Cast Iron Scrap - What to Save?

Discussion in 'General foundry chat' started by Fasttrack, Oct 30, 2023.

  1. Fasttrack

    Fasttrack Copper

    I've got a bunch of scrap from remodeling and I'm wondering if any is worth keeping for recasting or if I should prioritize higher quality scrap from machinery, etc. Anyone have any comments or advice on the following:

    Cast iron bathtub - breaks gray and was more resilient than expected, 1/4" sections or thicker, but has porcelain glazing

    Cast iron waste pipes - seems more brittle than the tub

    Cast iron window weights - haven't tried sawing or breaking these but show a lot of inclusions and I'm guessing they're not good for much

    Tops likes this.
  2. Ironsides

    Ironsides Silver

    Bathtub scrap is really good but the glaze usually contains lead so when I use it a lot of time is wasted using a air chisel chipping of the glaze.

    Cast iron pipes have a lot of rust inside them so you can waste a lot of time chipping of that rust or you can just melt the rust with the iron and get a huge amount of slag to deal with before pouring.

    Cast iron window weights, don't use unless you are really desperate.
    Tops likes this.
  3. Melterskelter

    Melterskelter Gold Banner Member

    If there is a foundry in your area, you might inquire about buying returns from them. I drive down to a foundry an hour away and they set out a large tote full of returns. I pick through them selecting pieces I like and toss them in a smaller tote on the scale. Once I have 800 pounds or so in the tote, they fork it into my truck. Yes, I do spend a few dollars this way, but a lot of time is saved compared to scrounging and I know what I am melting. I also usually get to spend some quality time chatting about foundry stuff and getting a few questions answered---side benefit.

    Tobho Mott, Mark's castings and Tops like this.
  4. ESC

    ESC Silver Banner Member

    My starting stock of cast iron was steam radiators. I wrecked some buildings in Oakland and recovered about a ton of them. I ran over them with the excavator and filled a couple of 55 gallon drums. As Ironside mentioned there is a lot of slag to deal with, but the iron is soft and very fluid. Another source was sprinkler fittings from, also from demolition projects. My latest source was the harp from a grand piano. Somehow it had been broken and replacement would have cost more than it was worth. My BIL salvaged the wood and I ended up with the harp. Absolutely beautiful soft iron.
  5. Ironsides

    Ironsides Silver

    I have always wanted to melt some of that but was never lucky enough to get one. So now I know it is good to melt the next piano I see will be broken up for scrap.
  6. Fasttrack

    Fasttrack Copper

    I wasn't going to post anything online, lest I find myself competing for old pianos :p but - at least in my neck of the woods - one can almost always find free upright pianos. You just have to be willing and able to move them from a house without damaging the house. Upright pianos still have cast iron harps of very high quality. My plan was to rely heavily on pianos for a source of melting iron.

    Thanks for the tips regarding the other scrap. I was surprised at how nice the tub broke; I'll plan on keeping at least some sections and maybe some of the pipe. The window weights are going in the scrap bin for the metal yard.

    Of course, this is all "academic" at this point. I still haven't started building a furnace - life got in the way and I've moved to a new place. Going to start building a shop this spring, though, and am already thinking about nice-to-haves for casting!
    Ironsides likes this.

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