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long core

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  • StoneTool
    I m trying to figure out how to cast a handle that will be hollow, about 14 long, and have an offset base with a bushing. A shaft will run through the length
    Message 1 of 9 , Feb 13, 2014
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      I'm trying to figure out how to cast a handle that will be hollow,
      about 14" long, and have an offset base with a bushing. A shaft will
      run through the length of the handle and have a mitre gear on the lower
      end, the lower end will be offset to one side for gear clearance, with a
      bushing area that will run on a shaft at right angles to the long shaft
      that runs down the handle, and will have the mating gear on it. Not a
      very good description I know, but I can see it in my mind's eye, and the
      details really aren't too important. What I want to avoid is having to
      bore the length of the handle........ not such a simple task! The bore
      will be about 7/8" and 14" long. With a sand core, it would need to
      stand vertically during the pour obviously.
      The ideal thing would be to be able to use a metal rod for a core,
      perhaps wrapped or painted with something that would char during the
      pour, allowing it to be released easily. A paper like material for
      example that would retain it's integrity to the extent of maintaining a
      space between the aluminum and the steel rod. Zamak would probably be a
      better choice of materials for this job than aluminum for strength
      reasons, and the lower pour temp might just make something like this
      realistic. I would actually like to make the hollow a larger diameter
      in the center portion, with 3/4" of each end smaller........ kind of a
      tall order ;-)
      My thinking is that a wrap of a suitable paper like material with
      adhesive of some sort could be made that would be thicker in the center
      than the ends, and would char as the zamak was poured, but remain intact
      enough to do the job. ZA2 or ZA27 with a pour temp of around 800F, and
      strength approaching that of mild steel looks like a good candidate.


      Howard
    • Rupert
      Hello Howard, I think any paint or tape you put on a metal rod would give you gassing problems. A carbon or graphite coating on the steel rod will make it
      Message 2 of 9 , Feb 13, 2014
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        Hello Howard,
        I think any paint or tape you put on a metal rod would give you gassing
        problems. A carbon or graphite coating on the steel rod will make it
        easier to remove but it will be tight and take a good push to move the rod.
        I think how I would do that is to make a wood form of half the core,
        then make a plaster of paris mold of the pattern half. I would then fill
        the POP mold with a sand/sodium silicate mix, use a rod to put in a vent
        through the centre, tap the mold lightly on the sides to loosen the
        sand/sodium silicate mix and then gas it with CO2. Then glue two half's
        of the core together to form the complete core. Bake at 250F for at
        least a half hour to drive off any moisture just before installing in
        the sand mold cavity and pour the metal asap. A similar procedure can be
        done using a baked sand core mix.
        I sometimes embed a stiff wire into thin cores for reinforcement. I
        think the mold can be poured either horizontally or vertical. Vertical
        with a bottom sprue might be best if the wall thickness is thin.
        Soak the casting in water to soften either core mix. I drop my aluminum
        castings in cold water as soon as I think the casting has cooled enough
        to hold it's shape. I found the castings machine much better when I
        quench a hot casting.

        Rupert

        On 2/13/2014 9:38 AM, StoneTool wrote:
        > I'm trying to figure out how to cast a handle that will be hollow,
        > about 14" long, and have an offset base with a bushing. A shaft will
        > run through the length of the handle and have a mitre gear on the lower
        > end, the lower end will be offset to one side for gear clearance, with a
        > bushing area that will run on a shaft at right angles to the long shaft
        > that runs down the handle, and will have the mating gear on it. Not a
        > very good description I know, but I can see it in my mind's eye, and the
        > details really aren't too important. What I want to avoid is having to
        > bore the length of the handle........ not such a simple task! The bore
        > will be about 7/8" and 14" long. With a sand core, it would need to
        > stand vertically during the pour obviously.
        > The ideal thing would be to be able to use a metal rod for a core,
        > perhaps wrapped or painted with something that would char during the
        > pour, allowing it to be released easily. A paper like material for
        > example that would retain it's integrity to the extent of maintaining a
        > space between the aluminum and the steel rod. Zamak would probably be a
        > better choice of materials for this job than aluminum for strength
        > reasons, and the lower pour temp might just make something like this
        > realistic. I would actually like to make the hollow a larger diameter
        > in the center portion, with 3/4" of each end smaller........ kind of a
        > tall order ;-)
        > My thinking is that a wrap of a suitable paper like material with
        > adhesive of some sort could be made that would be thicker in the center
        > than the ends, and would char as the zamak was poured, but remain intact
        > enough to do the job. ZA2 or ZA27 with a pour temp of around 800F, and
        > strength approaching that of mild steel looks like a good candidate.
        >
        >
        > Howard
        >
        >
        > ------------------------------------
        >
        > For discussion of Metal Casting and related issues
        > this list does not accept attachments.
        >
        > Files area and list services are at:
        > http://groups.yahoo.com/group/hobbicast
        >
        > For additional files and photos and off topic discussions
        > check out these two affiliated sites:
        > http://groups.yahoo.com/group/sandcrabs
        > http://groups.yahoo.com/group/Hobbicast1
        >
        > Please visit our sponsor: Budget Casting Supply
        > http://budgetcastingsupply.com/
        >
        > List Owner:
        > owly@...
        >
        > Yahoo Groups Links
        >
        >
        >
        >

