Brazing cast iron

[rossow (mn)]

I bought a Craftsman 10-inch table saw at a yard sale Friday. It has the web-type cast-iron wings. One web has a crack that probably will never hurt anything, functionally speaking. I've done lots of oxy-acetylene brazing on sheet metal and mild steel but not cast iron. Could I braze the crack the same way, or some different way, or just leave it alone? I also have carbon-arc available for my Lincoln arc welder, if that would be useful.

(The saw runs great and came with factory stand, locking factory wheels, rip fence, blade guard and miter gauge; I figured the 115/230 motor alone should be worth the $25 I paid for the saw. I already have, I think, nine other 8-inch to 10-inch table saws, but what the heck, I can't seem to resist a bargain, or at least what looks like a bargain until I come to my senses. Only a week earlier I bought an old cast-iron 8" Delta for $12 at the Le Sueur swap meet with a 115/230 Dayton 3450 motor, and it runs fine, too. Still waiting to come to my senses.)

 

[Ellis Kinney]

warm it gently to start, braze it and cool it down slowly with the torch. Ellis

 

[Richard G.]

I have welded thin and thick cast iron with a non nickle rod I get at my welding supply. It is also cheaper than nickle. I grind a vee and weld about 1/4 inch at a time then take a side grinder and grind it smooth. I have never seen the number of the rod on it. I just ask for the non nickle welding rod. It is very hard and cannot be machined, but grinds well. I use my old AC Lincoln.
Richard

 

[dr sportster]

If the crack can't be spread open to get some flux in there leave it alone due to chance of warpage. Best would be to hit it with a MIG welder to minimize heat. Actual best might be leave it be.

 

[RusselAZ]

As I have more saws than a sane person should have I know what you feel! As to the crack I wouldn't try welding it. I would get some of that white mix-it-together epoxy and use it to fill the air space under a sandwich patch over the crack. Clean the materials well and you shouldn't need stove bolts to hold it together.

 

[jeffcat]

I agree with your advice. There being very little stress because the frame cracked because of stress most likely. Just a good guess. Brass doesn't use that much heat if you slow cool it. Good abvice.

 

[RodinNS]

I'd just bevel it out with a die grinder and braze it. Then cool it slowly as already suggested. Try to warm up as much of the casting as you can before you braze it too... It's the uneven rate of cooling in intricate parts that causes the cracking.

Rod

 

[Dusty MI]

If anyone has an extra of those table extensions with the flat steel toothed bar that the ripping fence rides on, I could use one.

Dusty

 

[Dopp Creek]

I use UTP 85 FN rod in my arc welder. 1/8" rod at 100 amps DC. Weld no more than 3/4" ar a time, then walk away and let it cool. Come back and clear the slag and run another bead.