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Foundry design help

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  • kirkbecnel
    I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter , 3-4 high . I am using kaowool for the
    Message 1 of 11 , May 10, 2013
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      I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.

      My question is mainly how large of an area do I need around the crucible?

      I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.

      I am currently building the 3/4" burner in Mike Porter's book.

      How much of a gap do I want in between the crucible and the furnace lining?

      Thanks
    • Sage McGirk
      I m in no way an expert, but the size of the crucible sounds pretty small, and about that of a spin/centrifugal casting crucible. A torch might be an easier
      Message 2 of 11 , May 10, 2013
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        I'm in no way an expert, but the size of the crucible sounds pretty small,
        and about that of a spin/centrifugal casting crucible. A torch might be an
        easier solution. Having said that, only enough space to easily/safely get
        the crucible out of the foundry is really needed. Haven't run across any
        hard facts in my research.

        my 2 penny's worth

        /sm


        On Fri, May 10, 2013 at 7:57 AM, kirkbecnel <kirkbecnel@...> wrote:

        > **
        >
        >
        > I am building a foundry to melt small amounts, the crucibles will be of
        > the smaller size, maybe from 3-4in diameter", 3-4" high . I am using
        > kaowool for the lining with ITC 100 coat on it. I have seen crucibles say
        > to use in a foundry designed for their size.
        >
        > My question is mainly how large of an area do I need around the crucible?
        >
        > I am thinking of the burner sending the flame directly into the side of
        > the crucible as well as the circulation of heat around it.
        >
        > I am currently building the 3/4" burner in Mike Porter's book.
        >
        > How much of a gap do I want in between the crucible and the furnace lining?
        >
        > Thanks
        >
        >
        >


        [Non-text portions of this message have been removed]
      • kirkbecnel
        I d like to do some high temps, and want/need to contain the heat, I don t think a torch will work.
        Message 3 of 11 , May 10, 2013
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          I'd like to do some high temps, and want/need to contain the heat, I don't think a torch will work.

          --- In hobbicast@yahoogroups.com, Sage McGirk <freeflysage@...> wrote:
          >
          > I'm in no way an expert, but the size of the crucible sounds pretty small,
          > and about that of a spin/centrifugal casting crucible. A torch might be an
          > easier solution. Having said that, only enough space to easily/safely get
          > the crucible out of the foundry is really needed. Haven't run across any
          > hard facts in my research.
          >
          > my 2 penny's worth
          >
          > /sm
          >
          >
          > On Fri, May 10, 2013 at 7:57 AM, kirkbecnel <kirkbecnel@...> wrote:
          >
          > > **
          > >
          > >
          > > I am building a foundry to melt small amounts, the crucibles will be of
          > > the smaller size, maybe from 3-4in diameter", 3-4" high . I am using
          > > kaowool for the lining with ITC 100 coat on it. I have seen crucibles say
          > > to use in a foundry designed for their size.
          > >
          > > My question is mainly how large of an area do I need around the crucible?
          > >
          > > I am thinking of the burner sending the flame directly into the side of
          > > the crucible as well as the circulation of heat around it.
          > >
          > > I am currently building the 3/4" burner in Mike Porter's book.
          > >
          > > How much of a gap do I want in between the crucible and the furnace lining?
          > >
          > > Thanks
          > >
          > >
          > >
          >
          >
          > [Non-text portions of this message have been removed]
          >
        • Rupert
          Kirk Usually, what determines the clearance around the crucible is the room needed to get grasping tools between the crucible and the furnace wall. A number 1
          Message 4 of 11 , May 10, 2013
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            Kirk
            Usually, what determines the clearance around the crucible is the room
            needed to get grasping tools between the crucible and the furnace wall.
            A number 1 crucible measures 3-4" across the top.
            A number of other members and I built what we call a coffee can
            furnace. It uses the metal 2 lb coffee cans for a shell. It is about the
            right size for a #1 clay graphite crucible which holds about 1 lb of
            molten aluminum. I built mine in two parts. I lined the bottom with
            refractory for durability. I lined the sides with two layers. The outer
            layer is 1" kaowool. I used refractory for the second inner layer for
            durability. I lined the upper part with 1 1/2" kaowool which I coated
            with two coats ITC100.
            I burner I have was a gift. It is a 1/4" Mikey design.

            The burner needs to be located so the flame enters the furnace
            tangentially. Blasting the burner directly onto the crucible will
            destroy the crucible in a short time.

