Cast Iron Repair - Best Epoxy?

[Allan Speers]

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.

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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.

[Dave Cav]

I would use JB Weld (not Quick) and if it's too thin add a drop of two of acetone.

[Mike Kees]

JB weld was my first thought as well.

[Jacob Reverb]

If you've got it, I'd use West Gflex. It's real tough stuff. If not, I'd use whatever's on hand. The key is getting it wet out well at the epoxy-to-metal interface. Haven't used JB Weld, but if it's too thick, you might want to put a tack coat of some other kind of epoxy on the metal before using JB Weld (or adding a filler to whatever you're using), and be sure to add the second layer (i.e. with filler or JB Weld) before the tack coat fully hardens (should still be able to dig your fingernail into it). That way, the two epoxies will chemically bond and you won't need to deblush. If you have it, West 404 would be my choice of filler, but lacking that, just about any real fine powder should work, and you don't need much...just enough to thicken it enough to keep it from dripping out before it hardens. I wouldn't worry too much about color, since I suspect the "glue line" will be so thin that it will disappear. If you're left with a glue line that you can see, you probably used too much filler, resulting in a glue line that's too thick. It shouldn't be more than a few mils, if I'm visualizing what you're doing right...

[Erik Loza]

+1 for JB Weld. I've used it to repair engine parts numerous times. Be aware: Like any coating, the long-term success depends on surface prep. The rougher, the better, and zero traces of grease or oil. Good luck with it.

Erik

[Allan Speers]

If you've got it, I'd use West Gflex. It's real tough stuff. If not, I'd use whatever's on hand. The key is getting it wet out well at the epoxy-to-metal interface. Haven't used JB Weld, but if it's too thick, you might want to put a tack coat of some other kind of epoxy on the metal before using JB Weld (or adding a filler to whatever you're using), and be sure to add the second layer (i.e. with filler or JB Weld) before the tack coat fully hardens ...

Thanks, Jacob, but I'm not sure what "wet out" means.

Also, wouldn't this procedure make the epoxy layer itself too thick? Again, I want the crack to come back together as tightly as possible. My assumption (based on nothing, really) was that a thin layer / thin viscosity would be better, and that this could work because the cast iron is so porous, that it would hold enough epoxy in its pores to have a good bond.

But that's just an assumption, which is why I'm asking you guys.

And again, I worry the same way about JB Weld, which was designed specifically for filling in cracks and gaps, not specifically for strength or cleanliness of the repair. My thought is, why use an epoxy that contains fillers, when the break is clean?

Have you guys done this sort of thing, specifically on cast iron, and achieve a very tight repair?
Is Dave's idea to add a little acetone the answer? (Sure that will thin the epoxy, I fear that might also weaken the bond. Why not just use regular epoxy?)

[John K Jordan]

Depending on where the break is, perhaps you could strengthen the joint with machine screws, perhaps countersunk. I've drilled and tapped cast iron several times. Perhaps epoxy plus screws?

And is the area of the break painted? If so, repainting could make a joint invisible.

JKJ

[Jacob Reverb]

Regular epoxy would probably work just fine, possibly with just a tiny amount of very fine filler. With the tiny clearance between the broken pieces of cast iron, it's really a balancing act between "just enough" epoxy remaining in the joint, and not enough. With unthickened epoxy, my concern would be a "glue-starved joint." In other words, I would add a tiny bit of filler (to get it somewhere between the consistency of molasses and ketchup) to prevent too much of the epoxy from squeezing out of the joint. But you can add too much filler, too. With something like JB Weld (which, again, I have not used – but isn't it about the consistency of peanut butter?) my concern would be that it would have too much filler, and thus create too thick of a glue line, as well as possibly not "wet out" the bonding surfaces enough. By "wet out," I mean you want to really work the unthickened epoxy into all the pores and voids with a brush, the same way you would jam the bristles of a paint brush to get paint "wetted out" into rough wood, or voids in the wood – or the same way you "wet out" fiberglass cloth with polyester resin or epoxy, by pushing the resin down into all the voids in the fabric with a squeegee or paintbrush. When you do this with fiberglass cloth, the cloth changes from opaque to transparent, indicating that the fabric is fully "wetted out." You can also suck out the air by vacuum bagging.

