Pot Metal Welding. Anyone done this or had it done?

[Bloo]

The title says it all. Has anyone done this themselves or had someone do it? I have become aware we have a forum member who can actually weld this stuff. Previously I had only heard of soldering it with Muggyweld or something similar. A real weld would be a lot stronger I think.

 

This is the base a 36 Pontiac left tail light. It is the more common late 1936 round one, not the seldom seen teardrop. The damage is from my little off road incident in Montana a couple years ago. I did not realize how bad this was broken before I took it off of the car. I have been unable to locate this, or the diecast piece up on top of the light that holds the license bracket. If anyone happens to have those parts or a whole good tail light, my want ad is here. The broken parts are similar to Buick but not quite.

 

You can see the problem below. Actually the right side is also missing a little bit of metal, so I could use one of those also, but is not broken in two like this. It is much less of an issue.

 

 

 

 

 

 

[John E. Guitar]

I've seen a guy repair an old Volkswagen part (door handle?) with a low pressure oxy/acetylene torch. I think it was a Henrob/Cobra. He had a second door handle he melted down to make filler rods with so it was the same blend of pot metal. He also built up a kind of mould around the parts with a high temperature putty like Eastwood Anti Heat Compound.

 

It worked really well. This was at a metalshaping event. I'll see if I can find photos of the process.

[Guest]

I have used this business for pot metal repair, Jim does great work:

 

James Ruther 

7076215052

James@potmetal.repair 

https://potmetal.repair

Pot Metal & Antique Spelter welding,
Modification and investment casting. 

 

[wayne sheldon]

"Pot metal" is such a catch-all generic term that it really doesn't say what an individual part might be. I have successfully welded a couple of die-cast zinc pieces.

I don't recall what I used for a flux? It may have been sal ammoniac, or not? I still have a block of it in my welding supplies, but haven't used it in thirty years or more.

Sal ammoniac is more commonly used to maintain soldering irons

 

On a couple other occasions I have failed miserably at attempts to weld pot metal. Whether or not it can be welded depends upon the metallic chemistry of the particular mix of "pot" metals. Chemistry was never one of my strong subjects. Many common early blends had a bad mix of metals that would slowly self destruct due to incompatible metals in the mix. Most mixes after the early 1930s began to minimize that problem. Later pieces are more likely to be weldable.

 

Welding soft metals is quite different than welding steel or iron. I have welded quite a bit of brass over the years! Very tricky, but can be done with an oxy acetylene torch. Usually, a form must be made because the temperature difference between "not hot enough" and "oops it all just flowed away" is a very narrow range. It the piece being welded isn't supported by a form of some sort, it most likely will vanish before your eyes.

Die-cast, zinc, or pot metal I suspect will be just as bad in that regard.

For brass, I often make a form around the broken piece out of plaster. Allow the plaster to dry thoroughly for a couple days because any residual moisture inside will explode the form when it gets hot! When welding, the torch will burn the plaster away a bit, but if thick enough it should continue to support the piece. Very carful use of the flame can minimize burning away the plaster form.

 

If I were to again try to weld a pot metal piece? I would approach it in a similar way.

Like with many such tasks, there is a learning curve. Spend an hour or two practicing on worthless pieces before attempting anything you hope to ever use. I would also suggest doing a bit more research on metallurgy and the best fluxes to use for clean mixing of given metals. All metals and fluxes are not the same!

When I weld brass? I use common fluxed brazing rod from the local welding supply store. For brass, it has always worked very well for me, allowing old and new material to flow together cleanly. Brazing rod of course is not appropriate for die-cast zinc or pot metals.

[ron hausmann]

All - for non stressed pot metal pieces, like cowl lights bases, vacuume tanks, etc. , I have used JB Weld very successfully to “weld” pot metal pieces together. And it can be worked and painted like fiberglass. On parts that I tried this method on ten years ago, like my Stewart vacuum tank on my 1923, it’s staying put and looking great!

Ron Hausmann P.E.

[EmTee]

@MCHinson recently repaired a broken horn ring.  Hopefully he will chime-in, as I can't find his posting on this topic.  I recall he found a heat gun worked better than a propane torch for melting the pot metal solder rod.

[MCHinson]

As I recounted in a recent Torque Tube II article, I repaired a broken pot metal 1937 Buick horn ring with Muggy Weld's product:

 

https://www.muggyweld.com/product/super-alloy-1/

 

I read about it somewhere on the forum if I recall correctly. When I broke the horn ring in a misguided attempt to buff it, I went to their website, watched their videos, and ordered the product. The videos looked too good to be true. When I first started to use it with a propane torch, I wasted most of the first rod before I figured out I had the heat too high and I was being too agressive. One of their videos used an electric heat gun rather than a torch. I had one of those that I had previously used for some paint stripping.  I tried the heat gun and was almost immediately successful. On this product, less heat works better than more heat and when you get the hang of it, it does look almost too good to be true, but it works great. I think it will solve your problem with that piece. I think it will be plenty strong for that repair. 

