Favorite filler for cast iron?

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Comstock-Friend
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Favorite filler for cast iron?

Post by Comstock-Friend » Fri Mar 12, 2021 7:07 pm

My Coventry castings on the 3/4" D30 0-6-0 have a worm hole or two; some have some pits below the surface. As these are NOT John K's Friends Yankee Shop Models castings I can't expect him to replace them. Mostly cosmetic, but one connects the outside of a cylinder head to the counterbore the piston rod nut fits in.

Any suggestion for your favorite filler/bondo? Anything that will be steam tight?

John

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milwiron
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Re: Favorite filler for cast iron?

Post by milwiron » Fri Mar 12, 2021 7:34 pm

The original (not quick set) JB Weld is good stuff and readily available.

Denny
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FKreider
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Re: Favorite filler for cast iron?

Post by FKreider » Fri Mar 12, 2021 9:23 pm

JB Weld makes a whole range of different products including ones that are safe for high temperature applications. For any parts that will get hot from the boiler/steam I would be sure to use something well above the necessary temperature range.
-Frank K.

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Greg_Lewis
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Re: Favorite filler for cast iron?

Post by Greg_Lewis » Fri Mar 12, 2021 10:14 pm

As Denny wrote above, the regular JB Weld works great. It is easy to sand down to an imperceptible blend into the surrounding area, and it's good to 550 degrees.
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
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Celebrating 30 years of turning perfectly good metal into bits of useless scrap.

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rudd
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Re: Favorite filler for cast iron?

Post by rudd » Fri Mar 12, 2021 10:16 pm

Nickel bearing silver solder (safety silv 50n) does decent on CLEAN cast iron, use the black flux, and don't overheat the flux.

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SteveR
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Re: Favorite filler for cast iron?

Post by SteveR » Sun Mar 14, 2021 1:58 am

I've had good luck stick welding cast iron with this high nickel rod (ENi-CI (Ni99))from Mcmaster #7973A612. Get everything nice and toasty with a torch (sooty and then burn it off), weld, then cover with a fireproof blanket when done to let it cool down. Machines well.
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Santafescotty60
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Re: Favorite filler for cast iron?

Post by Santafescotty60 » Sun Mar 14, 2021 6:49 am

Hello Good People,
Possibly thinking about the pin hole /worm hole just thinkin could you drill and tap for a model bolt or model pipe hole fill it with jb weld assemble it while the goop is setting up , by screwing in the threads you would be hydraulically filling the void gently so you don't split the casting like finger tight several times before, letting it set up .And then saw off the plug,\/ bolt peen it down file it off . like your Play-doh days of youth if you have no welder or torches. marine epoxies "Splash Zone" brand name if they still make it worked well

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Bill Shields
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Re: Favorite filler for cast iron?

Post by Bill Shields » Sun Mar 14, 2021 6:59 am

I have filled in such with brazing rod (brass) and an oxy touch with borax flix.

Takes time to get hot and you should allow to cool slowly...but it works.
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jscarmozza
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Re: Favorite filler for cast iron?

Post by jscarmozza » Sun Mar 14, 2021 8:40 am

If it's cosmetic JB Weld is fine, if it's structural braze it.
I bought a Pacific project a few years ago that had rod binding issues; aside from the quartering being out, when I pressed out the axles I found the hubs looked like sponges. On one wheel there was only about 10% bearing on a key. I packed the axle holes with liquid steel and did the screw trick previously mentioned to force the liquid steel into all the nooks and crannies, drilled, reamed, bored and cut new key slots in a different quadrant. And although I'm continuing to rebuild the project, I don't think I will invest in a boiler, because in retrospect I don't trust that the wheels will hold up in service. Moral of the story...do an appropriate repair. John

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Re: Favorite filler for cast iron?

Post by Comstock-Friend » Thu Mar 18, 2021 6:08 pm

Thanks for your experiences guys!

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Bill Shields
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Re: Favorite filler for cast iron?

Post by Bill Shields » Thu Mar 18, 2021 6:48 pm

Note...if you are filling a deep hole with brazing rod it may be necessary to grind it out so that you can get the filler all the way to the bottom.. or air will bubble up and cause problems...think funnel...
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Kay_B
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Re: Favorite filler for cast iron?

Post by Kay_B » Mon Mar 22, 2021 6:25 am

I will add that it is better to fill the cavities with a thin tool so that there are no air bubbles left at the bottom. Metal hardens quickly in cold material.

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