        --

        yvt

        Rupert Wenig
        Camrose, Alberta, Canada.

        email: rwenig2@...

        http://users.xplornet.com/~rwenig/Home/
      • Dan Brewer
        To add to this if you use pins made out of the same material you are casting to support the core you will be able to keep the core positioned . I have used the
        Message 3 of 9 , Feb 13, 2014
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          To add to this if you use pins made out of the same material you are casting to support the core you will be able to keep the core positioned . I have used the vents made by putting a section of welding wire in the mold to do this.  The pins will become part of the casting and all you  have to clean up is the small section through the cavity,  Use sodium silicate with about 10% sugar mixed in.  The sugar burns out and then the core can be easly removed.  If you have purchaced Sodium Silicate from a casting house it is probally already mixed in.
          Dan in Auburn


          On Thu, Feb 13, 2014 at 9:12 AM, Rupert <rwenig2@...> wrote:
           

          Hello Howard,
          I think any paint or tape you put on a metal rod would give you gassing
          problems. A carbon or graphite coating on the steel rod will make it
          easier to remove but it will be tight and take a good push to move the rod.
          I think how I would do that is to make a wood form of half the core,
          then make a plaster of paris mold of the pattern half. I would then fill
          the POP mold with a sand/sodium silicate mix, use a rod to put in a vent
          through the centre, tap the mold lightly on the sides to loosen the
          sand/sodium silicate mix and then gas it with CO2. Then glue two half's
          of the core together to form the complete core. Bake at 250F for at
          least a half hour to drive off any moisture just before installing in
          the sand mold cavity and pour the metal asap. A similar procedure can be
          done using a baked sand core mix.
          I sometimes embed a stiff wire into thin cores for reinforcement. I
          think the mold can be poured either horizontally or vertical. Vertical
          with a bottom sprue might be best if the wall thickness is thin.
          Soak the casting in water to soften either core mix. I drop my aluminum
          castings in cold water as soon as I think the casting has cooled enough
          to hold it's shape. I found the castings machine much better when I
          quench a hot casting.

          Rupert



          On 2/13/2014 9:38 AM, StoneTool wrote:
          > I'm trying to figure out how to cast a handle that will be hollow,
          > about 14" long, and have an offset base with a bushing. A shaft will
          > run through the length of the handle and have a mitre gear on the lower
          > end, the lower end will be offset to one side for gear clearance, with a
          > bushing area that will run on a shaft at right angles to the long shaft
          > that runs down the handle, and will have the mating gear on it. Not a
          > very good description I know, but I can see it in my mind's eye, and the
          > details really aren't too important. What I want to avoid is having to
          > bore the length of the handle........ not such a simple task! The bore
          > will be about 7/8" and 14" long. With a sand core, it would need to
          > stand vertically during the pour obviously.
          > The ideal thing would be to be able to use a metal rod for a core,
          > perhaps wrapped or painted with something that would char during the
          > pour, allowing it to be released easily. A paper like material for
          > example that would retain it's integrity to the extent of maintaining a
          > space between the aluminum and the steel rod. Zamak would probably be a
          > better choice of materials for this job than aluminum for strength
          > reasons, and the lower pour temp might just make something like this
          > realistic. I would actually like to make the hollow a larger diameter
          > in the center portion, with 3/4" of each end smaller........ kind of a
          > tall order ;-)
          > My thinking is that a wrap of a suitable paper like material with
          > adhesive of some sort could be made that would be thicker in the center
          > than the ends, and would char as the zamak was poured, but remain intact
          > enough to do the job. ZA2 or ZA27 with a pour temp of around 800F, and
          > strength approaching that of mild steel looks like a good candidate.
          >
          >
          > Howard
          >
          >
          > ------------------------------------

