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Thread: r4z0r7o3's Crucible-furnace lifting mechanism / transport-stand.

  1. #11
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    I'd use a ball screw and direct drive motor. Most likely because I have them at hand...lol. Put a crank on the non drive end and that resolves any power loss / act of God failure.

  2. #12
    Quote Originally Posted by r4z0r7o3 View Post
    Actually I was originally thinking of a block/pulley arrangement.
    That's the approach I took. Below is a link to an early build Video testing my home foundry furnace lift. It's a mobile base and the lift has a counterbalance connected with a block/cable system such that half the furnace weight is used as balancing ballast. It's designed to lift upto about 400lbs. I should only be between 100-250lb depending upon the version of the furnace attached to it, which there are several. In the event of actuator failure or no source of electricity/battery, the furnace body can be lifted manually with one finger after pulling a hitch pinand disengaging the actuator.

    Though I'm pretty far along with the build now I'm not quite melting metal with it yet. If anyone is interested I can start a build log. I was going to complete it and do a reverse build log of sorts. I have lot's of pics but it is more metal fab than refractory content at this point.

    Also, I think you could include your lift in your furnace build thread. Or is that the intent and your just thrashing ideas here?

    Best Regards,
    Kelly


    https://www.youtube.com/watch?v=PVDX...ature=youtu.be

  3. #13
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    Quote Originally Posted by kcoffield View Post
    Also, I think you could include your lift in your furnace build thread. Or is that the intent and your just thrashing ideas here?
    If you're collecting votes then add a plus 1 to the above. While I understand the separate thread, I personally like to see all the information regarding a build within the build thread. Makes for easier, more linear reading. Even if you're just in the consideration stages of the lifting mech. Build threads that spawn alternate thinking, even if they aren't fully realized, make for interesting reading. At least I think so....

    That is totally badassed... Generally I don't understand the need for complication when it comes to this hobby. However that lifting mech will have me subscribed to your thread (which is something I never do by the way). Looking forward to it..

  4. #14
    Senior Member r4z0r7o3's Avatar
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    (Not to scale / proportion)


    ...I can offset the lifting point below the body of the furnace, and use a windlass mechanism to hoist by the lower point. Moving part cont: ---> 2 <--- That's even simpler than Gingery himself designed it. Thanks for the idea Moya (and mrpete222 and Wang Zhen).

    (r and r' are the radii of the drums)


    Some relatively-simple math describes the movement of R (the pulley): (r - r') with the lever-arm K providing additional mechanical advantage. I like the idea of (someday) adding a motor (in addition to the crank), so I need to size the drums appropriately for a small motor.

    I'll put a weight-budget of 100lb on the lid + body + lifting carriage, so roughly double that for a dynamic load, that makes Q: 200lb. The cables, S and S' will need to support 100lb each (dynamic), so that means I can safely use 1/16in Stainless Steel cable. SS seems the right choice for reliability and heat resistance. It's not going to be right ontop of the flame, but needs to withstand the radiation from the open furnace & crucible at maybe a 1 - 2 ft distance. I could go with 1/8in cable, however that implies larger radii for the pulley and drums. Applying the 10x minimum bending radius (average of 8 and 12) for stranded cable, I can safely run that cable around a minimum of a 1-1/4 in diameter w/o it getting all kinked or bent up.

    As for the drums, wood and PVC are out (as materials), and the axle will need to support significant weight anyway. So I'm thinking of using black-pipe "drums" with circles of steel-plate silver-soldered (b/c pipe is cast) to the ends so it can turn on a smaller diameter axle. Since only the difference in diameter determines the rotation:length ratio (windlass formula above), I can use a reducer to couple the two pipes together. Next up, research large dia. black-pipe/reducer availability (IIRC Lowes carries it by mail-order - that's what I used for my burner).

    - - - Updated - - -

    Quote Originally Posted by J. Vibert View Post
    I'd use a ball screw and direct drive motor. Most likely because I have them at hand...lol.
    I'll gladly go that route if you employ UPS to place them into my hands
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  5. #15
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by J. Vibert View Post
    While I understand the separate thread, I personally like to see all the information regarding a build within the build thread. Makes for easier, more linear reading.
    Yeah, it'll probably keep the mechanical/frame build here because it's closer to the forum-topic, and I won't be loading up a single thread with that many more pics Also, I did a similar thing for both the burner and my refractory vibrators. Plus, when you're searching for ideas, how many times is your research linear?

