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

  1. #411
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    If I may offer a mild criticism, some aspects of your build conform closer to the French definition of engineering ... "Why build simple if complicated also works" than Kalashnikov's axiom
    Mark
    Last edited by rotarysmp; 07-17-2017 at 07:12 AM.

  2. #412
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by rotarysmp View Post
    If I may offer a mild criticism, some aspects of your build conform closer to the French definition of engeering ... "Why build simple if complicated also works" than Kalashnikov's axiom
    Mark
    Lol, well now, "Simple" is really all a matter how good your eye-sight is and how closely you look.

    To a blind man 2-miles away, a corvette is a really fast horse, with an odd-smell and a terrible case of laryngitis...Simple!

    My only question is, is it Bluetooth compatible?
    Naa, none of that new-fangled crap, (though Bluetooth 4.2LE is cool).

    I've just got a pair of $5, 434 MHz, analog transceivers I bit-bang out Manchester code on. Good enough for a few 100-feet and it's so low-tech it keeps the NSA guessing. Only down-side is occasionally, some random house's garage door opens for "no reason"
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  3. #413
    Senior Member r4z0r7o3's Avatar
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    Yesterday I performed a shirt-in-lead-screw acciden....errr....load test

    The PTCs properly cut-out in time to save me and my shirt from certain-death. After more testing with heavier loads, I ended up soldered in like five more PTCs to raise the duty-cycle - it was way too short under load- Once up, half-way back down, now it's much more better, and there's still room to add more PTCs if needed.

    A little more welding is needed on the arms, and I need to spend time on the IFB retaining/leveling frame so I can mount up the actual furnace. Once I've got that, I can work on the lid pivot (finally), and then I can take it all apart for prep. and rattle-canning. I'm thinking neon-green Before I get ahead of myself though...pics...

    Yesterday I finished cross-drilling the gearbox shaft and pin-coupler (sliding-fit around the shaft). The little 3/32" half-hard brass stub, is the sheer-pin. That will go on the gearbox-side. The calculator showed it shearing around 192-in/lb torque (525-lb force w/ 0.375dia shaft-radius, 0.125 pipe-wall thickness). Dunno what that translates to in terms of lifting force w/ an 8 TPI 5/8" ACME screw. Though if it proves too small, I can ream the hole out for a larger size sheer-pin.


    Split the shaft in-between the pin-holes, so if either pin isn't locking the shaft, it just spins freely.


    The larger cross-pin and lock-pin (dunno their names) goes on the load-side of the shaft. If I need to drive the mechanism from the top, using a drill, I can just pull the cross-pin.








    Locked the acme jamb-nuts in position about 1/8" past where the upper limit-switch trips.


    Same for the bottom.


    Had a horrible vision of that pin spinning around @ 800 rpm on the shaft, and snagging one of the motor's wires. So I pulled the power-supply (protected under lower sheet metal) and fabbed up a quick shaft/wire guard (sheet metal sticking out). When the enclosure's door is closed (open in pic), it will protect the tangle-o-wires. Just need to weld it in place.


    Finally, laid out the IFBs, made some rough drawings/measurements, and rough-cut the angle iron. The hole in the center will be filled in by a 1/8" plate, with the IFB's resting on top (not like in pic). The whole thing will be mounted with 9-leveling screws to the bottom-plate of the platform. Bricks go in the pan, furnace sits on top. I'm planning to carve a channel down the center that will mate up with the drain-hole of the furnace. Some kind of plug will keep the flames from shooting out, maybe an aluminum-foil ball, dunno yet.


    Hopefully I can finish up the pan and welding today, but we'll see, the Family needs some care and feeding too.
    Last edited by r4z0r7o3; 07-16-2017 at 03:14 PM.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  4. #414
    Senior Member r4z0r7o3's Avatar
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    Updated last post w/ new pics.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  5. #415
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    Why 9 leveling screws...? Seems excessive... Why not just use 3...? 4 if you want to really up the game and fight a little with having it load evenly on all four corners and sit level.
    FLAME ON...!!!!

  6. #416
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by J. Vibert View Post
    Why 9 leveling screws...? Seems excessive... Why not just use 3...? 4 if you want to really up the game and fight a little with having it load evenly on all four corners and sit level.
    Good question. I'm not settled on it, and no holes have been made yet.

    I thought about using three, but I like the idea of each screw carrying less weight. Also, because the tray is a square, three-point support means there are two corners which can destabilize it. Then the other reason is laziness..I have a bunch of 1/4-20 bolts/nuts already.

    I can still use three to get it level, lock those down, then turn the remaining screws up to make contact.

    So maybe I only need six (two sets of 3) plus one in the center?

    The other suggestion was to use shims, which is still an option, and relatively simple besides having to make the shims themselves.

    Another idea that just occurred to me is I could cut the hump out with a hole slightly smaller than the pan, then weld the pan down over it.

    Lastly, the hump was caused by excessive heat around the periphery (O/A welding) of the 3/16" bottom plate, causing it to shrink. So I could heat-shrink the center of the hump, and maybe it would flatten out. It's a little scary though, since I hate to screw it up. Maybe it's worth trying, since I can always fall back on one of the options above.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  7. #417
    Quote Originally Posted by r4z0r7o3 View Post

    Lastly, the hump was caused by excessive heat around the periphery (O/A welding) of the 3/16" bottom plate, causing it to shrink. So I could heat-shrink the center of the hump, and maybe it would flatten out. It's a little scary though, since I hate to screw it up. Maybe it's worth trying, since I can always fall back on one of the options above.
    It an't broke till ya fix it

    Heat shrinking it maybe the fastest / easiest thing to try. and you have several viable fallback plans if it doesn't work. Really you could go with the heat it an beat approach too before getting too complicated. You're just looking for close not 0.00000001" or anything.

    CBB

    Glad you came out of the load testing with your shirt still on!

  8. #418
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    Quote Originally Posted by r4z0r7o3 View Post
    Then the other reason is laziness..I have a bunch of 1/4-20 bolts/nuts already.
    Ah... Your whole approach throughout this build is coming together for me now. You think you're being lazy by drilling/tapping 6-7 more holes for bolts than you need just because you have the bolts on hand....lol
    FLAME ON...!!!!

  9. #419
    Senior Member r4z0r7o3's Avatar
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    Hehehe, okay, I should qualify that...Lazy as in, it's faster than driving to the store, coming home with 10 new tools I didn't need, and having to explain it all to the wife

    I think I've settled on heat-and-beat first, then if I screw it up horribly, I'll screw/tap it horribly
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  10. #420
    Senior Member r4z0r7o3's Avatar
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    Got the IFB pan's outside bits (angle-iron) welded up (angle-iron) today. Now I'm working on clearing a salvage project from my table-saw so I can cut the bottom-plate for the pan - recovering some shafts, sensors, and motors from an old photo-printer.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

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