[tibalda]

I just replaced the lower section of my left fender. I tried to be very very careful. Before I started I made a template to be sure I maintained the same shape. I also created a guage for the curvature of the fender to make sure the curve was maintained. I even left the back edge to help make sure I had a good fit. Even after all that I messed up and the bottom of the fender is about 1/8 " too short. The rest of the fender fits fine. I am puzzled why I messed that up, especially since I kept the original edge.

Oh well i will try harder next time.
Art

 

[Pack_Rat]

Did you have to do any repairs to the brace behind your patch? I would have thought the brace would keep it from shortening up.

The first picture looks like there might be too much curve in the bottom of the fender at rocker height, but it's hard to tell.

Maybe post a picture from the same angle as the "before" shot.

Ernie

 

[tibalda]

Did you have to do any repairs to the brace behind your patch? I would have thought the brace would keep it from shortening up.

The first picture looks like there might be too much curve in the bottom of the fender at rocker height, but it's hard to tell.

Maybe post a picture from the same angle as the "before" shot.

Ernie

I didn't repair the brace and that is a good point why the new piece should not have changed the fitment. I think i can eliminate half that gap by lowering the back of the fender. I added pictures but it is hard to judge. There was some damage under the fender where the brace from the inner well bolted to the fender but not sure that mattered. I am going to chalk it up to experience.
Thanks for responding.
Art

 

[stoveboltgeek]

The filler wire shrank as it cooled and pulled it closer together.

Clamp the pieces together, and put several tack welds across the gap. Once you have that done, smooth out the tack welds as needed. If it's still aligned properly, then you can run your bead. If not, cut the tack welds loose and try again.

 

[tibalda]

The filler wire shrank as it cooled and pulled it closer together.

Clamp the pieces together, and put several tack welds across the gap. Once you have that done, smooth out the tack welds as needed. If it's still aligned properly, then you can run your bead. If not, cut the tack welds loose and try again.

You think it would shrink that much? I was trying to be careful with heat and it didn't seem to warp that much. I appreciate what you are saying. I think that with adjusting the alignment and then adding some material I can get it to line back up. I am trying to get a better handle on the problem as my next adventure is a lower door skin and frame and I know I have plenty of opportunity for mistakes there.

Thanks,
Art

 

[Rick_L]

The filler wire shrank as it cooled and pulled it closer together.

Clamp the pieces together, and put several tack welds across the gap. Once you have that done, smooth out the tack welds as needed. If it's still aligned properly, then you can run your bead. If not, cut the tack welds loose and try again.

If you do that, it's just going to shrink again. Also, from the photo it looks like more than tack welds.

To really fix it, cut the patch off the fender (can be on the new weld or a bit away from it) with a straight cut. Weld a 3/8" or 1/2" strip of sheet metal to the patch, then finish grind the weld. Now you can mark it and trim it. Don't leave a gap, the pieces must butt perfectly. Now you can weld the patch back on the fender.

 

[Custer55]

Make sure the fender is aligned with the top edge of the door, cowl and the hood. If it's still off put a straight edge or string on the bottom of the rocker to make sure it isn't off where it meets the fender. If it's still off your optipns are to add a piece to the bottom or cut a slice in the fender, get it lined up and tack and reweld.
A friend of mine had the opposite problem. His fender was a half inch to long at the bottom. Unfortunately for him he never test fitted the fender until it was painted and was doing final assembly.
That was a big oops.

 

[angs1957]

Double check the mounting of the fender, like others have noted see if the top alignment is correct, if its still short you have two options, splice and add a piece in between or add a piece at the bottom.

 

[oldguysrule]

I doubt if the original body tolerances were kept to a 1/8 inch.

 

[stoveboltgeek]

You think it would shrink that much? I was trying to be careful with heat and it didn't seem to warp that much. I appreciate what you are saying. I think that with adjusting the alignment and then adding some material I can get it to line back up. I am trying to get a better handle on the problem as my next adventure is a lower door skin and frame and I know I have plenty of opportunity for mistakes there.

Thanks,
Art

You're not understanding what I'm saying. I'm saying that when butt-welding sheet metal and you leave a gap when you start, the gap will often close up in the un-welded sections as the weld cools. You can start with a 1/16-1/8" gap, and the sucker will close right up to flush as it cools. (ask me how I know!) Hence, clamping not only keeps things aligned before you start the weld, but also as it cools.

