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  1. #1
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    Default Treadmill motor???

    Hi,

    I acquired a Hercus 9C several months ago. I am limited to single phase at home but have a few options for motors.

    1) I have the original 0.5hp 3 phase motor, which assuming is ok, I could power it via a VFD. I can't do this right away, as I have other more pertinent expenses, but I have seen suitable VFD's for about $150.

    2) I have a single phase 2840rpm 1hp 240v 2 pole motor which is reversible but will need to experiment with pulley ratios and may even need another countershaft since the motor pulley will end up being a bit small for the correct countershaft speed. (not impossible, could employ a simple 2 stage pulley belt drive reduction from the motor as per a lot of drill presses)

    3) I also have this treadmill motor, 1.5hp, 5700rpm at 180VDC, and the PWM motor controller it came with (I am capable of modifying it for my purposes though it is a task that will require time and effort) Or I could even salvage a step down transformer and a rectifier and smoothing caps to get a suitable voltage to get down to the 1400 odd motor RPM that the lathe is best run at.

    I am not an expert in DC motors, but I suspect that running the motor at 1/4 of its maximum speed is going to yield less than ideal power delivery??? Is there a simple or rule of thumb method to calculate the resultant available motor power at the reduced speed? I am currently focusing on feasibility of option 3, and if that is not do-able will take option 1 or 2.

    Thanks for any thoughts or advice.

    Steve.

  2. #2
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    Default Treadmill motor???

    1, 1, 1, 1, 1!

    Did this whole exercise with my 9C. Even water cooled the treadmill motor, but they struggle with the constant load and heat. Eventually they go pop.

    0.75HP and VFD is a whole new level. Wouldn’t do it any other way now. Plus variable speed control.

    Do number 1!!!

  3. #3
    BobL is offline Member: Blue and white apron brigade
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    Default

    I done all these sorts of conversions and reckon effort needed to set up 2 and 3 are more than that needed for a VFD setup.

    However, the original Hercus 9 motors are star (y) connected and have two be diddled internally to be delta (∆) connected to run at full power using a 240V SP- 240V 3P VFD. You could look at a 240V SP to 415V 3P VFD (Ecogoo) which means you all not need to idle the motor internally. A few people on this site have used these VFDs - look in the Electronics forum.

    The Woodies forums has two Stickies in their eElectronics forum that you might find useful
    https://www.woodworkforums.com/f271

  4. #4
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    Default

    option 1

    Quote Originally Posted by BobL View Post
    However, the original Hercus 9 motors are delta (∆) connected and have two be diddled internally to be star (Y) connected to run at full power using a 240V SP- 240V 3P VFD.
    other way around Bob?
    Chris

  5. #5
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    Default

    Bob and neevo,

    Thanks for your input. Neevo, thanks for influencing me away from the treadmill motor. I had a feeling it wasn't going to be appropriate and I'm glad I didn't waste too much time on it. I will probably hook the single phase 2840rpm motor temporarily, means I'll be using the back gears more often to drop the spindle rpm down, and will upgrade to a VFD + the 3 phase motor later. Bob, thanks for the info about the configuration of the 3 phase motor. I did notice that it was not configurable from the outside. But wasn't aware that I would need a particular type of VFD to drive it.

    jack, thanks for the possible clarification on the delta or star config.

    Steve.

  6. #6
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    Default

    A 3 phase motor can be run on single phase, in a pinch.
    Not a particularly efficient way to go, but cheap, realatively easy to do and works fine.
    Just letting you know....not reconending it.
    We had actuator that ran like this for years. Wasn't continuously running but ran for a few seconds, every few seconds..

    Sent from my SM-G970F using Tapatalk

  7. #7
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    Default Treadmill motor???

    Either find a dual voltage 3PH motor or one that is only running in Y can be modified to allow Delta, but not a novice job.

    The C’s are really capable when working and if you fancy getting rid of all the gears you can add an electronic leadscrew to really make them a model A beater. Still don’t have power cross feed though unfortunately.

  8. #8
    Join Date
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    Adelaide
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    Default

    As Bob said, I would go with the VFD, I am using the Ecogoo or the Nflixen brands available off Ali express, I was never a real fan of going this way but am seriously glad I did, I have a craftsman and a 260 and they both run great with them, they are 240v single to 380v 3 phase so no need to change the motors over from star to delta, little bit of playing around to set them up at first but they are great and the VSD is just an awesome option, you can even program them with a fairly decent stop time if you don't run the lathe at high speeds.