Probably if you got some regular vanilla unthickened epoxy (like the Loctite epoxy sold in Walmart for example), mixed it up, maybe added 10% acetone by volume, then really worked it into both pieces of cast iron with an acid brush or something like that, then waited a few minutes for it to tack up a bit, then put some unthinned epoxy on top, and clamped it, you'd be in good shape.

Good luck, and let us know how it works out. If you're still apprehensive, shoot some pics of the pieces you want to glue -- it might help us advise you.

ETA: I would also echo Erik's comment about surface prep. You really want to degrease the living daylights out of it. I would use brake cleaner.

[Derek Cohen]

Is silver solder an option?

Regards from Berlin

Derek

[Tom M King]

I've never had one of these 3M DP epoxies fail under any use I've put them to. They aren't exactly cheap, and you need mixing nozzles, and a special gun to operate them at their best. I've also used a number of the different JB Weld epoxies for a variety of things, and never had one of those repairs fail either. My first choice would be one of the 3M's.

https://www.3m.com/3M/en_US/company-us/all-3m-products/?N=5002385+8710815+8710979+8713609+8711017+3294857 497&rt=r3

It's thin enough that the parts should go closely back together. I can loan you a gun, and send a nozzle, if you want to go this way.

I also recently threaded some holes in cast iron, up to 1", so can offer some advice from experience, if you go that route.

edited to add: I use the black version of this acrylic adhesive to glue golf club heads on with. It may even be stronger than the epoxies, but I don't remember comparing the specs. This price is Way off though, for some odd reason. I think the single unit price must be for a case.

https://www.ellsworth.com/products/by-manufacturer/3m/adhesives/acrylic/3m-scotch-weld-dp810-low-odor-acrylic-adhesive-tan-200-ml-duo-pak-cartridge/

You can get any of them through Amazon, but of course, you have to pay a higher price to cover the "free" shipping. https://www.amazon.com/s?k=3m+dp810&gclid=Cj0KCQiAxrbwBRCoARIsABEc9sjZF4741tPnfwZhDKz5 WP_nXgZQBR4xE--GIVNs1MCAwQXG_HiTYj0aAktNEALw_wcB&hvadid=176296951415&hvdev=c&hvlocphy=9008621&hvnetw=g&hvpos=1t3&hvqmt=e&hvrand=5344256425232203720&hvtargid=aud-835997443427%3Akwd-12194597107&hydadcr=29306_10014220&tag=googhydr-20&ref=pd_sl_4yvlwbyfne_e

[Frank Pratt]

I would use and epoxy without any filler in it. When cast iron breaks, there is usually little or no deformation of the metal adjacent to the break. So you want an adhesive the will allow the metal to fit as closely as possible at the break. Use a slow cure and warm up the metal before applying the epoxy.

[Mike Cutler]

Belzona Molecular Metal.
JB Weld is a great product, but there is no comparison between the two.

[Allan Speers]

Man, this got more complicated than I expected! lol... Too many choices!

I greatly appreciate all the thoughtful responses, guys.


Still no idea how I'll proceed, though I'm better armed to decide now.

Silver soldering is an interesting idea, but I think it might be hard to make sure enough material gets in, without it flowing to the surface of the crack. That could be dealt with, aesthetically, but since I don't need a lot of strength here, I figure it's not worth the trouble. (Maybe with a hand plane, or an adjustment wheel, etc, it would be worth trying.)

The whole "wetting" thing seems to be the most important factor, now that I understand it, esp since cast iron is so porous. there's not a lot of "immediate surface area" to make a good bond. But too much epoxy and those some pores would inhibit squeeze-out. So I really like Jacobs idea for applyin the stuff- Wetting / filling both sides first, then maybe wiping down the surfaces, then brushing on a final thin coat once the first application is semi-cured.

So the application is set, I just still have to decide on the product.

