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Thread: First Muller... (a winter project)

  1. #1
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    First Muller... (a long drawn out project)

    Although I was doing my best to be ignorant to the changing weather, it looks as though I'll have to face the soon to be end of my first casting season. The entirety of which didn't see a single successful casting. Which I'm OK with as I learnt a ton.

    The biggest lessons I learnt was that making moulds takes serious time but is still fun IMO. However hand mulling sand just plan sucks. So I decided that this winter's project will be a muller, (and maybe a fuel tank heater system for another thread). Absolutely nothing is set in stone with this build and I have ran the gambit both on here, YouTube, and google images gathering examples of what I could do, so now here comes the questions. All opinions welcome.

    I'm a low brow hobbiest and will not be building on the scale of scavenger so don't expect to be awed...lol. I'm thinking that I'd like this muller to have a comfortable capacity of say 100lbs of green sand. Power will be perferably 120v. I could bump that to 240v if the need be but i dont see why. If there are details beyond those that need to be said, just ask.

    -which type works more efficiently. A spinning wheel or a spinning table..?
    -what's the minimum diameter for a useful mulling wheel..?
    -I have the opportunity to choose between drivetrains so what's the most desirable..., chain, belt, or directly coupled.
    -will the bottom of a 50gal barrel be large enough for effectively mulling 100lbs of sand. I'm assuming there's some sort balance between sand depth and wheel diameter.

    I'm sure I'm forgetting to ask things I intended to, so forgive me if I add a bunch along the way.
    Last edited by J. Vibert; 07-08-2016 at 02:20 AM.

  2. #2
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    Remembered another one... What's a good range for wheel rpm...? The gearboxes I have access to are 100:1 so the business end will be ~17rpm.

  3. #3
    I built mine around a 4x6 bandsaw gearbox. 24 inch dia. Does 40 to50 lbs easily. There is a thread here and on hobby-machinist.
    Dave

    Beone

  4. #4
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    it looks as though I'll have to face the soon to be end of my first casting season.
    I'm not clear as to why winter ends casting. Most professional foundries I have seen were just sheet metal sheds open to the cold, and even to the wind.

    Richard
    When I die, Heaven can wait—I want to go to McMaster-Carr.

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    Quote Originally Posted by Rasper View Post
    I'm not clear as to why winter ends casting. Most professional foundries I have seen were just sheet metal sheds open to the cold, and even to the wind.

    Richard
    Probably because you live in mexico and I live in Canada...lol. Seriously though, I don't operate a professional foundry so I don't have the resources they would and I have no interest in freezing my ass off.

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    Quote Originally Posted by Beone View Post
    I built mine around a 4x6 bandsaw gearbox. 24 inch dia. Does 40 to50 lbs easily. There is a thread here and on hobby-machinist.
    Dave

    Beone
    May have seen it, not sure. Did you directly couple the gearbox or use belts/chains to transfer motion to the Muller..? Did you spin the drum or wheels..?.., and was it an aspect you considered? How big are the wheels and do you think there would be any benefit to going larger?

  7. #7
    Chain drive from the bandsaw gearbox output( iirc 200 rpm) to bring the shaft down to about 60 rpm. Spins a wheel made from 2 10 lb barbell weights from wallyworld. The weight seem enough, there are no springs. Then a couple plows. Still work to do there the plows are held to the rotating bar with clamps. I have been too busy using it to take time to fix it pretty.
    Dave
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    Quote Originally Posted by Beone View Post
    There is a thread here and on hobby-machinist.

    Beone
    Found it... ...and nope I hadn't seen that one. Thanks for mentioning it

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    As of this moment I think I'm leaning towards a spinning drum rather than an arm with mulling hardware attached. The drum spinning just seems safer to me, (apologies for the 's' word...lol). The two things holding me back from that approach are ease of emptying, as I have to think a trap door is as easy as it gets, and I have it in my head that a spinning arm would work more efficiently.

    Thoughts..?

  10. #10
    Senior Member Robert's Avatar
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    If you use or plan to use Petrobond don't waste the time building a spinning drum. I have one. (signature) It works OK for greensand but is still not as effective a a conventional spinning wheel. The spinning drum is easy to empty (like a wheel barrow.) It is easy to change drums to go from greensand to petrobond. It does not work well for petrobond. It works but takes a long time and the sand does not reach maximum strength.
    If I were doing it over again I would build a conventional muller. I would do it like the one above but place the drive in underneath. Shoot for 30 rpm or less.
    R
    Last edited by Robert; 10-31-2014 at 07:15 PM.
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