I've tried the torch-quench method of shinkage you describe, not on weld
warpage but on stretched areas from large dents or on a oil canned roof or bed
sides. While I've found it will shrink metal, learning how much and where has
prooved elusive for me. Frequently I will make an improvment but then go too
much trying to get it better. What kind of luck have you had?
50 Chevy 3100
52 GMC 150
Marlene Rzepkowski wrote:
> 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.
> 1959 1 ton Apache - "Chief"
> ----- Original Message -----
> From: "Deve Krehbiel" <email@example.com>
> To: <firstname.lastname@example.org>
> 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
> > a 1/8" gap so the weld could sit low in the seam making it easier to
> > 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
> > the increased voltage, I would have to VERY quickly zip across that seam
> > I cant imagine how its even possible to get a decent result. I tried. All
> > 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
> > 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
> > the job. Good lesson learned anyway. And it WAS my first attempt at
> > 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
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959