I'm ruling out that acryllic stuff, despite Tom's generous offer (thanks!) & even though it looks like a great product for some applications. Its forte seems to be impact resistance (golf clubs) and fast cure time, but its tensile strength is actually fairly low. It might actually be perfect, but until someone literally uses it for cast iron repair, I think I'll go with a more "known" compound.

Thinned JB Weld still worries me, strength-wise, unless someone knows of a test that shows the resulting strength. So that's out.

Regular JB Weld is still in the running, esp if I will be filling the pores first with the same stuff, but I remain hopeful of using a thinner product.
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I wonder: Could I use a "filler" epoxy like JB Weld, Belzona, Met Weld, etc to fill the pores, but then use a different, thinner epoxy to actually mate the two pieces together?

Or alternatively, maybe use a thin compound, like G/Flex or regular old 30 minute epoxy, but add fillers for the "wetting" layers, but use it thin for the "mating layer?

[Tom M King]

Only the 810 I linked to is one of their acrylics. The others, in the first link, are all epoxies. I expect any regular epoxy will work fine, and don't think the fillers will be beneficial here. 24 hour cure is stronger than the quick cure stuff. I think you can even get some two part epoxy in a syringe in the box stores under the Locktite brand, which is fine.

I wouldn't worry about the porosity of cast iron. By putting a generous amount on both parts, and then clamping it together, it will be about as good as you can do anyway.

I'd brush it on both parts, then squeeze, and clamp together. I've even used a tourniquet on some odd shaped parts when any other type of clamps wouldn't work. Just clean off the squeeze-out with paper towels, and acetone, while it's still wet.

[John K Jordan]

I wonder: Could I use a "filler" epoxy like JB Weld, Belzona, Met Weld, etc to fill the pores, but then use a different, thinner epoxy to actually mate the two pieces together?


I have permanently repaired many things around the farm.

I personally would not worry a bit about the porosity in the cast iron. Porosity in cast iron is nothing like the porosity of wood. With a clean break with no missing pieces you will have two rough surfaces creating a large surface area. If you can fit the pieces together now with a tight line I think normal epoxy is fine mixed according to instructions with no thinning or additives. I prefer 1-hour epoxy where I want strength. West System G/Flex and Systemthree T-88 are good for general purpose. Note that you can call the epoxy makers and tell them your application and they can recommend a specific adhesive.

Blow off any dust or tiny cast iron chips/grains, wash with acetone and dry with compressed air filtered to remove oils, and apply epoxy - I use a spatula or small glue brush. If using a brush make sure no bristles come loose and remain on the surface. With a tight fit I see no need to put epoxy on both surfaces. Clamp tightly together with some method. Wipe off squeeze-out with paper towel slightly dampened with acetone or wait until cured and scrape/cut it off if surface scratches won't bother you. Do not heat but let it set in a warmish place at least overnight before using.

If it were mine I'd use JB-weld which has proven to me over and over it will bond incredibly well to metals. It does contain fine iron particles and may show a grey line. If I absolutely wanted the part to look like new I'd buy a new part and forget the repair.


I still don't see where you posted a photo of the two pieces which might have minimized assumptions and helped experienced people make useful suggestions.

Sliver solder is a type of brazing and can leave the binding metal on the surface.

[Erik Loza]

https://youtu.be/XObmZIbHOzY

[Tom M King]

That was a fun test, but I feel unfair to some of the brands. If he had tested only the fast cure epoxies that each brand sells, and then the slow cure, it would be a more clear test. The slow cure of any brand should always beat a fast cure in that test. JB Weld had the best chance of coming out on top, simply because of the numbers of each brand used.

I don't know about the High Heat version, but I think the JB Original may have been the only slow cure in the lot.

[andrew whicker]

I work with heavy pressurized gas equipment... Belzona is boss. That's all I'm going to say : )

[Tom M King]

I believe you. I've never seen any, but am ordering some to have on hand, as soon as I find it.

edited to add: no longer available from Amazon. The only online retailer I found that has it is on ebay. It's too expensive to justify buying some just to keep on hand. If I ever have a tractor block to repair, I can order it. I have friends in boat repair business, here on the lake, and I've heard them say multiple times that it amazes them how many aluminum outboard blocks, and jet ski blocks are still operating with nothing but MarineTex fixing a cracked block.

