rods for cast iron

[ronan]

Any recommendations for what tig rods to use for cast iron ? I have an old 1930's motorcycle cylinder head with a few small bits broken off (pics to follow), easy to get too with the tig tip and i would rather tig than stick. I welded cast iron before at work and hated it, so always avoided it, its been a while since i've attempted ci so maybe there are more advanced rods available ?

 

[Tinbasherdan]

Get a NiFe stick rod and knock the flux off

 

[Chris Stevens]

TIG braze with SIF No8 is the perfect way to repair broken fins.

 

[Hitch]

Ive done a few TIG cast repairs lately with some Aluminium bronze without any issues. Think they were 90/10. Been kicking around for a long time. A sif equivalent would be No32...Expensive rods.

One of them was to weld a mild steel cap onto a cast post, which was cast in a heritage foundry, so full of impurities. Was okay, not the nicest thing in the world to do, but successful. Another was these, the mermaids had been snapped off the wall plate, and one had part of the fish tail broken off. Seemed a solid joint.

 

[ronan]

Its not actually a broken fin strangely enough. Its a boss that takes a bolt to hold on the rocker box. I have the two bits that broke off, so the plan was to weld it up and then helicoil the hole, it doesn't need to be very strong, but i want it to be right.

 

[Bill Edwards]

If it's not something you do often, think about the heat problem.

Are you going to preheat the part, weld then slowly cool it? If not, the localized heat from a TIG will probably cause a crack, and you'd be safer stick welding it, keeping it cool and peening.

 

[ronan]

Yes Bill i intend to preheat and bury it afterwards in sand or something else to allow it to cool slowly. I'd braze it properly if i had oxy-acetylene bottles still.

 

[Chris Stevens]

Yes Bill i intend to preheat and bury it afterwards in sand or something else to allow it to cool slowly. I'd braze it properly if i had oxy-acetylene bottles still.

If you vee out the broken part carefully, blast clean, and then put the part in an oven to get rid of any oil, you should be able to TIG braze with No8, with no need whatever for any sort of pre-heat, or controlled cooling. Have brazed a fair number of exhaust manifolds, with no problems at all, and never used any sort of pre-heating. Also repaired a few cast iron gutters from listed buildings having work done, and again repairs were 100%, and quick and easy to carry out.

 

[Chris Stevens]

Ive done a few TIG cast repairs lately with some Aluminium bronze without any issues. Think they were 90/10. Been kicking around for a long time. A sif equivalent would be No32...Expensive rods.

One of them was to weld a mild steel cap onto a cast post, which was cast in a heritage foundry, so full of impurities. Was okay, not the nicest thing in the world to do, but successful. Another was these, the mermaids had been snapped off the wall plate, and one had part of the fish tail broken off. Seemed a solid joint.

Think I have some 32 somewhere. Did you use AC for your repairs?