Tips/Techniques welding cast!!

[grease monkey]

any tips/tricks to welding thin cast iron? I need to make 2 pulleys into one (long story)

 

[DPittman]

No cast iron welding tips from me other than " braze them together!" But even with that, you need to give more details about your project to get real good advice.

 

[Susquatch]

any tips/tricks to welding thin cast iron? I need to make 2 pulleys into one (long story)

I agree with Don. Brazing is the way to go.

But you can prolly find a double pulley for whatever you need to do.

 

[phaxtris]

If you want to weld use ni-rod 99 or ni-rod 55

Preheat helps, and wrapping it in a fire blanket to cool helps

Short beads

Brazing is the more fool proof method

 

[MashingMetal]

Warm the parts first and a slow cool down. I have brazed and used the special sticks, preferred brazing.

 

[MrWhoopee]

I've had surprisingly good luck welding cast with 309L stainless filler, both TIG and stick.
I also use it when welding alloy steels. Basically, if the welds are cracking, use stainless filler. The low carbon content and (oddly) higher ductility make it quite forgiving.

 

[grease monkey]

ok, somehow my last message crapped out, fat fingered something wrong I guess! Ok, I'm repowering 2 classic lawn tractors, that would be me, lets not do one to prove concept, lets do 2 right away and a 3rd when ready! in this process, I'm pulling an Onan CCKB motor to install a Kubota 722 super mini diesel, the front crank pulley is cast, 4" dia, single groove, A series belt, what I need is a 2 groove B series pulley welded to it, as the original is splined internally, so I figure on welding my desired pully to the original, both are cast, both are thin, 1/8" or less, after speaking to my weld supplier, and him talking to his weld engineer, he says to use silicon bronze wire in my mig machine with straight argon, small convex stringer beads and use short passes and keep heat below 100 degree's! that kinda sounded off to me, which is why I'm reaching out, everyone is telling me preheat and slow cool, this guy is opposite, because of how thin the V's are, guess I better suit up and find out! picture of tractor in question....

 

[phaxtris]

silicon bronze would work...brazing but with electricity instead of a torch

 

[Downwindtracker2]

Good cast iron can be welded. Poor quality brittle junk, good luck. That's for brazing. I've welded cold, almost hand touchable. It worked. A trick I read but haven't used, is use a BBQ to preheat. Of course rod for cast iron. We use to call it Ni-Cad, but the stuff the company supplied was labeled UTB 8, or something like that. There was two grades.

 

[Megar arc 5040dd]

Finally a question I can actually answer . I welded and brazed quite a bit of cast iron and cast steel in my career. Everyone so far has given great advice. From my personal experience over the years I would suggest you braze it unless there is a reason it needs to be welded. The most common reason I ran into was it needed to be welded for cosmetic reasons, usually on antiques. A good braze will hold stronger than the cast iron itself and is less likely to cause cracking of the cast iron. In both cases a very slow cool down is needed once you are done, especially if you braze it. There are a lot of ways you can do that from wrapping it in fire blankets to my favourite burying it in the middle of a 5 gallon bucket of either kitty litter or floor dry and leave it until it is cold, I usually just leave it over night. This will prevent cracking. If you have to weld it you run into a couple of options. Option 1) is preheat and welded it and slow cool. Don't make long welds and and try to maintain as constant of a heat as possible until it is done and then it needs to be very well insulated and allowed to slowly cool. Since you said it is thin I would go with option 2. Option 2) make very short welds, 1/2" to 1" in length at the absolute max, and do not let it get hot at all. Like you welding supplier said about 100 degrees sounds about right. I usually go with if the metal beside the weld is to hot to touch it's time to let it cool naturally. Don't be tempted to help it cool faster with compressed are or anything. Spread your welds out and take your time this is not a fast process. While the weld is cooling peening will help reduce the stresses and the chances of cracking. A needle scaler works great for this but the pointy end of a chipping hammer can work in a pinch. I have never used the wire your welding supplier recommended so I can't speak to how well it works. There is however one advantage to using stick welding and that is the slag covers the weld and helps slow the cooling of the weld. Most rod brands will have a couple types of nickel welding rods, usually something like Ni55 or Ni99. Get the ones with the highest nickel content they have. Usually they comein smalll quantities but prepare for sticker shock I haven't bought any ionabout 12 years and they were really pricey back then.

WARNING this is the most important part when welding anything with nickel in it like Ni99 or even any stainless rod make sure to do it in a well ventilated area and if at all possible a propper resperator with the proper cartriges should be used! Nickel builds up in you body and never leaves it is not something you want to be breathing in the fumes. Also make sure to have ventilation when brazing and try not to breath in the fumes as it contains zinc and can make you feel sick.

You never mentioned how you intend to line the pulleys up so they run true when you are done. If the a way you can jig them on a shaft or something?

