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

  1. #281
    Senior Member r4z0r7o3's Avatar
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    Limit switches, thermal-fuse, and drive-train

    (Sorry for crappy first few pics, my good camera-phone's battery was dead)

    Big splat of dykem with profile outlines used to locate a paper template and and punch hole-locations onto the platform.


    Three motor/shaft alignment holes drilled and tapped for 1/4-20 bolts.


    Lenox bi-metal hole-saw deployed for big shaft hole (har har har). This is needed because the shaft pokes all the way through the gearbox. I need access to the lower-end of the shaft, and the ability to slide it up/down to mate the lovejoy halfs together (later, below). Also, there's enough of the shaft poking through that I could maybe use it to drive some accessory later (w/ lifting mechanism disengaged).


    Here you can see the alignment bolts, two are installed (poking up). That big bolt will be used to clamp the motor-mount down onto the platform...


    ...like this.


    Yay! It's completely finished! Oh wait...there's more.


    Upper limit switch tacked in place, along with it's actuation rod on the lifting carriage. The switch has a spring-loaded button, but if something goes wrong, it's able to be forced upwards past a hard-stop. At that point a shear-pin will break or a fuse will blow. I haven't added the hard-stop yet.


    Lower limit switch mounted on the lower frame. The lower lifting frame acts as the hard-stop, contacting the carriage on the front-side if it tries to go too low.


    Mounted a small 105*c thermal-fuse I scavenged from a microwave. This protects the gearbox and motor (to an extend) from getting overheated, and auto-resets once they cool down. Still debating whether or not I need/want this. It's easy to take off if not, but would have been a bear to mount later.


    My good camera charged up now, my friend Thom and I to finished cutting the lead-screw keyway this weekend. Here's all the drive-train parts ready for assembly.


    The top-frame carries the load through a thrust pin-bearing (600lb rated), and a flange-mount roller-bearing under the frame locates the shaft.


    The screw passed through the lifting carriage, through a brass DIY sleeve-bearing. The acme-bolt on the underside will get welded (or otherwise connected) to the frame later.


    Lower-frame flange-mount roller-bearing, used to locate the bottom of the screw.


    Underside of the lower-frame, here the top-half of the lovejoy gets mounted to the lead-screw.


    Before mounting the other lovejoy half (and spider), the shaft is installed into the gearbox because...


    ...the alignment is quite bad.


    Cranking this adjusting screw (under the platform) jacks up the tail end of the motor and...


    ...the shaft aligns (close enough). The other lovejoy is mounted, and the buna-n spider goes between. The coupler's tolerance is 1.5* (out-of-parallel), so I don't even need to bother with measuring.


    A few taps from a rubber-topped "persuasion-device", on the bottom of the shaft, mates up the lovejoy coupler, and the set-screw is tightened. I'm going to need to add a collar of some sort, above the gearbox to prevent the shaft from working it's way downward. It's a tight, sliding fit, but certainly not rigid by any stretch.


    There are still a lot of tacked parts in the lifting-assembly that I need to finish weld, but the drivetrain is together enough for some light (~20-lb) load testing. Yay! Now I need to get back to the electronics / wiring so I can make 'er chooch, to find any binding/rubbing problems.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  2. #282
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    Nice to see it coming together...

    Lose the thermal overload on the gear box. Totally unnecessary... You'd have to continually run the motor back and forth for an hour+ just even hope to reach that temp.
    FLAME ON...!!!!

  3. #283
    That's the Z axis for a really big 3D printer If you have binding issues try to loosen up the top flange bearing mounting bolts....Letting that top wobble to make up for any little bend in the lead screw.

    Your getting close now!

    CBB

  4. #284
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by J. Vibert View Post
    Lose the thermal overload on the gear box. Totally unnecessary... You'd have to continually run the motor back and forth for an hour+ just even hope to reach that temp.
    The gearbox does heat up a bit, but it's rated for continuous duty, so...ya, you're right, it's gone.

    Quote Originally Posted by CrazyBillyBob View Post
    That's the Z axis for a really big 3D printer If you have binding issues try to loosen up the top flange bearing mounting bolts....Letting that top wobble to make up for any little bend in the lead screw.
    Hmmm, there is one spot, near the top where it's either bent or some threads got mashed clamping it up for milling. I'll try your idea and see if it helps at all. I certainly can't spot any wonky threads.

    Now...I do need to test out some ideas for covering up the thread. At least something cheaper than the several-hundred-$$$ protectors on McMaster-Carr :S Hmmm, maybe this is the excuse I need to buy a slip-roll
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  5. #285
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    Quote Originally Posted by r4z0r7o3 View Post
    Now...I do need to test out some ideas for covering up the thread. At least something cheaper than the several-hundred-$$$ protectors on McMaster-Carr :S Hmmm, maybe this is the excuse I need to buy a slip-roll
    Nah... it's the excuse you need to buy a big assed lathe so you can turn the rollers for a diy slip roll. You need to start thinking "big picture"...lol

    You could probably fab something out of thin sheet metal formed around a pipe. You can buy long strips of flashing from big box reno stores.
    FLAME ON...!!!!

  6. #286
    Just split the side out of some 1 1/2" emt. Cheap and quick. (assuming you have a plasma cutter, torch, or something other than a hack saw.

  7. #287
    Senior Member r4z0r7o3's Avatar
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    Hmmm, why would I split the side? I have access to both screw ends, though the top is easier. I was thinking sheet-metal too, though not sure about flashing. That stuff's so light-weight I'd be afraid it would jam up too easy. EMT is cheap-ish, I may play with that and see, if not, sheet metal it is.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  8. #288
    Senior Member r4z0r7o3's Avatar
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    Still conflicted about where/how to mount the PSU and control box. Trying to pick a location that's convenient from the front-side of the cart, yet out of the way WRT molten metal dealings. Briefly considered hanging it from an overhead arm. Then thought of the headaches that might cause (literally). I think the best place might be on the right, since the blower/burner is there anyway. That makes the entire front and left-side of the platform clear, and the lid swings to the left anyway.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  9. #289
    Senior Member caster's Avatar
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    You should give some thought on how you will use the furnace so you can choose the optimal placing of your controls. The way I think of my furnace is in 4 quadrants; front, back, right and left as you look head on. I have the burner, blower, fuel and associated controls and lines on the left. To open the lid, charge, remove dross, measure the temperature and degas the front. To lift/open the furnace the back (I have a come-along as my lifting mechanism and need room to use the leaver). To access the crucible and pour right. The molds are 4-5 feet in front of the furnace, you want a clear short and uncluttered path from the furnace to the molds. Each quadrant has a function and the tools/controls for that function are near and in a predictable location.

    Caster

  10. #290
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    What caster said...

    I've seen a few builds wherein the white hot lid rotates over the fuel lines to the burner. Just an example...
    FLAME ON...!!!!

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