Of all the things I've fixed with epoxy, when I was in the boat business, and keeping the Ponderosa operating for 40 years, I can't remember ever having anything fail.

As an extra, useless aside, the reason I use that acrylic 3M DP810 on golf club heads is the same reason a lot of Tour Vans use it. It's plenty strong enough, but the best thing about it is it turns into a crackly, expanded mass, when heated below a temperature that would melt the resin in a composite golf shaft, and is very easy to clean off, back down to bare material. It makes it really easy to try different shafts on the same head. Epoxy, which is also used a lot, is many time harder to clean off the shaft, and out of the hosel.

[andrew whicker]

If you knew anyone in heavy industry, they might hook you up. I'm not sure how much it costs. I think most companies in that old tech, big equipment field would have some handy.

[Tom M King]

I think it was something like $126.00 for 1kg, for both parts. No heavy industry anywhere near us. So far, I've never cracked a block on anything.

[Allan Speers]

I believe you. I've never seen any, but am ordering some to have on hand, as soon as I find it.

edited to add: no longer available from Amazon. The only online retailer I found that has it is on ebay. It's too expensive to justify buying some just to keep on hand. If I ever have a tractor block to repair, I can order it......

Yeah, the problem with some of these more exotic compounds isn't just the price, but the fact that they all have a pretty short shelf life. Typically as little as a year, to a luxurious 3 years for a few. I'd love to have expensive adhesives around just for emergencies, but it's not too economically feasible.

[John K Jordan]

I work with heavy pressurized gas equipment... Belzona is boss. That's all I'm going to say : )

Never heard of Belzona so I looked it up. I want some.

[Jacob Reverb]

I wonder: Could I use a "filler" epoxy like JB Weld, Belzona, Met Weld, etc to fill the pores, but then use a different, thinner epoxy to actually mate the two pieces together?

Or alternatively, maybe use a thin compound, like G/Flex or regular old 30 minute epoxy, but add fillers for the "wetting" layers, but use it thin for the "mating layer?

Normally, you use thinned/unthickened epoxy to "wet out" the surface of whatever you're gluing. Think of it like pizza dough: The more flour you add, the less likely the dough is to stick to your work board, and the less likely it is to "get into the pores" of that board. If you WANT it to stick to your work board, you should keep it "sticky" by not adding too much flour...or, if too much flour has already been added, by "thinning" it with additional water. Imagine trying to squash pizza dough down into a knot hole, or the rough section of a board. The more flour (filler) it has added to it, the less likely it is to a) squash down into those tiny pores and voids, and b) stick to them once it's in there.

To diagram, the components of your joint "sandwich" should look something like this:

CI | UPTER | OPTIONAL: TE | UPTER | CI

where

CI = cast iron
UPTER = unthickened, possibly thinned epoxy resin
TE = thickened epoxy (optional)

Hope this helps. It's not as complicated as it might sound.

ETA: See the fifth paragraph here for a helpful explanation of what you're trying to do to the resin by adding a tiny amount of filler here (you're trying to make it thixotropic – i.e., "resistant to dripping" – rather than simply "thicker"):

http://www.eagerplastics.com/cab.htm

[Jacob Reverb]

The slow cure of any brand should always beat a fast cure in that test.

I've been messing with epoxies for boat repair for decades, and I've always lived by that same rule of thumb that slow hardeners yield a stronger composite, but...

I don't know whether something recently changed in West's formulations or what, but I recently discovered that West claims their fast hardener yields more tensile strength (about 7.8 ksi vs 7.3 ksi) than their slow hardener. (Although the elongation figures suggest the slow hardener gives more "toughness"/ductility, and "Gflex" gives about 10X as much, though only half the tensile strength.) And I didn't watch the video, so I don't know whether he was testing for tensile strength or toughness. If he was testing for ductility, you're right – slow hardener should fare better – in which case, disregard my comments above.

