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Thread: Gearing up for sand casting

  1. #181
    Senior Member Tobho Mott's Avatar
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    I believe so, yes. Although the "real" alloys all seem to have a little iron in them too. From what I've read you should not go much more than 10% Aluminum or you can get a very brittle alloy.

    Good luck and let us know how it went if you try it!

    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.

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  2. #182
    Senior Member Tobho Mott's Avatar
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    Quote Originally Posted by Tobho Mott View Post
    ...Also I don't think I sharpened it right, I will probably work on it a little more...
    Well that was a mistake. Not to want it to be sharper, I still think that was needed. But I let it get too hot re-grinding the edge I think, after more hammering. One corner of the sharp edge even changed colours. First to a darker gold colour, then to a sort of purple. Oops! Dammit!

    It got much sharper, but I totally mangled it within only a minute or so of chopping on the tree I took down in the last video.

    Screenshot_20170911-121430.jpg

    Back to the bench to try and fix it I guess... Gonna do a bit more grinding (going much easier this time) and more hammering to see if I can bring it back with more work hardening, followed by sharpening with files/stones so it won't get too hot again. If that doesn't work and I can't figure out how I can try the heat treatment, I'll probably have to melt it down and try again.

    Been reading C. W. Ammen's 'Casting Brass' book a little more. He suggests the heat treatment of aluminum bronzes is only necessary if you leave the casting in the mold too long; you're supposed to shake it out while it's still red hot and brush off all the sand and let it cool that way. To me this hints that if you demold at the right time, it kind of heat treats itself. Could be I am reading too much into that. But if not, maybe that is why the axe stood up so well to my testing before I decided to redo the grinding? I did not shake it out that early but maybe I got lucky? Or else it was the work hardening, which I must have undone by overheating it with the grinder.

    Anyone have any thoughts or suggestions on fixing this? I am getting beyond my depth here with all this heat effects stuff, which is weirder than it usually would be since it is being applied to a copper alloy instead of steel, and few who have commented seem to have much personal experience with that. And I'm not sure how far to trust Ammen's info in the first place since some of it disagrees with some other things I have read...

    Jeff
    Last edited by Tobho Mott; 09-11-2017 at 05:26 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.

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

  3. #183
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    There are alloys which act like steel, and since yours softened with low temperature grinding I'll bet it will harden upon quenching. Try heating it to a good red (1,200F) and quench in water, then see if it is harder to a file.

  4. #184
    Senior Member Tobho Mott's Avatar
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    A bit of grinding to straighten the edge back.out followed by more cold hammering seems to have restored its hardness - I made it through the tree trunk in the previous pic easily and with no further damage. It's actually sharper than when I tested it in the video above now. Thanks to those who have commented for the advice. I should probably try something like what oldironfarmer suggests with a piece of the gating or something, so I will know what to expect if there is a next time...

    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

  5. #185
    Senior Member Tobho Mott's Avatar
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    Already 'spoiled' by the previous post, but here is more video showing the edge getting ruined, then re-tested after successful repairs were done. Work hardening in action!



    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

  6. #186
    Senior Member Tobho Mott's Avatar
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    Quote Originally Posted by Tobho Mott View Post
    I took another shot at casting those dogs with the key hook tails.

    Another attempt, another failure. I give up, the whole point was to get some molding practice and to try using followers, and now I have done that.
    .
    .
    .
    Well, jagboy promised to ceramic shell cast me one in bronze and make a video of the process! I'm holding you to that buddy. Just PM me a mailing address and the pattern will be heading your way.
    Turns out Jagboy is as good as his word; I received his amazing ceramic shell lost wax cast bronze dog-hooks and light switch cover plate in the mail a few days ago. The castings themselves look great, in fact even better than the original dogsthanks to his attention to detail working the wax, and the patina is beautiful. Check out the videos he made on his youtube channel, "worldtraveler", showing all the steps from how he made the shell molds to dewaxing to pouring etc. His grand finale part 4 of that series should be online soon too. But first, here is the unboxing video I promised him and a couple pictures for those who don't do video:



    IMG_20171006_213119550small.jpg

    IMG_20171006_213224180small.jpg

    If this is what he can do copying a cheap imported hardware store trinket like those dog-hooks, I can't wait to see how his bronze lantern is gonna turn out!

    Thanks again jagboy! I hope nobody will be able to read your return address on the box in the video, it just occurred to me I should have blocked it out somehow... Nah, it's probably fine, what could really happen anyway?

    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

  7. #187
    Senior Member chubbyjp77's Avatar
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    With work like that I would bet he'll get a pile of patterns in the mail if someone makes out the address. Very nice.

  8. #188
    Senior Member Tobho Mott's Avatar
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    Yup. "Patterns" galore, and he has earned it.

    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

  9. #189
    Moderator DavidF's Avatar
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    Ill be sending him a "Pattern" roflmao...
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  10. #190
    um hmmm... Keep it up and I'll send you one of these finished in BRONZE
    https://www.spencersonline.com/product/73122.uts

    The series is found here. https://www.youtube.com/channel/UCuY...hWwDIX7a4x9ZWg
    Order a pizza and grab a case of beer. This is a long series. I really tried to keep it short.
    I still have work to finish up on the mirror frames, then it's back onto the lanterns.
    WWW.TheHomeFoundry.org
    Visit me: WWW.HandcraftedLanterns.com
    "Sometimes by losing a battle you find a new way to win the war"
    -- Donald Trump --

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