View Full Version : Cast iron crack suggestions?

03-16-2007, 07:35 AM
Anybody got any suggestions on how to address this? Cracked this section out when I pressed out the stuck bearing and shaft. My welding skills are in the infancy stage so I'm gun shy on that, but do have a neighbor that's a good weldor. I was thinking maybe drilling and tapping in 4 places, 2 on each side of the crack and inserting 6-32 capscrews. Any other suggestions? JBweld maybe? This is good old iron, 1940's era, not the china cheese grade of today.
Thanks, Cadwiz


03-16-2007, 07:58 AM
Braze it.
I repaired a lever on my lathe by brazing, just like soldering but with higher heat.

kap pullen
03-16-2007, 08:10 AM
Welding cast iron usually produces a heat effected zone that is barely machinable.

It is glass hard.

Proper preheat, nickel rod, or some specality rod may reduce this condition but not eliminate it.

I would drill a hole at the end of the cracks to stop them, grind the crack out, and fill with brazing rod.


A.K. Boomer
03-16-2007, 08:17 AM
I had an old BMW 1600-2 engine block that had disintigrated a piston ring and tore up its bore at TDC, I took it to a "farmer" welder and he welded the little section with nickel rod --- it held up fine --- it would have raised holy hell if it came uncorked but it held for nearly a decade and as far as i know it never let go...

This may be a stupid question but why cant cast iron be tigged? or can it be?

A.K. Boomer
03-16-2007, 08:22 AM
another look at your pick and If nobody has a magic answer I would go with the braze and the old piece and build it up, You actually have an ideal situation for building up strength between those webs, it will be ugly but who cares if you can make it strong...

Forrest Addy
03-16-2007, 08:25 AM
Kap's got it. If the casting is bare, fairly clean, and can take general heat brazing up the damage and re-machining the bore is your best repair.

Alternatively, bore out the old boss and braze in a new one of steel with an undersized hole. Bore after brazing.

Work clean. Braze doesn't stick to dirt. Bead blast the area and fracture faces to white metal. Use plenty of borax brrazing flux.

Drape the casting in ceramic fiber cloth or kaowool insulation. Heat the whole casting up to some preheat like 700 degrees with a weed burner. The less thermal shock and localized heat the casting sees the less chance there is for distortion. Expose only enough of the casting to accomplish the work. After brazing hold the preheat for an hour or two and allow to slowly cool in still air.

The glassy flux residues come off in hot water but it will take some time.

A little work with a die grinder and a carbide burr will make the casting look like it has never been broken. All depends on the time you want to put in it.

03-16-2007, 09:48 AM
I bet you said

"Darn & shucks"


03-16-2007, 09:53 AM
I'd go for Silver solder (silver braze) just because there's less heat input than with bronze but it'll still do a decent job.


03-16-2007, 10:58 AM
Get some 'Gricast' welding rods not a cheap alternative bit you only need a couple, I think it is a form of Eutectic welding rod so it will be a low temperature weld and it is designed for cast iron repairs.

03-16-2007, 11:21 AM

I have just bought a Henrob torch and am getting into welding myself. I am not speaking from experience, but from a research stand point.

The DVD that came with my torch shows the fellow repairing a cast iron manifold using the torch and cast iron rod. The repair is as easy to machine as - well - cast iron! He actually hand files the built up weld to demonstrate.

Pre heat and post heat are important to prevent cracking.

I feel like a snake oil salesman now! It was very impressive to watch this cast iron repair nonetheless.

03-16-2007, 04:28 PM
The best way to repair cast iron is to spray weld it.If nobody around your area does that,then I would braze it.Should be fine with a good braze.

Your Old Dog
03-16-2007, 05:45 PM
It was very impressive to watch this cast iron repair nonetheless.

Kap, Forest, one of you guys do that DVD that Chris is talking about? :D

Chris, welcome to the forum. Haven't noticed your other post. We don't have E.F.Hutton here but usually when Kap or Forest speak it can usually be taken to the bank! But it's nice you want to be helpfull, that's what this site is all about. You know anything about SoutBend 7" Shaper oiling repairs ? !!! I'm having a good time at the moment trying to figure out whats wrong with mine!

03-16-2007, 08:36 PM
I have watched the Henrob demo too, the same thing can be done with any O/A. torch. But just because the guy in the video can do it does not mean YOU can, he is a very talented guy with a torch.

03-16-2007, 08:54 PM
I'm with Kap and Forrest on this one.

I know spray welding is used on build up work, but I have not heard of it used for crack repair or joining. Can anyone address this?

I have seen the Henrob torch demo many times. It does do nice work during the demo, but have not seen any actual work done with it. I only know of one person who has purchased one of these torch sets. He said he it did what it was supposed to do. I do believe if I did the same sample welds all day long, I could probably get good at it too.


03-16-2007, 10:02 PM
Braze it,it's the easiest way.

The method I have used in the past is to start by heating the area dull red and the letting it cool first to cook off any oil,grease etc.Then I do the grinding to make the part fit back in place and grind everything clean to prep for the barze job.

Now you need that old bearing,get it and knock the inner race and balls out of it.Stick it back in the hole and use it to position and clamp the loose piece back in place then do the braze job being careful not to braze the race in too.

