# OEM VFD on lathe vs. Full Gear Head with Aftermarket VFD



## Ed W (Feb 28, 2014)

Hi Everyone!
I've had a PM-1030 lathe that I've been very happy with but outgrown.  I've had an order in with Matt for a Taiwan-built PM-1440TS thinking I would add a VFD to the 3 hp 3 phase spindle motor and change the controls to match the pre-VFD, etc.  On the PM-1440TV model the lathe is supplied with a larger motor, 5 hp, and a Yaskawa V1000 VFD that will allow me to run the lathe on single phase.  The fully gear head model has 12 speeds down to 50 rpm and the TV model has 2 geared ranges with the VFD supplying the speed ranges otherwise.  I believe the speed ranges are 36-360 rpm and 220-2200 rpm.  My question is, will I notice at lower speeds a distinct difference between the fully gear head lathe and the gear plus VFD model?  Less gears usually translate to a smoother finish and less noise.  Five hp would seem to be more than sufficient for a 14 inch lathe.  It would be easier not to have to add the VFD and change all the control circuits.  Any opinions (especially from Ray C!).
Thanks.
Ed


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## hvontres (Feb 28, 2014)

I can't speak for the PM lathe, but we have a Kent 14x40 lathe with VFD in the Prototype shop at work. It seems to work pretty well, and being able to "tweak" the RPM during a cut is pretty nice. Also, you are not limited to the 12 speeds that some committee decided on at some point. Hope this helps.


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## Ed W (Feb 28, 2014)

hvontres said:


> I can't speak for the PM lathe, but we have a Kent 14x40 lathe with VFD in the Prototype shop at work. It seems to work pretty well, and being able to "tweak" the RPM during a cut is pretty nice. Also, you are not limited to the 12 speeds that some committee decided on at some point. Hope this helps.



Thanks, that's very helpful since the Kent 1440 and the PM lathe have generally the same speed range and a 5 hp motor.


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## Ray C (Feb 28, 2014)

Ed W said:


> Hi Everyone!
> I've had a PM-1030 lathe that I've been very happy with but outgrown.  I've had an order in with Matt for a Taiwan-built PM-1440TS thinking I would add a VFD to the 3 hp 3 phase spindle motor and change the controls to match the pre-VFD, etc.  On the PM-1440TV model the lathe is supplied with a larger motor, 5 hp, and a Yaskawa V1000 VFD that will allow me to run the lathe on single phase.  The fully gear head model has 12 speeds down to 50 rpm and the TV model has 2 geared ranges with the VFD supplying the speed ranges otherwise.  I believe the speed ranges are 36-360 rpm and 220-2200 rpm.  My question is, will I notice at lower speeds a distinct difference between the fully gear head lathe and the gear plus VFD model?  Less gears usually translate to a smoother finish and less noise.  Five hp would seem to be more than sufficient for a 14 inch lathe.  It would be easier not to have to add the VFD and change all the control circuits.  Any opinions (especially from Ray C!).
> Thanks.
> Ed



Ed...

  Those lathes are generally not found in in the hobby realm but, we can certainly discuss them...  They are the "industrial versions" of the Taiwanese 1340GT.  It's a highly refined lathe, same fit and finish as the 1340GT but, twice the mass.  It has a 9" wide bed and weighs in the 2700 lb range if I'm not mistaken...  Very high end...  I've enclosed some eye candy and yes, I can get them...

So, to your question...  When you put a VFD on a regular multi-speed lathe, you still need to change gears a lot.  In those operational scenarios, the VFD speed should only be varied between about 50 and 65 Hz.  So, if you're in a gear and don't like the speed, you can tweak it up or down and if you still are not happy with the cut, you need to shift the gear lever to the next desirable speed -and then, you can fine-tune with the VFD.  When you do it this way, you preserve the torque capability of the motor.

When you have a 2 speed gearbox that is primarily controlled with a VFD, you need a lot of horsepower in the motor to cover the cases when the motor is spinning at low RPM.  That is why two speed machines need a 5 HP motor.

Which is better?  Neither.   All depends on convenience.  On machines like that, with balanced and honed gears and multi bearing spindles...  They both cut real good...  It's all about suiting different preferences...

I would really like to have that machine but, it's not in the cards...






Ray


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## Ed W (Feb 28, 2014)

Thanks, Ray.  I've had the order in with Matt for about 3 months now.  The question was just the TS vs the TV version.  It seems that this is a non-problem.  I've left word with Matt that I'll go with the TV version.  Enough said.  I will post pics when it arrives (eventually)!
Ed


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## Ray C (Feb 28, 2014)

Ed W said:


> Thanks, Ray.  I've had the order in with Matt for about 3 months now.  The question was just the TS vs the TV version.  It seems that this is a non-problem.  I've left word with Matt that I'll go with the TV version.  Enough said.  I will post pics when it arrives (eventually)!
> Ed



You've got good taste in lathes....  Those are outstanding machines and an outstanding (and I truly mean it) financial value.   Very, very high end and very, very robust and still capable of cutting with delicate precision...  That is as versatile of a manual lathe as you'll ever get!


Ray


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## Ed W (Feb 28, 2014)

I only wanted to buy this size lathe once.  Anybody want to buy a PM-1030?


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## Ed W (Mar 2, 2014)

PM sent to Ray C. Thanks.


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