VFD & Motor close on the horizon

[Bart Leetch]

Well I am looking into a turn key VFD & Motor system that I can mount plug in & start using Put together by the Motor shop I've done business with for years. I figure that I can use this on my Delta Double duty lathe Until I get ready & then build my own bowl lathe & move the VFD & Motor to it.

I like the Delta 46-460 but I also like the Delta double duty lathe I have now & it allows me to be able to turn on the outside of the head which will make it possible to turn bigger then 10 1/2" - 11" that can be turned over the bed ways & bigger then the 12 1/2" of the Delta 46-460.

So if this VFD & motor system has the slow power I need I can turn the way I want too & save up to build a bowl lathe.

 

[Bill Boehme]

Be sure to size this system for your future lathe and not just what you currently have.

Everything has a performance downside price to pay that goes hand-in-hand with its upside:

• With stepped cone pulleys you are limited to a few fixed speeds, but the upside is that the motor is always capable of full rated horsepower which means that the power at the spindle is also the rated horsepower of the motor.
• With electronic variable speed control, the upside is that speed is continuously variable, but the downside is that rated power is only available when the motor is running at its base speed (typically around 1750 RPM). The available power decreases as speed decreases.

Despite the rather significant power issue when running a motor with an EVS drive, it is still very attractive. There are two things that you can do to minimize the problem:

• Use a larger motor -- a good rule of thumb is 1.5 to 2 times the HP of an equivalent fixed speed system that uses stepped cone pulleys.
• Plan on having two or three speed ranges and operating the lathe so that the motor will run at about 70 - 120% of base speed in each range.

These two things will enable the motor to produce a reasonable power output at the spindle while also covering a wide range of speeds. It is also important to keep the motor speed up so that the motor will run cool. If the motor speed goes too low, it will overheat rather quickly.

You basically have two choices on controllers (there is a third choice, but it is rather expensive). The least expensive is a Volts/Hertz controller. It does not have great speed regulation especially at slow speeds and its speed range is limited at both minimum and maximum values. I would recommend going for the better sensorless vector controller. It has much better speed regulation and also allows a much wider range of speed control. The third and very expensive option can have up to 0.01% speed regulation and smooth control on speed all the way from zero up to whatever the motor can handle.

 

[waltben]

Is this the lathe you're thinking of upgrading:
http://www.owwm.com/photoindex/detail.aspx?id=9779

If it is, how will you be able to turn outboard?

 

[Bart Leetch]

Is this the lathe you're thinking of upgrading:
http://www.owwm.com/photoindex/detail.aspx?id=9779

If it is, how will you be able to turn outboard?

waltben

There are several models of the Doubleduty lathe mine has both inboard & outboard ability & has 5 1/2" from bed to center of arbor.

 

[James E Gaydos]

Tell us more about the VFD and Motor size HP etc.
Jim