Welding Cast Iron

Okay...please note...I am not a professional welder, but this has worked for me in the past. I have an old Ford square baler that uses Cast Iron "needles" for the twine. My baler got out of time and broke both of these. First off, I bought a new set. Within a 100 bales these broke again. I carried these to a local welding shop and was told that it was going to cost as much to have them welded as a new set. Talked to a retired welder and this is what he told me.

First off....get some agriculture lime. Use a disposable Turkey Roasting pan that you get at a big box store. Put as much lime in this pan as it will hold. Put it in the oven at 350-400 degrees and let it sit there for a couple of hours. I stir it about half way through the heating process. Remove this just before you are ready to weld.

I am using a Lincoln Cracker Box welder AC only. (DC would be better, but this is what I have.) Did the normal prep work by cutting some recess bevels on the pieces. I used a small propane torch to heat the pieces. Use NICKEL rods to do the welding. These are normally coated with black flux. They are not cheap. Adjust welding amps to where you get a good bead. Weld the pieces together. As soon as you are finished, cover these with the HOT lime. This lime will help the pieces cool slowly. The next day remove the pieces and do the clean up with your grinder/flap wheel. Check the welds for voids/pitting. If you need to re-weld / fill in the gaps....repeat the above process. The lime will help dissipate the heat evenly and prevent it from cracking at the welds.

I used this process to weld the needles on the baler. This was 10 years and about 15,000 bales ago. Worked!
 
One-match fire said:
Over the past several years, I have been fortunate to be able to break some cast iron parts for things I was moving from where they were to my shop where they are now.
I was told that the only good way to weld these parts back together was TiG. Does anyone have anything GOOD to say about this? I would really like to get these parts repaired.

Two of the parts involve a large hand-spinner for collecting honey. The spinner fell while in transit and broke not only the handle but the plate gear that actually drives the spinner. I have kept these parts in hopes that I would eventually become "less afraid" to try to weld them back together. The handle isn't that critical but the gear wheel seem to need some accuracy.

Does anyone have any suggestions? Recently, I sent away for some EZ Weld TiG wire from a guy on Lopez Island in Washington State. I saw these used on a video on YouTube by "Mr. TiG" and he gave them a very good review. I'd like to use them and would be interested in knowing if anyone else has any experience with them or was Mr. TiG just blowing welding smoke?

Thanx
Trim sends
Click to expand...
i have used stick,tig and braze to repair cast iron. cast is a very unforgiving material the size shape and metalurgy can effect what type of repair will work best. there are a few basic procedures that are followed by most welders they are pre heat peen and slow cool and cross your fingers you don't heat the dreaded "ping" while its cooling. for the average joe, your best chance of success is brazing followed by a tig using silcon bronze rod. there are all sorts of "miracle rods" sold for cast iron repair. before you spend your hard earned money talk to some professional welders.
 
I've had good luck with Invar 42 nickel/iron tig rod . The new cast iron fire pot welded very nicely , but the old grates from a wood burning stove were a disaster ... I couldn't even get brazing rod to puddle and wet that stuff . I've heard similar stories about welding/brazing CI exhaust manifolds . Preheat is important in some cases , especially if there is a possibility of a cooling weld being put into tension because of the shape of the item . Peening helps a lot , mostly because as you peen the hot weld bead you're actually causing the metal to expand sideways and eliminating the tension stresses .
I've also used some strips cut from an old CI stove door (about 1/8" square) to successfully weld a part . Be sure to grind/sand as much of the rust as you can from the strips .
 
I have had much success with flux coated brazing rod and oxy/acetylene torch. I brazed the handle back on for my mothers cast-iron frying pan and it never failed. I also brazed a crack in the base of my 5" cast iron bench vise ,years ago and it's still working. The last braze job I did was on the apron on my HF 12x36 lathe that broke when I tipped it over on it's face while trying to move it alone(dah).

Lathe repair 002.jpg Lathe repair 2.jpg
 
Nice work.
OK, so the term "Brazing" has come up numerous times. I do have an O-A rig and two torches. One for welding and one for "silver soldering" carbide tips on saw blades. Is THAT the torch you would call "Brazing"?
I guess I just don't understand the difference other than the size of the hole in the end of the torch and the gas settings. Do any of you have an "easily understood by an amateur" explanation of "brazing" when working on Cast Iron?"
It turns out I am finding more broken cast iron things that need to be repaired.
Cheers,
Trim sends
 
Brazing is the joining of metals with bronze bearing alloys.
the parent metal is not melted, just the brazing rod, you can use a welding tip, but mind your heat
unless you are braze welding. then both the parent metal and rod are melted to form another alloy.
 
