Repairing cracks in cast iron

[CrabtreeengineerParticipant @crabtreeengineer]

Years ago metal stitching was very common for cracks or breaks in materials such as cast iron & there are still companies out there that offer this service.

Its not that difficult to do & a scan of the web will show you the basics.

Regards R

[speelwerkParticipant @speelwerk]

I do not know how the part looks you want to repair, but the few times I silver soldered cast iron it went fine. Make the joint as clean as possible and if reaching the temperature is a problem, perhaps you can ask a friend to hold a second torch for heating. Niko.

[The Merry MillerParticipant @themerrymiller]

The company I used back in the '50's, that's 1950's not 1850's . was called "Metalock Engineering UK" and it's still going strong after all this time.

It was brilliant watching how they did the business on a giant steam receiver in a power station.

Len. P.

[JimillsortitParticipant @jimillsortit]

Posted by The Merry Miller on 08/01/2014 12:40:36:

The company I used back in the '50's, that's 1950's not 1850's . was called "Metalock Engineering UK" and it's still going strong after all this time.

It was brilliant watching how they did the business on a giant steam receiver in a power station.

Len. P.

I have used the same company and in fact got some strips from the engineer and since made up a jig for drilling and inserting the strips, used on a diesel engine that had a cracked block job was a complete success.

Jim

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Whenever repairing anything important with a crack it is usually worth while making sure that the crack can’t continue to grow any wider or longer over time .

There are several procedures for terminating cracks – simplest is to drill a hole at each end .

MikeW

[RJWParticipant @rjw]

I used to weld cast iron manifolds with a stick welder and cast rods, but there were always problems with cracks reforming despite pre-heating and stress relieving etc, then I was given a tip by a welder to use Stainless rods instead!

I've since both TIG and arc welded cast with stainless and never looked back, TIG gives a much more neat and clean a result, but pre-heating is necessary to get the job going!

No idea what the experts think of this route, but it always works for me – also repaired broken T slots on an old lathe crosslide and milling table the same way, just a slight difference in colour to the parent metal!

John

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Dougie, the trouble with cast iron is that comes in various grades depening on who makes the casting and the process used. It is not impossible to weld most cast iron successfully. In most cases you will need preheating and good preperation followed by a continuation of heating, but avioding overheating and you may need some postheating and a slow cool. Nickle welding rods are usually the ones to be used. Personally I would not use stainles steel on cast iron as it expands and contracts at 1 1/2 times the rate of mild steel. It is when your casting is cooling down and the weld contracting that will cause it to crack again and more often than not it will be in the next weakest place. I've never silver soldered cast iron so can not comment but I've not knowen it to be a normal proceedure. Brass welding is a recognised proceedure, but it will need preheating. Preheating will be needed to the whole of the casting and not to just the bit you are welding whether using brass or nickle.

This **LINK** may help you, and there are some guidelines within it by clicking on the "Welding How-To's" in the left hand list.

You can also find cast iron welding rods here **LINK**

There are specialists that do cast iron welding like these people **LINK** but you would most likely need deep pockets to pay them.

Regards Nick.

Edited By Nicholas Farr on 08/01/2014 18:52:06

[Mark P.Participant @markp]

You could try metal stitching,I have done this in the past on big diesels and pump casings. I believe kits are available and there some good guides on youtube.

Mark P.

[stan pearson 1Participant @stanpearson1]

Hi Merry Miller

Thats the name of the firm that did our block stiching, they also stiched the cylinder on Flying Scotsman some years ago, i think the name of the chap who came to us was called Camieo.

Regards

Stan

[julian atkinsParticipant @julianatkins58923]

silver soldering cast iron is a definite NO NO!

sifbronze brazing is excellent for cast iron. the flux is a stiff red paste, and the sifbronze rod should be easily obtainable (ive got loads if you want some). ideally a muffle furnace is required for the castings to get them up to heat (860 degrees celcius) then a torch. ive brazed up all sorts of old cast iron bits with sifbronze the old fashioned way. seems to be a bit of a lost/forgotten art these days. more modern methods may be far easier, but im old fashioned anyway and i havent TIG gear!

cheers,

julian

[Speedy Builder5Participant @speedybuilder5]

 

Old thread, but worth viewing.
Today's job is to mend the village cross which the footie lads bust !! Its cast iron and about 1 Cm thick. I have silver solder, sifbronze and Stainless Steel MIG with Argon or CO2 shield gas. Also propane torch and Oxy Acetylene. What do the team think would be best.
BobH

Oops, forgot to add the photos.

