Announcement

Collapse
No announcement yet.

Metal Casting

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Metal Casting

    Just wondering if anyone casts their own metal parts. I have though about making a casting furnace for some time now but really dont know that much about it and if its even worth trying to do. Right now then I need a large type part I end up having to make it from plate or block steel, which can get a bit expensive if you have to buy the stuff. I guess the best example is me having to make metal discs by lathing down steel plate, which makes buckets of scrap curlies.

    So, has anyone made a small casting furnace (don't want to cast 2 foot square blocks, just stuff that would be no bigger than 6" cubes at the max, as i don't want something big that takes up my precious garage space).

    Thanks for any help

  • #2
    Have a look on aloyavenue. You should be able to find all the info you need there. Most start with aluminium, then brass, then cast iron.
    This is the only pick I have of my 20lb furnace. The outer shell is a 100lb propane tank. I just pored a lost foam casting for a flask.

    The foam part.

    The finished flask.
    Last edited by sdeering; 03-16-2013, 11:03 AM.

    Comment


    • #3
      Casting anything beyond aluminum isn't for the inexperienced. Brass is difficult. The most ambitious make it to iron. I have never heard of a home foundry being able to cast steel.

      There's no way to make this hobby cheap unless you have an angel that lets you snag drops for free. But then you'll just use the money saved to buy another machine

      But what of it? The point of a hobby is to suck up extra cash.

      edit - one way to get less expensive materials is to buy drops from machine shops. Bring a sample of your best work so you can show the folks there you aren't a schmuck, and be prepared to pay scrap price at the minimum. Bring donuts too.

      You can buy rounds, if you don't want to convert the corners of squares to shavings. Many metal suppliers will sell you the length you need so you don't have to buy a foot of something when you only need an inch. check out speedymetals and onlinemetals.
      Last edited by Tony Ennis; 03-16-2013, 08:15 PM.

      Comment


      • #4
        Hi Stern,
        I set myself up to do lost foam aluminium casting. I made the furnace and burner, used a homemade refractory, used stainless steel kitchen containers as crucibles and the total cost was about £20 ($30US).
        I also built a hot wire cutter to make polystyrene patterns.
        There is much more information here:
        http://mikesworkshop.weebly.com/foundry.html
        Mike

        Comment


        • #5
          Thanks all for the info, as I wasn't sure that casting would be my best way to go. I guess the fact that all would end up casting would be iron or steel means I should stick to current methods. I do buy steel when I need it, and a few places are good enough to cut me what I need (although you do pay the going rate which is ok), just looking for ways to make my projects easier. Seems like casting wouldn't help with the easier parts lol

          I do however want to make some sort of small furnace to do hardening work, which should be easier than needing something hot enough to melt iron. Been reading some books about tempering, but think I may need to read a lot more as it seems to involve more than one "heating/cooling" step. Its always nice to add another "hobby section", but I have to know where to draw the line

          Comment


          • #6
            Stern, I hear your anguish, but setting up to make small lumps of steel in your garage just is not going to happen, its much easier to keep doing what you are doing.

            There is a lot of reading on the ins and outs of all this on www.alloyavenue.com and its predecessor www.backyardmetalcsating.com

            At the other end of the scale, casting you own lumps of machinable aluminium at home is very doable.

            EDIT. You post faster than I do

            Comment


            • #7
              Originally posted by Stern View Post
              I do however want to make some sort of small furnace to do hardening work, which should be easier than needing something hot enough to melt iron. Been reading some books about tempering, but think I may need to read a lot more as it seems to involve more than one "heating/cooling" step. Its always nice to add another "hobby section", but I have to know where to draw the line
              Look around for a ceramic kiln. They're much more plentiful than a HT furnace and reach the necessary temps. Consequently they tend to be cheaper on the used market.

              Comment


              • #8
                What is it about steel that would make it so hard to cast? I worked in a commercial foundry, and we poured a variety of materials, and the steel pours weren't all that different than the aluminum, bronze, or other things. Certainly it'd be difficult to get the exact alloy you wanted, but we didn't do a lot of tweaking to the scrap steel we dumped in, on most heats. If it was a specialized alloy, then there'd be a number of adjustments we'd have to make to get the composition right, but for most stuff, it was shovel in a pile of XYZ metal, let it melt, take a sample, run it through the spectrometer, get the ok, and pour the metal after skimming the slag off.

                Hitting the necessary temps at home would be hard, but not impossible. You could run into problems, of course, if you dumped too many different alloys in at one time, but if you're using all the same material, I don't see how you could get too far off from what you originally started with. I didn't run the furnace or the spectrometer, so I could be wrong on all this, and the foundry I worked at was pretty bad about cutting corners, so it wouldn't surprise me if they skipped a number of necessary steps, but I didn't see anything there so complex that some steels couldn't be poured if you had a furnace that got hot enough.

