How does a VFD integrate with manual lathe and mill speed functions?

adamsgt

adamsgt

Jerry Adams
Didn't want to hijack the thread on the Bridgeport mill but the discussion on adding a VFD got me going to the Temco web site to peruse various
VFD products. The main question I came away with was How does the VFD work in conjunction with the gear selection on my lathe or the pulley drive on my mill. My lathe runs on 230v single phase and the speed is determined by setting a gear train in the headstock. My mill is 230v 3 phase and is currently running off a rotary phase converter.

For the lathe, if I installed a VFD would I set the gears to produce the highest speed and then the VFD would vary the speed on the motor to produce the desired rpm? As the current motor runs at one speed, is this good for it? My mill is a Taiwanese Bridgeport clone with the speed crank on the head. Would the same principle apply here? :confused:
 
Nope

A search for "VFD" comes up empty on these sites. Must not be holding my mouth right.
 
I have both lathe and mill on VFD. The lathe is belt drive Jet 13x 36 and I have the belts in the position that produces 1200 RPM on the spindle @ 120 Hz on the motor. The motor is a Siemens TEFC, 2 Hp, 4-pole ( 1750 RPM @ 60 Hz). This arrangement has proven to be completely satisfactory for about 15 years.

The mill is a J head Bridgeport with the original 1 Hp motor (230V, 4-pole). The belt is positioned to give 2250 RPM on the spindle @ 120 Hz on the motor. This has proven to be the ideal position for my use.

I have never needed back gear on either machine. I recommend Automation Direct as a source for VFD and associated controls. They have a full selection, good pricing, and very good tech support.

RWO
 
The lathes that are built for VFD operation have cooling fans on the motor that run all they time that the lathe is running. The cooling fan runs full speed all the time. When you run a motor with a VFD, the motor has to be a three phase motor. You can either run it with single phase power in or three phase power in and three phase coming out of the VFD. My lathe has a high speed and low speed range with a speed of 80 rpm to 500 rpm on low speed and 500 to 3000 rpm on the high speed side. With a geared head lathe, having VFD control will not be of as much benefit as it would be on a belt drive lathe, although you could run it on a medium speed and have the ability to go up a little from the rated speed to just about as slow as you would want to run it by varying the VFD. If you run it at slow speed for very long, you will need a fan on the motor for cooling. The motor that is made to use with a VFD is called an inverter motor. I also have a LeBlond geared head lathe, that I haven't worried about getting a VFD for it, just put it in the correct gearing for what I want to do with the lathe.
 
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RWO said:
I have both lathe and mill on VFD. The lathe is belt drive Jet 13x 36 and I have the belts in the position that produces 1200 RPM on the spindle @ 120 Hz on the motor. The motor is a Siemens TEFC, 2 Hp, 4-pole ( 1750 RPM @ 60 Hz). This arrangement has proven to be completely satisfactory for about 15 years.

The mill is a J head Bridgeport with the original 1 Hp motor (230V, 4-pole). The belt is positioned to give 2250 RPM on the spindle @ 120 Hz on the motor. This has proven to be the ideal position for my use.

I have never needed back gear on either machine. I recommend Automation Direct as a source for VFD and associated controls. They have a full selection, good pricing, and very good tech support.

RWO
Click to expand...

+1

I have been switching to VFD on most of my ships electrical drives. Automation direct is one of our best sources, they will give you all the literature and tech help you can want. One thing we have found, if you VFD an exhisting motor, run it at lower RPMs without a motor fan, I have experience lower toque than the motors rated spec, generate motor heat (as allready stated) and also may heat up the the VFD in the process. For industrial, continuous, auto speed following or long term use, get a VFD rated motor. Hope this helps
 
I beleive the need for "inverter duty motors" on the typical home shop or gunsmith shop lathe or mill is greatly exagerated. The reason is that the duty cycle is very low and the motors themselves are very seldom if ever run at rated load for more than a few minutes. Now, for continous process VFD applications in industrial service, this is not necessarily true and inverter duty motors might be needed if the speed range and speed-torque characteristic demand it. Each application needs to be fully defined before spending extra money on unneeded capability.

RWO
 
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