After it all cools,chip off the flux and tap the race out,it should be loose in the hole.Clean everything up,chck your bearing fit and add a swipe of Loctite 271.

03-17-2007, 06:47 AM
I have the henrob torch and have had it for a number of years,I haven't tried the cast iron welding yet the other stuff about cutting non ferrous, and a way smoother cut than with my large torch and welding aluminum. seem to work like shown.
Most welding supply don't carry the gas rod in stock. And being in a large Metro area,some of the looks I got when asking for it was priceless :D.I think they were looking for the time machine. It too some time for them to get it, It was expensive. The preheat and slow cool down to relief or adjust stress after welding is important.
I would go with Forrest and braze it too.

03-17-2007, 10:11 AM
Thanks for the advice. Looks like brazing is the way to go. Wish me luck, if I screw this up any further I just as soon scrap the whole thing.


loose nut
03-17-2007, 11:03 AM
two more points:
someone mentioned silver solder, don't, it usually doesn't work very well and you would gain zip over brazing.
cheap cast iron welding rod like "nirod" is a pain to use, good rod like that sold by Xergon out of Texas works great BUT it cost over $100 a LB.
By brazing it you don't have to worry much about it cracking any more, hard spots and a point to note is that the tensil strenght of the cheap genaric brazing rod is about the same as good cast iron. If you don't have any experience brazing get someone to help you, it can be a tricky thing to learn but kinda fun.

03-17-2007, 12:31 PM
two more points:
someone mentioned silver solder, don't, it usually doesn't work very well and you would gain zip over brazing.

That was me.
Agreed some CI won't silver solder well, but for those which do, what you gain is a lower heat input. In my book that's always a good thing with a casting.


03-17-2007, 06:03 PM
Vee the crack, heat to dull red with a blowlamp, MIG with 316 & Argon, machine & grid. Result is extremely structural, machines & taps real nice.
Rebuilt cracked exhaust manifolds for classic cars in this way with permanent results,

03-17-2007, 07:21 PM
I found the addy for this site I had lost it in the bok mark mess.http://www.muggyweld.com/castiron.html :D

loose nut
03-18-2007, 11:00 AM
That was me.
Agreed some CI won't silver solder well, but for those which do, what you gain is a lower heat input. In my book that's always a good thing with a casting.

For someone who hasn't done a lot of CI brazing, welding, etc. silver soldering still wouldn't be the way to go, could end up with a mess where brazing is a tried and proven method.

03-18-2007, 11:32 AM
I watched the old FIL do this, always successfully.
Mind you, I'm talking about CI manifolds here.
Done in late evening so you can see the colour:
Preheat on coke (BBQ beads) if you can see any colour, it's too hot.
Remove to the bench and braze crack with oxy-propane.
Return to the coke until the bronze just starts to show a sheen.
Set aside from the fire to anneal and cool slowly.
Memory may let me down on detail, but that is the gist of it.
Mind you, the old &@**#% was a blacksmith too.
Blacksmith welding is an art, once seen, never forgotten.
But it IS an art.

John Stevenson
03-18-2007, 11:32 AM
I found the addy for this site I had lost it in the bok mark mess.http://www.muggyweld.com/castiron.html :D

Good God seen those prices?
25lb reel of MiG wire $372 plus shipping, I think I pay about $35 to $40 in US money for a 15Kg reel.

Mine probably don't have snake oil flux :D


03-18-2007, 11:44 AM
Yep John I know but that is one option, and I thought the $15.00 a pound for the gas cast iron rod with out flux was so High I asked the counter guy at the welding shop were his mask and gun Was;)

03-18-2007, 10:57 PM
Don't drill and tap if you can help it. That is sure to weaken the area and lead to future breakage. Also, if the repair is not taken with care, even more non-repairable damage could be done.

As has been said, in lieu of the exotic, the usual fix for cast iron is to braze the crack.

That being said. You appear to have lost about 10 percent of bearing support in only one direction of lateral movement. Much depends on the expected load on that section. If you can machine the pocket out about .125" or such, you could press in a sleeve to accept the new bearing and it would probably last for years.

If it were mine and the piece was important; I would probably clamp it close, drill a 1/8" hole at the crack end to keep it from traveling further, grind a vee along the crack and braze. I would then machine the pocket larger and press/locktite in a steel or stainless sleeve.

03-19-2007, 07:41 AM
Well I brazed it. Looks like crap but at least it didn't crack when it cooled. Had some torch clearance problems on the left side. I didn't bring the bead all the way out to the end so I hope that wasn't a mistake.

Also took the time to try the "TIG out broken stud" trick on the busted stud I posted about a few weeks ago. Came out quite nicely.

Thanks for the help

03-19-2007, 03:00 PM
I didn't bring the bead all the way out to the end so I hope that wasn't a mistake.

Looks pretty good considering, but you should have brought the bead right out, because that wee bit of a crack is just guaranteed to want to grow again.

03-19-2007, 09:00 PM
Looks good. There appears to be some capillary flow into the crack on the "short" side.

I don't think I would worry about the crack any further unless it is subject to excessive vibration or side loading at the weakened area.

Earlier I said I might machine the pocket and sleeve it, but the original pocket looks tight and any bearing race or bushing should provide good support.