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  • Furnace Build Sucsessful

    You may remember a long-ago post about furnace builds.

    Well, I have finally finished my furnace. It reaches 1640 degrees, possilby up to 1800. Runs on 600 watts approx power, and takes a 2.5 inch dia by 5 inch high crucible, which I made myself.

    I have tried melting aluminum chips, which gave me flurries of oxide powder and a few little nuggets. Anyone know what the flux for Al is?


    Pictures coming later,.

  • #2
    Aw heck, Teenage Machinist. It gets that hot on the sidewalk in front of my house on days like today.

    Some guy in Phoenix ran out into the street to stop the postman, burned both of his feet so badly he couldn't walk. Two neighbors had to drag him back to the grass in his yard.
    No good deed goes unpunished.

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    • #3
      I look forward to seeing the pictures.

      I've never melted aluminum (except by accident ) but some googling suggests that a variety of salts are commonly used.

      http://www.budgetcastingsupply.com/A...lux_Asbury.php
      Last edited by MTNGUN; 07-18-2010, 05:56 PM.

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      • #4
        Originally posted by Teenage_Machinist
        You may remember a long-ago post about furnace builds.

        Well, I have finally finished my furnace. It reaches 1640 degrees, possilby up to 1800. Runs on 600 watts approx power, and takes a 2.5 inch dia by 5 inch high crucible, which I made myself.

        I have tried melting aluminum chips, which gave me flurries of oxide powder and a few little nuggets. Anyone know what the flux for Al is?


        Pictures coming later,.
        Nope, but its cheap at most industrial supply houses. Something like $5 for a pack. LaGrande Industrial sells it in Portland. You could order some from them if you cant find it locally. This is
        only used after melting and just before pouring to degas the molten metal. You will need something to push a chunk of it below the surface of the aluminum. Be sure to stand upwind.

        When selecting feedstock you need dense chunks. No turnings, chips, pop cans, etc. They will oxidize into nothing. Also pop cans have a coating over the printing that will give you more dross when it burns off. Best thing to use for casting is aluminum castings. Extruded aluminum does not pour as well.

        Get an ingot of aluminum from a supply house and use a bandsaw to chop it to smaller pieces. You will be surprised how cheap it is.

        Also watch your temp. Overheating aluminum is not good. It messes up the alloy. Use a Type K thermocouple. If you dont have a display for it you can get a cheap digital multimeter and read the millivolt output from the thermocouple and reference it against a chart. Charts are available online. Do not use an exposed junction thermocouple.
        Last edited by macona; 07-18-2010, 06:00 PM.

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        • #5
          I use low sodium salt as a flux. It is available at most supermarkets in the UK under various trade names such as LoSalt. It is 75% potassium chloride and 25% sodium chloride. Add it once the aluminium has melted and stir. The dross immediately changes to a fine powder that is easily skimmed off.
          Mike

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          • #6
            No turnings, chips, pop cans, etc. They will oxidize into nothing. Also pop cans have a coating over the printing that will give you more dross when it burns off. Best thing to use for casting is aluminum castings. Extruded aluminum does not pour as well.
            This needs to be stressed! Pop cans are the worst! and it sounds like something Macona described is what you were using - Extrusions - window framing, trim, ladders, etc are poor choices, tho a few small pieces mixed with some good Al wont hurt. GOOD melting Al is the stuff that has been previously cast (I love pistons!). You will soon be able to spot cast stuff and glom on it.

            Al will start melting at around 1200° and should pour nicely around 1400°. so your little furnace should do nicely --- IF you've got some good stuff to melt....

            I've been casting for years and have never used additives - dont worry about using them till you get comfortable with just getting a good pour, which you can get quite nice castings with a plain melt.

            You know our requirements here -- need pictures
            Last edited by Bill Pace; 07-18-2010, 06:36 PM.
            If everything seems to be going well, you have obviously overlooked something........

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            • #7
              Anybody know if he can use cast aluminun rims? I've heard they make good castings but have never tried casting. One other thing on my bucket list to do. I'm going to need to live to be 200 !

              Congrats on the furnace. Always feels good to see a plan come together.
              - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
              Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

              It is true, there is nothing free about freedom, don't be so quick to give it away.

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              • #8
                Don't use any Volkswagen engine parts, they are 80% magnesium, 20% aluminium and 30% Deutchlandium [TM ]

                .
                .

                Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                • #9
                  I look forward to the pictures.

                  TMT

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                  • #10
                    You may remember a long-ago post about furnace builds.
                    Sheesh, that was only six months ago or so.

                    Be very careful that you never add anything that might contain ANY water to molten aluminum. If you do it will explode. Aluminum foundries have been completely destroyed this way.
                    Free software for calculating bolt circles and similar: Click Here

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                    • #11
                      Originally posted by Evan
                      Sheesh, that was only six months ago or so.
                      .
                      yeah but its kind of like dog years, it was the passing of a much bigger percentage of his life than yours or mine

                      way to go TM, where are the pics?
                      in Toronto Ontario - where are you?

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                      • #12
                        Originally posted by saltmine
                        Aw heck, Teenage Machinist. It gets that hot on the sidewalk in front of my house on days like today.

                        Some guy in Phoenix ran out into the street to stop the postman, burned both of his feet so badly he couldn't walk. Two neighbors had to drag him back to the grass in his yard.
                        I'll second that. I was afraid my thermometer was going to pop today. It only goes to 120.

                        Must be something wrong with my internet connection. I don't see any pictures.
                        Guaranteed not to rust, bust, collect dust, bend, chip, crack or peel

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                        • #13
                          Originally posted by Evan
                          Sheesh, that was only six months ago or so.

                          Be very careful that you never add anything that might contain ANY water to molten aluminum. If you do it will explode. Aluminum foundries have been completely destroyed this way.

                          When I had my music store, I once gave guitar lessons for about 6 months to an older fellow who was visiting Los Angeles to see specialists at the Jules Stein Eye Institute. He owned a foundry in the South and had been casting aluminum one morning. There was some water in a contained into which he was pouring molten aluminum from a furnace.

                          It exploded and went right through his safety mask and partially blinded him. I don't know what the outcome was from his treatment but that Evan says here is quite important when doing aluminum foundry work.

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                          • #14
                            In this melt I started up the furnace with the chips (pelletized with my pelletizer) already in the crucible (a homemade graphite crucible) so there was no explosion risk. Got some smoke from burning cutting oil.

                            I have a K-type thermocouple from a ceramics and kiln supply place in Richmond and a readout, too. It's a bit heavy, so it seems to respond slowly.

                            The furnace is frankly lower power than I hoped. It would have been better to use all firebrick like some people did. Maybe someday I'll rebuild it. The main expensive part was the coil. Either way it's pretty useful to be able to heat stuff well, melt, etc. Also, it can heat metal parts up nice and hot for hardening.

                            I was hoping to get it to 1800 degrees but it does not look like it gets there.

                            I can purge with argon. Pix coming NOW/

                            This is the furnace. THe center is Kast-O-Lite refractory, and the outside is Kaowool ceramic fiber wool capped with Kastolite.



                            A PID control is to be implemented.
                            Last edited by Teenage_Machinist; 07-19-2010, 02:06 AM.

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                            • #15
                              Your best casting alloy is found in the chassis of old hard drives. I forget which alloy it is now but I identified it some time ago and posted it in a thread a few years back. A search will probably turn it up.
                              Free software for calculating bolt circles and similar: Click Here

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