Welding a cast iron tool (Roper-Whitney XX punch)

[Sodo]

I hope he responds!

Do you think I should gas-weld this? It could only be a weld around the perimeter.

How likely will brazing work? My gut feel is - no way will I be able to break a hand punch that has the cut completely filled (provided it does fill & fuse nicely ).

 

[Shield Arc]

People braze cast iron material all the time. You see a lot of old tractor exhaust manifolds brazed.

 

[LD1]

I think you will have a hard time lining it up. I would have tried a little heat and bending first, and if it broke, weld the break as a last resort.

Careful welding it with a mig. Even tacking. If it is cast iron, the welded area will be VERY hard. So hard that HSS wont touch it.

 

[RedNeckGeek]

I hope he responds!

Do you think I should gas-weld this? It could only be a weld around the perimeter.

How likely will brazing work? My gut feel is - no way will I be able to break a hand punch that has the cut completely filled (provided it does fill & fuse nicely ).

You could try to gas weld it, but you're going to have the same problems with distortion due to the weld metal shrinkage that you would if you MIG or stick welded it. The braze metal layer is much, much thinner and there will be little or no distortion.

Brazing will work fine. The problem you'll face with the joint as it is now is that the braze metal will tend to just flow out the bottom of the slot because the slot is too wide for surface tension to be able to hold it in place. A correctly sized shim will reduce the gap. Make it about 0.010" thinner than the gap and it should work fine. I'd use hard silver solder, but regular brazing rod would work, too. Just use lots of flux and heat the parts only enough to get the braze metal to flow. That should be to a dull red as seen in a darkened room.

Tacking the parts with your MIG gun would probably be OK as long as you don't go overboard. But I bet those tacks would throw off the alignment enough that the punch wouldn't work. You could avoid that by clamping the parts to a steel bar prior to brazing, but it's gonna take more heat that way. The best way to go is to turn up a steel round that would hold the two halves in alignment during brazing.

 

[Sodo]

I think if heat & bending method had a chance, it would simply result in the threaded part (where the die screws in) being ovalized.

What is the reason for concern about tacking? Obviously if its not aligned I have to cut the tack and do-over. Once its holding the part in position, whats to worry about?

I am thinking four large corner tacks will hold it in place against shrinkage of the brass. If thats a concern.

 

[muddstopper]

I think cutting it in two was a mistake and going to make for a harder fix. Why dont you just send it to me so you dont have to worry about it anymore.

 

[Sodo]

Kinda wish I left a little 1/8" "post" in the center to hold it together. And then I could try to "shrink it" (1/32") with a hammer. Then braze it up. If I'da tested it first with the centerpunch I'da know'd it was a little bit ductile.

Can't send it to you yet, this thing still owes me 45 minutes more shop time :laughing: (plus untold # of 1s and 0s)

 

[PILOON]

For alignment why not install the largest size punch set B4 any welding.
Your die set then becomes your alignment jig.
Tack the 4 opposite corners but check alignment after each tack as probably you could tap back to alignment as you go along.
I'd tack in an X fashion and if that works (and I think it will) then fill in the gaps.
I'd bevel all the edges for better strength and penetration.

 

[Sodo]

Piloon, thats my plan exactly, except I'm not so sure about arc welding at the final step. Wondering if I have to braze it.

If it was mild steel I'd arc weld it for sure, that circumferential weld would be plenty strong. But since its cast I'm afraid a crack would follow the weld all the way around.

 

[george md]

Sodo,

The fellows that said bore and bush had the best ideas , but since you cut it you now have much more of
a problem . No matter how you weld it ,it will move .If is cast iron , a surface weld will not hold. To weld properly
you will need a vee 1/2 way in from each side (top and bottom) , heat to 1200 weld and post heat to 1500
and hold for 15 minutes in an oven ,slow cool from 1500 to 1200 (minimum of 30 min) and slow cool on down,
in oven should take 10 to 12 hrs.. And you will probably still have to bore and bush it.

Number is in the web site that shield arc posted , call if you want . I'm in the shop most 12 to 12 .

BTW ,Keep the arc weld rod in the cabinet , The best way to ruin a casting is to arc
weld it. Gas weld it .

george