Anyway, for a comparison of the mechanical properties of various West System resins and hardeners, see:

https://www.westsystem.com/products/compare-epoxy-physical-properties/

[Pete Staehling]

I'd have just silver soldered or brazed it, but I have never heard of Belzona.

[Mike Cutler]

I'd have just silver soldered or brazed it, but I have never heard of Belzona.

Belzona is "magic" in a tub. We use it at work for large machinery repairs, at times.
There are many different formulations of Belzona, but they definitely have one for CI.

[andrew whicker]

I'm thinking heavier than your engine block. I'm thinking refineries, big CAT engines, turbine mfg'ers, things like that.

Like Greenville, SC (GE builds turbines down there) definitely would have some. But that's an entire state away from you.

[Tom M King]

Fortunately, the last cast iron repair didn't require epoxy, but did require some specialized equipment to rethread some holes up to 1". This Milwaukee magnetic drill press is a Real Beast. I thought I would resell it, when I got through with it, but like it so much, I'm going to keep it. The rethreading part wasn't so bad, once I was able to redrill the holes. Redrilling the holes was easy, once I bought this thing. That's a 3/4" steel plate it clamped itself onto. It also drilled the holes in the plate to mount it to the block. The drill press weighs 85 pounds. That's a 7/8" bit in the chuck.

Little bit of a long story, but these were the loader mounting holes in the block.

[andrew whicker]

What?! You've got a magnetic drill? You're awesome in my book.

[Patrick Walsh]

Hmm this Belzona stuff has my interest. I have a cast aluminum shaper fence dust port that’s gonna need a repair. Sounds like if I want the best fix this stuff is it. Is there a specific formulation geared toward aluminum and or should I just call the manufacturer.

[Brice Rogers]

Silver solder is incredibly strong. Probably stronger than the cast iron. But you need to get the cast iron quite hot. It works best for very narrow gaps and flows like water. I'm not sure if it is the best choice for this application, but it is REALLY strong. I use it to silver solder (45% silver) broken bandsaw blades and have never had one fail at the solder joint.

[Rob Luter]

I'll second (or third) the silver solder suggestion. Brazing with brass would work too. Almost any tool and die shop should be able to do this.

[Tom M King]

Hmm this Belzona stuff has my interest. I have a cast aluminum shaper fence dust port that’s gonna need a repair. Sounds like if I want the best fix this stuff is it. Is there a specific formulation geared toward aluminum and or should I just call the manufacturer.

JB Weld Marine would be fine with that repair.
https://www.jbweld.com/product/marineweld-twin-tube

[Patrick Walsh]

I figured so much Tom. It’s a crack in the same exact place in the same exact machine as Joe Calhoon did on his T23 with JB weld. You know me I’m the king of overkill. God forbid that port should ever crack enough to warrant it non functional. I’d have a freaking egg.



JB Weld Marine would be fine with that repair.
https://www.jbweld.com/product/marineweld-twin-tube

[Tom M King]

Judging by the prices I found on Belonza stuff, the difference in price between it, and the JB, would be a bit more than 100 bucks. As I've said earlier, in this thread, I've never had any such epoxy repair fail, and that doesn't seem like an unusually high stressed piece.

edited to add: If you wanted to do a pretty repair, which I expect you do, the 3M duo cartridges using a gun, and mixing nozzle will allow you to run a very small bead right where you want it. Both the plastic nose on one of my tractors, and one of the back fenders on my dually have been held together with DP100 for 8, or 10 years now, and you have to look really closely to see that there is even a crack. I even have a long term fix still holding on a plastic fuel tank, on a generator, with that same stuff.

I'm not sure which one is right for aluminum. There are quite a lot of different ones.

If you go the duotube route, the best prices I found on guns and nozzles, back when I was looking for one, came from Golfworks, for both the gun, and nozzles. The Golfworks gun works just fine. https://www.golfworks.com/the-golfworks-epoxy-cartridge-gun/p/esg2/ Poke around on their site, and order some mixing nozzles in the same order.

