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Thread: Need help hacking my lathe!

  1. #1
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    Need help hacking my lathe!

    OK, Folks,

    I'm back on it. I've gotten pretty far with figuring out this project, but I'm stymied at this point. I thought I had it all figured out last night, but the harsh light of day shattered everything.

    Here's the lathe I'm hacking:





    Nice, solidly built frame, halfway decent bearings in the spindle, reeves drive. We all know the problem: lowest speed is too fast. Only solution: VFD and a new, 3 phase motor. I'd like to stay at 2 HP, since most of the better lathes are 1.5 to 2 HP. Based on the VFDs I've found, that pretty much means I need to run 220 into the shop, which I guess I should do anyway. The 110 VFDs pretty much top out at 1 HP. So...

    220 to the shop (it's really only a 20 foot run from the main panel in the basement, and I've already got a now unused 220 breaker on the main that used to power the oven). Subpanel in the shop, with both 110 and 220 coming out of it. Here's the VFD I'm thinking will do the job:

    http://www.factorymation.com/s.nl/it....f?category=32

    single phase in, 3 phase out. I'm not real clear on how to hook it up, but I can probably figure it out. I figure I can route around the switch on the lathe. Not real clear on how to set speed controls on it, but again, I can probably figure that out. It's $145, so that's inside the budget.

    OK, on to the motor. I want to keep the reeves drive... and doing that uncomplicates part of the project. That means I only need to worry about the motor spindle size, which I take it is not universal or standardized. But I can measure the shaft on the existing motor. The real problem:

    As far as I can tell, I need a motor that is

    3 phase
    2 hp
    tefc
    inverter duty
    c-face
    about 1700 rpm

    and probably a bunch of other variables that I have no idea about. I found this motor last night:

    http://www.surpluscenter.com/item.as...tname=electric

    for 70 bucks, and got very excited. That's a price within reach. it's not tefc. It's not inverter duty (whatever that actually means). And I don't know the spindle would match. So, I go searching for a motor that I think might match my percieved specs, and can't find anything for less than many hundreds of dollars. Am I barking up the wrong tree? How does one go about finding a motor like that for under a hundred bucks? This all started because people said I could pick up a 3 phase motor cheap. HELP!

    Thanks,

    Bill

  2. #2
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    okay bill......givens are;
    1)"c"face
    2)reeves id..= shaft od

    darn near any 3 phase motor can be frequency controlled but if loaded at 1/2 speed they can get hot......hence the recomendation for a motor rated for inverter use.....where it me and i found a motor of suitable mounting (see #`s1&2) i`d get it whether or not it was rated for inverter use, and try to keep it close to it`s rated rpm`s.......i don`t think that by putzing around an hour here and an hour there at lower rpm`s that you`ll severely shorten it`s usable life?
    but know that i ain`t no `lectrition!

    even if you`re able to toast a motor in a couple of years.....and that`s questionable...... it`s pretty likely that you`ll be ready or at least wanting to upgrade.....
    some thing to think about.... tod
    [SIZE="1"] associated with several importers and manufacturers.[/SIZE]

  3. #3
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    Calling Jeff Horton, Calling Jeff Horton...........

    Methinks Jeff is up on this kind of stuff.....
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  4. #4
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    Funny Stu, I was just reading this thinking I needed to reply.

    I have done something very similar with and Old 3 phase lathe. The VFD with Reeves works well. No problems there.

    As for you motor I would simply call the Surplus center and ask for more info. I believe there are standards on c face motor mounts. You just have to determine what you need vs. what they are selling to see if it will fit. If it will fit your half way home. Check the shaft dia. and length too!

    Wiring a VFD is fairly straight forward. But the manuals are written for Electricians and even though I am very comfortable with this type of stuff, I had to read it a few times to understand it. If you wire one up backward it sounds like shotgun going off when you give it power. DAMHIK. BTW, if you shop you can probably find one cheap on EBay. Just takes some patience.

