Repair on Cast Iron Railing

[OSU-WE10]

The top of the railing at my parents house has rusted a bit and is coming lose. My dad suggested just grinding down the paint and doing some tack welds to just keep it in place, he doesn't really care that much because they will likely be moving soon. I know that welding on cast iron is difficult because of the higher carbon content and the issues this causes. I also know that preheating is usually required. However, if I am just performing small, maybe half inch tack welds every 6" to 12" inches, is preheat really necesarry? Or could I just wrap each tack in an insulator to slow down the cooling, and leave time between tacks?

I would be using a cast iron electrode, 3/32 in diameter, low amperage (~70ish), on AC. I don't know the exact dimensions of the railing, because I havn't really looked at it that close, but wouldn't put it at anything more than an 1/8". The top of the railing is slightly convex and over laps a small piece of c-channel if I remember correctly. I would place the tacks on the underside and then grind them down a bit so they wouldnt be that noticeable.

If I left some information out, let me know. This weekend I will be checking it out and will take some measurements.

Thanks,
Nick

[Jim-Tx]

I'm thinking that it's not cast iron if it's the top of the railing. Is it something like this?

http://www.kingmetals.com/default.aspx?page=item%20detail&itemcode=45-905-8

If it's steel, then it will be simple to weld. Some of the end pieces are cast iron, but I don't find any cast iron railings in King Metals book. Cast iron would be awfully brittle for a top railing.

[OSU-WE10]

I'm thinking that it's not cast iron if it's the top of the railing. Is it something like this?

http://www.kingmetals.com/default.aspx?page=item%20detail&itemcode=45-905-8

If it's steel, then it will be simple to weld. Some of the end pieces are cast iron, but I don't find any cast iron railings in King Metals book. Cast iron would be awfully brittle for a top railing.

That's a lot thicker than the top of the railing as far as I remember. I'll try a grind test on it and see if that helps. It has no design to the top, just a convex piece over top of a c-channel, kinda like this

[)

But with the top ) overlaping the bottom [ and I think the top is a little thinner as well. I was just messing around with some scrap and was able to do some 1" tacks between 16 gauge and 1/8" thick coupons on A36, so I hope my dad just told me wrong and said it was cast iron when maybe it is steel. I will have to check it out more.

Thanks for the reply,
Nick

[Hotfoot]

I'd just do it with my EZ125 with flux core. I've done a couple railings and some actual cast iron lawn furniture pieces. The railings welded fine (they are steel). the lawn furniture welded fine,but its just "stuck together", and are pieces just used for plant holders now.:)

[TEK]

I'm thinking something got lost in the translation...he was thinking 'wrought iron', said 'cast iron' but really, its probably steel, like Jim-Tx said...I've seen many miles of ornamental top cap just like you describe, none of it has been cast iron....you could use the 7018 if you want, flux-core wire may be easier, like 'foot said, if you have a machine...

[Jim-Tx]

I've welded cast iron post caps and stars for ornamental purposes with ER70S-6 and had no problems. I'm far from an expert, but I think that there is a lot of difference how "cast iron" welds depending on what it's made for. The stuff King Metals sells welds okay for ornamental work but I wouldn't ever depend on it where strength and safety are a concern.

[Rocky D]

Doing a spark test will determine what it is...I think it's steel, too.

[OSU-WE10]

Doing a spark test will determine what it is...I think it's steel, too.

Ha, I read your post earlier about the spark test and I can't believe I hadn't heard of doing that before. I'm hoping its steel cause it would be fairly easy to fix. I called him yesterday and he said he wasnt sure if it was cast iron or steel so I will check this weekend and hopefully be able to finish it up while hes gone and give him a nice surprise.

Thanks for all the replies,

Nick

[Hotfoot]

Flap disc and wire brush are your friends! Get all that rust and paint away from the actual weld. Scrub it all down with the wire brush afterwards to get it ready for a shot of Rustoleum. It'll go fine! have fun!!:)

[OSU-WE10]

Flap disc and wire brush are your friends! Get all that rust and paint away from the actual weld. Scrub it all down with the wire brush afterwards to get it ready for a shot of Rustoleum. It'll go fine! have fun!!:)

Well this will be my first actual project outside of my lab that I work at. I still need to get all my equipment, and with no permanent residence yet (still a student), I have to double check that I will be able to keep my newly aquired toys in my dads garage/basement (Like my Champ 4500 sitting in his garage :p). But I figure if I can fix the railing, he shouldn't mind much. And maybe I'll show him how to weld and he can practice while im at school and my welder is still in his posession.

Never used rustoleum, do you just apply it before paint? As you can prolly tell, I am just starting out welding/repairing. Only work I have really done before this summer was painting houses which is boring and dull after a few summers work. Hopefully I can figure this stuff out and get a few side projects while in school to keep some money in my pocket for weekends not spent studying or in the lab. :D

Thanks again for the help!
Nick

[Rocky D]

Nick, Rustoleum comes from Home Depot in a spray can...lots of us use it for our projects because it adheres so good and covers rust, and you don't need a primer.

[Zrexxer]

Never used rustoleum, do you just apply it before paint? Rustoleum IS paint.

[OSU-WE10]

Rustoleum IS paint.

Ha, I thought it was just a coating. Well that works!