          >
          > For discussion of Metal Casting and related issues
          > this list does not accept attachments.
          >
          > Files area and list services are at:
          > http://groups.yahoo.com/group/hobbicast
          >
          > For additional files and photos and off topic discussions
          > check out these two affiliated sites:
          > http://groups.yahoo.com/group/sandcrabs
          > http://groups.yahoo.com/group/Hobbicast1
          >
          > Please visit our sponsor: Budget Casting Supply
          > http://budgetcastingsupply.com/
          >
          > List Owner:
          > owly@...
          >
          > Yahoo Groups Links
          >
          >
          >
          >

          --

          yvt

          Rupert Wenig
          Camrose, Alberta, Canada.

          email: rwenig2@...

          http://users.xplornet.com/~rwenig/Home/


        • Nelson Collar
          Howard As vivid as you are in description, it s leaves a lot to imagination. If you use steal for a core and  try to pour at a lower temperature, you will
          Message 4 of 9 , Feb 13, 2014
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            Howard
            As vivid as you are in description, it's leaves a lot to imagination. If you use steal for a core and  try to pour at a lower temperature, you will wind up freezing and that will not work. A core 14 inches long would be better horizontal than vertical. More description might help but 14 inches is a task in itself.
            Nelson Collar


            On Thursday, February 13, 2014 11:38 AM, StoneTool <owly@...> wrote:
             
            I'm trying to figure out how to cast a handle that will be hollow,
            about 14" long, and have an offset base with a bushing. A shaft will
            run through the length of the handle and have a mitre gear on the lower
            end, the lower end will be offset to one side for gear clearance, with a
            bushing area that will run on a shaft at right angles to the long shaft
            that runs down the handle, and will have the mating gear on it. Not a
            very good description I know, but I can see it in my mind's eye, and the
            details really aren't too important. What I want to avoid is having to
            bore the length of the handle........ not such a simple task! The bore
            will be about 7/8" and 14" long. With a sand core, it would need to
            stand vertically during the pour obviously.
            The ideal thing would be to be able to use a metal rod for a core,
            perhaps wrapped or painted with something that would char during the
            pour, allowing it to be released easily. A paper like material for
            example that would retain it's integrity to the extent of maintaining a
            space between the aluminum and the steel rod. Zamak would probably be a
            better choice of materials for this job than aluminum for strength
            reasons, and the lower pour temp might just make something like this
            realistic. I would actually like to make the hollow a larger diameter
            in the center portion, with 3/4" of each end smaller........ kind of a
            tall order ;-)
            My thinking is that a wrap of a suitable paper like material with
            adhesive of some sort could be made that would be thicker in the center
            than the ends, and would char as the zamak was poured, but remain intact
            enough to do the job. ZA2 or ZA27 with a pour temp of around 800F, and
            strength approaching that of mild steel looks like a good candidate.

            Howard


          • StoneTool
            Let me be a bit more descriptive of the application. There is a horizontal shaft which must be turned for adjustment. Often many revolutions. The current
            Message 5 of 9 , Feb 13, 2014
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                  Let me be a bit more descriptive of the application.   There is a horizontal shaft which must be turned for adjustment.  Often many revolutions.  The current set up has a 14" handle with a ratchet cog that engages a gear.  You flip the cog one way or the other to rotate the shaft clockwise or counter clockwise.   It's a crude, and simple system that works.   You swing the handle one way and it ratchets by, pull it the other way and it grabs and turns the shaft.  Unfortunately the problem is that the tension is often so loose that you must hold the shaft while ratcheting back, or the drag of the ratchet will simply turn the shaft also.   A very clumsy device.     What I am doing is mounting a side gear from a Ford 9" rear end on the shaft, and a building a hollow handle with a shaft running up the middle and a spider gear on the shaft.    At the end of the handle, you will be able to engage the end of the shaft that runs up the handle with a hex drive in a cordless drill, hold the handle, and quickly spin the shaft.   It will not be able to be drawn up to full max tension with the power tool, so the shaft inside the handle has an inch and a half of acme screw thread, and the handle will have a dog with a half nut that engages this thread..... spring loaded engage.   To ratchet now, you will pull the handle in the tight or loose direction, and squeeze a lever to release the dog so you can "ratchet" it back with no resistance except what it takes to spin the shaft inside the handle as the spider gear walks around the side gear.   The only time you will use the handle manually is when the tightness exceeds the power of the drill to turn the shaft. 
                  The side gear and spider is used because they are cheap, readily available, offer a 2x reduction, and are about the right size.  I don't have a drawing of this, or a photo of a prototype, or I'd post it.........

