Mig Welding thin sheet

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ctwo
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Mig Welding thin sheet

Post by ctwo »

I own a HF dual mig, that's about all I know about welding...

What's the trick to welding thin sheet? I was trying to weld a bicycle fender to a small angle bracket, thicker bracket underneath and a couple holes through the fender to fill weld to the bracket (these were to replace the original rivets that held the original bracket that broke).

The fender was just melting a larger hole. Welder set to lowest MIN, 1, and feed about 2-3.

Maybe I had it on too long? My approach was to just feed the wire into the middle of the hole and let the puddle fill the hole.
Standards are so important that everyone must have their own...
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redneckalbertan
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Re: Mig Welding thin sheet

Post by redneckalbertan »

I don't know much of anything about Harbour freight welders, but here are some suggustings that may help.

Use thinner wire as opposed to thicker. Usually solid wire are availiable in smaller sizes than gasless wires so it may be benificial to get a gas kit for the welder (Not sure if the HF welders are set up to run a shielding gas). Take a quick perusal through the manual for setting information on your particular machine, but if you are just blowing holes when welding you are probably too hot. Make sure the surface is clean no rust, paint etc. As opposed to trying to fill a hole in one go try short little tacks and slowly fill the hole in. Let the material cool between tack. Once a hole has been filled in, go back and reweld it with a nicer 'bead' so when you grind it down it will look nice. I have a carbon block (weld wont stick to it) that I will place behind light metal when I am trying to fill holes, the carbon block does 2 things 1 acts as a heat sink to draw heat out of the material, and 2 supports the metal while it cools so it doesn't fall away. I have heard of guys using copper and aluminum blocks for the same purpose but have never tried either of those.

Best of luck to you, welding thin materials can be a royal pain in the butt.
david5605
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Re: Mig Welding thin sheet

Post by david5605 »

I'd say you have to get the thicker bracket hot enough to melt/weld.
Also sounds like the ground was on the fender rather than the thicker bracket.
It has to all be clean, back side of fender too, with no airspace between the fender and the bracket. The fender has to be firmly held to the thicker bracket.
You want the weld to mainly start on the thicker bracket. This may require higher amperage and just a quick wash on to the fender.

You want to pulse the trigger, don't go full bore balls to the wall and expect it to work. You want to try and do more of a spot weld approach rather than continuous weld process.

I had to weld about 40 lineal feet of expanded wire mesh to 16 gauge steel tubing. You learn real quick what works and what doesn't when you are doing a weld every 1/2" or so.

Oh yeah, I was using a real welder (Miller 210) that did nice predictable welds. :mrgreen:
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ctwo
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Re: Mig Welding thin sheet

Post by ctwo »

Hey, I think that was it! I did have the ground on the fender, and there was a gap around the fender and angle. I just envisioned that the weld would puddle up on the bracket and eventually melt the fender for a nice clean weld. Of course all the current had to go through the fender and leave the thin edges, melting away...
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
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warmstrong1955
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Re: Mig Welding thin sheet

Post by warmstrong1955 »

Something I do with both MIG & TIG, with small & thin walled parts, is run an extra ground. Basically, a ground to both, or all the parts being welded. Just depends on the setup.....sometimes everything may or may not ground, and will be grounded but changes with a little heat. Really annoying when you have two different thickness' of parts, and you start the arc on the thicker of the two, and then zap over to the thin one.....and you can't arc to it. With MIG....often no more arc, and with TIG....it keeps arcing to the thicker piece....just a longer arc. :evil:

Doesn't take much of a jumper. I have some 12 gage jumpers with alligator clips I use, picked up at Radio Shack.

Bill
Today's solutions are tomorrow's problems.
rustyh
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Location: Hornby Island, B.C., Canada

Re: Mig Welding thin sheet

Post by rustyh »

I have to get ready for work, but this just came in my e-mail from Lincoln, perhaps it will help, sorry but I haven't time to read it.

http://www.lincolnelectric.com/en-us/su ... mWldgGuide
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