            Rupert

            On 5/10/2013 5:57 AM, kirkbecnel wrote:
            > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
            >
            > My question is mainly how large of an area do I need around the crucible?
            >
            > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
            >
            > I am currently building the 3/4" burner in Mike Porter's book.
            >
            > How much of a gap do I want in between the crucible and the furnace lining?
            >
            > Thanks

            --

            yvt

            Rupert Wenig
            Camrose, Alberta, Canada.

            email: rwenig2@...

            http://users.xplornet.com/~rwenig/Home/
          • Wonk
            Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.
            Message 5 of 11 , May 10, 2013
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              Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.

              <http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>

              The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?
              Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.

              A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!

              Cheers Wonk

              --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@...> wrote:
              >
              > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
              >
              > My question is mainly how large of an area do I need around the crucible?
              >
              > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
              >
              > I am currently building the 3/4" burner in Mike Porter's book.
              >
              > How much of a gap do I want in between the crucible and the furnace lining?
              >
              > Thanks
              >
            • kirkbecnel
              That is really nice. I don t recall if I have all the pieces for the 1/2 burner or not. I may have gotten them. I was going to build the furnace in the book
              Message 6 of 11 , May 10, 2013
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                That is really nice. I don't recall if I have all the pieces for the 1/2 burner or not. I may have gotten them. I was going to build the furnace in the book with a propane tank but I did not want to really go that big and I have a small party balloon tank about the size of a freon tank I am employing.

                I think I will also put the refractory at the bottom. I don't know if what I have is 2300 or 300 degree, but I know it is up there.

                --- In hobbicast@yahoogroups.com, "Wonk" <tiwonk@...> wrote:
                >
                > Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.
                >
                > <http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
                >
                > The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?
                > Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.
                >
                > A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!
                >
                > Cheers Wonk
                >
                > --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@> wrote:
                > >
                > > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
                > >
                > > My question is mainly how large of an area do I need around the crucible?
                > >
                > > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
                > >
                > > I am currently building the 3/4" burner in Mike Porter's book.
                > >
                > > How much of a gap do I want in between the crucible and the furnace lining?
                > >
                > > Thanks
                > >
                >
              • mikey98118
                The smallest MIG tip is called .023 because it is meant to run that size wire, but its orifice sizes actually run between .030 and .031 ; this isn t an ideal
                Message 7 of 11 , May 11, 2013
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                  The smallest MIG tip is called .023" because it is meant to run that size wire, but its orifice sizes actually run between .030" and .031"; this isn't an ideal size, even for 1/2" burners, but just the nearest convenient size. More precision can be had by inserting a 5/8" long piece of capillary tubing into the tip's end. Check the cap tube's actual outside diameter before drilling out the MIG tip (tolerances do vary). Try for a press fit first; you can always solder the tip in if the blow that.

                  Cap tube can be found on line from various sources (even eBay); it is used as needle stock, gauge tubing, and EDM tube. The ideal size for 1/2" burners is .028"; for 3/8" burners it is .024".
                  Mikey

                  ----- Original Message -----
                  From: Wonk <tiwonk@...>
                  To: hobbicast@yahoogroups.com
                  Sent: Sat, 11 May 2013 02:51:27 -0000 (UTC)
                  Subject: [hobbicast] Re: Foundry design help





























                  Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.



                  <http://web.mail.comcast.net/zimbra/h/%3Cspan%20class=" yui-spellcheck?>http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc" target=_blank>http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>



                  The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?


                  Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.



                  A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!



                  Cheers Wonk



                  --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@...> wrote:


                  >


                  > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.


                  >


                  > My question is mainly how large of an area do I need around the crucible?


                  >


                  > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.


                  >


                  > I am currently building the 3/4" burner in Mike Porter's book.


                  >


                  > How much of a gap do I want in between the crucible and the furnace lining?


                  >


                  > Thanks


                  >












                  [Non-text portions of this message have been removed]
                • Wonk
                  I just measured my 3/8 and indeed it is .024, guess that was in memory since I used cap tube for that build! Mig tips are made of a fairly soft copper and
                  Message 8 of 11 , May 11, 2013
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                    I just measured my 3/8" and indeed it is .024, guess that was in memory since I used cap tube for that build! Mig tips are made of a fairly soft copper and tend to grab while drilling so use a good lube and go slow. I think I used 'tap magic' when I built with drilled mig tips?

