Deve,
You've been given great advice so far on how to do it better next time, this
note tries a little twist on how to save it this time without a total re-do.
First, warping is caused because the molecules in the metal expand on one
side (The top side where you were welding) more than on the other and don't
get reassembled back into their original place as they slowly cool. To
counteract the "set" that the steel has taken, you can apply some heat from
the back side of the original weld if you can get at the back side. If you
can only get at the top side, then try the following.
If you have an Oxy-Acetylene torch (I suppose a propane torch could also
be used but I have no experience with propane for what follows) you can
heat a small spot, then quench with cold water and the steel on the top
will suddenly cool quicker than the steel below giving you the opposite
direction of warp from the slowly cooled weld joint. Do this in small
spots, almost like tack welding, no more than an inch at a time. I use a
Rag dipped in cold water and still dripping profusely to quench the hot spot
I create. This also works for tightening up sheet metal in places that tend
to "oil can". You can heat the bulge, quench it to shrink the top side
metal and "tighten up" an area that is "oil canning".
The suggestion of using cold air to cool a weld as you go is very similar to
this. If the weld spot is cooled with air right after the weld is completed
you can better equalize top and bottom cooling and end up with less warping.
Try these techniques on a scrap piece to see the effects. Heat is a pretty
amazing force in dealing with sheet metal! Good Luck.
Dick,
1959 1 ton Apache - "Chief"
----- Original Message -----
From: "Deve Krehbiel" <dkrehbiel@kscable.com>
To: <oletrucks@autox.team.net>
Sent: Thursday, May 11, 2000 9:55 AM
Subject: Re: [oletrucks] Welding Help Needed!
> It was a flanged weld that warped so badly. I flanged it and then left
about
> a 1/8" gap so the weld could sit low in the seam making it easier to
grind.
> The location is clear across the inside bottom of the door (about 4 inches
> up).. no strength there. I will try the 80/20 mix, and spot weld the whole
> thing alternating around to reduce heat. I am using .025 wire. I will also
> try further reducing the voltage and see if that wont help.
>
> A few people (including my local professional welder) said to INCREASE the
> voltage and run the bead faster. I do not like this!! To make that weld
with
> the increased voltage, I would have to VERY quickly zip across that seam
and
> I cant imagine how its even possible to get a decent result. I tried. All
I
> get is holes in the metal. Its very frustrating and as an electronics tech
> for years, soldering wasnt anywhere near this hard. Same principle tho and
> to me, you need just enough heat. More than that is wasted. I am hoping I
> can reduce the voltage to just get good penetration and then work slower
and
> more accurately.
>
> If I use a hammer and dolly, I have to put the dolly inside the door panel
> and hit it from above.. exactly backwards from what it really needs. The
> warpage is concave and needs pounded OUT. I will try that anyway and see
> what happens. I am pretty sure tho I will be cutting it all out and
redoing
> the job. Good lesson learned anyway. And it WAS my first attempt at
welding
> sheet metal.
>
> Thanks everyone for the encouragement and advice. Please keep it coming!
>
> Deve Krehbiel
> Hesston, Kansas
> 1950 3100 * 1949 3600
> www.speedprint.com/Deves50/index.html
>
>
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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