                                                                                          Howard

              On 02/13/2014 11:58 AM, Nelson Collar wrote:
              Howard
              As vivid as you are in description, it's leaves a lot to imagination. If you use steal for a core and  try to pour at a lower temperature, you will wind up freezing and that will not work. A core 14 inches long would be better horizontal than vertical. More description might help but 14 inches is a task in itself.
              Nelson Collar


              On Thursday, February 13, 2014 11:38 AM, StoneTool <owly@...> wrote:
               
              I'm trying to figure out how to cast a handle that will be hollow,
              about 14" long, and have an offset base with a bushing. A shaft will
              run through the length of the handle and have a mitre gear on the lower
              end, the lower end will be offset to one side for gear clearance, with a
              bushing area that will run on a shaft at right angles to the long shaft
              that runs down the handle, and will have the mating gear on it. Not a
              very good description I know, but I can see it in my mind's eye, and the
              details really aren't too important. What I want to avoid is having to
              bore the length of the handle........ not such a simple task! The bore
              will be about 7/8" and 14" long. With a sand core, it would need to
              stand vertically during the pour obviously.
              The ideal thing would be to be able to use a metal rod for a core,
              perhaps wrapped or painted with something that would char during the
              pour, allowing it to be released easily. A paper like material for
              example that would retain it's integrity to the extent of maintaining a
              space between the aluminum and the steel rod. Zamak would probably be a
              better choice of materials for this job than aluminum for strength
              reasons, and the lower pour temp might just make something like this
              realistic. I would actually like to make the hollow a larger diameter
              in the center portion, with 3/4" of each end smaller........ kind of a
              tall order ;-)
              My thinking is that a wrap of a suitable paper like material with
              adhesive of some sort could be made that would be thicker in the center
              than the ends, and would char as the zamak was poured, but remain intact
              enough to do the job. ZA2 or ZA27 with a pour temp of around 800F, and
              strength approaching that of mild steel looks like a good candidate.

              Howard



            • Nelson Collar
              Howard  Send us a picture of your project On Thursday, February 13, 2014 3:00 PM, StoneTool wrote:       Let me be a bit more
              Message 6 of 9 , Feb 13, 2014
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                Howard 
                Send us a picture of your project


                On Thursday, February 13, 2014 3:00 PM, StoneTool <owly@...> wrote:
                 
                    Let me be a bit more descriptive of the application.   There is a horizontal shaft which must be turned for adjustment.  Often many revolutions.  The current set up has a 14" handle with a ratchet cog that engages a gear.  You flip the cog one way or the other to rotate the shaft clockwise or counter clockwise.   It's a crude, and simple system that works.   You swing the handle one way and it ratchets by, pull it the other way and it grabs and turns the shaft.  Unfortunately the problem is that the tension is often so loose that you must hold the shaft while ratcheting back, or the drag of the ratchet will simply turn the shaft also.   A very clumsy device.     What I am doing is mounting a side gear from a Ford 9" rear end on the shaft, and a building a hollow handle with a shaft running up the middle and a spider gear on the shaft.    At the end of the handle, you will be able to engage the end of the shaft that runs up the handle with a hex drive in a cordless drill, hold the handle, and quickly spin the shaft.   It will not be able to be drawn up to full max tension with the power tool, so the shaft inside the handle has an inch and a half of acme screw thread, and the handle will have a dog with a half nut that engages this thread..... spring loaded engage.   To ratchet now, you will pull the handle in the tight or loose direction, and squeeze a lever to release the dog so you can "ratchet" it back with no resistance except what it takes to spin the shaft inside the handle as the spider gear walks around the side gear.   The only time you will use the handle manually is when the tightness exceeds the power of the drill to turn the shaft. 
                    The side gear and spider is used because they are cheap, readily available, offer a 2x reduction, and are about the right size.  I don't have a drawing of this, or a photo of a prototype, or I'd post it.........

