New to welding, cast iron.

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I am new to welding, trying to teach myself watching videos and practicing on a Hobart AC/DC 235 Stickmate I bought. My first project will be welding a very small broken piece on cast iron tub, see pics. I plan on cleaning rust/paint, preheating with propane torch and cooling with sand. Plan on using a 55% nickel 1/8 rod.  My first question is should I grind and V groove both sides? And rod box says to use AC or DC- 70-110 amps. I have been practicing on some 1/8 thick metal and DC is blowing holes in it, should I use AC or DC- when welding tub? I am not too concerned with looks, just want it to hold. Attached Images
Reply:What exactly does that part do?
Reply:Originally Posted by rlitmanWhat exactly does that part do?
Reply:So you're not worried about the porcelain on the inside?                               MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Originally Posted by mla2ofusSo you're not worried about the porcelain on the inside?                               Mike
Reply:Originally Posted by ugabulldogThis is on the outside of tub...?
Reply:Originally Posted by rlitmanThe heat is going to go right through. If there's any porcelain on the inside, it's going to be trash after welding. I'd try to figure out a way to make epoxy work.
Reply:I'd say that with no experience welding cast iron, if you were successful in sticking it back on, that the weld would have little strength.  Put a wedge in there to hold a claw foot and I bet the weld job would break right off, tub on the floor, water everywhere.
Reply:This sue isn't a good project for the first one. Cast iron rods are 80+ dollars a pound. I personally think you will trash the tub.
Reply:Mig it. Hot and fast.Miller 211Hypertherm PM 451961 Lincoln Idealarc 250HTP 221  True Wisdom only comes from Pain.
Reply:Just weld it with out preheat and see what happens. Maybe get some 312 super missile rod. I've seen them in red sticks before
Reply:Originally Posted by motolife313Just weld it with out preheat and see what happens. Maybe get some 312 super missile rod. I've seen them in red sticks before
Reply:If the porcelain in the inside looks like the porcelain in the outside, I don't think damaging the inside should be much of a concern. Where in GA are you?-Chris
Reply:I've done a couple of these exact repairs.Grind everything clean and shinyPreheat with OA and rosebudweld with er70s-6 .024 wirestress relieve with a needle scalerlittle post heatcool with a welding blanket over itit'll slightly discolor the porcelain on the inside. The customers have always planned on having them refinished anyways afterwards so it's never been a concern.-DoogieMiller 350PMiller Trailblazer 325 EFI w/ Excel PowerLincoln LN25 suitcase welderXMT 304/22a feederMiller Syncrowave 350LXMiller EconotigHobart Handler 140(2) Uni-Hydro 42-14Hypertherm 65 plasmaWEBB Gap bed lathe
Reply:Originally Posted by derekpfeifferThe customers have always planned on having them refinished anyways afterwards so it's never been a concern.
Reply:Originally Posted by Mr. SmithIf the porcelain in the inside looks like the porcelain in the outside, I don't think damaging the inside should be much of a concern. Where in GA are you?
Reply:To the fellow that asked about the porcelain on the outside, on an old tub like that there is none on the outside, they were usually painted on the outside.
Reply:How about drilling holes through the loose piece and a short distance into the tub, so dowels can be used together with epoxy? I know, welding IS fun, but sometimes there are more suitable options.