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AL356 casting for Model Airplane crankcases

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  • davidcam406
    Hi all, I m designing a model airplane engine that will have a cast AL crankcase. I assume that I may eventually sell maybe 50-200 engines (if I m lucky!)
    Message 1 of 7 , Oct 30, 2005
      Hi all,
      I'm designing a model airplane engine that will have a cast AL
      crankcase. I assume that I may eventually sell maybe 50-200 engines
      (if I'm lucky!)

      Therefore investment casting would be the logical choice of casting.
      I have the machinery and the ability to make the mold, but there are
      a few gaps in my knowledge.

      I guess I have several questions.
      1) what shrinkage should I apply to the mold to account for Wax
      shrinkage and to account for the AL356 shrinkage.
      2) I have an HR wax injector that is used for injecting wax. It
      operates at 8psi, I always thought that the wax was injected at much
      higher pressures than that. Is 8psi sufficient to inject wax into an
      AL mold and get it completely filled?
      3) What is the best mold releease to use on wax
      4) Do wax's vary as to there shrinkage properties?

      I appreciate any help that the forum can provide, Thanks in advance!

      Dave Cam
    • Shiney Paper
      Casting a crankshaft in Aluminum is looking for a trouble before you start. Cast the engine case and head in Aluminum but not the crankshaft. Cast Aluminum
      Message 2 of 7 , Oct 30, 2005
        Casting a crankshaft in Aluminum is looking for a trouble before you
        start. Cast the engine case and head in Aluminum but not the
        crankshaft. Cast Aluminum is not strong enough for that application.
        356 Aluminum even if heat treated won't stand up to the forces
        placed on a crankshaft. Turn of have someone turn the crankshaft
        out of steel. I can't say for sure but I don't know of any model
        airplane engine that uses an Aluminum crankshaft, for that matter
        I don't know of any recipricating engine that uses an Aluminum
        crankshaft. Although you may be the first. I think you had better
        prepare for lots of returns.

        Milt


        >From: "Raymond Heckert" <jnr@...>
        >Reply-To: hobbicast@yahoogroups.com
        >To: <hobbicast@yahoogroups.com>
        >Subject: Re: [hobbicast] AL356 casting for Model Airplane crankcases
        >Date: Sun, 30 Oct 2005 23:04:47 -0800
        >
        >Perhaps you should consider making a silicon rubber mold, and not have to
        >worry about mold release. And, 8 psi might be the right pressure for a S-R
        >mold.
        >
        >RayHex
        >
        >-----Original Message-----
        >Date: Sunday, October 30, 2005 4:10 PM
        >Subject: [hobbicast] AL356 casting for Model Airplane crankcases
        >
        >
        > >Hi all,
        > >I'm designing a model airplane engine that will have a cast AL
        > >crankcase. I assume that I may eventually sell maybe 50-200 engines
        > >(if I'm lucky!)
        > >
        > >Therefore investment casting would be the logical choice of casting.
        > >I have the machinery and the ability to make the mold, but there are
        > >a few gaps in my knowledge.
        > >
        > >I guess I have several questions.
        > >1) what shrinkage should I apply to the mold to account for Wax
        > >shrinkage and to account for the AL356 shrinkage.
        > >2) I have an HR wax injector that is used for injecting wax. It
        > >operates at 8psi, I always thought that the wax was injected at much
        > >higher pressures than that. Is 8psi sufficient to inject wax into an
        > >AL mold and get it completely filled?
        > >3) What is the best mold releease to use on wax
        > >4) Do wax's vary as to there shrinkage properties?
        > >
        > >I appreciate any help that the forum can provide, Thanks in advance!
        > >
        > >Dave Cam
        >
        >
        >
        >
        >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
        >
        >
        >
        >
        >
        >
        >
      • Raymond Heckert
        Perhaps you should consider making a silicon rubber mold, and not have to worry about mold release. And, 8 psi might be the right pressure for a S-R mold.
        Message 3 of 7 , Oct 30, 2005
          Perhaps you should consider making a silicon rubber mold, and not have to
          worry about mold release. And, 8 psi might be the right pressure for a S-R
          mold.