The review that says it only fits their brand of cartridges is not correct. It does indeed fit the little 3M duotubes.

[Richard Coers]

Silver solder is incredibly strong. Probably stronger than the cast iron. But you need to get the cast iron quite hot. It works best for very narrow gaps and flows like water. I'm not sure if it is the best choice for this application, but it is REALLY strong. I use it to silver solder (45% silver) broken bandsaw blades and have never had one fail at the solder joint.
Silver soldering a carbon steel bandsaw blade and a grey iron casting are wildly different animals. The graphite in the cast iron will likely not play well with the soldering process. Depends on the alloy of course.

[Patrick Walsh]

Tom

Good news. I have one of those guns and the tips. I use a them for a project I use to glue the joints of fiberglass gutters.

I also use a product sold for gluing Azek or pvc trim boards.

https://fibergutter.com/installation/

http://www.pvctrimwelder.com/pvctrimwelderfastcure50mlcartridge.aspx

Couldn’t find the gun but it’s the same for the small tubes in the bottom link.

Sweet product the gutters themself if your not familur.

Core era get mitered and joints are laid up from the inside with fiberglass sheets. Been I staling them for a number of years now and have had zero failures. I even put them on my own house. I can hang of them and bounce up and down as hard as I can right at a joint and no issues.

$17lf though last I used them.








Judging by the prices I found on Belonza stuff, the difference in price between it, and the JB, would be a bit more than 100 bucks. As I've said earlier, in this thread, I've never had any such epoxy repair fail, and that doesn't seem like an unusually high stressed piece.

edited to add: If you wanted to do a pretty repair, which I expect you do, the 3M duo cartridges using a gun, and mixing nozzle will allow you to run a very small bead right where you want it. Both the plastic nose on one of my tractors, and one of the back fenders on my dually have been held together with DP100 for 8, or 10 years now, and you have to look really closely to see that there is even a crack. I even have a long term fix still holding on a plastic fuel tank, on a generator, with that same stuff.

I'm not sure which one is right for aluminum. There are quite a lot of different ones.

If you go the duotube route, the best prices I found on guns and nozzles, back when I was looking for one, came from Golfworks, for both the gun, and nozzles. The Golfworks gun works just fine. https://www.golfworks.com/the-golfworks-epoxy-cartridge-gun/p/esg2/ Poke around on their site, and order some mixing nozzles in the same order.

The review that says it only fits their brand of cartridges is not correct. It does indeed fit the little 3M duotubes.

[Tom M King]

I'm sure they're nice, but I have nowhere to use plastic on the old houses I work on. Most of them don't even have gutters, but this one needed them, so we used these. They come in special shipping boxes that you can walk on, and every piece separated in the boxes by specially designed dividers, and foam sheets.
https://classicgutters.com/

I put them on this house.
http://historic-house-restoration.com/images/CIMG2129.JPG

[Patrick Walsh]

Tom,

I wanted to do copper built in gutters but the cost was crazy. I think like 50-60k. Copper half rounds I was discouraged from by the copper guy I used to work with.

Being my home a bungalow the only right thing to do was replace the original wooden gutters. I had replaced a few runs over the years and honestly in less than ten years the new growth timber would rot even keeping them oiled.

The fiberglass gutters I used are actually made using actual wood gutters. In person you can’t tell the difference as the grain is also cat into them.

Not historic but pretty darn nice.

Again I wanted copper but even the half rounds fully soldered “not the kind with fittings for joints and corners” where like $33lf I think. I’ll throw lead coated down spouted in to match my valleys drip edge and chimneys lead coat through pan and be happy.
‘

I'm sure they're nice, but I have nowhere to use plastic on the old houses I work on. Most of them don't even have gutters, but this one needed them, so we used these. They come in special shipping boxes that you can walk on, and every piece separated in the boxes by specially designed dividers, and foam sheets.
https://classicgutters.com/

I put them on this house.
http://historic-house-restoration.com/images/CIMG2129.JPG

[Tom M King]

Those weren't copper, since they wanted them to be white. They were about 5200 for the materials. I forget what the copper was, but it was multiple times that, and wouldn't have looked right anyway.

