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Thread: Gearing up for sand casting

  1. #211
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    Looks like you're ready to rock and roll with it.
    I haven't tried this yet but I will for my next glue up. I'm going to wax the base pattern to see if the numerals will release easier. I use a tiny drop of super glue on the top and bottom of the numbers and they pop off with a razor blade but the glue leaves a residue. I'm hoping to get a cleaner release.
    Bones

  2. #212
    Senior Member Tobho Mott's Avatar
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    Ok that's great to hear, I hadn't decided what type of glue to use yet. Thanks again!
    Last edited by Tobho Mott; 01-08-2018 at 03:26 PM.
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

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  3. #213
    Senior Member Tobho Mott's Avatar
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    Well, I got a mold rammed up last weekend when it got unusually warm out (~+10C), stuck it in my molding bench to stay fresh (frozen) for a week, then finally poured it this past Saturday...

    https://youtu.be/hPokV0F_dlA


    Video of the melt/pour/shakeout, for those who may want to see a little fire and molten metal:

    https://youtu.be/46SIwX2JQws


    The bump on the back of the plaque comes from the cope scraping against the window sash lock on the back of the flask when I was opening it to draw out the pattern, which has me thinking about repositioning those locks... I'll have to do a bit of grinding there, I guess. (edit - maybe more than 'a bit', as in, I already ground that off and I'm thinking it likely would have taken less time to just make up a new cope when I first gouged that sand out opening the mold...)

    20180120_232534-1040x780.jpg

    IMG_20180120_233152590_HDR-585x1040.jpg

    IMG_20180120_233129872_HDR-1040x585.jpg

    Not my best ever casting, but not bad for a week old mold... and I think I can save it. If i end up having to redo it, maybe it will get poured in bronze rather than aluminum.

    edit:
    The broken sand around the numbers happened when I was drawing out the pattern, not while the mold sat in cold storage for a week... So I think I need a better fitting and longer pin to rap against than a drywall screw for loosening the pattern when it's as wide and heavy as this one is compared to my others.

    Jeff
    Last edited by Tobho Mott; 01-24-2018 at 04:48 PM.
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

  4. #214
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    Looks good Jeff.
    That's a big chunk to grind off. Since you have handles on the sides, try using spring clamps to hold the flask together. You could get rid of the sash locks. I have about a dozen of them now, kept buying 4 every trip to Harbor Freight. https://www.princessauto.com/en/deta....pal-prod-com3
    I find it easier to cut the vents rather than molding them in, that's a lot of tamping around them and the arrows are quite thin walled and cut cleanly.
    What's the plan for finishing it, paint?
    Awaiting the next vid!
    Bones

  5. #215
    Senior Member Tobho Mott's Avatar
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    Thanks Bones,

    Yeah, paint and some sanding I guess. I have a fairly aggressive flap disc that I'm quite sure ill make sort work of that lump, I'm not too worried about it.

    So do you cut the vents from the inside of the mold out while it is open, or do you just have really good aim and cut them through from the top of the cope?

    Clamps might be easier than the window locks in the end, but I was thinking about moving the locks to the sides that have the pins, that way I can avoid gouging out the cope and still don't have to hunt for any missing clamps!

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

  6. #216
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    I lay the cope down on it's top and cut from the inside.
    Bones

  7. #217
    Senior Member Tobho Mott's Avatar
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    Makes sense. Heck, they may not even be needed, seeing as I got the blank pattern to cast up OK without them...

    Anyhow, thanks again for the suggestions!

    edit - as it happens, I got a gift certificate for Princess Auto for XMas this year, so maybe I'll pick up a couple of those clamps you linked next time I'm there. You can never have too many clamps!

    Jeff
    Last edited by Tobho Mott; 01-24-2018 at 04:52 PM.
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

  8. #218
    Senior Member evlwht-guy's Avatar
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    Quote Originally Posted by Tobho Mott View Post

    The bump on the back of the plaque comes from the cope scraping against the window sash lock on the back of the flask when I was opening it to draw out the pattern, which has me thinking about repositioning those locks... I'll have to do a bit of grinding there, I guess. (edit - maybe more than 'a bit', as in, I already ground that off and I'm thinking it likely would have taken less time to just make up a new cope when I first gouged that sand out opening the mold...)

    Jeff
    You are correct when you suggest that re-ramming the cope would have been quicker. One other suggestion.....I have watched many YouTube videos of pot casting in Africa. When those guys have an error like this they just spritz the area with a tiny bit of water and take some sand and repair it by rubbing sand in with fingers and usually a spoon. I was shocked to see this as I had never imagined actually touching the mold after ramming, but i tried it and it worked. Even if you reduce the lump a little it is worthwhile and if it doesn't work, you ca always re-ram.

  9. #219
    Senior Member Tobho Mott's Avatar
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    Lesson learned... Next time (if there is one) I'll try to repair the cope as you suggest, nothing to lose by trying... Other than a minute or so. If that doesn't work, I'll just remake it. A 60 grit flap disc worked ok to shave off that lump, but a new cope would have meant much less finish work and zero wear and tear on my brand new grinder disc...

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

  10. #220
    Senior Member Tobho Mott's Avatar
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    If you like watching some guy do a whole bunch of edge, spindle, and hand sanding in high speed, you'll love the final episode of my house number plaque casting video series!

    But if you're only into bandsawing and flap disc grinding and drilling, you'll probably only kind of like it.

    For the rest of you, dont feel left out - here's a YouTube thumbnail showing what the finished plaque looked like before I hit it with some sealer spray, which you probably won't want to click on.

    https://youtu.be/42GqsW2PAW8


    I also cheated a little and dabbed a tiny bit of silver paint into the little dings on the left side of the 6 and in the center of the lower border. They show up a lot less now.

    Jeff
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos | TheHomeFoundry Forums

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