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IndustryArena Forum > Mechanical Engineering > Epoxy Granite > Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)
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  1. #1
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    Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    This thread is meant to provide a practicum for the application of Epoxy Granite (Mineral Casting, Polymer Concrete).

    From test samples to filled bases to large scale machines to precision gantrys to metrology tables and more, all photos, videos, links and comments are welcome.

    Please assign appropriate copyright notices where necessary.

    To learn more about the theorectical use and application of Epoxy Granite, I highly recommend reading the thread entitled "Epoxy-Granite machine bases."

    Once you have increased your understanding and are ready to give it a try, please feel free to share your work here.

    ~John

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    Thank You For Getting Us Here.

    The first post in this thread should rightfully pay homage to walter, lgalla, ckelloug, greybeard, jhudler, brunog, martinW, Geof, and the many others who continue to make the original Epoxy-Granite thread so interesting.

    Thank You.

  3. #3
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    Here is a good link from WilliamD
    http://www.cnczone.com/forums/showthread.php?t=33434
    Larry
    L GALILEO THE EPOXY SURFACE PLATE IS FLAT

  4. #4
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    Vintage DIY Turret Lathe

    Page 2 of this article describes using concrete for the lathe bed.

    http://www.vintageprojects.com/machi...urretLathe.pdf

    ~John

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    Alumina Oxide Sample

    5 grades of Al2 O3. Nice stuff to work with. I prefer it to the silica.

    I remember seeing very high precision systems at the last IMTS show that looked just like this.

    Al2O3 has a Mohs hardness of 9.

    1. The resolution of the cast is very nice.

    2. From the side.

    3. Close-up 1 from the side.

    4. Close-up 2 from the side.

    5. The bottom showing bug holes.

    6. Better close-up. Shows density of material.

    ~John
    Attached Thumbnails Attached Thumbnails 2010-03-07_EG01.jpg   2010-03-07_EG02.jpg   2010-03-07_EG03.jpg   2010-03-07_EG04.jpg  

    2010-03-07_EG05.jpg   2010-03-07_EG06.jpg  

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    Alumina Oxide Sample #2

    This mineral is a joy to work with.

    1. Latest cast piece includes sharp edges.

    2. Close-up of the mixture. Still using 5 different sizes from mesh 30 to sub-micron. Changing the percentages as I go.

    3. Close-up of letters in the plastic bowl. The lines are .50mm wide. What appears to be a bug-hole is actually particles.

    4. Close-up from the side. This piece is untouched. No sanding or polishing. I hand-vibrated it.

    5. Bottom view.

    Dental vibration table is on order -- due in a few days.

    ~John
    Attached Thumbnails Attached Thumbnails 2010-03-10_EG01.jpg   2010-03-10_EG02.jpg   2010-03-10_EG03.jpg   2010-03-10_EG04.jpg  

    2010-03-10_EG05.jpg  

  7. #7
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    Wow those samples are really looking good. Have you tried taking a hammer to them yet?

    I like your approach, there is something to be said for intelligently iterating through a set of options. While the other thread has done a great job of determining what should be possible you are doing a great job of showing what is possible.

    kudos

    bob

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    Alumina Oxide Sample #2

    rowbare:

    They're still curing. It takes patience to not touch them too soon (fingerprints).

    I took some of the silica samples to my friend's granite shop and had the guys cut it. It scorches the same as quartz countertops -- very hard.

    Al Ox has a Mohs hardness of 9 and may be what the grinding wheels are made from. He has big diamond saws which might be needed. I'm going throw a belt sander on the top and then polish them at 3000 grit. I'm interested in how much air is still in there.

    Both pieces are already waterproof. It rolls right off and dries with simple dabbing from one sheet of paper towel.

    I don't think I'm going back to silica. This latest piece used 10% epoxy and probably could have been less.


    1. Recycled glass just for fun.

    2. Beer bottles I'm told.

    ~John
    Attached Thumbnails Attached Thumbnails 2010-03-11_EG01.jpg   2010-03-11_EG02.jpg  

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    Alumina Oxide Sample #1 -- Exposed

    Happy St. Patrick's Day !

    Got a chance to stop by my friend's granite place. I was interested in seeing what was below the surface of AlOx sample 1 (the hockey puck).

    First we hit the top with a belt sander. This stuff is hard. Harder than working with Mohs 7 granite that's for sure. It took time.

    Then we polished it using a water polisher at grit 800 / 1200 / 3000.

    Overall, the compaction is good. We know the surface resolution is okay. Lack of good vibration still yields microscopic bug holes. But it's close.

    1. Top view, sanded and polished. The white discoloration is actually where it needed to be sanded further. I stopped because the belt was beginning to burn and smell.

    2. Up close. You can see the bug holes. The aggregate seems evenly dispersed which is good. Note the sparkle. Part of the mix.

    This piece is 10% epoxy by weight. I tried another at 7-8% but it's too difficult to work with without vibration. I don't recommend it. I'm staying with 10%. Seems to work best.

    ~John
    Attached Thumbnails Attached Thumbnails 2010-03-17_EG01.jpg   2010-03-17_EG02.jpg  

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    Alox Sample #3

    This is the 7-8% piece I mentioned in the previous post.

    1. Top view. Dimensions: 380mm x 250mm 19mm (15" x 10" x 3/4")

    2. Top shot with ruler.

    3. Workability is affected by epoxy percentage. It's difficult to get the air out without vibro-compaction at 7-8%. The Zanite video shows the workers troweling the cast. But vibration is the key.

    Another point. I think the 93% aggregate / 7% resin number is related to polyester resin not epoxy resin. Epoxy resin/hardener seems very happy at 10%. At least with AlOx anyway.

