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Old 07-29-2009, 10:11 PM
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SumTingWong SumTingWong is offline
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Default Lap welding

Okay-

After much contemplation, I think I will be lap welding my fender flares on. Pride makes me want to butt-weld the panel in place, but there's just too many places for it to burn through. Edges or end welds are a sure hole, even with two pieces of copper behind.
I have a HF two-setting fluxcore/gasless Mig welder- which at the moment the settings seem to be either "splatter" or "burn-through".
Two tenths of a second separate penetration and a smoldering hole. It's also brittle. I have made some nice welds, 80 percent of the time, but I've also spent an inordinate amount of time trying to contain the damage, and not make it look like hell.

At the moment I have neither the money or the time to buy a Henrob, teach myself to gas weld and then make it work on a compound surface.

The disadvantages to lap welding seem to be in rust, further down the road. A fatory style sealer can be applied from the inside. It's also going to mean more bondo than I'd like.

Any opinions, thoughts on this?
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Old 07-29-2009, 10:18 PM
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tdoty tdoty is offline
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Before you commit to that........flux core welding on sheetmetal is tough. Unfortunately, if you have the welder I think you do, there really isn't a way to convert it to actual MIG usage. There might be a couple of options, but they are a bit, umm, "tacky". You're right, flux core tends to be a bit brittle to work too.

Know any generous folks in the area who might be able to give ahand with the welding?

One more thing, before you commit to lapping, PM me your address, and I'll send you a nice copper heatsink. Might be a bit toough to fit to your curves, but I have never had issues with burn-through when using the "tabs" from a 350-amp fuse for a heatsink

Tim D.
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Old 07-30-2009, 06:10 AM
Bob Bob is offline
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Quote:
Originally Posted by SumTingWong View Post
...but there's just too many places for it to burn through. Edges or end welds are a sure hole, even with two pieces of copper behind.
Can't help you with the welder, but something to consider doing when welding along the edge is extending the patch past the edge and clamping a piece of scrap in the resulting corner, then run your bead out on that. Cut it off when you trim your patch.

One thing about using a coper backing, don't get it too thick as it will really steal your heat. I use just roof flashing or a squashed tube when I use a backing. Then there is very little difference between the times I use it and when I don't.

Bob
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Old 07-30-2009, 06:54 AM
ProMetalShop ProMetalShop is offline
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Hi Rob
What part of central PA. are you at ?
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Old 07-30-2009, 11:06 AM
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Hi Rob
What part of central PA. are you at ?
I think you're about an hour away.. I live just across the river from Harrisburg.
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Old 07-30-2009, 11:16 AM
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Have you considered renting a wire feed with gas, or a small oxy-acetylene torch? From my past experience with lap welds on bodywork they are a sure place for filler shrinkage which can leave a ghost line where your are welds are, even years after you thought the panel was perfect. Butt-welds are the best way to ensure a high quality job that lasts a life time.... with or without filler.

John www.ghiaspecialties.com
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Old 07-30-2009, 11:20 AM
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SumTingWong SumTingWong is offline
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Have you considered renting a wire feed with gas, or a small oxy-acetylene torch? From my past experience with lap welds on bodywork they are a sure place for filler shrinkage which can leave a ghost line where your are welds are, even years after you thought the panel was perfect. Butt-welds are the best way to ensure a high quality job that lasts a life time.... with or without filler.

John www.ghiaspecialties.com
Are small tips readily available? (in other words, are they so common that I could stand a decent chance of getting one with a rental torch)
It's my understanding that you need a small torch tip, low pressure and a some skill..
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Old 07-30-2009, 12:07 PM
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I like a 000 tip or a 00 tip in a pinch. If they don't have them where you rent I would be surprised. The skill is something you can develope and is well worth the effort.

From what I've heard, David Gardiner's video does a nice job of teaching gas welding.

John www.ghiaspecialties.com
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Old 07-30-2009, 01:52 PM
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Kerry Pinkerton Kerry Pinkerton is offline
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Quote:
Originally Posted by SumTingWong View Post
...Any opinions, thoughts on this?
Ya gotta do what you gotta do ....but I'd hate to see you do that. Especially to weld the sub panels together...

We've got several members in your part of the world. Hopefully someone will volunteer their assistance.
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Old 07-30-2009, 08:16 PM
ProMetalShop ProMetalShop is offline
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Now who on earth lives in PA near Harrisburg


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