MIG welding cast iron with Stainless wire

[brewdexta]

I've got a handle to weld on a casting that has been snapped off and a crack in the base of a power hacksaw frame

Reading around the subject, either brazing or austentic SS wire is the way to go, See as the handle will get some loading then I was going to drill the casting then weld around it. I was thinking of making the handle out of a piece of SS rod about 15mm diameter with a spigot to fit in the hole. The crack in the base I was just going to make a v- groove and slowly fill it with SS.

So which particular grade of SS wire? it needs to be 3xx grade to be austentic, 308 or 316?

Next question, the little 0.7kg spools, will they fit in a portamig? I can get a 5Kg in with the adapter but will they take the little spool or do I need to rig something up temporary - I don't warrant buying a 5kg reel for the amount of SS I do currently but open to suggestions.

Cheers
Andy

 

[KemppiFrog]

The small reels have a hole around 20mm, so unlikely to fit on a standard MIG.

My first MIG was a hobby 100amp on small internal reels. After getting tired of the excitement winding wire off 5kg reels onto the little ones, I rigged the 5kg ones on a bracket off the back, revers of what you are doing. But you could off load the wire onto a bigger spare reel? probably quicker than fixing a holder.

Be interested to hear how it goes with the welding. I have just done a few jobs with MMA. Came out OK, used the info in the tutorials.

 

[jinjahbiscuit]

Type "wire spools conversion" in the search box at the top of the page and you'll find two neat devices that will solve the small reel problem. I have the same problem with my Clarke 150TM. I've not actually made up the device yet, but I will soon as I'd also like a go at stainless and don't want to fork out 75 quid plus for a 5kg reel.
Took me ages to find it searching the web; and it was here all the time!

 

[octo0072000]

small reel fitting

piece of tube over the mig reel fitting weld a piece of 3mm x25 mm to it vertical about 4 or5 inch long then weld a long bolt to it horizontal
for the .7 reel to fit on
you get the idea



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[TechnicAl]

http://www.mig-welding.co.uk/steels.htm

 

[brewdexta]

http://www.mig-welding.co.uk/steels.htm

Thanks Al, I got the SS tip from this the bit at teh bottom of the article

 

[brewdexta]

piece of tube over the mig reel fitting weld a piece of 3mm x25 mm to it vertical about 4 or5 inch long then weld a long bolt to it horizontal
for the .7 reel to fit on
you get the idea

Good idea as well as the just winding it onto a 5Kg reel. I'll probably weld up this so I can use it again.

Cheers
Andy

 

[TechnicAl]

Thanks Al, I got the SS tip from this the bit at teh bottom of the article

I had never noticed that

The problem with Stainless is that Chromium likes Carbon. Chromium Carbide is very hard and brittle.

It may work, it may not. Mild steel may work, it may not

Nickel or Nickel Iron will probably work, its not 100% because we dont know the type of Iron and some will crack if they see any heat, but the odds are stacked in your favour.

The problem is its expensive. I think sticks are best anyway and you can buy a few sticks

 

[brewdexta]

I have an ancient SIP 140 arc welder lurking that my dad used to use, I think I have used it once about 10 years ago. I may blow the dust off it and practise on some mild steel first before trying nickel rods - or I may just invite my mate around who has a bit more experience, and probably some nickel rods - sounds a fair swap for some home brew

 

[TechnicAl]

and a lot cheaper than a spool of either SS or Ni or NiFe

and probably better

 

[brewdexta]

Had a go with bog standard MS MIG wire on cracked cast pulley today, worked OK. There are 3 pulleys in the same casting of 8, 9 and 3 inch diameter, there was about a 1.5" long chip down almost to the bottom of the V on the 3" pulley. Built it up and ground it back a couple of times. I didn't preheat the casting.

Unfortunately I couldn't get it into the lathe easily/safely as it was an odd shape to I used grinder and file to finish it. Not the prettiest repair but passable and I've tried giving it a bit of welly without damaging the casting further and it seems stable. Its a low speed pulley so I don't envisage an issue in service but I do realise that this may not be workable for more demanding uses.

I did notice the weld gets harder as it meets the casting as predicted due to carbon in the cast but it was a relatively thin area and gound down OK.

Next to tackle is the power hacksaw frame and handle however I have a feeling these will be a different grade of cast iron.