Building up thinned automotive sheet metal

[El Sordo]

I restore old cars and trucks for fun and one of the problems I run into is dealing with body steel that is thinned out by corrosion.

For popular vehicles I can find replacement metal. But from not-so-popular vehicles such as a Rambler or an International Harvester Carry All, the sheet metal is hard to find.

So, I have been wondering if one could use metal spraying to thicken the metal and to cover up pinholes.

I have run across mentions of zinc-sprayers. But I don't know how well this works. Also I'm looking at other possibilities.

El Sordo.

 

[BuckMagnet]

Sounds like a project for custom made panels on the English Wheel. Small non structural areas could be leaded over. Been a restorer over 40 years and still haven't found the majic bullet.

 

[poncho62]

Sounds like a project for custom made panels on the English Wheel. Small non structural areas could be leaded over. Been a restorer over 40 years and still haven't found the majic bullet.

Agreed.....Corroded metal is just going to keep corroding.

 

[Toby Von Snaefell]

Always a problem.
I have not heard of a metal spray solution, but would like to know if there is one.
Seems to me there would be too much heat involved for the thin auto body metals, which could cause warpage issues.
Best solution I have found is to make a larger patch than you needed to replace the rust, to take it back to sounder metal for easier welding.
Not great, love to hear of any better solutions.

 

[PILOON]

Traditionally the method was to use lead.
I presume that acid etch prepping followed by flowing (oxy torch) some lead bar stock.
Next would be a file or 'rasp' to even things out.
BUT, today's method is called 'Bondo".
LOL, I only did the Bondo route!

As to metal spray, I did once see Eutectuic offerings that option, Pricy!

 

[Bearskinner]

You can patch or cover up anything, but really the best repair is to cut the pinhole rusted metal back to where it’s solid and replace it with solid stock. If you use some heavy rosin paper or cardboard, to make a pattern before removal, you can take it to a sheetmetal shop, and they can make you anything. Yes, your paying labor costs to someone else, but doing it the best way you can to start with, is in my humble opinion worth more than just money.

 

[Gary Fowler]

You can patch or cover up anything, but really the best repair is to cut the pinhole rusted metal back to where it’s solid and replace it with solid stock. If you use some heavy rosin paper or cardboard, to make a pattern before removal, you can take it to a sheetmetal shop, and they can make you anything. Yes, your paying labor costs to someone else, but doing it the best way you can to start with, is in my humble opinion worth more than just money.

I totally agree replace with new metal. There are flame spray build up processes, but they would surely warp the heck out of sheetmetal. They are mostly used for metal shaft repairs that are worn a few thousandth, built up, machine back to original size. There are several videos of this by a machinist ABOM79

 

[Bearskinner]

If you lay a panel of replacement metal on top of the bad area that needs to be replaced, attach them with clamps or screws, then cut thru both pieces with a thin cut off wheel. The slight gap that the cut off wheel created is perfect for welding new to old, without sandwiching two pieces over each other. Upon grinding the welds slightly ( use a stitch weld process, to keep warpage to a minimum) it’s the overlapped areas that hold in moisture and debris that create corrosion. A clean flat, butt welded piece of metal, has no place to hold moisture, and is easy to keep painted or coated, and simple to see if any rust is starting.

 

[Gary Fowler]

I saw a video of a guy doing that, He cut both pieces holding the cut off wheel at a 45 angle. Then when he pushed them together, they fit tightly.

 

[Bearskinner]

You want just enough to weld and have the weld material fill and seal without having a large gap to have to fill that way the replaced piece fits nice and tight, and doesn’t warp. The key is small stitch welds. If it gets hot, you start to get warping

 

[Gary Fowler]

You want just enough to weld and have the weld material fill and seal without having a large gap to have to fill that way the replaced piece fits nice and tight, and doesn’t warp. The key is small stitch welds. If it gets hot, you start to get warping

For sure, he spot welded about every 3" then came back and spot welded in center of each. He kept spot welding in this manner till he had a solid weld and not warping. I have never gotten into body work but that seemed pretty easy.

 

[Bearskinner]

It is easy. It also is the best way to keep heat down, although it is a little more time consuming during the welding process, it saves lots of time and effort in the finishing process. having to shrink and prep warped metal add a lot of extra effort.

 

[BuckMagnet]

I keep an air gun handy and quench it for a couple let seconds between "stitches" if needed. I always fit my patches to butt against existing metal with no gap. When you are working with 20 gauge it's easier than filling in a gap. Also use .032 wire.

 

[Gary Fowler]

I keep an air gun handy and quench it for a couple let seconds between "stitches" if needed. I always fit my patches to butt against existing metal with no gap. When you are working with 20 gauge it's easier than filling in a gap. Also use .032 wire.

Do you mean .023 wire?

 

[BuckMagnet]

My bad, yes .023. was overheated yesterday here. Set a record. 97 and humid.

 

[Gary Fowler]

You must be close by to me. IT was 97F at 5PM Saturday evening. It cooled off to 93 Sunday at the same time. Today at around 2 Pm it is 90F. It has been cloudy all day so it is holding down the temps a bit.

 

[Bearskinner]

I restore old cars and trucks for fun and one of the problems I run into is dealing with body steel that is thinned out by corrosion.







El Sordo.

Do you have any pictures of of your replacement made panels, or areas that need rebuilt?

 

[Bearskinner]

This has been a while, did you take pics of the work you performed? Is the job all completed?

 

[PILOON]

To prevent warpage while welding thin stock there is an aviation product called 'Clickos' , tiny spring loaded fingers devices that you insert in (usually) 1/8" pre drilled matched holes. They firmly hole the metal sheets (patches) together as you weld your way along.
Weld up close, remove next one and so on. Keeps everything aligned and greatly deters warpage.
While in aviation rivets are used they work very well for welding as well with minor grinding and then Bondo or lead finish.

 

[Bearskinner]

I’ve used those while over laying panels, it makes it very easy to place a panel right where you need it. If it’s in an area like over the wheel house or alone the rocker panels or aprons, I like to take them out a couple at a time, use a cutoff wheel, and cut thru both panels, then weld ( slow stitch welding) them together so both front and back can be ground and finished off. By doing the butt weld instead of an overlap, it keeps the panels flat, without the overlap, which always seems to hold moisture and road crud, which starts the rust issues all over again.

The Clicko’s are a great way to align the body lines to start the work though.