[Harold]

Just a half-baked thought....is there a way to create a new part by 3D printing?

[dodge28]

This fellow in Australia does reproduces lots of parts in stainless steel. Not cheap. vintageproductions@bigpond.com   or try getting to them by Cindy Meyers Dodge. Phone  Mark Henry 416 661 3964 for information. He did the windshield crank for the 28 Dodge windshield for me.

[Fordy]

1 hour ago, dodge28 said:

This fellow in Australia does reproduces lots of parts in stainless steel. Not cheap. vintageproductions@bigpond.com   or try getting to them by Cindy Meyers Dodge. Phone  Mark Henry 416 661 3964 for information. He did the windshield crank for the 28 Dodge windshield for me.

You may be thinking of vintage and classic reproductions in Queensland. Frontpage - Vintage & Classic Reproductions (vintageandclassicreproductions.com)

If they can't help, go the 3d printing the scanning and fixing faults is affordable and printing direct to metal is also getting cheaper.

Steve

 

[Jubilee]

For me, that would be a fiberglass repair. Looks like plenty room inside for fiberglass.

I’d make a locating plate attached to part with coupling nuts and bolts to allow working behind plate and hold broken part in place.

[californiamilleghia]

A couple questions on pot metal  , 

I assume its the same as diecast which is a Zinc mixture  - also called Zamak.

 

I would think one of the problems welding pot metal is getting a clean surface and I do not know how you would get the chrome plating off something like a door handle at home . 

 

 Muggy weld and the stuff they demo and sell at the swap meets is soldering not welding .

 

 

[Bloo]

Thank you everyone for the responses!

 

19 hours ago, John E. Guitar said:

I've seen a guy repair an old Volkswagen part (door handle?) with a low pressure oxy/acetylene torch. I think it was a Henrob/Cobra. He had a second door handle he melted down to make filler rods with so it was the same blend of pot metal. He also built up a kind of mould around the parts with a high temperature putty like Eastwood Anti Heat Compound.

 

It worked really well. This was at a metalshaping event. I'll see if I can find photos of the process.

Thanks, I would appreciate seeing that. I don't have a Henrob, but I'm pretty good with a torch.

 

@Writer Jon, That is the guy I was thinking of. I'll be contacting him shortly.

 

11 hours ago, ron hausmann said:

I have used JB Weld very successfully to “weld” pot metal pieces together.

That was going to be the next step If it can't be welded, probably JB weld and some screen for strength. I didn't want to go there if there were some chance of welding it. A license plate is supposed to be up on top, so it needs to be pretty strong.

 

10 hours ago, MCHinson said:

As I recounted in a recent Torque Tube II article, I repaired a broken pot metal 1937 Buick horn ring with Muggy Weld's product

Is it holding up well? A horn ring is pretty highly stressed.

 

9 hours ago, Harold said:

Just a half-baked thought....is there a way to create a new part by 3D printing?

Probably. @Fordy has made problem castings that way. It would probably require several people needing the part. I wouldn't rule it out.

 

5 hours ago, Jubilee said:

For me, that would be a fiberglass repair. Looks like plenty room inside for fiberglass.

I hadn't considered that. I wonder if it would be any stronger than epoxy like JB weld?

 

5 hours ago, californiamilleghia said:

A couple questions on pot metal  , 

I assume its the same as diecast which is a Zinc mixture  - also called Zamak.

Yes, sort of. Unlike Zamak, it is probably not specifically formulated to make a good casting. A lot of it is utter crap, and the older it is the worse the alloy probably is. Sometimes it breaks on it's own by expanding and pushing itself apart. Fortunately, my parts do not seem to have that problem. The lower casting broke after an off road excursion trying to miss about 30 deer. The upper casting was already broke and missing pieces when I bought the car.

 

 

Edited October 3, 2023 by Bloo (see edit history)

[MCHinson]

1 hour ago, Bloo said:

Is it holding up well? A horn ring is pretty highly stressed.

Yes, it works fine. It feels like it is just as stong as it was before I stupidly broke it with the buffer.

 

The trick is basically, less heat rather than more heat, with the heat applied indirectly, heating the part, not the solder. As soon as I figured that out, it worked easily and quickly. 

[dodge28]

Fordy, yes I bought lots of reproduction parts from Australia for my 1928 Dodge Senior. Without them I would have had to send my car to the scrap. Inner and out side door handles and rob rails to name a few, They even cast in aluminum and pot metal

[dodge28]

Bloo, this message is for you and those interested. There is Tig welding that welds almost all kinds of metal. Welding pot metal with a oxi acetline torch require lots of skill, practice and patience. (you cannot buy patience  in Wall Mart) how to control your torch heat, the secret is in your wrist, takes lots of practice.  Over fill the spot then grind down to required level. Chroming guys knows how to remove existing chrome. I cannot remember the name of the company that sells a triangular shaped aluminum based welding rod . The salesman was welding pop cans using  a propane torch. Good material to weld pot metal. In this case the host material does not need to be heated to melting point, Just enough to melt the rod which has a low melting point. This material can be filed and chromed.  This company is US based and is very popular with restorers, at the moment I cannot remember the name

Harry.

