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RE: [hobbicast] Compressing sand with a press?

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  • Dennis
    I think the secret is free flowing sand. I used Petrobond, but shook it through a screen into the flask. About window screen mesh. This makes it fluffy , Also
    Message 1 of 35 , Dec 13, 2012
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      I think the secret is free flowing sand. I used Petrobond, but shook it
      through a screen into the flask. About window screen mesh. This makes it
      'fluffy', Also the depths of the flask were probably twice normal. I would
      fill up the flask then 'jolt' it. Doing it several times, brought the sand
      down to less than half of what it had started with. The 'squeeze' part
      didn't reduce the volume much, it just seem to consolidate the sand. My
      hunch is that any attempt to pre compress the sand eliminates the flowing of
      the sand during the jolt leaving high and low density's in the sand. Also
      pre-compression would interfere with the squeezing, preventing even pressure
      over all the mold.

      Now my Petrobond sand is dry and exhibits no stickiness. It has been used a
      couple of times and was made using a true muller, not a mixer. Using the
      sandmans test of grabbing a handful of sand and squeezing in the hand, the
      resulting blob holds together and shows some rigidly. In the commercial
      operations I have seen, the sand is delivered overhead by a air system which
      keeps the sand loose. The sand is than dropped in the flask, the flask
      jolted several times. The follow board fits inside the flask sides and is
      of stout material. The compression cylinder then presses down to a preset
      pressure.

      I actually use one half flask, which I use for both cope and drag. After
      squeezing, I set the mold on the ground then use the flask for the cope. I
      set each one next to each other so each acts as the side of the other. After
      a half dozen or so, I put a row of bricks around the outside perimeter, put
      some weight on the molds and pour away.

      This looks like a good area for DIY experimentation with the results
      reported to the list.

      Dennis Cranston
      Houston Texas



      -----Original Message-----
      From: hobbicast@yahoogroups.com [mailto:hobbicast@yahoogroups.com] On Behalf
      Of David Knaack
      Sent: Thursday, December 13, 2012 10:16 AM
      To: hobbicast@yahoogroups.com
      Subject: Re: [hobbicast] Compressing sand with a press?

      Ah, I knew there must have been a technique we were missing!

      Can you give me an idea of the pressure you are using?

      Also, when using this technique, how do you go about filling the flask?
      We placed the pattern on a board, put the drag over it, filled it and
      lightly compressed by hand, then flipped, placed the cope on top and added
      more sand, then put it in the press with a top board slightly smaller than
      the inner dimensions of the flask.

      The result looked good, with firm sand on the top, but the sand in the
      middle was nearly uncompressed and immediately fell out of the flask when it
      was picked up.

      Thanks!
      DaveK

      On Thu, Dec 13, 2012 at 9:44 AM, Dennis <dlcranston@...> wrote:

      > **
      >
      >
      > In the older small foundries, they used machines called jolt squeeze
      > molding machines. The technique requires the 'jolt'. When doing this
      > myself, I fill the flask, which is of extra depth, with loose sand
      > which has been screened to be sure it is really loose. I then bang the
      > flask and bottom plate against a solid object. A couple of bangs
      > settles the sand. Then the flask is put in a press with a follow board
      > on top and 'squeezed'. Obviously, this only works with smaller flasks.
      >
      > The commercial machines use an air cylinder to raise the platen
      > holding the flask. At the top of the stroke, the air is removed and
      > the platen-flask suddenly drops. This is repeated several times. Then
      > a top platen is placed on top of the flask and an air cylinder slowly
      > presses the top board down to compress the sand.
      >
      > There was a segment on 'Dirty Jobs' where Mike Rowe operated one.
      >
      > Check videos for Jolt Squeeze machine operations.
      >
      > Dennis Cranston
      > Houston Texas
      >
      >
      > -----Original Message-----
      > From: hobbicast@yahoogroups.com [mailto:hobbicast@yahoogroups.com] On
      > Behalf Of David Knaack
      > Sent: Thursday, December 13, 2012 9:19 AM
      > To: hobbicast@yahoogroups.com
      > Subject: [hobbicast] Compressing sand with a press?
      >
      > Some of my friends have been interested in the option of packing
      > casting sand (we're using an oil sand purchased from a local aluminum
      > foundry) with a hydraulic press rather than with the usual tamping method.
      >
      > Initial experiments with this have not not gone well (loose sand,
      > creaking
      > flasks,etc) I suspect because the pressure required is going to be
      > quite high for anything other than very small flasks.
      >
      > I wonder if some of you with more experience in this area could
      > provide some insight into how large of a press we might need for this,
      > and what other kinds of issues we might run into?
      >
      > Thanks!
      > DaveK
      >
      > [Non-text portions of this message have been removed]
      >
      > ------------------------------------
      >
      >
      > 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
      >
      >
      >


