brazing cast iron

Great description. I do brazing all the time and I can't think of any point that you didn't cover. My only addition is that it helps to use a flux made for cast iron. My current favorite is Peterson #2 which is for cast and malleable iron at high heat. I used to use Peterson #3 at my former employer and when I first got back out on my own but as far as I can tell you can buy it any more.

Oh and I might mention for some of the readers that the reason you don't leave a sharp corner at the top of the V groove is that it tends to over heat before you can get the bottom of the groove up to temperature. If you ever overheat the cast iron you'll have to stop and regrind it because it become impossible to get a good bond to it. This is also one reason it's so important to preheat the work piece. Especially if its a heavy casting and even more important if there's a heavy piece next to a light piece. It can become impossible to get the heavy piece up to temperature without overheating the small piece without a good preheat.

I've got some pictures somewhere of some of my brazing that I've been meaning to put up on my web site. Unfortunately I've never had the time to.

Wayne Cook Shamrock, TX

Yes I prefer to add my own flux if I have the choice. In this case I was using the shop brazing rods that have been on the shelf collecting dust for umpteen years. One ends up adding rod when you are trying to add flux to get that good bond. Randy

Randy and Wayne,

Your post got me thinking. I've got a 1978 aluminum body dump trailer that I just took off the road due to some cracking of suspension components.

Unfortunately, the suspension system is now obsolete and parts are no longer available.

If I'm not mistaken these are steel castings and not iron.

Of course, the DOT regulations may prohibit any kind of repair to these components. And frankly, if they do, this would not surprise me in the least.

Nevertheless, you got me thinking about the possibility of a bronze braze repair rather than a weld repair.

Right now the trailer project's on a back burner. But if a repair to these components is permitted under the DOT regs, then in the near future I might want to seek your and Wayne's counsel about this.

Likely steel though it's not guaranteed that they are. I've seen a few that are cast iron.

I'm not sure what the regulations are to be truthful. I have repaired and or modified a few suspension components but most have been farm related in some fashion or another.

If they're cast a good brazing job will be stronger than the cast iron around it. However a brazing job tends to jump out at you when you look at it and the DOT inspectors are more likely to say something about it.

It depends on what the parts are but sometimes it's better to fabricate new out of steel. I've done that as well.

No problems there.

Hmm. You're welcome to stop by anytime. But your hops must be rather large. Shamrock is in the panhandle. About 13 miles from the OK state line on I-40 to be precise. If that's Brenham, TX then that would be

According to mapquest there's two Shamrocks in TX though I've never managed to find the second one. Supposedly it's in the Dallas area.

Wayne Cook Shamrock, TX

BTDT. I definitely don't like prefluxed rod. You either have to much flux or to little (usually the later). Not to mention the fact that the white flux is about the worst flux out there for anything other than super clean steel.

The fact is that most of my brazing is done on pump jack bearings or the like that have been soaked in grease for 30-60 years. It's just about impossible to get a good bond without a good flux under those conditions.

Wayne Cook Shamrock, TX

I find plain ol' Borax works well for me. Cheap, easy to find, effective.

It works but nothing like what a good flux can do. The fact is most fluxes are based on borax and I'm pretty sure the white flux is just plain borax. However if you're doing a difficult job like brazing grease soaked cast iron it just doesn't work well enough. I clean all my castings as well as I can but when you heat them up the grease will come out of the pores in the metal. In this situation plain old borax just doesn't cut it.

Wayne Cook Shamrock, TX

Hmm, maybe I'll have to buy a can of flux and compare them again. It's been.. damn, 20 years since I bought flux.

Re; the greasy stuff, I guess I don't get much cast that's real greasy. Them Amish'll bring you some pretty poops stuff if you let 'em, they ain't too bashful about the various poops, gotta watch for that.

Many thanks,

John

Wayne , try pre heating a cleaned piece of cast and hitting it with brake cleaner

we oven heat to about two hundred degrees and give it the brake clean

pulls a lot of the trash out

two or three cycles and its like new cast

Just be sure it's the good stuff. Most flux they sell isn't going to be any better than the borax (especially since they're one and the same). The best I've found for cast iron is the Peterson #2 or #3 though I've definitely not tried every kind out there. My former employer who has been brazing for 70+ years swore by the #3 when he was in business and came and borrowed my #2 after he quit. He was impressed with the #2 doing a good job on the very burnt out old tractor exhaust manifold he was brazing.

:-) I get some like that as well. I must say that the worst has to be the aluminum cattle trailer. I'm talking the kind that you pull behind a real truck ie 18 wheeler. That one was definitely full of

:-)

Wayne Cook Shamrock, TX

I've done that as well but it takes time and gas. At todays gas prices it's to much expense added to most jobs. If it's a critical load bearing piece I'll do it but most of what do to pump jack bearings is build up worn surfaces so that they can be machined back to proper dimension. Bond isn't as critical there most of the time but there still needs to be a bond. I won't get much of any with standard flux but I get almost as good a bond as doing it your way with the Peterson #2 flux.

Wayne Cook Shamrock, TX

My favourite to date was repairing an aluminum dump trailer used to haul fish guts to the fertilizer plant. Some very interesting smells I hope to forget some day.

John Noon

Ouch. Having grown up around a slaughter plant I can imagine what that was like. :-)

Wayne Cook Shamrock, TX

Gack! Welding on a gut wagon....bad juju

Gunner

My labs used to love to ride by the plant that processed Menhaden into fish meal, fish oil and whatever. I had to keep a close eye on them as I used the boat ramp near there as they would disappear.

Talking about hauling livestock in a trailer, a friend that drove a semi hated to get bothered by DOT at the scales etc. If they upset him he would jerk the trailer HARD by hitting the brake then the accelerator, leaving a stinking mess all over the scale.

Diamond Jim

I worked for a garbage hauling place some years back, welding on the split seams in the packer boxes got pretty funky sometimes..

There's a rendering plant about 20 miles from me, I've talked to a couple of guys who have gone in there to weld, they both said they threw their clothes away when they got home.

John