Repairing machine vice

[MrFluffy]

Hi, how would you people go about repairing this?
Someone has already had a go at brazing it long before I got hold of it. If I mill in a square piece of steel and clamp it through the slide holes, the vice opening would be too restricted. I don't think there is the structural strength to mill out where the piece has torn from flat and bolt in a insert there.
Id like to braze it up again, but I have doubts I'd do a better job than the previous attempt, which would mean it would just break again. I also thought of machining some pins into the two pieces to give it a bit of mechanical strength and use the braze to back it up.
Now, will I get enough heat into this myself by preheating it in the oven for a few hours then using a oxy propane torch or is it off into the realms of someone elses kit. Alternatively I have the big tig, so would it possible to cast weld this sucessfully perhaps?
Its well into the hundreds of pounds territory to replace it with one this size, and the smaller temporary one just doesn't hold pieces quite as well as this one...

Your suggestions please...

 

[Drains]

Snowcat would stainless tig it.
So would I


Edit. I would stainless tig it, or use a high nickel MMA on it. But also, as it's a high stress item, i'd drill and tap and stud wherever poss, and include the studs into the weld, if you get my drift.

Another edit. You need to grind out shedloads of the cast and refill . Leave a load in the middle for alignment, but vee out from both sides, stud up, and fill with weld.
Preheat?? not sure.... Peening - lots.... take your time - 20mm at a time, allow a few hours for the job.

 

[Welderpaul]

What a shame it is broken - i think i would clean it all up, clean off the old brazing, put back together and vertically drill through the two parts. Insert hardened steel pins with a tight fit into the holes. Fix the pins with engineering adhesive. I would then rebraze. The pins would keep the force on the brazed areas to a minimum so they don't snap. Me mate would be able to do a cracking weld on the cast, but he's 60 - odd and been doing cast repairs most of his life. I'd opt for the mechanical repair/brazing.

 

[Drains]

. I'd opt for the mechanical repair/brazing.

If you go that way. make a better job of the brazing than what's on it! - That was just around the edges, never got into the join. Which will always be a problem on a repair like that. If the joint is tight the braze won't flow in. If the joint's loose, the alignment will be out.

 

[malcolm]

If you go that way. make a better job of the brazing than what's on it! - That was just around the edges, never got into the join. Which will always be a problem on a repair like that. If the joint is tight the braze won't flow in. If the joint's loose, the alignment will be out.

That's what angle grinders and V joints are for. Got to depend on the stress it's under. Given it broke once probably a lot. I'd go for some sort of welding. Soft rod - stainless or nickel maybe (edit > like Simon said) so it doesn't crack the cast on cooling, and do a deep V and put a load of weld in so you get a big join area.

 

[irondarren]

Might get away with Mig in it, i have on certain cast iron, weld cast steel stuff. Disimilar rods might do. As paul said bolt and braze it.

 

[Hitch]

Another vote for the Tig, but i think id put quite a big prep round the outside, and try a bit of copper silicone. As well as 2 dowels down through.

Stop hammering the handle down tight in future

 

[Drains]

try a bit of copper silicone.

Wossthatthen?

 

[MrFluffy]

In answer to malcoms post,
In daily use clamping, just the clamping force pushing it that you exert using the square acme, the trouble starts if you have a tool dig in, for instance a fly cutter head failed causing the last calamity and the mill decided it could take on 15mm depth of cut in one go and win. In those situations, that repaired area undergoes the brunt of the force to be absorbed while Im frantically scrabbling to throw the clutch. The disconcerting thing is the vice snapped and allowed the workpiece to make a exit before the clutch slipped...

I had spotted the edges hadn't been vee'd in much last time, but brazing big lumps of cast iron is into unknown territory for me so I wasn't even sure if that was needed. Ill have a look at fancy rods, maybe I can pin it too. I can take my time over it, there's no rush.

 

[Hitch]

Its realy silicone bronze, but the two primary componets are silicon and copper.

 

[snowcat]

As Si said, Tig it up fluff it will be fine trust me, Nice big prep V tho, you could drill and put a couple of plugs in, personaly wouldnt bother but depends on how confident you are with the welds.
Pre heat nah, waste of time in my book, failing the tig route disimlar or stainless rod, or both tig root MMA Cap,