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



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

      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
    • Alan
      I watched the whole thing. That does NOT mean the pro caster here does it that way. AS I already wrote, His vibration table is very active like a couple
      Message 35 of 35 , Dec 25, 2012
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        I watched the whole thing.
        That does NOT mean the pro caster here does it that way.
        AS I already wrote, His vibration table is very active like a couple hundred of those thumps shown in that video for the deep ones and less for the shallower ones.
         
        Alan

        --- On Tue, 12/25/12, Nelson Collar <nel2lar@...> wrote:


        From: Nelson Collar <nel2lar@...>
        Subject: Re: [hobbicast] Compressing sand with a press?
        To: "hobbicast@yahoogroups.com" <hobbicast@yahoogroups.com>
        Date: Tuesday, December 25, 2012, 8:39 PM


        I guess you over looked the final squeeze before he removed the match plate. This is a way a foundry in Pa does it and has done it for almost a century. There is a pressure squeeze in that video.
        Nelson Collar


        ________________________________
        From: Alan <rustaholic777@...>
        To: hobbicast@yahoogroups.com
        Sent: Tuesday, December 25, 2012 8:24 PM
        Subject: Re: [hobbicast] Compressing sand with a press?


         
        Hey Nelson,
        What I know is roughly how one man that has beed casting almost daily for forty years does it.
        Are you trying to tell me I am saying something wrong?
        His table is a very active vibrator when he steps on that pedal.
        It is not a simple thumper like in that video.
         
        Alan

        --- On Tue, 12/25/12, Nelson Collar <nel2lar@...> wrote:

        From: Nelson Collar <nel2lar@...>
        Subject: Re: [hobbicast] Compressing sand with a press?
        To: "hobbicast@yahoogroups.com" <hobbicast@yahoogroups.com>
        Date: Tuesday, December 25, 2012, 8:13 PM

        Alan
        I do not understand why everything is taken as wrong. The old foundrys use a press when making there sand casts. You might want to take a look at this video and you may be corrected. Watch this http://www.youtube.com/watch?v=dlQ54WATvzA
        Its about 4 minutes, enjoy
        Nelson Collar

        ________________________________
        From: Alan <rustaholic777@...>
        To: hobbicast@yahoogroups.com
        Sent: Tuesday, December 25, 2012 7:37 PM
        Subject: RE: [hobbicast] Compressing sand with a press?

         
        At the Buckley Old Engine Show we have a foundry that mostly casts aluminum dinner bells and the hangers for them with the show logo and date.
        The group is headed up by a man that has been casting for a living for a lot of years in his own shop.
        What he has there is a vibration table that settles the sand before the aluminum is poured in. That is after he separates the flasks and pulls the pattern out.
        There is no press involved.
        I am too much of a newbe to tell you what sand they are using.
        I do not remember seeing a muller though.
        Alan in Michigan

        --- On Thu, 12/13/12, Dennis <dlcranston@...> wrote:

        From: Dennis <dlcranston@...>
        Subject: RE: [hobbicast] Compressing sand with a press?
        To: hobbicast@yahoogroups.com
        Date: Thursday, December 13, 2012, 1:03 PM

        I think the secret is free flowing sand. I used Petrobond, but shook it
        through a screen into the flask. About window screen mesh. This makes it
        'fluffy', Also the depths of the flask were probably twice normal. I would
        fill up the flask then 'jolt' it. Doing it several times, brought the sand
        down to less than half of what it had started with.  The 'squeeze' part
        didn't reduce the volume much, it just seem to consolidate the sand.  My
        hunch is that any attempt to pre compress the sand eliminates the flowing of
        the sand during the jolt leaving high and low density's in the sand.  Also
        pre-compression would interfere with the squeezing, preventing even pressure
        over all the mold.

