welding on cast iron

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Summer is here so that means no more boilermaking\ back to small side jobs for extra beer money\ income.  Anyway a friend of mine works for an art dealer they have these huge cast iron planters.  They're about 3' tall by about 2' 1/2'  in diameter.  The planters are cast iron and about 3/4"-1' thick. The owner want s two simple things done to five of these planters1. three to four hole drilled into the bottoms for drainage2.several of the planters have large round handles that have broken and need to be afixed back to the planter it selfMy friend tried to drill through the bottom but said it was a pain even with the higher end drill bits. i told him I could come up there with my oxy/acetylene torch and blow some holes through it quicker and easier.  Then he asked if I could bring my miller stick machine up there and weld these rings back onto the planter.  I don't really have much experience with cast iron.  Could this be done?  If so what rod should I use for it( I have 7018, 6010, and 308& 309 rods)?  Any precautions about cutting those small holes in the bottom of the planters?  Thanks.all I want in my life are....... white castle cheese burgers
Reply:For the holes use a small bit for a pilot hole and work your way up also use no lubricant or if you insist use kerosene and use a slow speed. As far as the welding I haven't done much cast iron but when I have I've always used nickle rod.“Life is not a journey to the grave with intentions of arriving safely in a pretty well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out and loudly proclaiming ... WOW! What a ride!”
Reply:using a grinder for a spark test,if sparks are orange 7018,if sparks are red nickle rod.
Reply:Originally Posted by 4421frankSummer is here so that means no more boilermaking\ back to small side jobs for extra beer money\ income.  Anyway a friend of mine works for an art dealer they have these huge cast iron planters.  They're about 3' tall by about 2' 1/2'  in diameter.  The planters are cast iron and about 3/4"-1' thick. The owner want s two simple things done to five of these planters1. three to four hole drilled into the bottoms for drainage2.several of the planters have large round handles that have broken and need to be afixed back to the planter it selfMy friend tried to drill through the bottom but said it was a pain even with the higher end drill bits. i told him I could come up there with my oxy/acetylene torch and blow some holes through it quicker and easier.  Then he asked if I could bring my miller stick machine up there and weld these rings back onto the planter.  I don't really have much experience with cast iron.  Could this be done?  If so what rod should I use for it( I have 7018, 6010, and 308& 309 rods)?  Any precautions about cutting those small holes in the bottom of the planters?  Thanks.
Reply:As castweld said, your OA torch won't cut cast iron. There were cast iron torchs at one time but they were gasoline/oxygen I think. For the weld see if you can find a UTP dealer. Get UTP 85FN rod. It will weld it and look like the cast iron after your done.
Reply:The best way to drill cast iron is with Cobalt drills and in a drill press, low RPM, with constant pressure. I’d also think you need to pre-heat the cast iron to about 350’ or you risk cracking problems.
Reply:Ok, so maybe if I preheat  the area to be drilled with my torch and then went at it with smaller pilot holes working up to the larger, should be alright then, correct?Can't use a drill press because of the size of these things, plus all the work has to be done on site away from my drill press.How come the oxy/acetylene torch won't cut through cast iron?  Thanks for giving me the heads up on this one. You guys saved me from  making a mistake.all I want in my life are....... white castle cheese burgers
Reply:First, understand that cast iron is brittle, it cracks. It’s not ductile, doesn’t stretch, it cracks. Heat it too much in one spot, it cracks. Weld it without pre heat, it cracks. Weld it without post heat, it cracks. I’m not sure what temperature you  need to heat it to, what ever you do you’ll need temperature crayons to show what the temperature is or if you have a inferred thermometer that will work too. You’ll need a rosebud tip on your torch and play the flame around the whole jug heating it evenly. You don’t need to heat the casting to drill it. Slow rpm and constant pressure. Cast iron is somewhat abrasive, I’d use cobalt drill bits, in any event, the bits must be sharp and expect to break a few.I don’t know that kind of drill press you have, floor or bench. I have a bench and I’ve drilled large tall objects by 1 ] singing the table out of the way. 2 ] Swing the drill head around to the side.  A couple of ¼ inch holds should do the trick.Last edited by transit; 06-28-2009 at 12:25 PM.
Reply:I Think ni55 is the cheaper of the nickel electrodes and works like a charm.
Reply:Sorry I didn’t think of it before, Google to, how to weld cast iron. You will find hundreds of sites. Lincoln goes into detail, others show how to Mig, and recommend rods.