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

  1. #221
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by Peedee View Post
    Sometimes the longest way round is the quickest way home..............
    Very true, thanks for sharing that. I've decided to grind it all off and start again with lessons-learned: Bolt it all up with a nice fit, THEN weld (since I already drilled the holes). I also realized I don't even need to use square tubing, regular bar-stock will work fine- The rear braces/supports will be under tension, not so much compression, and there's no worries about anything twisting.

    The other part I'm pondering now is the bit that connects the two arms together. It will also need to adjust length-wise in 1/8th in. increments. However, it's also the part my acme-screw will by pulling on, so it's gotta be skookum-as-frig. What I'm thinking is:

    Weld together two lengths of angle-iron to make a C-channel. Cut that in half, for welding to each arm (adding bracing later). Span the gap in between them, with a custom-fit C-channel (built-up) that will nest upside-down between the first two (making a box). Then have a hole-array on each end of the box to allow for incremental adjustment.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  2. #222
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    I dont have the AvE dictionary handy... What does 'skookum" mean again...? Good or bad..?
    FLAME ON...!!!!

  3. #223
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by J. Vibert View Post
    I dont have the AvE dictionary handy... What does 'skookum" mean again...? Good or bad..?
    Lol...to the wikipedia!
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  4. #224
    Senior Member r4z0r7o3's Avatar
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    Drive mechanism notes

    http://www.daycounter.com/Calculator...lculator.phtml

    Capacity needed: 200-lb.
    ACME Rods: 5/8" x 8tpi
    Coeff. of friction (steel on steel): 0.17
    --------------------------------------------
    Raising Torque needed: 5.65 lb-in (0.6383 N-m)


    Speed: 15in per 15 seconds
    = 1 in / sec
    ACME Rods: 5/8" x 8tpi
    Rotations: 8 per second
    --------------------------------------------
    Raising speed needed: 480 RPM


    http://www.magtrol.com/support/motorpower_calc.html
    Torque: 5.65 lb-in (0.6383 N-m)
    Speed: 500 RPM
    --------------------------------------------
    Output Power: 33.42 watts



    http://www.engineeringtoolbox.com/el...ncy-d_655.html
    NEMA D (equipment with very high inertia starts)
    Minimum Efficiency: 91.7%
    --------------------------------------------
    Electrical Input power needed: 36.19386 watts



    http://www.rapidtables.com/calc/elec...culator.htm#dc
    Volts: 90 v DC
    Power: 36.19386 watts
    --------------------------------------------
    Current: 0.4 amps @ 223 ohms



    Gearmotor options:
    http://www.leeson.com/Literature/pdf/b1600IEC.pdf
    http://www.bodine-electric.com/Asp/P...093&Sort=11235
    500 RPM, 0.7 Nm torque, 1/17 HP, 90v @ 0.7 amps (full load)
    --------------------------------------------
    Leeson: #M1115022
    Bodine: #93
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  5. #225
    Senior Member r4z0r7o3's Avatar
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    Done and settled.

    After too much time spent searching, I settled on this from ebay:

    BALDOR GE, 1/4 HP ( 4k RPM, 4 amps, 60 volts DC) coupled to a Motovario NMRV/030 (5:1 ratio).


    I remembered that when it comes to moving heavy things, slower is almost always better. This used one was also priced about 5x cheaper than a new leeson/bodine gearmotor as spec. above. It should max out around 250 RPM (full-load) at well over the torque I need (shear-pin and shaft coupler for safety). It's got a 9/16th in (14mm) through-bore, and I checked the datasheet to make sure it can be mounted / used how I intend..

    My thinking is to mount this on my platform, and drive the top-supported ACME-rod from below. The sheer-pin will also serve as a disconnect in case I need to drive the mechanism with a drill + socket from above (in an emergency). As for power, 60V DC is simple to derive from our (wimpy) 110v outlets using just a 2:1 transformer and full-wave rectifier. Another option could be to skip the transformer and just use a half-wave rectifier and smoothing cap. Up/Down will be selected by a dual-throw switch on the outputs of top/bottom limit switches.

    Though I'm happy to take comments / input on the setup or mounting/connecting or electronical angry-pixie wrangling
    Last edited by r4z0r7o3; 12-28-2016 at 05:18 PM.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  6. #226
    Senior Member r4z0r7o3's Avatar
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    Things are taking shape!

    Made a wooden furnace stand-in with some right-angle pieces. Also made some 1/16-in steel spacers (clearance between arms and rail faces), and hammered them in. Clamped up the carriages to the rails, and the furnace stand-in to the arms. Everything is at a measured height above the platform surface, and the rails are held parallel by the wooden spacers. You can also see I've ground-off the goofed braces, and bolted on some new angle-iron (rail bottoms). I'll weld braces on to these later.


    The pitch between threads on my 5/8-in ACME lead screw is very close to the 1/8-in wall thickness of my tubing. After some test holes and rummaging in my (growing) scrap collection I found some copper sheet of the perfect thickness to make a bushing. I cut a pair of trapezoids, and here I'm forming one of them around a solid 5/8-in bar.


