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

  1. #231
    Senior Member r4z0r7o3's Avatar
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    Ran through power and torque calculations again and got more reasonable results.

    Lifting 200-lb of load up a 5/8-8 Acme thread takes in the neighborhood of 3 foot-pounds of torque. Call it 5 lb*ft to include resistances from my brass sleeve-bearings. Turning that at 250 RPM will take 177 watts of power. Call that 200 watts to account for gearing and electrical losses. The Baldor motor is rated for 4amps @ 60 volts, which works out to 240 watts. So it's good I sprang for this combo as it's close to the power level I needed.

    I'll need to double-check my emergency drill and socket can handle this. If it can't, I'm thinking of replacing the DIY sleeve-bearings with proper sealed roller bearings (and protecting them from heat).

    Not a lot of work done today except some re-jiggering of the track-rollers to add an extra washer/spacer to increase rail-side clearance. I also welded up a pair of angle-irons into a C-channel to be used with another sleeve or roller-bearing to better support the bottom end of my lead-screw and shaft.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  2. #232
    Senior Member r4z0r7o3's Avatar
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    MOAR stuffs

    After digging around, found none of the transformers I had were skookum enough to be used here, even if re-wound. Also, since I'm back to working full-time after the holidays, time isn't on my side. So I splurged for a giant chunk-o-wound copper: 800 watt 63 volt linear power supply. It's a very simple arrangement of giant toroid (doughnut) transformer and a few 0.1f caps. As a bonus, it's got an auxiliary +12v tap also, so I can power a cooling fan (dunna wanna melt lovejoy's spider) and any other accessories I may need in the future.

    Since the Baldor motor is rated at 60v max, I also got a pair of Vishay power diodes rated for 100 volts and <ridiculous> amps. The voltage-drop across one will put me in the motors safe-range for voltage. The other one will be used as a "snubber" (facing backwards across the output) to eliminate the nasty voltage spike caused when inductors (coils) become disconnected from their source. Like this:


    Code:
    110v    [ POWER ] 63v --> DIODE -> 61.5v -> long wire -> 60v to motor
     in  -> [ SUPLY ]           ^
            [       ] 0v        |
                       |      DIODE
                       |        ^
                       +--------+----> long wire -> 0v to motor
    N/B: I'll check the PSU first, to make sure it doesn't already have a snubber.




    In other news, I received my shaft, couplers, and bearings yesterday. I also connected with a guy at my work that's willing to help me cut keyways in exchange for beer

    I've also drawn up a quick sketch of a motor mount, which I'll post if anybody's interested in reviewing or (constructive) criticizing.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  3. #233
    Senior Member r4z0r7o3's Avatar
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    Quick update

    Winter weather basically shut down activities for this weekend Not that I'm scared of winter-driving...it's all the other damn idiots who aren't scared enough, keep me inside! So no machining of shafts, but we'll get er done soonish.

    I did do some basic testing of the power supply, and worked a few must-have mods: Silicon adhesive globs around the capacitors - keeps 'em frum wigglin' their leeds broke. An some hot-shrink-n-tubin' (from sweeden!) the wires around into a fabracobbled electrical box (from an old RF antenna amplifier).

    Butt! I done did sniff toooooooo much that silicon and gone got meeeeee self all country-boy'd up! Orderved all deez electrifornication jimmer-jammers from Newark (shippin' cheapin' to me), bee her next week:



    Save n' collekt n' pix for a nutter post n'
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  4. #234
    Senior Member r4z0r7o3's Avatar
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    Lifting / Lowering circut

    Threw this together for my own sanity when wiring, but thought it might help others.

    Fritzing didn't have a part for the 4PDT (on-off-on) rotary switch, so I stuck in a DPDT in it's place (i.e. it's missing the "off" position). Also, the connections by the motor make it look like there's a short, however the up/down switch actually prevents this (i.e. both terminals are switched at the same time).



    This setup is extraordinarily simple, which is normally a good thing. However, it will place a lot of stress on the motor when it starts moving because it has to overcome all the static-friction in the entire drive-train, including the gearbox. This will result in a lot of heat, which will limit the duty-cycle and/or I'll have to get rid of with a fan.

