Cast Iron Repair - Best Epoxy?

[Mike Henderson]

Whatever you do, my advice would be: Don't try to weld it. In my opinion, that's the worst possible (attempted) solution. And I weld a lot.

I would definitely agree with this. I'm no expert welder but even trying to braze cast iron is difficult. Cast iron expands when you heat it and then shrinks when it cools and it's brittle. Local heating, even the lower temperature needed for brazing, causes local expansion and then possible cracking when it cools. And the cast iron often warps, even if it holds together.

Mike

[Mark Hennebury]

photo of the piece please.

I have to repair a piece of cast iron that has a very clean break. This is the base of my jointer fence, so it doesn't get much stress in-use. So, since I want to make the repair as "invisible" as possible, I don't want to weld / braze.

Any ideas on which epoxy would be best? There are several factors involved:

1: Obviously, the ability to bond cast iron well. - not just tensile strength. In fact, tensile strength is probably the least important factor in this case.

2: The ability to bond when the pieces are clamped tightly. Most epoxies work best with LESS clamping pressure than typically used with wood glues, but I want this break to disappear as much as possible, so....

3: A cured color that comes as close to cast iron as possible. Something "too light" can always be darkened, but not vice-versa.

---------------

JB Weld is always a consideration, but I fear it might be too thick.

Standard 30-minute epoxies are incredibly strong, and thin, but I can't find any data on them, re cast iron.

System Three recommends their "Met Weld." The cured color looks pretty close, and the stuff is STRONG, (!) but again I fear it might be too thick.

Permatex 84109 also looks promising.
-------------------------------------------

Your thoughts / recommendations?

thx.

[Allan Speers]

photo of the piece please.

I'll post before / after pics once I do the repair (very soon.)
- But it' just a clean break in cast iron. You seen one, you seen 'em all.

[Allan Speers]

BTW-

I'm surprised no one has mentioned one part (heat cured) epoxy.

From what I've read, it can be superior to 2-part in several ways. Oddly, the few I looked at carefully had lower tensile strength, but I wasn't able to find too much data that was apples-to-apples. Often I saw different strength ratings based on whichever material was being glued.
- Or maybe that was shear strength? I dunno, it got confusing fairly quickly.

Any thoughts on 1-part epoxies?

[Tom M King]

Is that a piece that was broken during the move? I would have epoxied it back together that night, with something I had on hand, while the surfaces were fresh.

[Jacob Reverb]

I'm surprised no one has mentioned one part (heat cured) epoxy.

From what I've read, it can be superior to 2-part in several ways...

Such as...?