , bobbobs77vet/37ford4drEastwood digital TIG200HH190Lincoln Invertec 155sLincoln weldpak 100sears/craftsman (lincoln) 50a 240v buzz boxO/A rig Harris gaugesnexion cut 50 dxchicago electric (HF) 240v spot welder
Reply:I thinks you must visit any Garage*in*your city and tell your question their and get the right solution easily.It is the best way to get rid from the problem,.scrap metal buyers brisbane
Reply:be aware that when you weld thru copper for cosmetics,the weld is not as strong as the dimpled one. copper is used in areas where appearance matters---like where the quarter panel wraps into the door opening and welds to the lock pillar.miller thunderbolt 250vlincoln square wave tig 175 prolincoln idealarc mig sp250everlast tig 210EXTeverlast power plasma 50chicago electric (hf) 130 tig/90 arcchicago electric 90 amp flux wire3 sets oxy/acet