[Patrick Walsh]

I didn’t think they were copper they are white.

They just reminded me of the copper half rounds that’s I am used to working with..

Nice windows on that house..


Those weren't copper, since they wanted them to be white. They were about 5200 for the materials. I forget what the copper was, but it was multiple times that, and wouldn't have looked right anyway.

[Tom M King]

That company makes the exact same profile, and different sizes, in copper too.

Those are the original 1850 sash that I redid. There were only 18 original panes remaining, so cylinder glass sheets were ordered from Bendheim in Germany (edited to add: the company that sells it is here, but we ordered a whole "case", on a pallet, so they drop shipped it from Germany), and it matched the original almost exactly. http://www.restorationglass.com/antique-window-glass.cfm They had all been painted shut, and now operate better than ever, I'm sure.

The sash on the back of that house had been replaced, so on my to-do list is to make four exact replacement sash.

I have all the parts run for those few sash, and modified an old molding plane to match the profile, but I got sidetracked saving a falling 18th Century chimney, and other family stuff, so haven't gotten back to them.

My to-do list is longer than I can possibly ever get done. That's a museum house, and they want me to build a replacement, separate kitchen, which would be one of four that I have requests for, etc., etc.

[Jacob Reverb]

Silver solder is incredibly strong. Probably stronger than the cast iron. But you need to get the cast iron quite hot.

I do quite a bit of tig, stick and oxy-acet welding and brazing, and I agree that silver solder is wonderful stuff, but I would be leery of heating cast iron – particularly something that needed to stay straight/flat or stay put – unless it was absolutely necessary.

Depending on what kind of cast iron it is, epoxy, with a tensile strength of ~ 7.5 ksi, could approach (if not exceed) the tensile strength of the CI. Cast iron is a lot like concrete: Plenty of compressive strength, tensile strength not so much...which is often why it cracks (often as a result of uneven heating/quenching).

If the part isn't too stressed, and not critical, I would lean toward a glue-type solution. FWIW, I've seen epoxy "crack patches" last on raw-water-cooled marine engine blocks for years and years...

Allan, have you fixed it yet?

[Allan Speers]

Allan, have you fixed it yet?

Not yet. I'm still weighing the various options, & performance vs cost.

I should get to it sometime this week. I'll report back & with pics.

[Michael A. Tyree]

I too know how to weld, have the equipment and would not use epoxy. When I did work in industry I/we used epoxies that are not typically sold to street trade and perhaps that's a good fix, but I would braze it. It's a common, old time fix to braze cast iron, not something strange or expensive unlees nobody will do it for you reasonably in place. There are also stick weld rods made for cast iron welding. Every tech school I ever worked in used kept them around for repair jobs that came around. If it's not a high stress crack area, brazing is far cheaper than things mentioned above. Once you begin putting some epoxy on it the crack will never be as easily welded or brazed as it is right now. On a machine that vibrates it would avoid epoxy repair. All IMO of course.

[Tom M King]

Not yet. I'm still weighing the various options, & performance vs cost.

I should get to it sometime this week. I'll report back & with pics.

I hope it's somewhere that the surfaces won't oxidize.

[Monte Milanuk]

Hah! Never thought I'd see 'Belzona' mentioned on SMC ;)

The hydro-electric dams where I work use that stuff by the tub for repairing cavitation damage on the turbine runner blades and the liner for the water passage. Work it in, smooth it out, let it cure and grind it smooth. When things get to the point where there is more Belzona than steel... air-arc torches to remove sections and then weld in replacement pieces. Big boy toys... ;)

423118

Baby version, but it shows the cavitation damage a little better...
423119

[Patrick Walsh]

He said it’s a big boy toy.

Now I gotta use just cuz ;)

Really I do.

[Allan Speers]

I hope it's somewhere that the surfaces won't oxidize.


Actually, after degreasing, I plan on soaking them in a rust solution overnight (Rust911) then a quick detergent bath, and then immediately doing the repair afterwards. That should give me as clean a surface as possible.