    It's a perfect fit into the 11/16-in hole I happened to have a bit for. The trapezoidal shape was cut deliberately short, so the inside ends don't quite meet when it's coiled up. The spiral gap will help serve as a place to catch any grit that gets in, and hold a bit of oil.


    Some silver-solder, a bit of grinding, and my DIY bushing is secure enough.




    Same treatment done on a 1-in square bit that will (eventually) be joined to the lifting arms by a telescoping assembly from a dream confabulation (more below).


    Pin-roller (thrust) bearings and washers let the top end spin freely. Still debating if I should try and drill through the nut and screw to secure with a roll-pin...or if I just drill/tap the nut for a pair (or six) set-screws. Opinions welcome.


    These inner-tubes slide inside the 1-in tubes with about a 0.060-in gap. To take up that space and keep things sliding nicely, I TIG-brazed on some blobs of silicon-bronze.


    Sanded the blobs down until they were about equal on both sides, and w/in about 5-thou. of the 1-in pipe's ID.


    Here's the telescoping connecting tube fit up for tack-welds. There's about 1/8-in of play across the span, which I took up temporarily with some bent 1/16-in filler rod. The ACME nut on the bottom of the center piece will be welded on (eventually). For now it's just holding the vertical position.


    Once I tack this up it's going to be a royal pain to get it off again (remember there's that smaller square tube nested inside). So my plan is to take advantage of the setup to also add on the four arm braces (two horizontal, two vertical).

    I also spent some time looking at these spring-steel coils you can buy to help protect lathe carriage screws. Unfortunately the size for this rod only expands to 10-in long, but my travel is 15-in. The coils that are long-enough are also really spendy, I'd have to pay over $200 for a pair! Instead, I did some poking around and found some 304 SS tubing sizes that can be made to nest/telescope. It's still expensive, but about 4x cheaper than the purpose-built coils.

    Feedback/questions/comments always welcome.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  7. #227
    Senior Member Tobho Mott's Avatar
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    Go Toe! I'm still watching, just don't have much to add. Some of it is a little over my head, but still fun and interesting to watch. And my AvEse is getting a little more fluent.

    Looking forward to seeing you get this completed so we can see it shooting out some flames and melting stuff!

    The furnace, I mean. Not the lifting mechanism itself...


    Jeff
    Last edited by Tobho Mott; 12-30-2016 at 05:19 PM.
    Tobho had learned to work Valyrian steel at the forges of Qohor as a boy. Only a man who knew the spells could take old weapons and forge them anew.

    How I built my oil furnace | My Photo Album | My Videos

  8. #228
    It’s coming along RZR. I originally thought you were planning to use a cordless drill to power the lead screw. Since you have the motor/gear reducer, will that be mounted low near the base under the lead screw? If so it’s probably the best place as far as heat goes but I presume you are still planning some additional heat shielding too?

    Not sure what you are planning for actuator controls. In use, I can tell you it’s nice to be able to just push a latching switch and have it travel to limit and stop in both directions so you don’t have to tend to the switch while managing the molten metal. This means incorporating limit switches and relays. I originally had a foot switch planned for this but then decided it would just be something to trip over. Also considered a pendant. When I priced out the discrete components to handle the reversing and switching at limit, I discovered the cheapy wireless reversing remotes on eBay did the entire job at a fraction of the price and simplified the wiring considerably, and you got the wireless control for free, which is about what I was willing to pay for it. It also has a fixed rocker switch provision for redundancy. They were $15 from the People’s Pepublic of China so I bought a couple of them.

    You may also want to give a little thought to how you would handle an actuator/lift failure mid melt. I know I’m not one to talk, and though the whiz-bang stuff is neat, the added complexity means higher likelihood of failure, especially in a foundry environment. In my case, my furnace lifting mechanism is counterbalanced, so lifting the furnace by hand can be done with little to no effort. The actuator was an addition that wasn’t in the original plan. However, in case of actuator or circuit failure, I can quickly disengage the actuator by pulling a hitch pin and manually actuate the lift.

    In my case, I don’t really have enough sidewall furnace clearance for tongs on the largest crucibles, and since it was lift off furnace, I grip the crucible directly from the side with either a freehand shank or one on a cart…….but the furnace must be lifted to do so. If you are going to access your crucible from the top with tongs, you’re probably covered in this respect.

    Best,
    Kelly
    Last edited by kcoffield; 12-30-2016 at 01:54 PM.

  9. #229
    Senior Member r4z0r7o3's Avatar
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    Thanks for taking a squiz and checking in guys! Was starting to wonder if anybody was left

    Yes Jeff, I'm eager to get at the melting part as well. I'm using it to keep my OCD in check - sorta-round holes, mostly straight, somewhat-square, and kinda lines up. All being spread around as much as I'm able to w/o getting an eye-lid twitch

    Some excellent questions and feedback Kelly. I wrote thoughts on some of these topics but they're all scattered about. So, to get it all in one place...