  9. #9
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Tinkerer77 View Post
    As Bob said, I would go with the VFD, I am using the Ecogoo or the Nflixen brands available off Ali express, I was never a real fan of going this way but am seriously glad I did, I have a craftsman and a 260 and they both run great with them, they are 240v single to 380v 3 phase . . . .
    Just a minor point but they should convert 240 SP to 415V 3P.
    220V should be converted to 380V.
    The conversion factor is Input V x SQRT(3)

    Did you manage to find a "max current" setting amongst the VFD parameter limit?
    If not then a fuse of some kind that suits the max 3P current of the motor should be added.

  10. #10
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    Quote Originally Posted by Sterob View Post
    A 3 phase motor can be run on single phase, in a pinch.
    Not a particularly efficient way to go, but cheap, realatively easy to do and works fine.
    Just letting you know....not reconending it.
    We had actuator that ran like this for years. Wasn't continuously running but ran for a few seconds, every few seconds..

    Sent from my SM-G970F using Tapatalk
    How does that work? With my limited understanding of how the magnetic fields rotate around each of the windings I can't quite figure out how you could get a rotation with only a single phase?

    If I can modify the configuration of the original 3 phase motor I would consider it, I have an strong electronics background, and have worked as a trades assistant with an Electrician, its just that I don't know all that much about 3 phase electric motors but I'm willing to learn. I imagine it involves tapping into the windings to get new pickup points to reconfigure the windings? Or if you don't want to spell it out in a publicly viewable forum (sometimes I am hesitant about providing info regarding mains and wiring in case someone hurts themselves with it), do you know of a source of info of these mods?

    Thanks for all the info.

  11. #11
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    You have it correct on both fronts. The principles of pulling out the star point and the forums nervousness to advertise this modification.

    I did it myself for my Hercus motor and it’s not complicated, just takes some know how. But it comes with its risks.

    My understanding is that the modification allows dual voltages to be used. Which also means 1Ph 240v in and 3PH 240v out, maintaining the peak power of the motor.

  12. #12
    BobL is offline Member: Blue and white apron brigade
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    Running single phase motor on 3phase uses what is known as a "static capacitor phase converter" eg ehttps://www.electrotechnik.net/2011/07/running-three-phase-motors-with-single_30.html
    This is completely different to using a single phase VFD to produce 3 Phase power.

    The first method is usually inefficient, especially under load, and eventually can damage the motor.
    The second method is highly efficient modern VFDs use very little of the power they convert and can run for many years without probs.

    The conversion between ∆ and Y for 3P motors is a separate issue.
    A motor designed and connected to run at full power on a specific 3P voltage can be constructed as either a ∆ or Y.
    It just so happens that if a motor connected up specifically as Y to run on Voltage V (eg 415V) is converted to ∆, it can run at full power at V/SQRT(3) or 240V
    In a similar manner a motor connected up specifically as ∆ to run on Voltage V when converted to ∆, can run at full power at VxSQRT(3)

    So 415V Y can run on 240 ∆ and VV
    A 415V ∆ needs 690V to run at full Power as a Y.
    A 240V Y motor needs 138V to run as a ∆

    I hope I got these right - I'm falling asleep at the screen here.
    Clear as mud

  13. #13
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    Default

    Ok, starting to make sense, thanks Bob and neevo.

    I did find some independant info (wasn't hard to find) and a video demo running a 3 phase motor from a single phase but I won't elaborate. The inefficiency and probability of damage plus the effort is guiding me back to option 1, especially the realisation about increasing the complexity of the switchgear to get a reverse direction option (which I prefer to have for thread cutting)

    But thanks for coming with me on the journey.

    I probably will run it for a little while on the 2840rpm single phase motor, it will be temporary, but will invest in a VFD when it becomes feasible in the budget (other things are more urgent as mentioned)

    Thanks very kindly for the help.

    Steve.

  14. #14
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    Quote Originally Posted by BobL View Post
    Just a minor point but they should convert 240 SP to 415V 3P.
    220V should be converted to 380V.
    The conversion factor is Input V x SQRT(3)

    Did you manage to find a "max current" setting amongst the VFD parameter limit?
    If not then a fuse of some kind that suits the max 3P current of the motor should be added.
    Sorry Bob, I think you have me there, I think without looking at the unit it is 220 to 380, I raised the voltage issue with the industrial electrician at work and he thought that I would really only notice that power voltage issue at higher loads, the vfd does have a max current setting in it, I was very sceptical about it at first but it has impressed me so far, my only issue is that I need to adjust my run down time as at max speed on my 260 is 2600rpm it trips out with a run down fault as it can't stop the motor in the time frame I have set that parameter.

  15. #15
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    Quote Originally Posted by BobL View Post

    Did you manage to find a "max current" setting amongst the VFD parameter limit?
    If not then a fuse of some kind that suits the max 3P current of the motor should be added.
    Yes, there’s definitely a max current setting in the motor parameters of the Ecogoo VFDs.
    Can’t recall the parameter number, but it’s obvious in the manual.

    Steve

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