 

Edited By Speedy Builder5 on 19/06/2016 11:59:18

[MWParticipant @mw27036]

Posted by The Merry Miller on 08/01/2014 12:40:36:

The company I used back in the '50's, that's 1950's not 1850's .

I should hope so, i think back then even owning a set of your own mill files would've been considered extravagant.

[John McNamaraParticipant @johnmcnamara74883]

Hi Speedy

Gee they picked the wrong place to break It. Any weakness and it will break again.

I notice the pattern has 2 straight lines running almost top to bottom. Would it be possible to place 2 say 12mm, (or whatever size fits) square stainless steel backers behind the object lined up with the pattern, at the very bottom they may have to have a kink in them to go behind the legs, and they may need to be bent and relieved with an angle grinder to follow the line of the back surface. Finally the piece could be wired the same way lead light windows attached to the stiffener bars are. if the back of the piece and the supporting bars were sandblasted you should be able to use epoxy to attach it to the backers. one coat to glue it then epoxy putty to fill in the gaps and blend it in, then plenty of paint applied by brush for texture.

Many years ago I made a traditional Victorian style iron fence for our house out of 3/4" steel bar, a local foundry cast 300 steel spears for it. They had a small cast recess in the base to fit over the bars, the recess was a bit small I had to turn down all the bars for a loose fit, the cast hole varied. the spears were chilled and very hard, too hard to bore out.

I used nickel iron rods to attach the spears. The spears were preheated in a domestic oven to about 500F before welding. I made a jig to hold the bar and spear in alignment and allow the work to turn as I welded turning them at the same time with the other hand. I ran a couple of heavy passes. The bars were not preheated by the time the second pass was going the bars were very hot. I used plenty of current for good penetration. With so many to do there was no time to fuss around.

The welds were dressed to a nice fillet with a bench grinder with the wheel edge dressed round to create a nice fillet.

Over the more than 20 years only 2 of the welds cracked. easily fixed with epoxy. the rest have held firm.

The story above is a success story….

It would be tempting to try nickel Iron rods on the cast Iron cross however with such a small section to work on the chances of success are diminished. If the piece is historically important and part of a building failure is not an option. Back supports are less invasive. The basic rule of restoration is that no further damage is done, and Ideally that the process can be reversed. If it falls again it may not just break into 2 pieces. cast iron can shatter.

Regards
John

[mechman48Participant @mechman48]

Posted by Jimillsortit on 08/01/2014 13:05:30:

Posted by The Merry Miller on 08/01/2014 12:40:36:

The company I used back in the '50's, that's 1950's not 1850's . was called "Metalock Engineering UK" and it's still going strong after all this time.

It was brilliant watching how they did the business on a giant steam receiver in a power station.

Len. P.

I have used the same company and in fact got some strips from the engineer and since made up a jig for drilling and inserting the strips, used on a diesel engine that had a cracked block job was a complete success.

Jim

Have used the same company whilst in the MN back in 1969; happened to be in home port of ( old )Teesport when steam compressor developed a crack in the casing, I believe the company was based in Guisborough at the time, they soon had it sorted & as far as I'm aware it lasted to the day the ship was scrapped.

George.

[Ian S CParticipant @iansc]

I'm not sure of the size, but I think the cross is quite big, if it were smaller I would suggest using it as a pattern, and re casting it. Ian S C

[Neil WyattModerator @neilwyatt]

I would drill out each fractured surface for a stainless peg about 2" long then probably try sifbronze as you can build it up a bit around the outside of each joint making it look like a bit of the leaves.