 

[grease monkey]

Megar, thanks for your input! I did not know that about the fumes so that will be noted for sure. as far as alignment, a made a shaft that fits snugly through both bores and tapped holes in the ends to afford a touch of clamping force to keep them where I want them, the other issue is that the original pulley is keyed for balancing, so I've already talked to my race engine builder and he's going to balance them for me using the stock balance profile. I do also have a small 90 degree gearbox that suffered from frost jacking, its in a no pressure situation on the box, the crack only effects its ability to keep gear oil inside, so that crack I intend to drill crack end points, V grind a touch and weld, its also 1/8" thick, so I figure the same techniques will apply. Thank You all for the tips. I'll try to post some pics of both projects and results, which should be visible if I can take a pic properly!

 

[Dan Dubeau]

Silicon Bronze (SilBr) would have been my recommendation as well. I have used it successfully both with Tig, and Mig before. Preheat was key in both cases, but way more critical with the mig option IMO. I have some nickle rod, and have always wanted to try it too, but don't have a suitable project to give it a go.

 

[Megar arc 5040dd]

Megar, thanks for your input! I did not know that about the fumes so that will be noted for sure. as far as alignment, a made a shaft that fits snugly through both bores and tapped holes in the ends to afford a touch of clamping force to keep them where I want them, the other issue is that the original pulley is keyed for balancing, so I've already talked to my race engine builder and he's going to balance them for me using the stock balance profile. I do also have a small 90 degree gearbox that suffered from frost jacking, its in a no pressure situation on the box, the crack only effects its ability to keep gear oil inside, so that crack I intend to drill crack end points, V grind a touch and weld, its also 1/8" thick, so I figure the same techniques will apply. Thank You all for the tips. I'll try to post some pics of both projects and results, which should be visible if I can take a pic properly!

When repairing the gear box crack make sure to burn out all the oil from the crack before you start your repair. I usually give a good cleaning with a non chlorinated brake cleaner then heat the crack with a torch and burn out all the crap inside that you can't see. I'm sure it has been said on here before if you are going to weld something that you have cleaned with brake clean make absolutely sure it is non chlorinated! Chlorinated brake clean when heated produces chlorine gas the same type of stuff used in WWI trench warfare.

Post back picks and let us know how it all goes and how you chose to do it. There are lots of good ways to do these repairs so don't be scared. It really comes down to sticking to one way. If your going to do it hot then keep it hot and if you are going to do it cold then keep it cold. And the most important advice that no one has given is have fun and learn something

 

[Ironman]

ok, somehow my last message crapped out, fat fingered something wrong I guess! Ok, I'm repowering 2 classic lawn tractors, that would be me, lets not do one to prove concept, lets do 2 right away and a 3rd when ready! in this process, I'm pulling an Onan CCKB motor to install a Kubota 722 super mini diesel, the front crank pulley is cast, 4" dia, single groove, A series belt, what I need is a 2 groove B series pulley welded to it, as the original is splined internally, so I figure on welding my desired pully to the original, both are cast, both are thin, 1/8" or less, after speaking to my weld supplier, and him talking to his weld engineer, he says to use silicon bronze wire in my mig machine with straight argon, small convex stringer beads and use short passes and keep heat below 100 degree's! that kinda sounded off to me, which is why I'm reaching out, everyone is telling me preheat and slow cool, this guy is opposite, because of how thin the V's are, guess I better suit up and find out! picture of tractor in question....

He was right. I would use Ni-rod and weld 1" beads, and then peen while cooling. Peening swells the weld as cooling occurs to counter shrinkage that causes cracking. You should always be able to touch the work. When it gets too hot to do that walk away for a bit. I have welded tractor engine blocks with a 24" long crack in it this way. Modern cast is very weldable as it has a high nickel content compared to WW2 grey cast iron.
Heating the whole object , weld, and then cooling it in ash or floor dry also works, but is harder to do for some repairs.

 

[Stuart Samuel]

As others have noted, I’ve also had best results with torch brazing. Have done some field work with nickel stick electrodes, and have done some tig brazing.

This is a cast collar from a post lantern outside Osgoode Hall, downtown Toronto (cast iron doesn’t like it when you back a truck into it). Flux coated brazing rod, just what we had around.

 

[Susquatch]

As others have noted, I’ve also had best results with torch brazing. Have done some field work with nickel stick electrodes, and have done some tig brazing.

That repair is amazing!

You are a lucky man you know! Not many guys find a job they love. Those that do, never have to work.

 

[phaxtris]

I would not weld that gear box, that is a perfect candidate for brazing

Thin sections are even more susceptible to cracking from the welding process, then you add in the chances of inclusions within the casting, its really a recipe for un-needed frustration when brazing is the perfect solution

 

[Bandit]

I have used epoxy a few times on thin casting. Getting it clean and oil free is important, even with brazing, sometimes when cooling, corners cause different shrinkage rates and stresses. But you don’t know till you try.

 

[Stuart Samuel]

That repair is amazing!

You are a lucky man you know! Not many guys find a job they love. Those that do, never have to work.

I still think of that one as ‘Humpty Dumpty’ .

 

[Stuart Samuel]

While it’s less applicable here (maybe?), I’ve been setting aside a pile of scrap bits at work, broken castings especially, with different cross sections. My hope is that I’ll get to a point where I always have something at least vaguely similar to test a technique on, whether that’s welding, brazing, some sort of corrosion prevention, etc.

At least it’ll let me try out an educated guess, rather than learning I was wrong on something higher value.