Repairing cast iron?

[Jelly]

I won a Stanley mitre box on ebay recently, and when it arrived the courier had bashed it about sufficiently to crack the angle adjustment mechanism in two places, one crack either side of a hole which fits round another part, and thus it's important to maintain the dimensions closely. I could do with advice on how to repair this as it's outside my area of expertise.

As I understand it I can use Brasing with brass, TIG welding with high nickel content rods, Use an oxidising flame to burn off the surface carbon and then silver solder, or use a structural epoxy or cyanoacrylate adhesive with a metal filler.

My temptation is to use structural adhesives as I'm more experienced with them, and if it fails I can always burn them off during preheating for welding or soldering if it comes to that.

Final option is simply to make a new one either by sand-casting using the original as a pattern, or machining it from steel.

 

[blackrodd]

From a repairing point of view, Sounds like it would almost be better if it was actually broken, and not cracked.
Whatever repair medium used, it will need to "flow" within the crack, so as to rejoin it, which will be difficult.
Personally, I would send it back, poor packaging, or claim from the courier's rugby team who used it for practice,
After all Its hardly fair to end up with a repaired item for you're money.
Believe it or not, A very good friend welded the thumb grip side back together on a very cheap Stanley 91/2 adjustable block plane I bought for a fiver,
He used his professional mig and just weld 1/2" at a time and cooling off for a minute in between at a good 1/2 power.
I use my recycled block plane all the time.
Regards Rodders

 

[johnbaz]

Hi

If you do decide to weld it then you'll need to chamfer a vee so the weld can fillet in to the channel..

A friend of mine snapped his vice in two, I took it in to our welders, One told me to grind a chamfer on both halves then I left it with him, An hour later he brought it to me, The weld was utterly fab! He'd filled the groove dead flush with the faces of it!! No need for filing/Grinding..



John..

 

[Monkey Mark]

Drill a hole at the ends of the crack to prevent it spreading. As above, Grind a V into the crack before welding.

 

[MikeJhn]

Old thread I know, but last year I successfully welded a cast iron parasol base using my mig welder, on advice I used Stainless Steel wire and Argon gas, it worked superbly, very pleased with the results and two summer seasons later its still in use.

Mike

 

[dickm]

One other thing if welding CI - make sure the casting is as hot as you can get it before you start welding, or it will almost certainly crack. I've successfully welded a Record metalworking vice (don't ask how it got broken ) and an old Parkinson woodworking vice that was broken when I got it, using appropriate cast iron rods in a standard arc welder. In both cases, sticking the parts on a primus stove was enough to get them to a reasonable temperature.
(and as far as I know, both tools are still in service!)

 

[Jelly]

Thanks guys, I still have that along with other bits to now do, in a box marked "to braze" when I build up enough I'm planning to do the whole lot in one go, as it's a bit more convenient (and justification to buy a new oxy bottle for the wee turbo torch I have).

 

[MikeJhn]

About thirty years ago when I bought my first MIG welder, I broke my vice (don't ask) and before I knew better I just welded it back together with standard MIG wire and a Co2 bottle, that's before everyone told me it could not be done and I had to heat it up to stop cracking use Argon gas and SS wire. :lol:

Oh yes its still in use.



Mike

 

[DTR]

I would have thought silver solder would do the trick, as it will naturally flow into the crack?

 

[MikeJhn]

Ah! not silver solder, (too soft) but stainless steel wire, sorry for any confusion.

Mike