Soldering cast iron

Any tips on how to soft solder cast iron please? I'm struggling to get it to 'wet'

David

Hello David,

I'm not surprised! The carbon content will make it impossible as it tends to act as a surface contaminant.

Much better success is assured in joining to Cast Iron with high temperature bronze welding which also makes a strong joint. You do need oxy/acetylene to get the temperature needed though

Regards Brian

Preheating to red heat will drive the carbon to the surface which can then be wire brushed off when the part has cooled, you can then silver solder and I believe the same method can be used for soft soldering though I have only used this method for silver soldering..

Thanks, I haven't got enough heat to silver solder or to get it to red heat. I'll have to think again.

I started by going to a local engineering shop to ask them to braze it. They said that they don't use acetylene any more for various reasons i.e. cost and availability and the gas they use isn't suitable for brazing. The second and third shops that I tried gave me the same answer. The fourth told me 'yes no problem' but after three weeks I've just been to collect it as they still haven't done it.

David

Edited By David Noble on 21/12/2022 16:13:18

Depending on application and whether you consider soldering essential. I have used JB weld on CI and it works a treat. Much prefer the original to the fast stuff.

Hello again David,

I have the necessary gases and will do the brazing for you but a bit of information beforehand would be helpful in planning the work if it is a big job.

Send me an email please wood_y(at) btinternet(dot)com There is an underscore between the d and the y

Regards Brian

Decent cast iron welds pretty easily if you've got a pal with a buzzbox

Thank you Brian, that's very kind.

David

Hi David, no idea what needs to be repaired, but if it is a simplish sort of part, is fabbing/machining a new one from solid CI stock like Durabar or Meehanite a possibility? Obviously this won't be an option if it's something big or complex but worth a thought of it's smaller and not too involved. Just a thought.

Thanks Jeff, yes it would be possible but a repair will be easier and more cost effective/cheaper

David

What are you trying to repair? can we see? I'm curious to know what a professional outfit put off for 3 weeks.

Hi David I was given a cast iron base casting for a Stuart steem engine. If had been cast faulty with a piece of the base not filled. I cleaned up the area and made an insert of cast iron to match with a little to clean up after soldering. Fluxed and heated in a hearth to keep in the heat in with my blow torch and silver solder no problem.

David

Hello Pete, of course you can see, it's just that I'm a little embarrassed having admitted that I'm trying to soft solder it!

It's a steel gear wheel and a cast iron sleeve on a Mellor lathe that I'm restoring.

David

Could you key it on? Better for high torque applications

High strength loctite?

I hadn't thought about a key, thank you.

The problem is a little more complex though. Having got the lathe as a box of bits, I 'think' that originally the gear wheel was also cast iron and part of the sleeve. for some reason the wheel has broken and this is an attempt by someone to repair it. The wheel is only bored out for 3 or 4 mm just enough for a register. If I machine the wheel all the way through to accept a key, I think that it will leave the sleeve too short. There is a triple pulley to fit on the other end of the sleeve.

Last resort I think will be to make a new sleeve and wheel in one piece.

David

Hi David, not sure where you are but I'm on the N Norfolk coast = Hunstanton. If Brian is a long way from you and I'm nearer then I also have oxy propane Etc and will happily do it for you. Even a while you wait ! PM me if I can help. Noel.

Four quick tackwelds with a decent buzzbox would do it in 5 minutes

100-120 amps with mig gasless wire

Instant practical problem fix... but cosmetically ugly

I had to use a key because my replacement cog was aluminium

Edited By Ady1 on 22/12/2022 11:28:48

Thanks Noel, Brian is definitely nearer.

David

O.K. After chatting with Brian, I've decided not to prevaricate any longer and I've ordered a piece of cast iron to make a new one in one piece.

Thanks all, David