          RayHex

          -----Original Message-----
          Date: Sunday, October 30, 2005 4:10 PM
          Subject: [hobbicast] AL356 casting for Model Airplane crankcases


          >Hi all,
          >I'm designing a model airplane engine that will have a cast AL
          >crankcase. I assume that I may eventually sell maybe 50-200 engines
          >(if I'm lucky!)
          >
          >Therefore investment casting would be the logical choice of casting.
          >I have the machinery and the ability to make the mold, but there are
          >a few gaps in my knowledge.
          >
          >I guess I have several questions.
          >1) what shrinkage should I apply to the mold to account for Wax
          >shrinkage and to account for the AL356 shrinkage.
          >2) I have an HR wax injector that is used for injecting wax. It
          >operates at 8psi, I always thought that the wax was injected at much
          >higher pressures than that. Is 8psi sufficient to inject wax into an
          >AL mold and get it completely filled?
          >3) What is the best mold releease to use on wax
          >4) Do wax's vary as to there shrinkage properties?
          >
          >I appreciate any help that the forum can provide, Thanks in advance!
          >
          >Dave Cam
        • Salisbury, NH
          crankcase Milt. Not crankshaft. BC ... From: hobbicast@yahoogroups.com [mailto:hobbicast@yahoogroups.com]On Behalf Of Shiney Paper Sent: Monday, October 31,
          Message 4 of 7 , Oct 31, 2005
            crankcase Milt. Not crankshaft.

            BC

            ----------------------------------------------------------------------------
            ----




            -----Original Message-----
            From: hobbicast@yahoogroups.com [mailto:hobbicast@yahoogroups.com]On
            Behalf Of Shiney Paper
            Sent: Monday, October 31, 2005 1:15 AM
            To: hobbicast@yahoogroups.com
            Subject: Re: [hobbicast] AL356 casting for Model Airplane crankcases


            Casting a crankshaft in Aluminum is looking for a trouble before you
            start. Cast the engine case and head in Aluminum but not the
            crankshaft. Cast Aluminum is not strong enough for that application.
            356 Aluminum even if heat treated won't stand up to the forces
            placed on a crankshaft. Turn of have someone turn the crankshaft
            out of steel. I can't say for sure but I don't know of any model
            airplane engine that uses an Aluminum crankshaft, for that matter
            I don't know of any recipricating engine that uses an Aluminum
            crankshaft. Although you may be the first. I think you had better
            prepare for lots of returns.

            Milt


            >From: "Raymond Heckert" <jnr@...>
            >Reply-To: hobbicast@yahoogroups.com
            >To: <hobbicast@yahoogroups.com>
            >Subject: Re: [hobbicast] AL356 casting for Model Airplane crankcases
            >Date: Sun, 30 Oct 2005 23:04:47 -0800
            >
            >Perhaps you should consider making a silicon rubber mold, and not have to
            >worry about mold release. And, 8 psi might be the right pressure for a S-R
            >mold.
            >
            >RayHex
            >
            >-----Original Message-----
            >Date: Sunday, October 30, 2005 4:10 PM
            >Subject: [hobbicast] AL356 casting for Model Airplane crankcases
            >
            >
            > >Hi all,
            > >I'm designing a model airplane engine that will have a cast AL
            > >crankcase. I assume that I may eventually sell maybe 50-200 engines
            > >(if I'm lucky!)
            > >
            > >Therefore investment casting would be the logical choice of casting.
            > >I have the machinery and the ability to make the mold, but there are
            > >a few gaps in my knowledge.
            > >
            > >I guess I have several questions.
            > >1) what shrinkage should I apply to the mold to account for Wax
            > >shrinkage and to account for the AL356 shrinkage.
            > >2) I have an HR wax injector that is used for injecting wax. It
            > >operates at 8psi, I always thought that the wax was injected at much
            > >higher pressures than that. Is 8psi sufficient to inject wax into an
            > >AL mold and get it completely filled?
            > >3) What is the best mold releease to use on wax
            > >4) Do wax's vary as to there shrinkage properties?
            > >
            > >I appreciate any help that the forum can provide, Thanks in advance!
            > >
            > >Dave Cam
            >
            >
            >
            >
            >For discussion of Metal Casting and related issues
            >this list does not accept attachments.