Eastwood sells these special clamp thing-a-ma-bobs that go between the pieces of sheet metal to keep the gap correct during the initial tack welding. I never bought them, but I think they'd be handy if I did a lot of welding.

When MIG welding, you'll often get a bit of warpage where the metal warps away from you as it heats and cools. That's a separate problem.

 

[tibalda]

Thanks for all your responses. I am certainly appreciating that there is a lot to learn. I don't have a picture of the gaps in my patch panel. The top was very tight - too tight for those Eastwood clamps (which I do have). The back side was less tight after I got the front edge aligned and enough to fit those clamps so I could see shrinkage there - although I would have thought that would be more front to back and not on the bottom. I did cool my welds as I went - trying to follow suggestions on avoiding warping. Did that work against me? The shrinkage angle makes the most sense. I am going to try aligning the fender to see how far that gets me and if not satisfied do as Rick_L suggested and redo the seam (although not looking forward to it ).

Thanks again..
Art

 

[LEE T]

I did cool my welds as I went - trying to follow suggestions on avoiding warping. Did that work against me?

Yes

 

[55wagoncrazy]

Yes when the metal is super heated by the weld, it will expand. When you force cool it with air it causes the metal to shrink... there in lies
the problem. Usually you can control the heat by just using less air pressure and from a further distance. Remember this because there will
be times when you want to shrink the metal.

 

[tibalda]

Ok another lesson learned the hard way - youtu.be videos aren't always right. I am usually suspicious of them but cooling was recommended by Sylvester shop and the Make it custom guy who promoted cooling the weld and thought they would be reliable.

I was thinking of trying a "tack" setting on my welder. I ramped up the heat and wire speed and it runs very quick but leaves a small tack with good penetration but limited hot zone. I am trying to get the courage to start my door skin and want to do the best I can to limit warping. Any opinions are appreciated.

Art

 

[stoveboltgeek]

I am trying to get the courage to start my door skin and want to do the best I can to limit warping. Any opinions are appreciated.

Art

My opinion - keep practicing a little bit more before you do the door. You're getting the hang of it, but a little more practice with scrap metal on forming and welding. Doors can very easily warp and make a mess. You want your skills to be really good first.

 

[Rick_L]

I am usually suspicious of them but cooling was recommended by Sylvester shop and the Make it custom guy who promoted cooling the weld

"Cooling" the weld does nothing one way or the other. The weld cools no matter what. It's the rate of cooling that's debated (water, air blast, or just air over time) - and it does not matter what the rate of cooling is. The only thing that varies is how long before it's cool. You can use that to your advantage, faster cooling lets you see what you have sooner.

 

[Custer55]

Anytime you weld metal there is going to be shrinkage. There is no way to avoid that. Making quicker tacks with a smaller haz (heat affected zone) helps control the shrinkage a bit. Try to make your seams in area that allows you to planish out the seam. That is how you elininate the shrinkage. It's not always possible to planish the seams though because you won't have access to both sides of the seam. In those cases just do the best you can to keep the haz as small as possible and keep unavoidable shrinkage in mind when fitting things up.
It's not easy and I'm sure I will never completly figure it out.

 

[tibalda]

I practiced using the "tack" setting on my welder and I think it looks good. I had to turn the welder settings almost to the top end and that's running with 240V.. it isn't showing the shrinkage my other technique. I am going to try it out and hope for the best. I was also able to align the fender a bit better although not perfect. I may try to coach it a bit more.

Pictures attached. Thanks everyone for your help.

Art

 

[Vintage Iron]

I would suggest practicing tacking 2 pieces of metal together instead of just dropping a tack on a solid sheet of metal. Will give you a much better idea of what it takes to not blow through and also an chance to tweek spacing for finding the best gap for best penetration.

 

[55 Tony]

I practiced using the "tack" setting on my welder and I think it looks good. I had to turn the welder settings almost to the top end and that's running with 240V..
Art

My mig is a small 120vac unit and I tack sheet metal using its lowest heat setting. I butted it up tight, no need for a gap for penetration.