    Quote Originally Posted by J. Vibert View Post
    https://www.youtube.com/watch?v=PVDXXYf-nf4&feature=youtu.be That is totally badassed...
    Lolz, I hadn't even seen that before I started the thread, but common now, I've already dropped the linear-actuator idea (I think that's even the same brand I was looking at). Look how tall the frickin' thing is though, that's why I was going to (greatly) shorten mine by using a lever/scissor mechinism.

    Anyway, y'all have pointed some, and what I see as the two major flaws in that and my idea #2:

    • You're screwed if the mechanism breaks, manual control is impossible/very hard - "The Fast Way" down is not kind to refractory cement, esp. when glowing hot.
    • Also, there's no "slop at the stop" meaning the furnace body is always tightly-coupled to the mechanism, adding stress/strain to it with every movement, reducing it's life/reliability.


    OTOH, Gingery would most certainly approve of using a Windlass. It can be powered later as an add-on, and I think you'd be hard-pressed to find a simpler mechanism. In fact the drum doesn't even need to be a cylinder, it could be conical*...hmmm...I could do that in sheet-metal, and then back-fill it around it's axle with epoxy + carbon-fiber (plenty of all, on hand).




    *Note: With a conical drum- As long as the cable unwinds in the opposite direction/spool-side as it winds (as in the wikipedia photo above), the difference between diameters will remain constant. Thus there will be no change in leverage across the entire hoisting range.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  6. #16
    I kind of like the idea of a big frame above the furnace. Mine is real light and I push it around on a rolling clothes rack. The bar up top makes a good place to hang crucible tongs and what not. And would make a great place to put a windlass.

  7. #17
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    Quote Originally Posted by r4z0r7o3 View Post
    Plus, when you're searching for ideas, how many times is your research linear?
    What I meant was, when I read a build thread it makes sense for it to progress in a linear fashion. Having to jump around the forum to read multiple segments of the same build is tiresome. Your build, and most certainly not my place to tell you how to document it.

    I will say that I back in the day and most likely anyone new to the forum now, wouldn't search in the "machines and manual machining forum" for tips on building a furnace. There's a much more glaringly obviously place for such a topic....lol

  8. #18
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    Quote Originally Posted by FrostOakFoundry View Post
    I kind of like the idea of a big frame above the furnace. Mine is real light and I push it around on a rolling clothes rack. The bar up top makes a good place to hang crucible tongs and what not. And would make a great place to put a windlass.
    Agreed... If you going to hoist a large heavy ridiculously hot piece of whatever into the air, a nice strudy frame is the way to go. Last thing you need is some wishy washy mech swinging around while you should be paying attention to something else.

    I'm struggling with this windlass thing as the best course of action as well. Isn't like every oem car jack on the planet based around a rotating screw expanding a scissor mech...? You don't see those scissor jacks dropping cars. If by some oddity the electric drive train fails then put a hand crank on it.., done. What happens to the windlass design if one if the cable(?) breaks..?..., or the pulley seizes..?..., or the coil of cable binds on the spindles...? Lots of what ifs...

  9. #19
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    Quote Originally Posted by J. Vibert View Post
    large heavy ridiculously hot piece of whatever into the air, a nice strudy frame is the way to go
    Yep, though nice and sturdy does not imply tall, in fact tall requires more support than short, but actually I need to limit the height for storage reasons.

    Quote Originally Posted by J. Vibert View Post
    I'm struggling with this windlass thing as the best course of action...Lots of what ifs...
    Any design is full of "ifs". I researched electric/manual scissor jacks already. The new ones come from China and are crap. The old ones came from China and are crap. They're intended for emergency, road-side service, not light-duty. Lastly, they're not as simple as a windlass: more moving/siding parts == more to go wrong.

    Though you're right about the cable being the most critical, I should probably step up to 1/8in just to be extra safe. IMHO, as long as it's stainless, and wrapped around appropriate diameter parts, there's little chance for binding. If the pulley seizes, the cable will still slide around it just fine. Perhaps as a backup lifting system, I could make provisions for sticking a high-lift hydrolic jack under the lifting carriage.

    Anyway, no point in arguing, and I'm not brushing off your concerns. I'll certainly consider all these opinions carefully, including moving this back to my furnace thread.

    Thanks everyone, for the ideas so far!
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  10. #20
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    Here is how I did it, maybe it will help. A $20 HF come along and a sliding cartridge using skate bearings.
    Don't know why the pictures are flipped, tried to get them right but failed.

    Caster


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