Sanity check, feedback - VFD for 3hp, 3ph on Wade 8a lathe
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  1. #1
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    Default Sanity check, feedback - VFD for 3hp, 3ph on Wade 8a lathe

    I'm freshening up a 1940's Wade 8a lathe (Details can be found here.) The original Wade motor was 3hp. Due to many factors, I've decided to drive the lathe using a 3hp, 3ph WEG motor. (Data plate below). I'm in the typical 220, 1ph availability, situation and need to convert to 3ph, 3hp. To complicate the situation, I'll be relying on the VFD to vary the motor speed, instead of the original Wade variable speed mechanisms. (I.E. Rube Goldberg, design.)
    Taking a cue from Clough42, on Youtube, I'm looking at the TECO l510-203-h1-u VFD. (Model number composite from page 2-1 in the L510 Instruction manual L510 - Model, 2 - 230v input, 03 - 3hp, h, 1 - 1ph input, u.)
    Recognizing I'll be losing a bit of power in the VFD, I believe the 3hp WEG will be fine. (Non-production turning on this lathe.)

    I'll be sourcing the VFD soon. Therefore, the sanity check. Does anyone see any flagrant issues with this plan? I'm also open to any feedback you may have. My intent is to have a nice lathe, done right, while attempting to keep true to the 1940's vintage style. (VFD will be enclosed and "hidden".)



    Click images, turn phones sideways, for larger version. (Minor warning: Free image site redirect.)

    WEG data plate


    Just for giggles, Lathe as I received it.



    Lathe as it sits today.

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    I typically would recommend a 1750 or 1200 RPM 3 phase 60Hz motor on lathes and over speed the motor. You will have too much Hp loss with a 3500 RPM motor if you need to spin it below say 20 Hz (~700 RPM). Assume you will be belting the speed down quite a bit, assume the lathe maximum speed is limited by the bearings so 600-800 RPM?. A lower speed motor you can easily over speed to 120 Hz and maintain Hp. The Teco L510 is OK and inexpensive if you just want basic functions, normally I do not recommend them for lathes if you are going to be braking quickly as they do not support an external braking resistor. But otherwise they work well enough for your application.

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    3hp seems a bit high for that size lathe. The Rube Goldberg contraption is the counter shaft assembly, it gives you torque multiplication, you can eliminate it and drive direct, but you might find that you have no torque at low speed.

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    I'm gonna amalgate both MKSJ and Kris's responses:

    Definitely a 1800rpm motor, and overspeed it to at least 120hz.

    2hp should be more than enough for this spindle.

    The variable drive probably ate a half horsepower of your original motor anyway.

    I would use a 2hp 1800rpm motor, then give it a simple belt reduction of somewhere between 2 and 3 motor turns per 1 spindle turn.

    You WON'T be swinging large diameters, so great torque at creeping-slow speeds will not be useful. Most of your turning for this machine's type and size will probably occur between 200 and 1800rpm... that'd put a 3:1 on 1800 as 5400rpm, which would be 180hz... and most 2hp motors will spin that fast with no complaints.

    For the motor, remove the shaft-mounted cooling fan. Replace the shroud, but before you do, mount a fixed-speed fan on it. When you energize the machine, you'll energize the lighting system, coolant pump, VFD, and motor cooling fan, and this will assure that regardless of what speed the motor is running at, you'll have constant cooling airflow. If you leave the original fan in place, it'll be an air-raid siren when you've got the speed dial turned up.

    You mentioned that you'd be 'recognizing a little power loss with the VFD'... if the VFD is rated for single-phase input, you won't be loosing any power... it will develop whatever it's rated for under single-phase input.

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    Great feedback, as I expected from PM. Thank you. Your concerns about torque and speed are ones I've read before and am willing to take as caveats to this lathe build. Since I dont have the original motor or assembly, I'm forced to make some compromises. The slow down is obviously one of them. I I have to wait, so be it. However, is there an alternative VFD I shouldbe investigating if I ever do wish to add a breaking resistor? (Just talking about resistors made me remember my EET 101 resistor band mnemonic. Thanks for the chuckle! Bad Boys.....)

