Shrinking a warp out of a casting?


Greetings all.
Turning once again to the wisdom of the group for advice on a
peripherally
metalworking topic:
Does anyone have any experience/advice dewarping a cast-iron casting?
I have a cast iron part (radiator bolster from a Farmall cub) that had
water
freeze in it and bulge & crack it (previous owner's indiscretion). He
also
brazed up the crack, but didn't work the bulge back out. The problem
with the bulge, is that it throws the mounting surface for the
radiator out
of plane. If there was a little more meat there, I'd just mill the
mounting
surface down and be done with it, but that would leave very little
metal
in the mounting flange at the peak of the bulge.
So... I know one can shrink sheet metal a couple different ways, and
I seem to remember seeing someone bend an I-beam by placing periodic
welds along the flanges and letting the weld shrinkage pull a radius
into
it. I'm wondering if I can play a similar game with cast iron. The
radiator
mounting flange requires little structural strength, so I don't have
to worry
too much about weakening it by heating/local heating differential.
If there's no success to be had along those lines, my fallback is to
mill it
down, then braze on a .25in raiser flange that will put the entire
radiator
.25 too high, but at least leave enough metal to seal, and be properly
aligned.
Any thoughs/ideas/suggestions most greatly appreciated,
Will Ray
Reply to
willray
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Cast iron doesn't like to move. It likes to break. If you could look inside that bolster you would likely find that the edges of the split area are cracked as well. What I would probably do myself would be to cut out the bulge and braze or weld in a new chunk of iron or steel. Cut out the old part so you have a tapered edge. Cut the new one with a taper to match and then grind a reverse taper on the top edge to give you a place to fill with brass or weld (you could silver solder it as well IF you keep it a tight fit.
Reply to
Steve W.
You can certainly play this game with cast iron, but the big question is how far can you go without cracking the casting again. The key to success in welding cast iron is to minimize residual stresses in the repaired piece. You're proposing to intentionally stress the casting.
I'd build up the warped surface with braze, cool the casting very slowly by burying it in wood ashes, vermiculite, or other suitable insulation, then machine. TIG brazing with silicon bronze (Everdur) rod would be my choice of technique. Silicon bronze isn't as fluid as normal brazing rod, it doesn't spit zinc, and is much stronger. For me, the placement or the braze is easier with TIG.
Are you a new owner of the Cub? I have a 1953 Super A, the Cub's big brother.
Reply to
Ned Simmons
How about making a new casting? There a guy up around Brandon, MN, Mn that does one-off jobs like this all the time. His place is called "The Hobby Shop". You UPS him the part, he quotes it, you agree or disagree. If you agree, you get the new one in a few days, ready to machine. If you disagree, he UPS's the part back to you. He has done good work for me and my friends.
The Hobby Shop Raymond P. Olsen, Owner 14260 Pheasant Dr. N.W. Brandon, MN 56315 tel.: 1-320-834-2476, 1-320-524-2118
Pete Stanaitis ------------------------------------------------------------------------------- willray wrote:
Reply to
spaco
Perhaps it's not an option but I have seen quite a few of these castings for sale on E-Bay and at various tractor parts places. I do not recall the asking prices.
Don Young (3 Cubs)
Reply to
Don Young
you could always heat the casting up until it was red hot and plastic and give the offening area a tap back with an old hammer.
Reply to
Stealth Pilot
No, no, no! Cast iron is very hot-short. What you're describing is the very method that small-time metalcasters use to break up old engine blocks and cylinder heads for re-casting. When you reach the right temperature, c.i. breaks up like rubbery Plaster of Paris.
When you have a crack or a warp in c.i., the smart thing to do is what others have recommended here: get a new casting. If you're really stuck and need to repair a cracked piece, you're in for trouble unless you're very lucky or very good (lucky is better). But a warped casting is a goner in most cases.
(BTW, using old engine blocks is not recommended, if they're from the leaded-gas era. They're illegal for use in most commercial casting for that reason.)
-- Ed Huntress
Reply to
Ed Huntress
What happens Ed? Is there that much lead absorbed into the cast iron that it's a hazard to the workers at the foundry? hazard to the environment?? If you can't remelt it, what do you do with those old engine blocks?