Neil

[Speedy Builder5Participant @speedybuilder5]

just to give an idea of size, the overall height is about 700mm and width 70mm. The "square" uprights are 10 x 10 mm. I think that drilling and pegging would weaken an already small section. I have seen on the net that if you use S/s filler wire, the nickel in the wire alloys with the carbon of the cast Iron in a similar way as the Nickel Iron rods would work. I also think that additional stiffeners would be a good idea. If I get good results I think our Mayor may find me some more to mend (as I don't charge for village repairs).
BobH

[Speedy Builder5Participant @speedybuilder5]

just to give an idea of size, the overall height is about 700mm and width 70mm. The "square" uprights are 10 x 10 mm. I think that drilling and pegging would weaken an already small section. I have seen on the net that if you use S/s filler wire, the nickel in the wire alloys with the carbon of the cast Iron in a similar way as the Nickel Iron rods would work. I also think that additional stiffeners would be a good idea. If I get good results I think our Mayor may find me some more to mend (as I don't charge for village repairs).
BobH

[michael darbyParticipant @michaeldarby61557]

You can weld that quite easily using oxy/acetylene and cast iron filler material .you will need a flux to float off any carbon in the casting.

[Trevor Drabble 1Participant @trevordrabble1]

Speedy,

Since you have Oxy-Acet available , you are welcome to a suitable cast iron rod . One will be more than enough for your needs . No flux yet , but will be ordering some this week , so you welcome to some of that too . Would suggest you thoroughly pre-heat , use a large nozzle ( I used a No 25 on a Sapphire shank to weld a broken vice ) , and then cool as slowly as possible . I buried it in a metal dustbin full of clean sand .

Trevor .

[Speedy Builder5Participant @speedybuilder5]

Thanks Trevor – I have sent you a PM.
BobH

[AjohnwParticipant @ajohnw51620]

As far as I know where the cast iron needs to retain it's strength on machine tools and etc the stitching method has always been the best. Generally it's going to be best when something has been "broken" some how. I'd guess this thread is more concerned with stress in a casting causing the cracks. Add heat, welding etc and more of that can occur.

I have a model engineer made rotary table. I needed to dismantle it to do a bit of additional machining due to it distorting over time. There was a strap across 2 parts of the casting. Shortly after removing that the casting cracked. It doesn't cause any problems but both aspects are down to who ever produced the castings allowing them to cool to quickly. This reminded me of when I started getting interested in model engineering. Many wise older people said don't make your tooling from castings for exactly this reason. Fabricate instead. They were implying that there will always be some movement over time. Given that "important" castings are generally left lying around for varying periods of time they are very likely to be correct.

John

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[Speedy Builder5Participant @speedybuilder5]

Just an update on the village cross.
In the end I decided to use MIG with Stainless Steel wire / Argon gas.
To support the joint, I mounted a piece of box section in the vice to support the weld area. To make sure the two halves were correctly supported, I put two big dollops of plaster of paris onto the box section, put some cling film on top of the plaster and then placed the broken cross on top of that , adjusting the cross to get the two broken sections aligned correctly. (Nb: I left the joint area free from support as the plaster would more than likely cause problems)
I then cut a "V" preparation at the cracked joint , removed the cling film and clamped the two halves onto their plaster supports.
Heated the general area with a propane torch then wire brushed the area whilst still hot. Then used the MIG starting in the centre and then the two outside fragile legs. It took about 3 runs of 0.8mm wire to fill the joint. Again after welding, I cooled the area gently using a diminishing propane flame and finally left in the hot sun. Some gentle tapping of the joint with a small hammer annoyed the neighbours for 10 minutes! I didn't dress the weld very much – didn't see the need to.
Just need to paint it and put it back onto its stone plinth.

Plaster support sitting on the box section

Finished joint.
BobH

[Michael GilliganParticipant @michaelgilligan61133]

Nicely done, Bob

… Hope you don't get a repeat performance from "the lads".

MichaelG.

[Jeff DaymanParticipant @jeffdayman43397]

The repairs look great! well done.

Michael G's post echoes a thought I had – maybe a replica cross could be cast in resin and painted, then the original stored safely in the church and the resin replica model placed outdoors in the path of the rampaging barbarians.

A silicone mould could be made from the original cross then copies cast in resin in the silicone mould. With a silicone mould there is extremely low risk of damage to the original cross and minimal cleanup compared to making a plaster mould. If a polyurethane or epoxy resin rated for outdoor use were used for the cross castings it would likely last many years and it would be resistant to damage.

Just a thought.JD

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