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    If the spindle nose is for thread-on chucks, I would NOT recommend using, or concerning yourself with dynamic braking capacity... as this can easily result in a chuck unthreading from the spindle nose and going on a high-speed tour of your workshop.

    IF it's got some other method of attachment (a D-type, for instance) or if you're using collets and a closer or drawtube, then having dynamic braking and quick reverse is extremely handy. On my 10EE (a D1-3 mount), I put a collet chuck in, and a piece of round-stock, set it up to cut threads, and when it's a complicated thread, I just reverse the spindle and spin it back, so my threads always register perfectly.

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    Quote Originally Posted by DaveKamp View Post
    ....
    The variable drive probably ate a half horsepower of your original motor anyway.
    .
    +1 on that. If not a bit more.

    As far as losing hp by using an appropriately rated VFD, not happening. If the motor is
    3 hp and the drive is single phase 240 volt fed rated at 3 hp, you had better have a good
    belt going to the spindle.

    2 hp should be absolutely enough for this machine.

    Suggest you be sure to get a drive that has sensorless vector capability. The Hitachi I put on one
    lathe has a great autotune feature. I tuned the motor on the bench, and then autotuning in the
    machine altered some of the parameters for the better.

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    Manual is informative:
    Wade Tool Co. - Publication Reprints - Wade 8A Toolmakers Precison Lathe | VintageMachinery.org
    Wade 8A Toolmaker's Lathe

    The spindle is a 2" 10 TPI thread, so unless it has a lock, you do not want to have it stop too quickly. Interesting drive with variable speed via adjustable sheaves. Stock motor was listed as 1200 RPM which would have a higher torque than a 1750 or 3450 RPM. Speed range per this manual is surprisingly 32-2000 RPM so a 7:1 speed range and an overall low speed ratio 63 to 1 with the 9:1 back gear. There is a diagram of the drive and specs. in the manual, but this may be a more modern version.

    In either case, as I indicated and mentioned above, quick braking is probably not desirable with a thread on chuck. Attaining decent performance of the motor will be an issue, and almost futile if you do not have a back gear. Usable motor speed range under ideal conditions might be something like 20-200 Hz with a 1750 RPM vector motor (they are rated to 4000-6000 RPM) for 3 Hp, I have one of these sitting in my garage. So figure something like a 4:1 reduction ratio would give a speed range of 150-1500 RPM. If you have a back gear then that changes the equation a bit, I still would recommend a lower base speed motor. With a back gear you could do OK with a 2 Hp, w/o then 3 Hp. Hp drops off linear below the motor base speed.

    As far as VFDs, their was a recent thread on recommended VFDs, VFD brands I should consider? .

    These would be 2 Hp versions
    WJ200-015SF 2HP 1.5kW 230V Single Phase Input VFD - Hitachi
    E510-202-H-U | Teco Westinghouse | AC Drives
    E510-202-H1FN4S-U NEMA 4/12 | Teco Westinghouse | AC Drives
    Yaskawa CIMR-VUBA0010FAA, 3 HP, 200-240V, VFD
    Fuji also has some small VFD drives, I have no experience with them.

    Per Wolf Automation's site:
    The Teco E510 series is a great cross reference to these manufacturers drives:
    Mitsubishi D700
    Hitachi WJ200
    ABB ACS310
    Schneider Electric Altivar 312
    Yaskawa V1000
    Danfoss VLT FC280
    Toshiba VF-S15
    Last edited by mksj; 09-30-2019 at 01:17 AM.

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    Great breadth of feedback and input here. Thanks to you all! I worked with my mentor and he went through the math. Looks like I'll be "ok" with this motor relative to the intent of the lathe. (Non-production/hobby needs) We're still evaluating various VFDs. Thanks for the list! That auto-tune option looks to be a major factor and I'm sure I'll leverage that option. Otherwise, I'd very much like on I can program via PC. While not a show stopper, it would be nice/cool to look at the data and tweak parameters via a PC interface. (Away from the lathe.)