[Laughing Coyote]

Maybe?

 

https://www.amazon.com/Professional-Plastics-Ceramics-High-Temperature-Resistant/dp/B0BQ9C6BGL/ref=sxin_16_sbv_search_btf?content-id=amzn1.sym.5795aee5-71f0-4369-b632-e8c78407f2cf%3Aamzn1.sym.5795aee5-71f0-4369-b632-e8c78407f2cf&cv_ct_cx=welding+pot+metal+repair&hvadid=557272872656&hvdev=c&hvlocphy=9030220&hvnetw=g&hvqmt=e&hvrand=8772488946174487234&hvtargid=kwd-323297201480&hydadcr=7664_13469239&keywords=welding+pot+metal+repair&pd_rd_i=B0BQ9C6BGL&pd_rd_r=2fb942a1-2511-4772-b758-6410c84a47f7&pd_rd_w=e6poz&pd_rd_wg=lZ3Xt&pf_rd_p=5795aee5-71f0-4369-b632-e8c78407f2cf&pf_rd_r=ET39RNA7K6JFHBCQ5XHJ&qid=1696388022&sbo=RZvfv%2F%2FHxDF%2BO5021pAnSA%3D%3D&sr=1-1-5190daf0-67e3-427c-bea6-c72c1df98776

[wayne sheldon]

4 hours ago, dodge28 said:

Welding pot metal with a oxi acetline torch require lots of skill, practice and patience. (you cannot buy patience  in Wall Mart) how to control your torch heat, the secret is in your wrist, takes lots of practice.  Over fill the spot then grind down to required level.

 

This is similar to how I do delicate brass pieces. Over-fill then file to size. One of the first pieces I did several years ago was a model T Ford one year only brass steering gear case cover. The earlier brass era ones (1909 through 1914) have been reproduced for many years, and repros are readily available. 1916 through the end of production are basically two styles, both made of steel, and most originally nickel plated. However the 1915 (and some 1916s) gear case covers were in the shape and design of the later steel ones, but cast in brass.

They were reproduced for awhile some years back. Even reproduction ones are tough to find. Originals are almost unobtainable. I managed to grab one over thirty years ago, and haven't had a good opportunity to get one at a reasonable price since. The one I bought was stuck on a junk steering column. Someone had tried to use a cold chisel to force it to unscrew from the steering gear case. They failed. It was still very stuck, all they managed to do was cut four chunks out of the outer rim of the case cover (plus a few added extra gouges!)!

A very big (blacksmith's) vise, a large "strap-wrench", and several days of heating and freezing and penetrating oils, and I got it apart. Then it was just a matter of trying to make it look decent.

My first attempt was to bury the cover in wet sand. I had managed to weld some brass before, and was well aware of its propensity to melt and disappear. Not wanting to in any way risk losing such a rare part, I was trying to support the case in wet sand to support the brass as well as cool the majority of the cover and avoid excessive melting. However, before the area to be welded got hot enough, the wet sand around the welding area had dried and was being blown away by the torched flame/wind!. I could see disaster on the horizon, so stopped before any damage was done. 

After some thought, I decided to use casting plaster that I had gotten from a garage sale some time before. I left the majority of the cover in the sand as before, exposing over a half inch of the area to be welded above the sand. Then added the wet plaster filled to just short of the area to be welded.  I then allowed it to dry for a couple days. 

Then I began welding the bad chiseled out spot. It came out rough, but maybe passable. Repeated the process on another bad spot. The second one came out better. It took about two weeks with all the plaster drying time, but by the time I got to the last spot, I was ready to make the first one a bit nicer. I found that overfilling and then filing down was the way to go.

Once I had it all filed to shape, I used a sharp file and a center punch to fake the missing knurling around the edge. A difficult crosshatch pattern, but from just a few feet away, my original part looks great!

Since then, I have welded several other brass pieces using the same technique. And that is not counting the three brass headlamp rims with about twenty stress cracks each that I welded for my car (two plus an extra for a spare). Eight years later they still look fine. For the thin headlamp rims, I bent 1/16 inch strap steel to shape to support the thin brass. Don't get the steel hot enough for the brazing rod to adhere to it, and the thin brass welds fine AS LONG AS it doesn't get too hot! A few degrees too much, and once again it disappears before your eyes.

[Chris Bamford]

For the subject taillight repair, my inclination would be:

 

Step 1. A skim of JB Weld on the joining surfaces and clamp securely in desired position until the JB has cured. 
 

Step 2. An interior reinforcement of some kind… probably heavy sheet metal roughly contoured to bridge the inside surface. This is liberally JB Welded in place and allowed to cure. 
 

Step3. Trim off external squeeze-out and refinish to taste.