Cast iron fireplace, bolts missing

[Otto joiner]

Hi
We’ve bought a cast iron fire insert for decoration only. Unfortunately the bolts to attach
the side tile panels to the middle section are missing/ broken off. Any alternative ideas on how they could be attached?

 

[Tigercubrider]

Pictures?

 

[mrrusty]

I have done something similar in the past. Can you drill a hole where you need a fixing? -could even be in a slightly different place. You can't really weld anything on to cast iron, so what I have done is drill a hole and put a slight taper on it (by wobbling the drill around), then taken a bolt, cut the head off. Mounted the shaft in a vice and smacked the shaft to spread it so it's a jam-fit in the tapered hole. Rough cut to length, insert in the hole, bolt up and then tidy up the proud bit of the shaft back to level with a grinder/dremel. Once you have finished the fireplace with black, paint or whatever you won't see it.

If you have taps and dies, you could also do similar with a tapped hole.

 

[Otto joiner]

Thanks very much for the advice, will try that today.

 

[mrrusty]

You need a soft bolt that will spread nicely when hit, not a high tensile one!

 

[JohnD]

If you have any of the bolt left, there is a fair chance it will be a Whitworth thread (BSW) and you can still order them. See if is about a quarter or three-eights of an inch major diameter or some other convenient number. If you can count the number if threads per inch that will reinforce your identification. On Ebay they are sold in small numbers of ten or fewer.

There are quite a lot of other obsolete screw threads though.

I am reluctant to use a hammer on cast iron because it can break. It is not (usually) at all malleable.

 

[mrrusty]

I am reluctant to use a hammer on cast iron because it can break

No! don't use a hammer on cast iron - it WILL break. The method I described is just to drill a hole through the cast iron, and then give it a slight taper. The only hammer work is to convert a bolt into a threaded "rivet" which will jam-fit in the hole. This works, and making a "bolt rivet" is something I have done many times over the years to replace a broken off fixing (not just on fireplaces)

 

[Nige F]

Araldite is good for fixing in a bolt/rivet -particularly when there is only a small load on the bolt.

 

[Otto joiner]

I’ve managed to drill new holes and ordered the Whitworth bolts and nuts as suggested. Many thanks for all the advice here , really helpful appreciate it.