            [Non-text portions of this message have been removed]
          • Lyle
            That Rayhex dude is right about the silicon molds not needing a release. Your wax shrinkage depends on the wax and the temperature it s injected. You didn t
            Message 5 of 7 , Oct 31, 2005
              That Rayhex dude is right about the silicon molds not needing a
              release. Your wax shrinkage depends on the wax and the temperature
              it's injected. You didn't specify how large your crankcase is but I
              would venture to guess, that it's small enough to where if you were
              off a little, say a percent or so, it wouldn't make much difference.
              as long as you have enough machining allowance on the machined
              surfaces. I would use as low a pressure as possible to completely
              fill the mold. Using a higher pressure would increase the amount
              of "flash" around the mold at the parting line.

              By the way, if you have good temperature controls, you may be able to
              heat treat those castings in the same furnace as your burnout kiln.
              Works for me.

              LL

              --- In hobbicast@yahoogroups.com, "Raymond Heckert" <jnr@a...> wrote:
              >
              > Perhaps you should consider making a silicon rubber mold, and not
              have to
              > worry about mold release. And, 8 psi might be the right pressure
              for a S-R
              > mold.
              >
              > RayHex
              >
              > -----Original Message-----
              > Date: Sunday, October 30, 2005 4:10 PM
              > Subject: [hobbicast] AL356 casting for Model Airplane crankcases
              >
              >
              > >Hi all,
              > >I'm designing a model airplane engine that will have a cast AL
              > >crankcase. I assume that I may eventually sell maybe 50-200 engines
              > >(if I'm lucky!)
              > >
              > >Therefore investment casting would be the logical choice of
              casting.
              > >I have the machinery and the ability to make the mold, but there
              are
              > >a few gaps in my knowledge.
              > >
              > >I guess I have several questions.
              > >1) what shrinkage should I apply to the mold to account for Wax
              > >shrinkage and to account for the AL356 shrinkage.
              > >2) I have an HR wax injector that is used for injecting wax. It
              > >operates at 8psi, I always thought that the wax was injected at
              much
              > >higher pressures than that. Is 8psi sufficient to inject wax into
              an
              > >AL mold and get it completely filled?
              > >3) What is the best mold releease to use on wax
              > >4) Do wax's vary as to there shrinkage properties?
              > >
              > >I appreciate any help that the forum can provide, Thanks in
              advance!
              > >
              > >Dave Cam
              >
            • david cam
              Thank you all for replying, I ve never tried SR molds, I have a CNC machine and my preference is to machine the mold in 7075 AL. I might look more into the SR
              Message 6 of 7 , Oct 31, 2005
                Thank you all for replying,

                I've never tried SR molds, I have a CNC machine and my preference is to machine the mold in 7075 AL. I might look more into the SR route for the first few parts.

                It appaers from what I can find that 8psi is about right for SR molds, but some commercial Wax Injectors I have found online appear to be capable of 1000psi. I assume that's to fill the mold quickly and to get intricate detail. Obviously the mold would need to be metallic to withstand the 1000psi pressure. Also I assume that the 1000psi is held on the mold until it cools to minimise wax shrinkage.

                Lots of stuff to learn!!

                Lyle <creepinogie@...> wrote:
                That Rayhex dude is right about the silicon molds not needing a
                release. Your wax shrinkage depends on the wax and the temperature
                it's injected. You didn't specify how large your crankcase is but I
                would venture to guess, that it's small enough to where if you were
                off a little, say a percent or so, it wouldn't make much difference.
                as long as you have enough machining allowance on the machined
                surfaces. I would use as low a pressure as possible to completely
                fill the mold. Using a higher pressure would increase the amount
                of "flash" around the mold at the parting line.

                By the way, if you have good temperature controls, you may be able to
                heat treat those castings in the same furnace as your burnout kiln.
                Works for me.