                Comment


                • #9
                  Originally posted by Tuckerfan View Post
                  but I didn't see anything there so complex that some steels couldn't be poured if you had a furnace that got hot enough.
                  You answered your own question. 1250/1300 F to melt aluminum is not difficult to achieve in the back yard. Propane, natural gas, coal, or even charcoal will burn hot enough with just forced air. 2000+F is a different story.

                  Comment


                  • #10
                    Originally posted by Dr Stan View Post
                    You answered your own question. 1250/1300 F to melt aluminum is not difficult to achieve in the back yard. Propane, natural gas, coal, or even charcoal will burn hot enough with just forced air. 2000+F is a different story.
                    Building an induction furnace would no doubt be difficult, so that's certainly out for a home guy in most cases. But what about coal? Its not terribly expensive to buy. It burns hot enough, and you could, in theory, adapt one of the various charcoal designs to work with it.

                    Coal, after all, was what they used in the 1800s. Run an oxygen line into the forced air pipe if that wasn't enough heat.

                    Comment


                    • #11
                      Originally posted by Tuckerfan View Post
                      What is it about steel that would make it so hard to cast? ........
                      It certainly wouldn't be impossible. As HMSers we are often irrational re the time and/or money spent on projects, but a home furnace to make $40 or $50 lumps of steel every now and then would be waaay up there in terms of irrationality.

                      Comment


                      • #12
                        Originally posted by Tuckerfan View Post
                        Building an induction furnace would no doubt be difficult, so that's certainly out for a home guy in most cases. But what about coal? Its not terribly expensive to buy. It burns hot enough, and you could, in theory, adapt one of the various charcoal designs to work with it.

                        Coal, after all, was what they used in the 1800s. Run an oxygen line into the forced air pipe if that wasn't enough heat.
                        I used coal and forced air for my aluminum foundry as I had a readily available supply of free coal. However, I'm not about to attempt to use oxygen in this manner. Yes I have a oxygen/acetylene rig in my shop, but that's a very different situation and I've seen first hand just what can happen with an explosion in a steel foundry. An uncle worked in a mill in Youngstown and was burned 3rd degree on 50% of his body and 2nd on the remainder. In all rights he should have died, but did not. While he lived I can tell you his life was not one I would like to repeat.

                        There are just some things the HSMer needs to leave alone and I personally put iron & steel casting in that category. Even with an aluminum foundry accidents are not uncommon in industry with all their safety measures & controls. While I'd have no qualms about building and using another aluminum foundry the cost benefit ratio is not there for me. Maybe for others, but I would not use it enough to justify the cost, time and space it would require. After I retire that may change, but not now.

                        Comment


                        • #13
                          Really appreciate all the points of views on this, as i am the first to admit sometimes I think about doing something because I want to try it, and don't think hard enough about the cost or difficulty factors. Since Im running out of a garage at home, even if I could get hot enough for steel it would be hazardous and I would probably get in a lot of trouble if someone complained.
                          After reading the posts, even without these issues I think cost effectiveness would go out the window for what I make and how often it would be used. Think I will just work with what I have and when I need chunks of steel, get them. I does make me sad when I have to cart away 5 buckets of lathe curlies, but then again a REAL place will turn them back into metal I have a oxy/acet set, so what I should really do is read up a lot of tempering parts using what I have. Guess it will take time to know how hot, how to cool and what steps I need to do to make tempered parts. That way I just need to invest a few weeks in reading and not outlay money

                          Comment


                          • #14
                            What's so hard about casting steel?

                            1) Steels require 2800F+ temperatures. No conventional fuel (including coal or coke) can reach that high a flame temperature without some form of recouperization. Electric arc or induction furnaces are way beyond backyard casting in every way -- high intial cost, high operating costs and large dedicated area for operation. The only common back yard method that can melt steel is the bloomery furnace and it is limited to melting and casting in the same crucible. A bloomery just does not generate enough superheat to allow pouring into a mold.

                            2) Radition heat transfer increases with the forth power of temperature -- you don't even have to contact molten steel to get burned. For those who think that the fraction of an ounce of molten steel present during arc welding is hot, it's nothing compared to the sunrise of pulling a 100 pound white-hot crucible out of a furnace.

                            3) Aluminum, brass and bronze can be cast in silica sand molds. Even cast iron can be cast in silica with ground coal added.
                            Steel requires more expensive and harder to obtain refractory sands.

                            4) Worst of all, steel requires close chemistry control. Aluminum castings can be remelted with attention to limiting contamination. Same with most bronze alloys. Brass alloys often need a zinc addition to make-up for zinc losses, but generally a fixed percentage. Cast iron can need a silicon addition, but the test for low silicon does not use any extensive equipment. Steel can loose or gain enough carbon, silicon, nitrogen during melting that the casting does not behave like the original feed stock at all.

                            Comment


                            • #15
                              Casting aluminum is easy. Done it many times. Even fairly cheap and primitive furnaces can melt aluminum.

                              Casting steel at home is WAAAAYY more challenging and WAAAAAAYYY more dangerous.

                              You can cheat a little and melt steel with thermite at home, but still not recommended, and certainly not what the OP was asking about.

                              doug

                              Comment

                              Working...
                              X