    Quote Originally Posted by kcoffield View Post
    It’s coming along RZR. I originally thought you were planning to use a cordless drill to power the lead screw. Since you have the motor/gear reducer, will that be mounted low near the base under the lead screw? If so it’s probably the best place as far as heat goes but I presume you are still planning some additional heat shielding too?
    Yes and no. The old, gnarly, schmoo-filled, "DeWilt", cordless (broken and dead batteries) drill's soundness (grinding noise) remembered me what AvE reveled: Powdered, sintered-metal gears. Sooo...yeah...no, not gunna do it...dunna-wanna end up in that place.

    Quote Originally Posted by kcoffield View Post
    Not sure what you are planning for actuator controls. In use, I can tell you it’s nice to be able to just push a latching switch and have it travel to limit and stop in both directions so you don’t have to tend to the switch while managing the molten metal.
    My plan for the angry pixies is extraordinarily simple (unless someone has a simpler idea):

    Power Supply:
    Code:
    110v -> master switch -> 1.8:1 transformer ->
    full-wave bridge rectifier -> 0.1f, 50v, 105c caps (four in parallel) ->
    10a fuse -> ... (60-ish DC volts, 4amp full-load)
    Controls:
    Code:
           DPDT NC microswitch (top)
          /                          \
    ... -<                            >- 4PDT Toggle (up, stop, down) -> Motor
          \                          /
           DPDT NC microswitch (bot.)

    (note: each "line" represents 2 wires, except four to/from 4PDT toggle)

    (ref.: Switch Basics)

    Quote Originally Posted by kcoffield View Post
    You may also want to give a little thought to how you would handle an actuator/lift failure mid melt. I know I’m not one to talk, and though the whiz-bang stuff is neat, the added complexity means higher likelihood of failure, especially in a foundry environment. In my case, my furnace lifting mechanism is counterbalanced, so lifting the furnace by hand can be done with little to no effort. The actuator was an addition that wasn’t in the original plan. However, in case of actuator or circuit failure, I can quickly disengage the actuator by pulling a hitch pin and manually actuate the lift.
    I agree, check out my quote

    I was surprised to receive that Baldor motor + Italian gearbox in the mail yesterday. Fastest thing I ever got from Ebay, two days! It's a chunky, solid, continuous-duty beast. So much, it immediately made me re-think the piddly little motor mount I had in mind. Yes, the Baldor will go at the bottom, inside an enclosure, and protected by a heat shield.

    The 1-in nut. at the top of the frame will be used for emergency lifting. I'll have a 1-in socket chucked up in a working, more skookum cordless driver, at the ready. My calculations are, only about 6 inch-pounds are needed to raise 200lb with this screw. I plan on covering up the nut with a hinged pipe cap to keep the dirt out of the the thrust-bearing schmoo (oil). Same for the Acme rod itself, a telescoping cover will be employed eventually.

    For safety, as you've done and suggested, I'll use a quick-release, decoupling pin for emergencies. It'll be a simple piece of steel tubing fit over a split in my shaft. One end will have a clevis-pin, the other will have a sheer-pin (to protect my shirt-sleeve). So, like this:

    gearbox -> 14mm shaft -> (sheer pin) 3/4 tube (clevis-pin) ->
    14mm shaft -> lovejoy coupling -> 5/8 ACME thread


    Quote Originally Posted by kcoffield View Post
    In my case, I don’t really have enough sidewall furnace clearance for tongs on the largest crucibles, and since it was lift off furnace, I grip the crucible directly from the side with either a freehand shank or one on a cart…….but the furnace must be lifted to do so. If you are going to access your crucible from the top with tongs, you’re probably covered in this respect.
    Being oil-fired, side-clearance is required, so the largest I can run is an A8. As a side-effect, it lets me do both lift out or side-grab (third line of defense against Murphy). I went with this Gingery-style side-grab design for his reasons: Safety, convenience, and speed from furnace to pouring.
    Last edited by r4z0r7o3; 01-08-2017 at 02:51 PM.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  10. #230
    Senior Member r4z0r7o3's Avatar
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    Minor update:

    Loaded up some 50-lb worth of weight on my contraption. Looks like my power-train needs to look more like this (top-down):

    Roll-pin anchored Nut
    thrust-washer
    thrust-bearing
    thrust-washer
    top-of-frame w/ DIY brass sleeve bushing

    Lifting arms w/ DIY brass sleeve bushing
    Welded on Acme nut

    (New) Lower frame w/ 5/8 bearing or bushing
    Lovejoy coupling (keyed)
    14mm O1 steel shaft
    Upper 3/4 OD / 14mm ID Tube with sheer-pin (bottom) and clevis-pin (top)
    gearmotor keyed onto 14mm shaft
    Motor/gearbox mount
    Base platform

    Also, the connecting rod and braces need to be made more rigid. Once I took off all the clamps she went all weeble-wobble on me. Will probably add more silicon-bronze pads and four locating/locking pins / screws.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

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