    VFD's do not like two things (well three if you count backwards wiring). Vibration and dust! See where I am going yet? You really don't want to mount it on the late. I suggest you mount it on the wall, run power cord from it to the lathe. With most VFD's you can hook up remote control. Forward, reverse, speed and on and off switches. You just use very small cable, CAT5 should work. Mount some off the shelf toggle switches and a POT for speed control in a box and attach it to the lathe with a big magnet. Keeps the controls close and VFD out of the dust and vibration.

    How do you turn your lathe on? Is it on the speed control switch? If so then you will need to tie that switch into the VFD. I did that one mine and it's slick!! Works like factory and I use the speed lever most of the time. When I need slower speed I set it on low and then adjust the VFD. Most times I leave it (VFD) on full speed.

    That help or confuse?
    God grant me the senility to forget the people I never liked anyway,
    the good fortune to run into the ones I do,
    and the eyesight to tell the difference.


    Kudzu Craft Lightweight Skin on frame Kayaks.
    Custom built boats and Kits

  5. #5
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    This is just a guess, but I suspect the reason some 3 phase motors get hot at low speeds is that they're designed for a certain air flow, which is provided by the internal fan when operating at rated speed.

    I'd just get a fan and blow it on the motor to help keep it cool. And I'd also take Tod's approach and start with a low cost motor, even if you toast it in a few years. You'll get the experience and will know more about what you want after using it for a while.

    Mike
    Ancora imparo
    Go into the world and do well. But more importantly, go into the world and do good.

  6. #6
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    Hey, folks,

    Thanks for your responses so far. I really like the idea of going with a cheap motor. After all, this is really just an incremental step... someday, a few years from now, I hope to have a *real* lathe... If I burn out two motors over the next three years, the cost is not that much by comparison to a oneway...

    So are you saying I don't need to worry about the TEFC part, or the inverter status? In other words, is it worth a try to just go with the $70 motor I referenced above, even if it means that this time next year I'll have to pick up another? Seems like a decent trade off to me...

    More later,

    Thanks,

    Bill

  7. #7
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    if ya` got an air hose and 20 min a year the odp motor will work for a few to several hundred hours....blow it out when you`re done and clean it well once a year. 3-phase motors don`t have centrifugal switches and mechanical stuff to clog up like single phase units do, windings-n-bearings......
    [SIZE="1"] associated with several importers and manufacturers.[/SIZE]

  8. #8
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    Oh, one thing I have is an air hose!

    But did you mean

    "odp motor will work for a few to several hundred hours"

    A few hundred to several hundred hours?

    Or

    a few hours to several hundred hours?

    If it's the first, I'm in business!

    Thanks,

    Bill

  9. #9
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    Jeff,

    I'm intrigued by this paragraph:

    VFD's do not like two things (well three if you count backwards wiring). Vibration and dust! See where I am going yet? You really don't want to mount it on the late. I suggest you mount it on the wall, run power cord from it to the lathe. With most VFD's you can hook up remote control. Forward, reverse, speed and on and off switches. You just use very small cable, CAT5 should work. Mount some off the shelf toggle switches and a POT for speed control in a box and attach it to the lathe with a big magnet. Keeps the controls close and VFD out of the dust and vibration.

    First, the mounting: Yes, I could mount it to the wall. But here's a picture of my existing lathe stand:



    I was thinking of putting the VFD either under the benchtop, directly beneath where the lathe headstock is now, or off to the left side, attached to the front left of the lathe stand. I figured the wood would dampen the vibration, but maybe not enough.

    On the other hand, if there's one thing I've got plenty of it's cat 5. But what would the interface device be, where would I get one, and how would I hook it up to the VFD? Got any pics? Or places where I can start researching?

    Thanks,

    Bill

  10. #10
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    Quote Originally Posted by Bill Lantry View Post
    Oh, one thing I have is an air hose!

    But did you mean

    "odp motor will work for a few to several hundred hours"

    A few hundred to several hundred hours?

    Or

    a few hours to several hundred hours?

    If it's the first, I'm in business!

    Thanks,

    Bill
    i meant the first bill
    [SIZE="1"] associated with several importers and manufacturers.[/SIZE]

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