RWL
Reply to
GeoLane at PTD dot NET
Unless the foundry has the proper controls, the lead goes into the air. And I saw some figures on it years ago. The amount of lead released is very high.
Good question. My understanding, which is maybe 15 years behind, is that there are larger foundries equipped with stack-capture equipment that can use those blocks. IIRC, the recommendation was to send those blocks to the properly equipped foundries.
-- Ed Huntress
Reply to
Ed Huntress
The foundrys have a perodic testing for lead contamination. Don't even mention the word "Lead" if you are in a foundry. They get as little paronoid about it but rightly so. If they get a positive test they have a trememdous cleanup bill to contend with.
John
Reply to
john
How much lead is in 12L14? I tried googling it and didn't come up with a percentage. We used to turn a lot of it and we didn't segregate either chips or drops.
Any studies in the public domain about lead contanination of engine compents?
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
Reply to
Wes
Ah, yes, I remember reading that. I guess it caused them a lot of trouble when the scrap was all mixed and there were those old engine blocks in the mix.
I suppose that most of those blocks have worked their way through the waste stream by now, and it must be less of a problem. Is that correct?
-- Ed Huntress
Reply to
Ed Huntress
Certified 12L14 can range from 0.15% to 0.35% lead. I'm surprised the allowable range has that much spread but I see it online from various sources.
There must be, but my information came from AFS or ASTM, back when I was an editor on metalworking magazines. I probably got it all from their press releases.
Look up AFS (American Foundrymen's Society) online and see what you find. They're the most likely source. The EPA is a possibility, too.
-- Ed Huntress
Reply to
Ed Huntress
The foundrys that I have contact with like only nice clean # 1 scrap with no paint or atttachments. They get mostly drops from fabricators or stamping houses. Its nice if I need a small piece of angle or bar. I swap them for round bar drops that they use for chills.
For all that don't know what a chill is, it is a block of metal put in the mould to draw out heat from the molten metal so it cools faster at that point.
John
Reply to
john
Yeah, something like that :-)
One of these days, I need to learn to TIG. I bought what should be a pretty nice TIG setup, but just have never had time to put it together to learn. Most days I get around ok with a Ox/Ac torch, but I can see where TIG's real-hot, right-now capabilities would be a real bonus when working on something on a large casting.
I was thinking along the "braze in a flange" lines, rather than the build it up lines, because I wanted to strengthen the top of the casting, and kinda liked the sound of a .25 x .75 steel strap tying the top of the bolster together. Something I /hadn't/ thought at all about, was building up the inside of the bolster, so that I can actually just mill it flat on the outside and have it in the right place. It's depressingly ugly in there right now, but maybe I can sandblast it well enough to get brass to stick.
Yup. New to the cub.
I'm not unfamiliar with random old iron (and have secretly lusted after a Super A for a while), but I'd never thought much about, or of, the cub until a recent friend found himself in more need of cash than some of the junk in his barn, and while I didn't really need the junk, I had some some spare cash and figured one can never have too many tractors.
So far, I'm thinking he got the better end of the deal...
Thanks much, Will
Reply to
willray
I suspect it'd be financially ruinous to try to replicate the casting (especially when they do come up intact, from cubs being parted out on eBay with some regularity - this thing has multiple internal passages with complex geometries). However, I have a project I've been looking for exactly that service for, for some time. I've never heard of this shop, and am delighted to have the information.
Thanks! Will Ray
Reply to
willray
Ah, of course it's an option, but I'm a cheap, stubborn idiot :-)
Will I can certainly relate to that. I do not like to heat old cast iron very much. If the strength is not a problem or you can reinforce the repair, you can do a lot with epoxy. You can get JB Weld in a large size and I use a lot of it. Epoxy and some strategic reinforcing (think straps and bolts) can make workable repairs on many seemingly unsalvageable parts. Be aware that it does run a lot during curing so you may have to dam it up with duct tape or something. A cheap sandblaster helps a lot for getting it to stick well.
Don Young
Don Young
Reply to
Don Young

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