                LL

                --- In hobbicast@yahoogroups.com, "Raymond Heckert" wrote:
                >
                > Perhaps you should consider making a silicon rubber mold, and not
                have to
                > worry about mold release. And, 8 psi might be the right pressure
                for a S-R
                > mold.
                >
                > RayHex
                >
                > -----Original Message-----
                > Date: Sunday, October 30, 2005 4:10 PM
                > Subject: [hobbicast] AL356 casting for Model Airplane crankcases
                >
                >
                > >Hi all,
                > >I'm designing a model airplane engine that will have a cast AL
                > >crankcase. I assume that I may eventually sell maybe 50-200 engines
                > >(if I'm lucky!)
                > >
                > >Therefore investment casting would be the logical choice of
                casting.
                > >I have the machinery and the ability to make the mold, but there
                are
                > >a few gaps in my knowledge.
                > >
                > >I guess I have several questions.
                > >1) what shrinkage should I apply to the mold to account for Wax
                > >shrinkage and to account for the AL356 shrinkage.
                > >2) I have an HR wax injector that is used for injecting wax. It
                > >operates at 8psi, I always thought that the wax was injected at
                much
                > >higher pressures than that. Is 8psi sufficient to inject wax into
                an
                > >AL mold and get it completely filled?
                > >3) What is the best mold releease to use on wax
                > >4) Do wax's vary as to there shrinkage properties?
                > >
                > >I appreciate any help that the forum can provide, Thanks in
                advance!
                > >
                > >Dave Cam
                >






                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








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              • david cam
                Crankshaft in AL, uum, I d never thought of that!! Shiney Paper wrote:Casting a crankshaft in Aluminum is looking for a trouble
                Message 7 of 7 , Oct 31, 2005
                  Crankshaft in AL, uum, I'd never thought of that!!

                  Shiney Paper <shineypaper@...> wrote:Casting a crankshaft in Aluminum is looking for a trouble before you
                  start. Cast the engine case and head in Aluminum but not the
                  crankshaft. Cast Aluminum is not strong enough for that application.
                  356 Aluminum even if heat treated won't stand up to the forces
                  placed on a crankshaft. Turn of have someone turn the crankshaft
                  out of steel. I can't say for sure but I don't know of any model
                  airplane engine that uses an Aluminum crankshaft, for that matter
                  I don't know of any recipricating engine that uses an Aluminum
                  crankshaft. Although you may be the first. I think you had better
                  prepare for lots of returns.

                  Milt


                  >From: "Raymond Heckert"
                  >Reply-To: hobbicast@yahoogroups.com
                  >To:
                  >Subject: Re: [hobbicast] AL356 casting for Model Airplane crankcases
                  >Date: Sun, 30 Oct 2005 23:04:47 -0800
                  >
                  >Perhaps you should consider making a silicon rubber mold, and not have to
                  >worry about mold release. And, 8 psi might be the right pressure for a S-R
                  >mold.
                  >
                  >RayHex
                  >
                  >-----Original Message-----
                  >Date: Sunday, October 30, 2005 4:10 PM
                  >Subject: [hobbicast] AL356 casting for Model Airplane crankcases
                  >
                  >
                  > >Hi all,
                  > >I'm designing a model airplane engine that will have a cast AL
                  > >crankcase. I assume that I may eventually sell maybe 50-200 engines
                  > >(if I'm lucky!)
                  > >
                  > >Therefore investment casting would be the logical choice of casting.
                  > >I have the machinery and the ability to make the mold, but there are
                  > >a few gaps in my knowledge.
                  > >
                  > >I guess I have several questions.
                  > >1) what shrinkage should I apply to the mold to account for Wax
                  > >shrinkage and to account for the AL356 shrinkage.
                  > >2) I have an HR wax injector that is used for injecting wax. It
                  > >operates at 8psi, I always thought that the wax was injected at much
                  > >higher pressures than that. Is 8psi sufficient to inject wax into an
                  > >AL mold and get it completely filled?
                  > >3) What is the best mold releease to use on wax
                  > >4) Do wax's vary as to there shrinkage properties?
                  > >
                  > >I appreciate any help that the forum can provide, Thanks in advance!
                  > >
                  > >Dave Cam
                  >
                  >
                  >
                  >
                  >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
                  >
                  >
                  >
                  >
                  >
                  >
                  >




                  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









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                  Yahoo! FareChase - Search multiple travel sites in one click.

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