Brazing cast iron

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I was asked to repair a cast iron vise. I could not get the parts loose from one another to grind so I burred part of it the best I could. Where I couldn’t I brushed. When I was adding filler I couldn’t get it to flow into the crack in some places. I dipped the rod and got some flux and let it melt into the crack and that helped a little but not enough. Could I mix the flux into a paste and apply it then add heat to get the crack clean enough for the braze to flow?
Reply:Please photos and are a torch or tig.Dave  Originally Posted by vwguy3I was asked to repair a cast iron vise. I could not get the parts loose from one another to grind so I burred part of it the best I could. Where I couldn’t I brushed. When I was adding filler I couldn’t get it to flow into the crack in some places. I dipped the rod and got some flux and let it melt into the crack and that helped a little but not enough. Could I mix the flux into a paste and apply it then add heat to get the crack clean enough for the braze to flow?
Reply:Whenever I've brazed CI, I've had to get it a lot hotter than I originally thought...like orange-hot in the whole area where you want the bronze filler to go. Takes a while to get it that hot, particularly on a big casting like a vise. You've also got to be careful to spread the heat around, or you could crack it or make cracks grow.How hot it when/where you tried to get the filler to flow?Also, some types of cast iron require a lot of borax to float out the graphite and trash...Last edited by Kelvin; 3 Weeks Ago at 12:29 PM.
Reply:Grinding cast iron seems to uncover carbon andother stuff that prevents wetting. Wire brushing and cleaning with solvent helps. I’ve also had to heat,clean,heat,clean,braze.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:How did you determine it is cast iron?ChrisAuction Addict
Reply:Dave,Talk in language I can comprehend please.
Reply:It has narrow parting lines.
Reply:“ Grinding cast iron seems to uncover carbon andother stuff that prevents wetting. Wire brushing and cleaning with solvent helps. I’ve also had to heat,clean,heat,clean,braze”THAT Is helpful!I was brazing with a heating head(I don’t use rosebud)So I may have needed a slurry of flux to get it to flow.Last edited by vwguy3; 3 Weeks Ago at 07:36 PM.
Reply:Getting the flux into the joint will help big time. Start where your joint is the cleanest as it will heat up the best and your braze will flow the best. Once you get the brass to " take" it will pretty much take care of itself. When your pre heating with some flux applied it should cook out the crap contaminants.
Reply:Why can't you get it apart.  Stick weld it after a good preheat.  Will it need finishing, can you access it with it assembled?Seems like a crap shoot if you cannot clean it properly?
Reply:If it isn't some super rare (expensive) vise, bevel out the crack, fill it with Ni99, Ni55, or any other cast rod, and call it good. Let it cool SLOW after the weld. Shouldn't be too difficult. If it's real dirty (oil), burn all the crud off with a torch, then wire wheel it.Sent from my SAMSUNG-SM-G891A using Tapatalk
Reply:Some of you missed the part about it being brazed. If it was going to be welded it would be TIG but it’s not.
Reply:Originally Posted by vwguy3Some of you missed the part about it being brazed. If it was going to be welded it would be TIG but it’s not.
Reply:Originally Posted by tapwelderNope.  I got the part of inability to kleen properly and seemingly poor access and possibly poor preheat.  Stick a stick in it and be done cause ain't no.braze juice gonna hole without proper prep.Stick it in your grill.preheat the whole thing.  TIG if you feel so lead to do so.  May be able to clean it with AC?
Reply:Hi.  I got  an  8"  vice   cheap as there was a big crack in the  jaw.   I have always  had  good  success  brazing  steelhydraulic pipes  and  stainless  steel  fittings.  But  I had  never tried  cast  before.  I used  Lincoln  bronze flux coatedrods .  Cleaned  and  widened the crack with the angle  grinder  and  heated the area  fairly well.  Then    brazed   usingoxy  act   kept  dipping the rod  in a can  of flux  powder  as  I filled  out the crack.   The  results  were  way  better than I ever  expected.  It  has stood  up to  everything  in  a farm  shop.  even  hammering on it  for over a year  now.
Reply:Originally Posted by JoseyHi.  I got  an  8"  vice   cheap as there was a big crack in the  jaw.   I have always  had  good  success  brazing  steelhydraulic pipes  and  stainless  steel  fittings.  But  I had  never tried  cast  before.  I used  Lincoln  bronze flux coatedrods .  Cleaned  and  widened the crack with the angle  grinder  and  heated the area  fairly well.  Then    brazed   usingoxy  act   kept  dipping the rod  in a can  of flux  powder  as  I filled  out the crack.   The  results  were  way  better than I ever  expected.  It  has stood  up to  everything  in  a farm  shop.  even  hammering on it  for over a year  now.
Reply:I have a cheapo HFT 6" c-clamp that I cranked on too hard and broke the long part of the "C," so just for grins I braze-welded it, and it's held so far, and I abuse the heck out of it just to see what it'll take. And think about it -- the cross-section of a c-clamp doesn't amount to much, compared to most parts of a vise...I'd say it's glued pretty good.But I had to braze it twice -- the second time, I got it really orange-hot and that seems to have made the difference.I probably used $6 in filler to fix a $5 clamp, but it was an experiment as much as anything. Last edited by Kelvin; 2 Weeks Ago at 05:11 AM.