Lou:
You are correct. I was saying that the welds you are making now (in
weldor's jargon, these are "plug fusion welds") are structurally
stronger than the resistance welds you are replacing. This is because
fusion of both thicknesses of metal takes place (if you have full
penetration) and the weld area is larger. Resistance welding properly
done is only fusing a smaller surface area (less than diameter of the
dimple you mention) and (for cosmetic reasons) is not allowed full
penetration. This process is cheaper, faster, and adequate on the
assembly line.
Another reason I would not recommend the "new" method is that factory
spot weldors use air-operated tongs which have sufficient pressure to
force the metal together and prevent arcing. Your Eastwood-Miller model
just has those levers. Pressure would be slight with longer tongs, and
some poor welds would probably result.
Your final method is the forge or "blacksmith" weld, which would likely
result in too much distortion on thin sheet metal, as you said. I think
you should stick to what you are currently doing, because it is likely
better than the original process.
Louis & Laila wrote:
>
> Ron, please correct me if I am wrong, but I believe you are endorsing the
> current way that I repair sheet metal as better from a functional aspect.
> Please allow me to further elaborate.
>
> When I remove the old fender, I drill out the spot weld with a special
> cutter that leaves the original metal intact, except for a little tip from
> the removed piece that acts as a pilot for the cutting tool. This piece is
> ground off, creating a piece of sheetmatal not unlike the factory original
> appearance. The "new" fender is removed in the same manner so that it has a
> 5/16" hole where each of the spot welds were originally attaching it to the
> donor car. The two are lined up and then held in place by clecos. I then use
> 3" "C" clamps to create a very tight fit. I then MIG weld a small lump in
> the hole till it is full. I then repositon the "C" clamps and go down the
> edge till it is done. I then grind down the lump to create the best
> "original" appearance that I can.
>
> THe "new" technique would be to remove the old fender the same way, but
> remove the "new" fender by cutting off the ataching point with a saw or
> torch, then preserve the fender by cutting through the unused portion with
> the cutting tool. This would keep the fender in as close to OEM
> configuration as possible. The two would then be straightened as best with
> hammer and dolly, cleaned of all impurities, then lined up with clecos
> (these holes would have to be welded), and then using the same technique of
> spotweldning, then repoistioning of clamps till the entire fender was
> done.Care could be taken to hit the original spot weld dimple. The welds
> created by the cleco holes could be given special attention and any welds
> that could not be made by the spot welder could be made by the MIG, and
> given special care.
>
> This taken into account, do you still advocate the MIG welding technique?
>
> I have also thought of heating the ground weld with a torch and then
> "smacking" it with a flat center punch to create a "spot weld". Of course,
> this could only be done in an area not prone to warpage. Lou
>
> > Louis & Laila wrote:
> > >
> > > Howdy all,
> > > I am wondering if anyone has had experience with the Spot Welder
> that is
> > > sold by EASTWOOD. I would like to replace sheet metal without having it
> > > obvious that the fenders have ever been replaced. My current technique
> is to
> > > remove the spotwelds with a cutter, then MIG weld a small circle in the
> hole.
> > > This leaves a lump that can be ground down, though an experienced
> restorer can
> > > see that the fender was replaced. The Spot welder is rather expensive,
> at
> > > $459.00, plus you must buy a variety of tips and pay for shipping! If it
> was
> > > "worth it", then I might give it a shot. But I would rather not spend
> that
> > > kind of money if it isn't. Lou
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