                    Wonk

                    --- In hobbicast@yahoogroups.com, michael.a.porter@... wrote:
                    >
                    > The smallest MIG tip is called .023" because it is meant to run that size wire, but its orifice sizes actually run between .030" and .031"; this isn't an ideal size, even for 1/2" burners, but just the nearest convenient size. More precision can be had by inserting a 5/8" long piece of capillary tubing into the tip's end. Check the cap tube's actual outside diameter before drilling out the MIG tip (tolerances do vary). Try for a press fit first; you can always solder the tip in if the blow that.
                    >
                    > Cap tube can be found on line from various sources (even eBay); it is used as needle stock, gauge tubing, and EDM tube. The ideal size for 1/2" burners is .028"; for 3/8" burners it is .024".
                    > Mikey
                    >
                    > ----- Original Message -----
                    > From: Wonk <tiwonk@...>
                    > To: hobbicast@yahoogroups.com
                    > Sent: Sat, 11 May 2013 02:51:27 -0000 (UTC)
                    > Subject: [hobbicast] Re: Foundry design help
                    >
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                    > Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.
                    >
                    >
                    >
                    > <http://web.mail.comcast.net/zimbra/h/%3Cspan%20class=" yui-spellcheck?>http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc" target=_blank>http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
                    >
                    >
                    >
                    > The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?
                    >
                    >
                    > Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.
                    >
                    >
                    >
                    > A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!
                    >
                    >
                    >
                    > Cheers Wonk
                    >
                    >
                    >
                    > --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@> wrote:
                    >
                    >
                    > >
                    >
                    >
                    > > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
                    >
                    >
                    > >
                    >
                    >
                    > > My question is mainly how large of an area do I need around the crucible?
                    >
                    >
                    > >
                    >
                    >
                    > > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
                    >
                    >
                    > >
                    >
                    >
                    > > I am currently building the 3/4" burner in Mike Porter's book.
                    >
                    >
                    > >
                    >
                    >
                    > > How much of a gap do I want in between the crucible and the furnace lining?
                    >
                    >
                    > >
                    >
                    >
                    > > Thanks
                    >
                    >
                    > >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    > [Non-text portions of this message have been removed]
                    >
                  • Dan Brewer
                    If you have problems sourcing capillary tubing hypodermic needles for vet care come in all of the sizes you need for small burners. Use a larger mig tip if
                    Message 9 of 11 , May 11, 2013
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                      If you have problems sourcing capillary tubing hypodermic needles for vet
                      care come in all of the sizes you need for small burners. Use a larger mig
                      tip if you do not have the capability to drill (small drills ) Most of them
                      will fit . To capture the tubing use silver bearing solder. You can but it
                      in most welding shops and some ace hardware stores. If using the hard
                      solder silver/bronze use black flux. If using soft solder silver/tin/zinc
                      you can use white flux.

                      Dan in Auburn


                      On Sat, May 11, 2013 at 11:48 AM, Wonk <tiwonk@...> wrote:

                      > **
                      >
                      >
                      > I just measured my 3/8" and indeed it is .024, guess that was in memory
                      > since I used cap tube for that build! Mig tips are made of a fairly soft
                      > copper and tend to grab while drilling so use a good lube and go slow. I
                      > think I used 'tap magic' when I built with drilled mig tips?
                      >
                      > Wonk
                      >
                      > _Snip-


                      [Non-text portions of this message have been removed]
                    • mikey98118
                      Wonk, Between you and Dan, you have the picture; as Dan pointed out, MIG tips come in various orifice sizes; I list them in a chart of MIG tips found in my
                      Message 10 of 11 , May 12, 2013
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                        Wonk,
                        Between you and Dan, you have the picture; as Dan pointed out, MIG tips come in various orifice sizes; I list them in a chart of MIG tips found in my first book. So, by measuring actual outside diameter of a given cap tube, and choosing the nearest MIG tip orifice to it, then using Gene's "drill gently and use the right lubricant" advice, enlarging an orifice size a few thousandths of an inch, even in soft copper tubing, doesn't have to be challenging.

                        I would like to add that, of all the burner sizes I've built between 1/4" and 2", 3/8" is the most forgiving size when trying to match up the gas jet orifice with mixing tube diameters.
                        Mikey

                        ----- Original Message -----
                        From: Wonk <tiwonk@...>
                        To: hobbicast@yahoogroups.com
                        Sent: Sat, 11 May 2013 18:48:46 -0000 (UTC)
                        Subject: [hobbicast] Re: Foundry design help

                        1/4"




















                        I just measured my 3/8" and indeed it is .024, guess that was in memory since I used cap tube for that build! Mig tips are made of a fairly soft copper and tend to grab while drilling so use a good lube and go slow. I think I used 'tap magic' when I built with drilled mig tips?