        Now my Petrobond sand is dry and exhibits no stickiness. It has been used a
        couple of times and was made using a true muller, not a mixer. Using the
        sandmans test of grabbing a handful of sand and squeezing in the hand, the
        resulting blob holds together and shows some rigidly.  In the commercial
        operations I have seen, the sand is delivered overhead by a air system which
        keeps the sand loose. The sand is than dropped in the flask, the flask
        jolted several times.  The follow board fits inside the flask sides and is
        of stout material. The compression cylinder then presses down to a preset
        pressure.

        I actually use one half flask, which I use for both cope and drag. After
        squeezing, I set the mold on the ground then use the flask for the cope. I
        set each one next to each other so each acts as the side of the other. After
        a half dozen or so, I put a row of bricks around the outside perimeter, put
        some weight on the molds and pour away.

        This looks like a good area for DIY experimentation with the results
        reported to the list.

        Dennis Cranston
        Houston Texas

        -----Original Message-----
        From: hobbicast@yahoogroups.com [mailto:hobbicast@yahoogroups.com] On Behalf
        Of David Knaack
        Sent: Thursday, December 13, 2012 10:16 AM
        To: hobbicast@yahoogroups.com
        Subject: Re: [hobbicast] Compressing sand with a press?

        Ah, I knew there must have been a technique we were missing!

        Can you give me an idea of the pressure you are using?

        Also, when using this technique, how do you go about filling the flask?
        We placed the pattern on a board, put the drag over it, filled it and
        lightly compressed by hand, then flipped, placed the cope on top and added
        more sand, then put it in the press with a top board slightly smaller than
        the inner dimensions of the flask.

        The result looked good, with firm sand on the top, but the sand in the
        middle was nearly uncompressed and immediately fell out of the flask when it
        was picked up.

        Thanks!
        DaveK

        On Thu, Dec 13, 2012 at 9:44 AM, Dennis <dlcranston@...> wrote:

        > **
        >
        >
        > In the older small foundries, they used machines called jolt squeeze
        > molding machines. The technique requires the 'jolt'. When doing this
        > myself, I fill the flask, which is of extra depth, with loose sand
        > which has been screened to be sure it is really loose. I then bang the
        > flask and bottom plate against a solid object. A couple of bangs
        > settles the sand. Then the flask is put in a press with a follow board
        > on top and 'squeezed'. Obviously, this only works with smaller flasks.
        >
        > The commercial machines use an air cylinder to raise the platen
        > holding the flask. At the top of the stroke, the air is removed and
        > the platen-flask suddenly drops. This is repeated several times. Then
        > a top platen is placed on top of the flask and an air cylinder slowly
        > presses the top board down to compress the sand.
        >
        > There was a segment on 'Dirty Jobs' where Mike Rowe operated one.
        >
        > Check videos for Jolt Squeeze machine operations.
        >
        > Dennis Cranston
        > Houston Texas
        >
        >
        > -----Original Message-----
        > From: hobbicast@yahoogroups.com [mailto:hobbicast@yahoogroups.com] On
        > Behalf Of David Knaack
        > Sent: Thursday, December 13, 2012 9:19 AM
        > To: hobbicast@yahoogroups.com
        > Subject: [hobbicast] Compressing sand with a press?
        >
        > Some of my friends have been interested in the option of packing
        > casting sand (we're using an oil sand purchased from a local aluminum
        > foundry) with a hydraulic press rather than with the usual tamping method.
        >
        > Initial experiments with this have not not gone well (loose sand,
        > creaking
        > flasks,etc) I suspect because the pressure required is going to be
        > quite high for anything other than very small flasks.
        >
        > I wonder if some of you with more experience in this area could
        > provide some insight into how large of a press we might need for this,
        > and what other kinds of issues we might run into?
        >
        > Thanks!
        > DaveK
        >
        > [Non-text portions of this message have been removed]
        >
        > ------------------------------------
        >
        >
        > 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
        >

        >

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

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

        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

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

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

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

        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

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




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



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

        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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