    I've done a lot of research on motor controllers / drivers over the last few days. Unfortunately, for a gearmotor of this size, my only options are:

    * A $500+ black-box (who knows what's inside).
    * A $200 chip with a three-month lead-time (they must not sell many)
    * A bunch of time, $30 for microcontroler, N-channel MOSFET, pair of snubber diodes and various supporting nubbins.

    All of these basically work the same way, pulsing the motor power (very quickly) for a few seconds before going 100%. The other advantage they bring is some extra electrical protections for the PSU and motor, and the possibility of temperature monitoring + cooling fan control. Before jumping in to this, I think I'll start with the simple setup and keep an eye on the motor's temperature. I'll use screw/cap connectors for all the wiring and a larger panel-box than necessary. Then if I need to expand, I'll at least have a little extra room and wiring-flexibility to work with.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  5. #235
    Quote Originally Posted by r4z0r7o3 View Post
    ........ However, it will place a lot of stress on the motor when it starts moving because it has to overcome all the static-friction in the entire drive-train, including the gearbox. This will result in a lot of heat, which will limit the duty-cycle and/or I'll have to get rid of with a fan.

    I've done a lot of research on motor controllers / drivers over the last few days. Unfortunately, for a gearmotor of this size, my only options are:

    * A $500+ black-box (who knows what's inside).
    * A $200 chip with a three-month lead-time (they must not sell many)
    * A bunch of time, $30 for microcontroler, N-channel MOSFET, pair of snubber diodes and various supporting nubbins.
    I've had several DC gear motors driving home built lead screw actuators in service for 20+ years that only have transformed AC and a full wave rectifiers for a power source. They are using inexpensive power and limit switches for limit and directional control that aren't even DC rated. Wouldn't you expect your duty cycle to be very low?

    Best,
    K

  6. #236
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by kcoffield View Post
    I've had several DC gear motors driving home built lead screw actuators in service for 20+ years that only have transformed AC and a full wave rectifiers for a power source. They are using inexpensive power and limit switches for limit and directional control that aren't even DC rated.
    Thanks, I'm glad to hear that. I was careful to select components slightly overrated to give some head room.

    Quote Originally Posted by kcoffield View Post
    Wouldn't you expect your duty cycle to be very low?
    It all depends on the window, but for full-up and full-down, yes I don't expect I'll be doing that much. I'll probably be "jogging" it a bit while I'm setting it up, so I'll have to watch the temps then but otherwise I don't expect to need much jogging.

    It's such a nice motor, the damn brushes are barely worn-in and the printed (stoopid!) data-plate has exactly 3.1415 scratches...I'm just really afraid of ruining...but...so, okay, I should drink less worry-juice then.

    Thanks Kelly.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  7. #237
    Razor,

    If your really worried about that last 1.5V (61.5 vs 60V) to the motor.... Throw in another snubber diode. it will drop the remaining 1.5v (depending on diode 1.7V) and your golden. It's not going to effect the motor in any way... just another $0.10 part .

    As for a speed controller your over thinking it. It's a brushed motor with a gear box on the nose. What else uses a brushed motor? Scooters!! Wheelchairs, mobility scooters! and the speed controllers for them are CHEAP!! but they don't have a built in power supply. http://www.ebay.com/itm/9-60V-Max-20A-PWM-DC-Motor-Stepless-Variable-Speed-Controller-Switch-/302014786519 (I don't know anything about the quality of the one linked but there are at least 5 different designs/units on there right now...and this one ships from the US)


    [Edit--]The rest of this is redundant as just relized you already have a power supply!!![--Edit]
    The power supply because the more expensive item as you need at least 5 Amps or more @ 60Vdc. Switching psu are the most efficient
    Switching power supply https://www.amazon.com/Switching-Power-Supply-Router-S-350-60/dp/B00XTHM6TO/ref=sr_1_2?ie=UTF8&qid=1484167721&sr=8-2&keywords=60v+switching+power+supply (reviews aren't great...but meh)

    Then again K's right Motors are pretty tolerant of power A rectified 60V transformer will do it too but the efficiency is low.
    With low cycle times, and if you don't leave the transformer hooked into the mains all the time. it's a good option too.