                                                                                            Howard

                On 02/13/2014 11:58 AM, Nelson Collar wrote:
                Howard
                As vivid as you are in description, it's leaves a lot to imagination. If you use steal for a core and  try to pour at a lower temperature, you will wind up freezing and that will not work. A core 14 inches long would be better horizontal than vertical. More description might help but 14 inches is a task in itself.
                Nelson Collar


                On Thursday, February 13, 2014 11:38 AM, StoneTool <owly@...> wrote:
                 
                I'm trying to figure out how to cast a handle that will be hollow,
                about 14" long, and have an offset base with a bushing. A shaft will
                run through the length of the handle and have a mitre gear on the lower
                end, the lower end will be offset to one side for gear clearance, with a
                bushing area that will run on a shaft at right angles to the long shaft
                that runs down the handle, and will have the mating gear on it. Not a
                very good description I know, but I can see it in my mind's eye, and the
                details really aren't too important. What I want to avoid is having to
                bore the length of the handle........ not such a simple task! The bore
                will be about 7/8" and 14" long. With a sand core, it would need to
                stand vertically during the pour obviously.
                The ideal thing would be to be able to use a metal rod for a core,
                perhaps wrapped or painted with something that would char during the
                pour, allowing it to be released easily. A paper like material for
                example that would retain it's integrity to the extent of maintaining a
                space between the aluminum and the steel rod. Zamak would probably be a
                better choice of materials for this job than aluminum for strength
                reasons, and the lower pour temp might just make something like this
                realistic. I would actually like to make the hollow a larger diameter
                in the center portion, with 3/4" of each end smaller........ kind of a
                tall order ;-)
                My thinking is that a wrap of a suitable paper like material with
                adhesive of some sort could be made that would be thicker in the center
                than the ends, and would char as the zamak was poured, but remain intact
                enough to do the job. ZA2 or ZA27 with a pour temp of around 800F, and
                strength approaching that of mild steel looks like a good candidate.

                Howard





              • Russell Hiscock
                Only a few weeks ago I saw a model cannon that had been made by using a steel tube as a core. It was not removed afterwards. It was filled with sand during the
                Message 7 of 9 , Feb 14, 2014
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                  Only a few weeks ago I saw a model cannon that had been made by using a steel tube as a core. It was not removed afterwards. It was filled with sand during the pour.

                   

                  (this was an iron casting, but I suspect (with absolutely no knowledge) that the same approach would work in other materials. It also was about 14” long…

                   

                  -russ

                • StoneTool
                  Russ: This might actually be the best solution for me for this application. I d considered it already and rejected it. The steel tube would have a lot of
                  Message 8 of 9 , Feb 14, 2014
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                    Russ:
                            This might actually be the best solution for me for  this application.   I'd considered it already and rejected it.  The steel tube would have a lot of strength...I'd just have to press bushings into it.   My original thought was that the aluminum or zamak would provide the bearing surfaces as well as the structure.   The obvious advantage is that the tube sets the alignment of the two bushings at either end. That bore would be the reference for the lower bore at 90 degrees to it. 

                                                                                                           Howard


                    On 02/14/2014 05:32 AM, Russell Hiscock wrote:

                    Only a few weeks ago I saw a model cannon that had been made by using a steel tube as a core. It was not removed afterwards. It was filled with sand during the pour.

                     

                    (this was an iron casting, but I suspect (with absolutely no knowledge) that the same approach would work in other materials. It also was about 14” long…

                     

                    -russ


                  • Nelson Collar
                    If it is a cannon, It will need to be bored and reamed. Another thought is, if it is a cannon what are you going to do with it when you get tired of it?
                    Message 9 of 9 , Feb 14, 2014
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                      If it is a cannon, It will need to be bored and reamed. Another thought is, if it is a cannon what are you going to do with it when you get tired of it? Liability is a big factor, if it fires can some one over load it causing to blow up like a pipe bomb. Toys are nice but be careful.
                      Nelson Collar


                      On Friday, February 14, 2014 10:42 AM, StoneTool <owly@...> wrote:
                       
                      Russ:
                              This might actually be the best solution for me for  this application.   I'd considered it already and rejected it.  The steel tube would have a lot of strength...I'd just have to press bushings into it.   My original thought was that the aluminum or zamak would provide the bearing surfaces as well as the structure.   The obvious advantage is that the tube sets the alignment of the two bushings at either end. That bore would be the reference for the lower bore at 90 degrees to it. 

                                                                                                             Howard


                      On 02/14/2014 05:32 AM, Russell Hiscock wrote:
                      Only a few weeks ago I saw a model cannon that had been made by using a steel tube as a core. It was not removed afterwards. It was filled with sand during the pour.
                       
                      (this was an iron casting, but I suspect (with absolutely no knowledge) that the same approach would work in other materials. It also was about 14” long…
                       
                      -russ



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