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mrcleanr6 10-08-2004 05:56 PM

shaving handles
 
i recently had 2 cars in the shop that both needed shaved handles. i have seen someone that didn't know what they were doing do it before and nearly ruined the door. it was caved very bad from the heat (i assume). anyway, i had a buddy of mine come over to mig weld both cars. he knows he had to keep it cool so he went slow only tacking a couple spots at a time until it was welded all the way around. the damn door still dented in. not real bad but bad enough. about a 8x8" area which i was able to work back out. the second car he did the same thing but only tacked it every 3/4" or so. wouldn't you know it, the damn door still dented in. he would only do 2 tacks at a time then cool it right away with the air compressor. is there some kind of secret here or something i am missing?? whats the trick??

BarryK 10-08-2004 06:06 PM

This is not my expertise at all BUT I have helped the students at a tech school do about 7-8 of them over the last couple of years.
What we are doing to avoid the problem you had is BONDING a piece of metal in stead of welding. Than we grind with a 24 grit
spray two coats of epoxy and finish out from there as needed over the epoxy.
Long term this has held up good.
Like I said this is way above my skills so beware of above advice!

MARTINSR 10-08-2004 07:26 PM

There are some killer places for bonding adhesives in customizing, that is for sure. If you do, bevel the edge of the metal,that will lesson the chance of a "ghost line".

If you are welding a hole, filling the hole with a piece of metal and then butt welding the seam, you can control it as you weld and end up with little to no warpage. But if you were to weld a piece OVER a recessed area like with a 1990ish Toyota pickup, you REALLY, REALLY have to go slow.

I have done that a few times, do you know how long I take to weld it? How about a DAY, that's right, I would take a day to weld it up. Two or three small tacks and then let it cool completely down. I mean cool enough to put your tongue on it and feel no heat. If you weld it that slow, you will be successful.

sevt_chevelle 10-08-2004 08:37 PM

I think the problem is cooling with air right away.
For me that leads to nothing but problems. If you allow the weld to cool by itself, no compressed air or water, warpage is lessened...Eric

Ron M 10-09-2004 12:34 AM

If it pops in and out, I believe you have oil canned the metal. I have ran into this at work while metal finishing many times. The best solution I have found is to find the area of stress and stress relieve it. The metal is probably stretched at some point. I am in the process of working at heat shrinking techniques. Since I am no pro bodyman, I am using 3M metal adhesive (part #8510) for just this type of work. Wish I had more info for you.

Dubz 10-09-2004 12:43 AM

i warped 2 panels on my car welding in patches by cooling the metal down too quickly. After i stopped cooling it down i had no warpage problems at all, even with a higher heat setting on the mig.

mrcleanr6 10-09-2004 07:04 AM

i originally wanted to use adhesive but was talked out of it. i figured welding would be a better approach but since everyone is recommending the adhesive thats what i'll probably do from now on. just out of curiosity though, i'm going to have to try welding one more time and letting the door cool naturally. thanks everyone for all tips!!!

troy-curt 10-09-2004 07:53 AM

??????????, After the first dozen, I do them just like you are doing, works for me. Weld and cool, weld and cool with air.

Troy

BarryK 10-09-2004 09:15 AM

Quote:

Originally posted by mrcleanr6
i originally wanted to use adhesive but was talked out of it. i figured welding would be a better approach but since everyone is recommending the adhesive thats what i'll probably do from now on. just out of curiosity though, i'm going to have to try welding one more time and letting the door cool naturally. thanks everyone for all tips!!!
*********************************************
********************************************
Forgot to tell you, if you bond after the adhesive dries grind any excess that seeped out off. Never want any filler touching this stuff.
BWK

Ron M 10-09-2004 10:13 PM

Barry,
I have to ask. What happens if some of this adhesive comes in contact with filler? I have some small holes where I used adhesive to bond sheet metal plugs and it worked its way to the top of the hole. I have not sanded that area yet, and I was hoping that I could finish that adhesive flush and primer over it. But what if I needed a skim coat of filler? What is the correct way to do this? Thanks in advance.

I just wanted to add that I read your last post, but the problem is that these holes were embossed from the old trim, so they are somewhat lower than most of the surface. So I am thinking even if I grind it, there will still be some area of dried adhesive that could make contact with the filler if needed.

mrcleanr6 10-10-2004 06:26 AM

some of the adhesives like the acrylic type use an acid as a catalyst. this is the same reason you dont put bondo an top of self etching primer. best thing to do is scuff up the adhesive as much as possible and spray a little epoxy primer on it then when cured put your filler.

BarryK 10-10-2004 11:37 AM

If you have a metal patch and grind off the adhesive to the edge, its so minor that no problem will occur.
A pinhole is not going to be a problem either.
So anytime you are unsure before applying a polyester type product spray a barrier coat IE; epoxy or 2K primer.
Two reasons why, The adhesive has a different expansion rate than the polyester so after a while the polyester cannot keep up and will lose adhesion and look like a large solvent pop bubble.
Thats why hood scoops fail to last.

Next reason is a two part liquid polyurethane such as Duramix or Pastomix is not porous and waterproof so the solvent from the polyester when transferring under normal expansion and contraction have no where to go and the polyester will again lose adhesion and bubble.

Now some of the lower end acrylics such as Fuzor and maybe 3M say you can apply filler to theirs. But would never chance it on a flat surface such as a hood. Sides maybe.

Ron M 10-10-2004 10:42 PM

On some areas that I filled some quarter inch holes, the adhesive ended up slightly above the surface. I planned on grinding flush, DA and epoxy prime over. Is that going to be OK? I used 3M 8515 adhesive. Will it show down the road? The areas are on the side of the fenders and one on the roof post. After reading about movement on the last post, I wonder if this could be a real problem in a climate that goes from 100 to -30. I store my car in an unheated storage in the winter.

Randy Ferguson 10-10-2004 11:13 PM

I thought you guys were paying attention!!!!
The welding process caused metal to shrink. PERIOD!!!!
cooling with air, water, or waiting all friggin day isn;t going to have much effect on the outcome. I prefer to cool the weld seam, if need be, with compressed air. It doesn't give me any problems, and you are better off cooling quicker rather than letting the heat migrate further into the panel than need be. If you will always make butt welds and work the weld seam, only along the heat affected zone, your problems will be eliminated. There's absolutely no reason to use adhesives. That's a cheap, production body shop, get in/get out method. Do it right the first time and forget it!!

Randy Ferguson
Ferguson Coachbuilding
www.metalmeet.com

MARTINSR 10-10-2004 11:28 PM

Quote:

Originally posted by Randy Ferguson
and you are better off cooling quicker rather than letting the heat migrate further into the panel than need be. Randy Ferguson
Ferguson Coachbuilding
www.metalmeet.com

I have to admit Randy, that does make total sense. :welcome:


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