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Thread: Old-Metal Casting Newby

  1. #1

    Question Old-Metal Casting Newby

    Hello Everyone, I just finished my kiln and did some aluminum casting, and have alot of questions.

    I have kiln questions but will post in the correct area later.

    Maybe I should start out with the green sand..
    This is what I used, found the recipe somewhere on the internet.

    100 lb Silica Sand (I purchased some from a well driller and is very fine)
    12 lb Bentonite (Gel Type)
    7 lb Water

    I broke this down into small proportion, but ratio is the same.


    I think it is a little to wet.

    Next comes a few of the castings.

    Please let me know what you think please.


    And then the aluminum.. Is this dross or is it that its not hot enough, as far as I can tell its about 1375-1400 f.
    But not 100% sure, thats why I have some kiln questions..
    I was a little short on the face plate pour, but was fine for me, thought I would of had plenty for the pour
    but alot stayed in the crucible


    Thanks and let me know what you think or if you need more pics.


  2. #2
    Senior Member
    Join Date
    Dec 2010
    Vienna, Austria
    Blog Entries
    Good start Cork. Welcome.

  3. #3
    the castings look pretty good for a first castings, your sand is really looks too wet, and the crucible, it just looks like a thin foil that was on the walls of the crucible. That is normal for aluminum, it tends to leave a foil in there, just pull it out after it's cooled down if it really bugs you, lol.

    Ive never heard of bentonite gel, where did you find that at? Also, you may want to add your location on here so that people can help you find local supplies and such that you wouldnt normally find, and also to find other nearby metal casters that can help you sort out issues too.

  4. #4
    How long did it take to melt that crucible of aluminum in your kiln?? Did you take any amp readings on what that thing is pulling? (or what's your resistance on those coils like?)
    Reason why I ask, I just resurrected a junk kiln from a local pottery shop. It has 4 coils running on 220vt, one is burned out and this thing still hits 1700 degrees with ease.
    My old turd can be seen here>>>>>>>.

    Build yourself a cheapo pyrometer and don't guess what the temp is. There is too many variable melting metal and the more you can remove, the better it will help you solve other problems.>>>>>>>>
    Visit me:
    "Sometimes by losing a battle you find a new way to win the war"
    -- Donald Trump --

  5. #5
    Thanks Mark, this is going to be a fun hobby.

  6. #6
    Hi cae2100, I updated my profile, I forgot, thanks for saying they look pretty good, I was embarrassed to post let the sand dry out a little over night and feels a lot better, holds a good clump but doesn't stick to the the hand.

    In the bottom of the crucible is about 2-3" that never came out, Its hard to see..Its really grainy and rough, even when the crucible is red hot it wont pour out.
    I wonder if its just a bunch of junk building up down there.
    I got the bentonite gel from a well driller close by, have known them for years, paid $10 for 40lb, also for the silica sand.
    I guess the gel is alittle bit more slippery as compared to the regular bentonite. He gave me a little of each and when I wet it it felt better/slicker. He said that would work better for me.

  7. #7
    Hi jagboy69, it took about 1.5 hrs. Its 120v, 15 amps, 2 coils, pulling 8.4 amps in parrellel, or about 16.3 amps for each coil.

    At 100% power its actually pulling 13 amps when checked with an amp meter.

    I re-did the coils to get more amps, from 19 to 16.3 but still not happy with it. Was 1500 watts now 1800 watts.

    It is PID controlled with a thermocoupler, I'm always tinkering with it trying to better it.

    Maybe someone in the kiln making department on this forum can give me a hand..

    I'll post over there in a day or two.

    BTW you sure like doing a little of everything with fire and heat..LOL, its neat to have some fun.

  8. #8
    It looks like your pliths put the bottom of the crucible just about the same height as the bottom heating coil. You might want to raise it up another 1/2" - 1" the bottom of the kiln may not be getting quite hot enough. but sometimes you'll have a crust of dross in the bottom if it's dirty material that your feeding it. Do your best to scrape it out while the crucible is still hot. In this case you can heat it back up and try and clean it out. With a non steel crucible if you'd leave that much in the bottom the next time it heated up there's a good chance that it would crack because the aluminum expands more / faster than the crucible does (think Ice in water pipes).

    Nice casting!!

  9. #9
    Corky, that's about all the amps your can probably pull on the typical 110vt circuit. Most are wired either 15 or 20amps. Your only real option if you want to stay on electricity is to make the jump to 220vt. Most likely you have 30amp service on your 220vt at home. Take a peek at your circuit breakers, they tell the story. Upgrading service is usually possible, but comes with a price tag... $$$$$

    Got natural gas where you are?
    Visit me:
    "Sometimes by losing a battle you find a new way to win the war"
    -- Donald Trump --

  10. #10
    jagboy69, I think your right according to some calculating, Its about the max I can go.

    CrazyBillyBob made me think about the height of crucible, I might adjust that next time I melt and see if there is a change.

    I do have 30 amp 220v service, I'll do some figuring on that.
    ---EDIT: Sorry, I have 100amp service in my shop.---

    I could have used propane as I use I to heat my shop, but like the clean and quite of electricity. No natural gas.

    My air compressor runs on 220v, 20 amp I think, and welder on 220v 30 amp.

    I think I could change the kiln over two 220 if I changed to a 50 amp SSR,

    Well, I better do some thinking on this.

    Thanks for all the help,
    Last edited by corky; 03-07-2017 at 04:18 PM. Reason: Mistake on Elec

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