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OK, I get that part. Now, the question is about the brazing rod. Is there a nomenclature to use when I go to the welding shop to buy it or will they just KNOW what I need? I am THAT new when it comes to this.

I have some rod that I got some years ago and have been saving till I learned how to use it. I'm not the kind of guy that just starts melting metal til I know why I am doing it. At the moment I don't know the "nomenclature" of this rod. I have on with some white "flux" on it and some without that flux.

What I got from this is I can use the welding torch but "mind your heat"...to me is a bit vague. Can you please explain what that means? (I really DON'T understand the technical terminology here. I have training in another field and am trying to learn this as I go. I can cut, clamp, cauterize and sew it back together with relative skill. Working with metal has a few similarities but I always had to fix what I was working on "with the engine running" so to speak ) .
Would it be OK to ask for specifics in terms of "rod number", gas settings (PSI for Oxygen and PSI for acetylene). I do follow directions well.
Thanks
Trim sends
 
mind your heat, means that if you use a large welding torch and get too close to the work,
you can easily turn brazing into braze welding which is not always a good thing.
to braze you want the parent metal to be hot but well below it's melting point.

you'll want to practice with your flux covered rod until you feel that you have mastered it. flux covered makes it very easy to braze.
the fluxless rods should be scrutinized as to reveal their make up, sometimes steel welding rods are stored in close proximity to bronze bearing filler rods
you don't want to make the mistake of using a steel rod when you should be using bronze alloys to braze
bare bronze rod is ok to use, you'll need to use borax as a flux and reapply often to achieve good result.

personally, i prefer Harris LFB (low fuming bronze)1/8" flux covered rod when brazing
your torch settings will be determined by tip size
but a pretty good place to start is 2-5 psig regulated acetylene, 10-20 psig Oxygen
you'll want a neutral flame.
you'll know you have neutral when there is a blue cone and the torch goes near silent
if you need more information, i'm happy to add more:)
 
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Ulma Doctor said:
mind your heat, means that if you use a large welding torch and get too close to the work,
you can easily turn brazing into braze welding which is not always a good thing.
to braze you want the parent metal to be hot but well below it's melting point.

you'll want to practice with your flux covered rod until you feel that you have mastered it. flux covered makes it very easy to braze.
the fluxless rods should be scrutinized as to reveal their make up, sometimes steel welding rods are stored in close proximity to bronze bearing filler rods
you don't want to make the mistake of using a steel rod when you should be using bronze alloys to braze
bare bronze rod is ok to use, you'll need to use borax as a flux and reapply often to achieve good result.

personally, i prefer Harris LFB (low fuming bronze)1/8" flux covered rod when brazing
your torch settings will be determined by tip size
but a pretty good place to start is 2-5 psig regulated acetylene, 10-20 psig Oxygen
you'll want a neutral flame.
you'll know you have neutral when there is a blue cone and the torch goes near silent
if you need more information, i'm happy to add more:)
Click to expand...

Now I am getting somewhere. So, what I am hearing is that melting the brazing rod is like using a "hot glue"! You don't melt the CI, just the brazing rod. I went out today and bought some brazing rod. I got about 5 # of 1/16" and about 0.4# of 1/8" rod. The tube said,"Brazing rod" so I don't think it is steel. I didn't read the components but will tomorrow.

Now the heat issue appears to be variable. As I said, I have two torches. One that has quite a large hole and that I remember was purchased specifically to do welding. It gets pretty hot. The other has a smaller hole and that seems to give a "cooler" flame. It is the one I use to "silver solder" the carbide tips on a blade. It gets pretty hot but nothing like the other one.

I get the gas settings. That part is easy. Just needed to know what they should be.

One of the other guys mentioned using the Black Flux and I have a 5# bucket of it that was just shipped from Balboa Supply in San Diego. I'll try using the flux coated rod first (1/8") and see how I do. I have lots of old broken CI things around this farm that I can practice "brazing" on that stuff before I try to fix the parts I need to repair. Since they are old, I don't think I'll get a "second chance" if I booger it up.

The video is helpful. Thanks PlaneFlyer21. In my working days I was known by pilots in the US Navy as the guy they "love to hate and hate to love" .

Additionally, I should thank Ulma Doctor for your kind guidance as well. I will put it to practice as the "weather permits" because if I am reading this right, cold weather is NOT a good time to work with CI because it would cool TOO FAST after the application of the heat. My shop is at the best of times around +50*F if I have the fire going all day. Otherwise, it is often about 3-5*F above ambient temperature which is often in the +20*F to +30*F... It gets down to -30*F at times here so even with the best of fires AND the "jet engine" heater it can be pretty cold.

Once I have worked with this a bit and get the hang of it, I'll come back and report my experience.
Thanks again for the help.
Cheers,
Trim sends
 
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