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Thread: Need some help.

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    Help. Single phase to 3 phase.

    Hey guys. Need some help with a project.
    I have a Grizzly 9x49 milling machine I bought new 12 or 13 years ago. The only problem, for me, is it is a 220 volt 2 hp single phase belt drive. Every time I change speed I have to move the belts around. I can no longer raise my arms or extend my arms because of shoulder damage. What I want to do is change out the single phase motor for a 3 phase motor with VFD. I read a quick post on another site of a guy doing exactly this but he doesn't return messages.

    Has anybody done this?

    What would help is information on where to get a motor , VFD, and any other parts. I have been all over the internet looking for things. The VFD doesn't seem to be a problem. But the only motors are old well used take offs. I also don't want to spend $1000 for just a motor.

    Grizzly discontinued this model several years ago.

    Any ideas would be welcome.

    Thank you.
    Last edited by gfabs001; 02-27-2019 at 01:42 PM. Reason: New title

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    Supporting Member Toolmaker51's Avatar
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    Toolmaker51's Tools
    Quote Originally Posted by gfabs001 View Post
    Hey guys. Need some help with a project.
    I have a Grizzly 9x49 milling machine I bought new 12 or 13 years ago. The only problem, for me, is it is a 220 volt 2 hp single phase belt drive. Every time I change speed I have to move the belts around. I can no longer raise my arms or extend my arms because of shoulder damage. What I want to do is change out the single phase motor for a 3 phase motor with VFD. I read a quick post on another site of a guy doing exactly this but he doesn't return messages.

    Has anybody done this?

    What would help is information on where to get a motor , VFD, and any other parts. I have been all over the internet looking for things. The VFD doesn't seem to be a problem. But the only motors are old well used take offs. I also don't want to spend $1000 for just a motor.

    Grizzly discontinued this model several years ago.

    Any ideas would be welcome.

    Thank you.
    Right off, I think suggestions will center more on a variable DC motor.
    Edit into original post the existing motor horsepower, RPM and frame size if known. A big, clear shot of the motor tag would be ideal.
    Second questions will be of the lathe itself; metal or wood turning, range of speeds offered by the present belt change setup, possibly what variety electrical service you have.
    Ooops, on re-reading you have a mill, not a lathe. Ideas related above still apply, mostly. Achieving low gear speed range will be bigger issue, whether a DC can deliver good torque.
    Last edited by Toolmaker51; 03-15-2019 at 06:13 PM.
    Sincerely,
    Toolmaker51
    ...we'll learn more by wandering than searching...

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    Try Marshall Wolf Automation for single phase vfds

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    Quote Originally Posted by Toolmaker51 View Post
    Right off, I think suggestions will center more on a variable DC motor.
    Edit into original post the existing motor horsepower, RPM and frame size if known. A big, clear shot of the motor tag would be ideal.
    Second questions will be of the lathe itself; metal or wood turning, range of speeds offered by the present belt change setup, possibly what variety electrical service you have.
    Ooops, on re-reading you have a mill, not a lathe. Ideas related above still apply, mostly. Achieving low gear speed range will be bigger issue, whether a DC can deliver good torque.
    3 ph moters can be purchased in C face you can make an adapter plate to fit your mill you will have to make sure the motor shaft will fit your pulley.

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    This was something I caught onto and think it would work wonderfully for any conversion even single phase but also 3 phase so that you can use variable speed. its on Youtube and I have seen others like it on other forums as well.


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    Supporting Member metric_taper's Avatar
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    metric_taper's Tools
    Quote Originally Posted by gfabs001 View Post
    What I want to do is change out the single phase motor for a 3 phase motor with VFD.
    I have done this with all my single phase stationary tools with spindles in the shop. Very easy to modify the mounting plate of the motor. Depending on the machine, I've bolted the motor to a ~6mm (1/4") piece of steel plate, that has the mounting holes for the machine also drilled. If you need to use slotted holes for belt adjustment make an adapter that support this.
    I find I can leave the belt ratio right in the middle setting, and run the VFD for speed control. My motors were all 1800 RPM (~1725), so I programed the VFD to let me run 120Hz max as the same rotor for a 2pole motor is used in the 4 pole version.
    If you want smooth high torque operation down at low speeds you need to get a VFD that is Sensorless Vector type.
    Most VFDs will operate single phase input up to the 3HP model without derating. Motor sizes above that should have the VFD 2x power rating of the motor.
    Last edited by metric_taper; 03-19-2019 at 05:08 AM.

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    Supporting Member suther51's Avatar
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    I must first profess some ignorance of what I am about to say, But I do believe that there are 220v single phase vfd's available, try some Google searches. I have seen some posts on practical machinist forum where such single phase vfd's are spoken of.
    https://www.driveswarehouse.com/WJ20...QaAkHDEALw_wcB
    Eric

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    Supporting Member tonyfoale's Avatar
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    tonyfoale's Tools
    I was short of time when I made my earlier post, so here is some detail.
    With both DC and 3ph motors you lose torque as the speed is reduced. You can overcome this by using what would normally be considered an oversize motor. I replaced a 1.5 hp motor with a 5hp. I never need 5hp but it gives me acceptable low speed performance without additional gearing.
    When most people on this forum talk about DC motors they are referring to treadmill motors. If you are replacing a 2hp AC motor with a DC treadmill motor then if you gear it for a reasonably high maximum spindle speed then you will be very disappointed with the low speed performance. I have done that.
    You don't have to spend $1000 for a motor, at least in Europe you can get suitable 3ph motors for < $250

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    I just hooked one of the offshore VFD's 220 vac 1 phase in to 22ovac 3 phase out to my buddy's lathe. It was a larger unit (7.5 kw) as his lathe is 10 hp. This unit cost about 500 CAD to bring it to Canada off of Ebay. I was impressed with the low rpm torque. As for a motor you should be able to find a new standard duty 3 phase motor for a couple of hundred bucks in the US, and a used one for $50. Check somewhere like Automation Direct for a new motor. With your mill being belt drive it should be easy to configure a new motor mount if you can't use your existing. PS a three phase motor should be somewhat smaller than a 1 phase counter part.


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