                        Wonk



                        --- In hobbicast@yahoogroups.com, michael.a.porter@... wrote:


                        >


                        > The smallest MIG tip is called .023" because it is meant to run that size wire, but its orifice sizes actually run between .030" and .031"; this isn't an ideal size, even for 1/2" burners, but just the nearest convenient size. More precision can be had by inserting a 5/8" long piece of capillary tubing into the tip's end. Check the cap tube's actual outside diameter before drilling out the MIG tip (tolerances do vary). Try for a press fit first; you can always solder the tip in if the blow that.


                        >


                        > Cap tube can be found on line from various sources (even eBay); it is used as needle stock, gauge tubing, and EDM tube. The ideal size for 1/2" burners is .028"; for 3/8" burners it is .024".


                        > Mikey


                        >


                        > ----- Original Message -----


                        > From: Wonk <tiwonk@...>


                        > To: hobbicast@yahoogroups.com


                        > Sent: Sat, 11 May 2013 02:51:27 -0000 (UTC)


                        > Subject: [hobbicast] Re: Foundry design help


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                        > Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.


                        >


                        >


                        >


                        > <http://web.mail.comcast.net/zimbra/h/%3Cspan%20class=" target=_blank>http://web.mail.comcast.net/zimbra/h/%3Cspan%20class=" yui-spellcheck?><A href="http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc" target=_blank>http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc" target=_blank>http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>


                        >


                        >


                        >


                        > The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?


                        >


                        >


                        > Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.


                        >


                        >


                        >


                        > A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!


                        >


                        >


                        >


                        > Cheers Wonk


                        >


                        >


                        >


                        > --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@> wrote:


                        >


                        >


                        > >


                        >


                        >


                        > > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.


                        >


                        >


                        > >


                        >


                        >


                        > > My question is mainly how large of an area do I need around the crucible?


                        >


                        >


                        > >


                        >


                        >


                        > > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.


                        >


                        >


                        > >


                        >


                        >


                        > > I am currently building the 3/4" burner in Mike Porter's book.


                        >


                        >


                        > >


                        >


                        >


                        > > How much of a gap do I want in between the crucible and the furnace lining?


                        >


                        >


                        > >


                        >


                        >


                        > > Thanks


                        >


                        >


                        > >


                        >


                        >


                        >


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                        >


                        > [Non-text portions of this message have been removed]


                        >










                        [Non-text portions of this message have been removed]
                      • Bharat
                        I think you need 6 space both side ways of Pot and 7 in front area at back side it s 10 and for stop heat loss for pot sera wool must be applied in all
                        Message 11 of 11 , May 12, 2013
                        • 0 Attachment
                          I think you need 6" space both side ways of Pot and 7" in front area at back side it's 10" and for stop heat loss for pot sera wool must be applied in all the wall of furnace another main thing is in side wall of furnce 1.5" pipe must be installed at center level of pot for heat exaust and end of that pipe must be near 1" at chimney. This is best way for melting metal and flame must be 5-6" down than pot for pot safety

                          Sent from my iPhone

                          On 11 May 2013, at 08:21 AM, "Wonk" <tiwonk@...> wrote:

                          > Here is a photo from my album this group that shows a slightly bigger furnace than a coffee can size.
                          >
                          > <http://groups.yahoo.com/group/hobbicast/photos/album/493005517/pic/540815574/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
                          >
                          > The crucible is about the size you want to use. I agree with Rupert on the lining materials and clearance depends on your tongs. Height is also an issue as you don't want the crucible too close to the lid or upper section so as to block thermal rise then also not too far away as that tends to be a chimney effect and sucks the heat out. A 3/4" burner will be overkill and you probably can get by with a 7/16" or 1/2". The smaller burner sizes are a bit of a challenge as the mig tips only go so small .024 if memory is correct?
                          > Notice that I have a plinth block under my crucible, this is the best way to not have the intense flame burn a hole in the crucible due to impingment.
                          >
                          > A good plan comes together when things are thought out, good luck and ask questions, someone or many will try to help!
                          >
                          > Cheers Wonk
                          >
                          > --- In hobbicast@yahoogroups.com, "kirkbecnel" <kirkbecnel@...> wrote:
                          > >
                          > > I am building a foundry to melt small amounts, the crucibles will be of the smaller size, maybe from 3-4in diameter", 3-4" high . I am using kaowool for the lining with ITC 100 coat on it. I have seen crucibles say to use in a foundry designed for their size.
                          > >
                          > > My question is mainly how large of an area do I need around the crucible?
                          > >
                          > > I am thinking of the burner sending the flame directly into the side of the crucible as well as the circulation of heat around it.
                          > >
                          > > I am currently building the 3/4" burner in Mike Porter's book.
                          > >
                          > > How much of a gap do I want in between the crucible and the furnace lining?
                          > >
                          > > Thanks
                          > >
                          >
                          >


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