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Thread: Round and Round we go

  1. #1
    Moderator DavidF's Avatar
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    Round and Round we go

    I have always said that metal casting can be as simple or complex as you make it. The recent postings with lost foam casting are a prime example. The single lost foam pour that I have done has skewed me from my current project and caused me to start researching out a couple things that were farther down on my to do list as well as adding another avenue.
    The one thing that has been on the list for some time was to figure out how to make the slurry for ceramic shell casting. I only managed to find one recipe which is pretty dated. It uses a mix of clay, water, sodium silicate, and soda (assuming caustic soda to increase pH). I had experimented with this mix in the past with marginal results and after researching today believe I found out why. It takes 24 to 48 hours to develop (gel) properly, so that is back on the to do list but with the addition of talc this time around. The talc is supposed to reduce cracking and crazing in ceramic slip casting, I see no reason it would have an adverse effect on non ferrous castings. From there I started breaking down the msds sheets for the remit slurry. The remit is a colloidal silicate with a fine 200 mesh zircon added in. WTF is colloidal silicate?
    Interesting enough it appears the colloidal silicate can be produced from sodium silicate "imagine that !!"
    Ok, so we can make sodium silicate at home pretty easily now and it looks like by putting some SS in water and dropping the pH you can cause it to chain up and create colloidal silicate but need to re adjust the pH to over 7 to stabilize it once you have the correct particle size then evaporate it down to get the proper concentration....Yep all that just to save on shipping LOL. Ive contacted the Nurds to help confirm my research and will hopefully hear back soon.
    Ok so while i'm on my psyco babble rantings I have also ordered some EPS beads to experiment with making foam patterns in a mold at home for casting multiples of an item in lost foam. I plan on skipping the pre expansion phase (which I feel is just to create a uniform density of the foam pattern) and just shoot for making a foam pattern that may have varying densities. I think this is possible in a POP mold that is saturated and using either steam (such as a in a crab steamer) or perhaps even in a microwave. Time will tell and I may have to do the pre expansion phase but if I can avoid having to create a system to do that then I most certainly will. And just to top it all off I need to build a hot wire foam cutter now... So much for taking the simple route...
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  2. #2
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    Don't you have enough irons in the fire now David? LoL
    I've got a tube of this stuff.
    https://www.westmarine.com/buy/west-...CABEgJrCfD_BwE
    Bones

  3. #3
    It would be great to have both home brew shell and molded EPS beaded pattern making in the toolbox. Mix as needed shell for infrequent user would be useful. The molded EPS would be useful for reproducing complex shapes where a sample or 3D printed model is available and also for making multiple copies. I'll be watching with interest......but in the DW?

    Best,
    Kelly
    My furnace build ----- I toil and fettle then foam turns to metal!

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    Quote Originally Posted by FishbonzWVa View Post
    Don't you have enough irons in the fire now David? LoL
    For real! Did you ever get that shop cleaned up?lol
    I thought Mrs Petee was a garage widow. Some of your wives must really have her beat! I know that a post that takes 90 seconds to read might represent hours or days of work not mention all the obsessive pondering and googling.
    I'll be very interested to follow your experiments with EPS.

    Pete

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    Moderator DavidF's Avatar
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    Quote Originally Posted by FishbonzWVa View Post
    Don't you have enough irons in the fire now David? LoL
    I've got a tube of this stuff.
    https://www.westmarine.com/buy/west-...CABEgJrCfD_BwE
    That is a "fumed" colloidal silicate and not the colloidal silicate you are looking for... Sounds strange I know but it is an entirely different process and does not sound like the fumed colloidal silicate will work as an investment binder. However the rigidiser for K wool is in fact colloidal silicate.

    For real! Did you ever get that shop cleaned up?lol
    UMM NO.... But I am working with a contractor to build my new shop so I can spread the mess out further. Working on permitting now, but will depend on what the county says I can do. Hopefully this time next year it will be done.
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

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    Moderator DavidF's Avatar
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    Ok got my quote on the suspendaslurry, 5 gallon pail 160.47 shipped..... Not as bad as I was expecting.... going to order it today.

    Running an experiment on making colloidal silica, looks like it works but will require lost of evaporation to get it to 40%. Also making up the old school recipe investment to try out again.. But if the good stuff is only 160.00 why am I bothering???
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  7. #7
    Quote Originally Posted by DavidF View Post
    Ok got my quote on the suspendaslurry, 5 gallon pail 160.47 shipped..... Not as bad as I was expecting.... going to order it today.
    Was that from R&R? Got a link to where/what you bought? Need to strike while the weather is still warm.

    Best,
    Kelly
    My furnace build ----- I toil and fettle then foam turns to metal!

  8. #8
    Senior Member OCD's Avatar
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    Quote Originally Posted by DavidF View Post
    Ok got my quote on the suspendaslurry, 5 gallon pail 160.47 shipped..... Not as bad as I was expecting.... going to order it today.

    Running an experiment on making colloidal silica, looks like it works but will require lost of evaporation to get it to 40%. Also making up the old school recipe investment to try out again.. But if the good stuff is only 160.00 why am I bothering???
    Exactly!

    I went down this road when I first started messing with building my very first furnace out of back yard materials. <banging head on wall>

    Not worth the expense, time or aggravation, just pay the piper and be done with it.

  9. #9
    Moderator DavidF's Avatar
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    Kelly call or e mail this woman, Marti.Hunyor@dentsply.com 419-794-1210
    You want the suspendaslurry FS 60 lbs....

    Funny thing is when I look up colloidal silica, the shipping is as much as the product like 100.00 for 2 gallons and 97.00 shipping crazy!! If I knew the suspendaslurry was so much less I would have jumped on it years ago.
    Let the madness begin!!!
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

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    Quote Originally Posted by DavidF View Post
    Ok so while i'm on my psyco babble rantings I have also ordered some EPS beads to experiment with making foam patterns in a mold at home for casting multiples of an item in lost foam.
    David, im also interested in making foam patterns from eps beads but have really struggled to find a supplier here in france. Could you let me know who you are getting yours from and at what sort of quantities. Im not looking for huge amounts so it may be worth my while to order from the States and ship over here.

    Quote Originally Posted by DavidF View Post
    Time will tell and I may have to do the pre expansion phase but if I can avoid having to create a system to do that then I most certainly will. And just to top it all off I need to build a hot wire foam cutter now... So much for taking the simple route...
    If you do find you have to pre expand i did find a youtube of a guy making duck decoys for hunting that put a couple of handfuls of the unexpanded beads in an old pillow case and dropped it in a large metal bucket of boiling water for 15 seconds and took it out. Then he whacked it with a stick to break up the beads and stop them sticking together. He then left them overnight in a box and used them the next day pre expanded.
    This seemed to be suitably low tech enough for me.
    He also used the same metal bucket/boiling water set up for the final models but boiled the pre expanded beads in aluminum moulds for about 15 minutes.

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