Newbie wants to weld cast iron!

[Feltwell]

I can see the looks of horror from you all now!!

Let me explain. First off, I know very, very little about welding - don't worry about patronising me, you won't!

I have an old house that is a long term labour of love to bring it back from 100 years of neglect, on a budget. The aim is to keep it as original as possible - a sympathetic restoration you might say.

The bottom of one section of an old downpipe - the "boot" - is cracked, and as it is an unusual size a replacement can only be sourced from one place, at a cost of - £155 !

Which got me thinking - always a dangerous thing - that as there does not need to be any mechanical strength in a repair, it just needs to be a permanent seal, can it be welded instead? I can get a cheap gasless MIG welder for £150, do the job and still have the welder at the end for other jobs. I see from an article on this site that cast iron can be MIG welded, or brazed.

So - hopelessly deluded? Need a better welder than a £150 cheapie? Need some skill? Anyone in the Telford / Wolverhamption / Walsall area fancy a challenge in exchange for beer?

Pictures (hopefully!) below - they are close ups, crack is less than 1mm wide.

All advice gratefully received..........

 

[cumbriasteve]

I have done similar without a welder:
Drill a small hole at the end of the crack to stop it going further, grind a V into the crack for about a third of its depth, clean and degrease then use a quality plastic metal compound..total cost about £15

 

[cumbriasteve]

Cheaper than I thought...JB Weld is fantastic stuff, used it on an outboard engine cast water block..worked a treat.

http://www.ebay.co.uk/itm/J-B-WELD-...Scrapbooking_Glue_Tape_EH&hash=item43b3d65224

 

[KemppiFrog]

HUMMMM, since it is non structural, welding with a stick MMA welder would do. Read the tutorials on the top of this site.
I have just done my first cast welding. No need to show it here But it is sound. If you have no experience (I have lots in MMA MIG ) Then it will be tricky, so best way is to find a friend who can do it.

As in: It is much cheaper to learn from other peoples mistakes. You will not live long enough to learn from your own........
KF

Fogot:Welcome to the madhouse, er Forum..

 

[CTB]

I'd grind the crack out a bit then find someone to braze it with an oxy/acet torch. Much stronger repair and shouldn't cost more than the jb weld. Save your money and buy the mig when you have a more definite use for it. You might find you will need a more powerful machine than what you can buy now.

 

[dannyp]

you have two chances with that its ether goiing to weld easly with an arc or its going to be an utter twerp as sadly there is no specific way to weld cast as there are so meany flavors of it the skilll working ot how it behaves when you first try and weld it and switching to teqniues that work

sadly the really old ones are usally nigh on un weldable (and i weld a lot of cast)

bloody good cast roads on an inverter arc welder and if it's the type thats willing to be welded you won't have any problems.

however if it starts recracking straight away just give up and braze or epoxy it as to weld you'll be needing to use stupid amounts of pre heat and burry it in sand to cool for days, ive had some succsess on that sort of stuff with tiging useing arc rods with the flux beat off as filler wire.

 

[Feltwell]

Thanks everyone. It certainly seems that the consensus is that doing it myself with a small MIG welder is unlikely to work. This is indeed old cast iron - about 113 years old, in fact. I'll try epoxy and see how it goes - I don't know any firm round here that will braze with oxy-acytelene.