    CBB

  8. #238
    Senior Member r4z0r7o3's Avatar
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    progress pics

    A bit of an old photo (below), but you can see my clamped, jigged, and fixtured up setup for welding the angle-braces onto the lifting arms. My dangling TIG torch is pointing at one of them (sorry for the lack of color, everything really is very gray)


    (Below) Preparing to weld on this lower support. It's a "C" channel I made by welding two pieces of angle-iron together. The weld bead is on the under-side, but strangely it caused a small amount (maybe 3/16-in across the length) of bending upwards. The heat-marks you can see are from where I tried to remove some of that...but didn't end up getting it hot enough. Oh well.

    Right where the acme-screw is sitting, I'll be adding a flange-mount roller-bearing to support/locate the bottom end where it'll mate with the motor shaft through a lovejoy coupling. The screw has enough room to extend perhaps 3 more inches down below the "C" channel top.


    Today, I needed to cut this oddball angle for the motor mount. However my bandsaw's fences couldn't handle it so I removed them and just clamped the damn thing down. Surprisingly this worked brilliantly, in fact so well I'm not even going to bother making the cut more accurate to my line on the belt-grinder.


    Here's shot (below) of the motor mount plans, cut parts, and you can catch a glimpse of the gearmotor as well. I rough-cut everything out of this 3/16 plate with my angle grinder. Got the parts sized closer on the bandsaw. Final sizing, squaring, and paralleling was done on the band-saw. None are perfect, but well within "good enough".
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  9. #239
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by CrazyBillyBob View Post
    Razor,

    If your really worried about that last 1.5V (61.5 vs 60V) to the motor.... Throw in another snubber diode. it will drop the remaining 1.5v (depending on diode 1.7V) and your golden. It's not going to effect the motor in any way... just another $0.10 part .
    Not overly worried, I measured the PSU (unloaded) and it's showing 63-point-something. I've got two of these really nice vishay power diodes (one-point-something volt drop), so yeah, I'll probably slap one on as a dropper and the other as a snubber. The cable-lengths back/forth to the limit switches and whatnot will take care of the other few extra millivolts

    Quote Originally Posted by CrazyBillyBob View Post
    As for a speed controller your over thinking it. It's a brushed motor with a gear box on the nose. What else uses a brushed motor? Scooters!! Wheelchairs, mobility scooters! and the speed controllers for them are CHEAP!!
    Oh interesting! I hadn't thought they ran up to so many volts, nice! Yeah, overthinking it, I agree. No speed control is needed, gearbox output is only 250 RPM, how much slower does it need to go?

    Quote Originally Posted by CrazyBillyBob View Post
    A rectified 60V transformer will do it too but the efficiency is low.
    Aye, it's a beast! Damn thing must weigh 20 or 30 pounds, but it's completely zombie-brain-dead-simple. It was a bit pricey, but it's worth spending a little extra money on a better supply. I got one with a coil built to about double what I actually need (current-wise). That should provide well more than enough headroom to cope with the inrush (along with a skookum, silver-plated contact, on/off switch).

    I'm not too happy about the smoothing caps they've stuck on it (Epsilon brand, Shin-Zen-bulshit-China) but not in much of a mind to replace them. The only thing I've done is added some silicon around/between them to lock them down. This is a well-known failure-mode where vibrations cause the leads to work-harden and crack over time. Anyway, until they pop, I'm just going to blindly assume they really are 105c rated for 100v @ 10,000uF each. Laa laaa laaaaa, nothing to see here

    Yeah, duty-cycle will be low, and there's no reason I can't click-off the mains supply when I don't need to raise-lower. My mains switch MTBF is higher than the number of times I'll light this furnace...multiplied by 1000


    Thanks Billy Bob!
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  10. #240
    Senior Member r4z0r7o3's Avatar
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    made TWO new friends today...

    ...nuf said:


    Meanwhile, in another garage. A motor mount is sitting, awaiting a few more adjusting/clamping holes, cleaning and then tack-welding.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

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