[Allan Speers]

I too know how to weld, have the equipment and would not use epoxy. When I did work in industry I/we used epoxies that are not typically sold to street trade and perhaps that's a good fix, but I would braze it. It's a common, old time fix to braze cast iron, not something strange or expensive unlees nobody will do it for you reasonably in place. There are also stick weld rods made for cast iron welding. Every tech school I ever worked in used kept them around for repair jobs that came around. If it's not a high stress crack area, brazing is far cheaper than things mentioned above. Once you begin putting some epoxy on it the crack will never be as easily welded or brazed as it is right now. On a machine that vibrates it would avoid epoxy repair. All IMO of course.

All true, but brazing makes an UGLY repair. There's no getting around it.

Again, my particular piece doesn't get much mechanical stress at all, so I'm going for the cleanest repair, aesthetically.

I might also sink a couple of screws / bolts across the crack, as someone else mentioned earlier, but that's probably overkill for this particular repair.

[Jacob Reverb]

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.

[Allan Speers]

FWIW, there's another method for repairing metal, though I'm not sure if it works on CI.

I saw this on Youtube, on "Jay Leno's Garage." There's a guy in CA that has repaired some super-rare, cracked engine blocks for Jay, using a new method called (IIRC) "stitching." From what I can see, it's might be sort of like tapping thread and installing reinforcing threaded rods, but actually it looks more high tech than that. The repair looks insanely good.

Jay mentioned that it was very expensive, so not the kind oif thing to use on a Taiwanese jointer! - But very interesting, regardless.

Do any of you guys know anything about this process?

[Allan Speers]

Heck, I found it easily. It's called "Lock-N-Stitch" :

https://www.youtube.com/watch?v=Pq0wfU4ZaKk


Definitely for cast iron. Not quite as pretty a repair, in this video, than I saw with Leno's blocks. I guess it's an artistic skill to some extent.

[Frank Pratt]

FWIW, there's another method for repairing metal, though I'm not sure if it works on CI.

I saw this on Youtube, on "Jay Leno's Garage." There a guy in CA that has repaired some super-rare, cracked engine blocks for Jay, using a new method called (IIRC) "stitching." From what I can see, it's might be sort of like tapping thread and installing reinforcing threaded rods, but actually it looks more high tech than that. The repair looks insanely good.

Jay mentioned that it was very expensive, so not the kind oif thing to use on a Taiwanese jointer! - But very interesting, regardless.

Do any of you guys know anything about this process?

I've never done it, just read about & watched videos of it being done. To my knowledge, stitching is done only for cracks where the part is still together. It is to keep the crack from propagating and to tie the edges of the crack together and stabilize them. I don't see how it could possibly join 2 pieces that are actually broken apart.

[Erik Loza]

Allan, whatever you end up doing, please make sure to post "after" pics. I think we're all invested now. :D

Erik

[Allan Speers]

I've never done it, just read about & watched videos of it being done. To my knowledge, stitching is done only for cracks where the part is still together. It is to keep the crack from propagating and to tie the edges of the crack together and stabilize them. I don't see how it could possibly join 2 pieces that are actually broken apart.

In one of the Leno videos, they had repaired and engine block that had a huge piston blow right through the block. So they MUST have replaced that blown-off piece.

Maybe the idea is to do some kind of braze or epoxy repair first, to align the parts, then do the stitching?

[andrew whicker]

How hot for silver brazing? Rule of thumb for me is to watch heat input on post machined surfaces...

[andrew whicker]

The only brazing I've done (forget the filler) was on structural steel and required red hot. Too hot to reliably keep dimensions if that's a big concern.

[Frank Pratt]

In one of the Leno videos, they had repaired and engine block that had a huge piston blow right through the block. So they MUST have replaced that blown-off piece.

Maybe the idea is to do some kind of braze or epoxy repair first, to align the parts, then do the stitching?

It must have been a piece that could be put back & was confined on all the edges. There needs to be something to keep the busted part from just falling away from the repair.

[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...?