Welding castiron

I have a bath tub that I want to use to melt lead in [ for a boat keel] can a black iron pipe be welded to the drain hole? I would also like
cover the overflow hole.
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A friend just brazed a cast-iron steady rest for me, and it appears to work just fine. Brazing can definitely work. But to do it right is a lot of work. Preheat for a while, and after brazing, cool it slowly.
I've read that cast iron can be welded but it's quite difficult. I would consider instead making or buying a fitting that would connect the pipe to the drain---doesn't it have a thread already?---- then plug the overflow hole with furnace cement or something similar.
Regards -- Terry
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You can arcweld cast iron with nickel rod, but chances are it will crack as it cools. How are you planning to heat a whole bathtub full of lead? Heat the tub, do the welding, and then cool it slowly.
I think it would be easier (and safer) to build a tub out of steel. The last thing you want is a tub full of molten lead that suddenly gets a crack.
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On 13 May 2006 23:43:30 -0700, snipped-for-privacy@stny.rr.com wrote:

Depends on the cast iron. Some is fairly easy to weld, some is impossible.
Why don't you go in with Sierevello and me on some HTS-521 brazing rod? That would work, and it would withstand the temperature of melting lead.
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Hi, - I have stick welded cast iron (DC reverse I think it was) using an oxy/acytlene torch with heating tip to preheat the part. You use temperature crayons one on the low side of your heat range and one on your high side. I used Eutectic nickel rods specific for cast iron and Eutectec had a handy book at the time how to do it. I prepped the part (a big ol' cracked power hacksaw arm) by veeing the joint both sides and I very carefully made sure I had my mounting holes alligned properly. I 1st tack welded it to keep it together, then layed in my weld in layers. Between passes I peened the weld to stress relieve it. I had to be very careful not to warp it as it was a heavy section about an inch thick. When done I let it air cool to room temperature. - What had happened was I was cutting 6 inch cored out D2 in sections of various thickness for cold roll forming mills tooling sets. (I ran my own deparment making up 60 to 100 piece sets (not one the same) all freehand in an old clunker LeBlond lathe. When done they were hardened and double tempered at 65 Rc.) This was a power hacksaw using 2 inch wide Starret hacksaw blades. This big old clunker saw was always run in low speed of a 4 speed gearbox. I tried to speed up the process and the added torque sheared the hacksaw arm. I was working night shift. My heart was in my mouth, let me tell you! At one point in my life I used to do maintenance welding. In another department in our shop I knew the maintenance guy used Eutectic rods so I borrowed his. By quitting time that night I had repaired it and reassembled the saw. I never got chewed out for it. To cost that repair job out would have cost them a few hundred dollars. - Another time I did CNC production work in a specialty valve shop of automatic control valves. I was told by the engineering department there that you do not weld cast iron as a repair if the castings are cracked in high pressure steam applications. I know we have the engineering and scientific community also frequent here and maybe they can add more guts to this conversation of live steam application do's and don'ts. - More than you wanted to know I am sure... - I would think any porcelin in the mix might make welding cast iron interesting. - -+- Kurt {:{
===============re:
- Welding castiron - Group: rec.crafts.metalworking Date: Sat, May 13, 2006, 11:43pm (EDT-3) From: snipped-for-privacy@stny.rr.com - I have a bath tub that I want to use to melt lead in [ for a boat keel] can a black iron pipe be welded to the drain hole? I would also like cover the overflow hole.
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snipped-for-privacy@stny.rr.com says...

Find a steel tank. I sure wouldn't want to be standing anywhere near a cast iron tub full of molten lead when it cracks due to uneven heating. I'd also be surprised if the porcelain didn't spall off like popcorn. I've seen several keel pouring setups in boatyards here in Maine and all used steel vessels. The largest was heated with 3 or 4 domestic oil burners aimed into an enclosure under the tank.
Ned Simmons
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says...

I'm surprised no one mention Glenn's project. Go to this page and take a look at how its done. http://www.rutuonline.com/html/casting_the_keel.html
Tom
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http://www.rutuonline.com /
checkout this site, lots of info on forming and casting a lead keel.
--
J Miller
"Tom Wait" < snipped-for-privacy@sbcglobal.net> wrote in message
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