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    Quote Originally Posted by DaveKamp View Post
    If the spindle nose is for thread-on chucks, I would NOT recommend using, or concerning yourself with dynamic braking capacity... as this can easily result in a chuck unthreading from the spindle nose and going on a high-speed tour of your workshop.

    IF it's got some other method of attachment (a D-type, for instance) or if you're using collets and a closer or drawtube, then having dynamic braking and quick reverse is extremely handy. On my 10EE (a D1-3 mount), I put a collet chuck in, and a piece of round-stock, set it up to cut threads, and when it's a complicated thread, I just reverse the spindle and spin it back, so my threads always register perfectly.
    GREAT point! One I completely over looked. Noted and stricken from the decision tree.

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    Quote Originally Posted by mksj View Post
    I still would recommend a lower base speed motor.
    This is my biggest limiting factor, at this time. Should have gotten a slower motor. Live and learn. Worst case scenario, I end up buying a slower motor, replace this one and use the higher speed (w/ another VFD) for another application in the future.

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    Quote Originally Posted by DaveKamp View Post
    If the spindle nose is for thread-on chucks, I would NOT recommend using, or concerning yourself with dynamic braking capacity... as this can easily result in a chuck unthreading from the spindle nose and going on a high-speed tour of your workshop.

    ......
    While this is probably good advice, not knowing details, the braking is not more violent than acceleration, I have tested similar sized machines and was unable to get a 6" or a 5: chuck to disengage and unscrew when slamming the machine from forward to reverse driven with 60 Hz, The test unit was a Logan, with a 1 1.2: 8tpi spindle. It is a flat belt machine, and the belts did chirp on reversing.

    In the test, I d0d not tighten the chuck specially, just put it on with a somewhat unconcerned soft flip of the wrist for tightening. I believe the startup torque finished the tightening.

    So the concern may not be as much in reality as it is in theory. The only time I have had one unscrew was getting too cocky with a coarse thread I was cutting, Something around 2" or so and possibly 8 tpi. I do not recall the details., I just took too big a cut in reverse, and that time it did unscrew.

    Now, that reversing test was like MOTOR dynamic braking,

    If you include DC injection braking, that may be quite different, as it is generally more violent than regular motor braking. I would avoid DC braking entirely.

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    Quote Originally Posted by JST View Post
    While this is probably good advice, not knowing details, the braking is not more violent than acceleration, I have tested similar sized machines and was unable to get a 6" or a 5: chuck to disengage and unscrew when slamming the machine from forward to reverse driven with 60 Hz, The test unit was a Logan, with a 1 1.2: 8tpi spindle. It is a flat belt machine, and the belts did chirp on reversing.

    In the test, I d0d not tighten the chuck specially, just put it on with a somewhat unconcerned soft flip of the wrist for tightening. I believe the startup torque finished the tightening.

    So the concern may not be as much in reality as it is in theory. The only time I have had one unscrew was getting too cocky with a coarse thread I was cutting, Something around 2" or so and possibly 8 tpi. I do not recall the details., I just took too big a cut in reverse, and that time it did unscrew.

    Now, that reversing test was like MOTOR dynamic braking,

    If you include DC injection braking, that may be quite different, as it is generally more violent than regular motor braking. I would avoid DC braking entirely.
    I'm with JST on all comments.

    I also ran a Logan 12 inch with an 8 inch Buck Adjust true. I plug reversed that thousands of times with no issues after merely spinning the chuck on with a gentle thunk. Anything more made chuck removal a difficult task. Belts were squealing, but no chucks ran across the shop floor.

    A big non-issue in my book. But, the equipment was in good condition with a great fit-up between chuck mounting plate and spindle.

    Now I run a similar sized Weiler, but that has a pinch clamp on the backing plate to lock the threaded spindle "guten-tight".
    This lathe is on a Seimens VFD that is programmed to use DC injection braking with a 2.5 second ramp down . For collet work, I have set the ramp down to 1 second. Works fine.

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