Welding cast iron

[Pilgrim22]

Following my recent aquisition of a band saw from @Woody.v8, a bit of an 'only fools and horses' moment saw the saw falling from the back off the pick-up and ending up broken.

The only real damage is a snapped saw arm and a bit of cosmetic. I contacted CIWS Ltd but they quoted me £600+ so it wasn't a cost effective solution in this instance.

I've now established I can buy a replacement arm so I thought I would have a go at welding it myself. I can Tig and Gas weld and my Stick is reasonable but i have no experience of welding Cast Iron.

I think I will need something like CastRod (Deposits 95%Ni + 2%Fe weld metal) or is there someting more suitable? is small 1/2" tacks better that long runs?
Also I will clean the paint off but should I chamfer it? Do I need to preheat?
I was planning on 'practicing' on the cosmetic bit first

Any advice is greatfully recieved.

Paul

 

[Brad93]

CIWS are the best in the business. That cost is not unreasonable at all for the work involved. Understand that what they do is true cast iron welding - fusion welding with a cast iron material to give a homogenous deposit of matching filler material.

Don't practice on your part! You'll induce more stresses and chances of cracking.

I would personally gas braze it.
Cast iron arc rods can go really good or really bad.
All depends on the quality of cast iron and shape of the part.
That's gonna be a bit more difficult because of the shape.

Thats as much as i've got to say on the matter currently as i've got the hump with this forum and keep contributing but being treated like a leper by moderators.

 

[Pilgrim22]

CIWS are the best in the business. That cost is not unreasonable at all.

Don't practice on your part! You'll induce more stresses and chances of cracking.

I know they are the best but the complete saw is only £600 new, hence it wasn't appropriate for this job. I didnt mean to imply anything.
I've edited the original post to reflect this.

 

[truckdoctor]

I successfully welded a cast iron manifold from a 1947 Ford flathead engine by heating it in the barbeque until was as hot as it could get and mig welding, then replacing into the heat until cool the next day. Worked a treat and never broke. Got to be worth a try?

 

[Redsailor]

If brazing is not possible, can you fabricate or weld up something that bridges the fracture and then bolt the two pieces together?

 

[Porkypine]

Last time I had a go at welding something cast, some old tractor part for a mate, I stick welded it using some nickel rods, worked OK and hasn't busted yet, made a bit of a weird "hissy" sound when doing it though
As above gas brazing it is a good method, though would need serious pre heating I'd think.

 

[Pilgrim22]

Had a go at the welding yesterday. Cleaned all the joints and put a slight bevel on the edge. I got some 1.6 nickel rods and turned the amps up a bit. I preheated the area with a blow torch and then went for it.
Did ~15mm runs on both sides to spread the heat a little but it has worked better than I expected.
Put the saw back together and did some test cuts and all is working well.
I think I had a lucky escape.

 

[MattF]

Good to hear.