    4. Close-up. Did I mention bug holes? The white blotches are thin layers of epoxy over more bug holes.

    5. From the side. Shouldn't be difficult to get the precision everybody talks about.

    The piece is heavy. Even at this thickness.
    Attached Thumbnails Attached Thumbnails 2010-03-18_EG01.jpg   2010-03-18_EG02.jpg   2010-03-18_EG03.jpg   2010-03-18_EG04.jpg  

    2010-03-18_EG05.jpg  

  11. #11
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    Questions and Suggestion

    Hi John,

    1 -- Am I correct that whenever you say 7-8%, you mean by volume?

    2 -- Could you post the details of the mixtures you are using? What sizes and how much of each size? What epoxy/hardener?

    3 -- It would be great if you could send some samples to ckelloug so that he could measure and tell us the physical properties? (I believe that Cameron has offered to do this?)

    Ken
    Kenneth Lerman
    55 Main Street
    Newtown, CT 06470

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    lerman:

    7-8% by total weight. I do everything by weight when the material is the same and only varies by grade.

    For example an 8% mixture would look like this:

    AlOx = 1000g (a mixture of 5 grades)

    Epoxy resin: 60g
    Epoxy hardener: 30g

    The epoxy calls for a 2:1 ratio.

    Total weight when mixed = 1090g

    1000/1090 = .917 (91.7% of total weight)
    90/1000 = .082 (8.2 % of total weight)

    Are you attempting any pieces?

    ~John

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    Could someone elaborate on "Al2 O3". Where can you buy it, how is it mixed, and so on? Thanks

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    More Specifics

    Epoxy:

    U.S. Composites.
    635 resin
    556 hardener.

    Material:
    I'm using 3 different mixes made of 5 different mesh sizes. #36, #70, #120(?), #180 and #400 minus.

    The finest grades (#180 and below) seem to work well at 10-12% (combined by weight). I'm still messing around with the percentages above that.

    ~John

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    Copy Postings

    Gentlemen,

    Is it allowed to copy the data in your postings and making a file that I can use as a primer for the epoxy-granite process?

    Rick Kernell

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    Practice With Larger Pieces, Casting Inserts

    Still having problems with air but that will work itself out with a vibration table of some kind.

    Used a heavy baking pan ($12.99): 310mm x 220mm x 25mm.

    1, 2: Inside the pan. Inserts are attached using double-backed adhesive pads.

    3, 4: Close-up showing a plastic flange mounted to a pad.

    5. Type of pads used.

    6. Used rice to determine approximate volume. Got this idea from Fu-tung Cheng. His youtube videos on casting concrete are very good and worth a look.

    7, 8: Actually takes 2 of these (8 cups) to fill the pan.

    9. 8 cups of material weighs 4100g. Epoxy is then 11% by weight.

    10. Worked well. I thought it would be difficult to de-mold this piece but it popped right out. The pan's anti-stick surface is better than mold release -- which I forgot to add.

    11, 12: Pealed back the adhesive pad. Not a clean hole (my fault) but proof of concept. Casting inserts is no problem.

    13. Close-up of an insert. Absolutely smooth to the touch. No transition at all between material and pad.

    14. Surface is nice and flat. The pan makes a good mold.

    15. Indentations of the letters are 1mm wide.

    ~John
    Attached Thumbnails Attached Thumbnails 2010-03-26_EG01.jpg   2010-03-26_EG02.jpg   2010-03-26_EG03.jpg   2010-03-26_EG04.jpg  

    2010-03-26_EG05.jpg   2010-03-26_EG06.jpg   2010-03-26_EG07.jpg   2010-03-26_EG08.jpg  

    2010-03-26_EG09.jpg   2010-03-26_EG10.jpg   2010-03-26_EG11.jpg   2010-03-26_EG13.jpg  

    2010-03-26_EG14.jpg   2010-03-26_EG15.jpg   2010-03-26_EG16.jpg  

  17. #17
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    Quote Originally Posted by mredican View Post
    Could someone elaborate on "Al2 O3". Where can you buy it, how is it mixed, and so on? Thanks
    An alternate name for aluminum oxide is corundum; it is used to make grinding wheels, sanding belts, etc. One bulk source could be a supplier of sandblasting media.


    Johnohara; Are you not using vacuum degassing?
    An open mind is a virtue...so long as all the common sense has not leaked out.

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    Geof:

    I don't own adequate vacuum equipment for industrial degassing. I've based much of this process on the fact that commercial casters seem to rely on vibration rather than degassing (i.e. the Zanite video). The Scott Bader video calls for degassing but the mix is more a slurry with a high epoxy percentage.

    Doing is learning and I'm getting better at working with the material. Have you tried to cast anything?

    mredican:

    Al2 O3 is Aluminum Oxide, aka Corundum. It's used as an abrasive and comes in a large variety of sizes (36 - 1500). It has a Mohs hardness of 9 but more important seems to work better with epoxy than does silica. More expensive tho'. You won't be buying 50lbs for $10.00 that's for sure.

    ~John

  19. #19
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    I am wanting to build a Gingery style lathe and use a mineral cast base. I want to cast right on top of the piece of colr rolled I will be using for the bed way. I'm think of using sheet metal for the sides of the mold and start by using epoxy to glue the sheetmetal to the way and have the way attachments already drilled amd mounted before the pour. now comes the problem. I'm thinking of using waxed foam to form the voids I want in the mineral casting. Would the epoxy eat through the wax and attack the foam. I am also thinking of casting the base with several pours about 1/2 to 3/4 inch thick. do you think doing several thin pours would make getting the air out easier.

    Thanks
    David H

  20. #20
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    With styrenated resins, like polyester or vinylester (standard "fiberglass resin") you have to be careful because the styrene will eat polystyrene foam. Epoxy will not so you should be fine. It would be easy to test a small piece to make sure though.

    Matt

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