Powermatic motor swap

[measure once cut remeasure]

Anyone ever swap out motors on a pm 90 ?

My lathe has a single phase 1 HP, and I'm considering switching out the motor for a 3 phase.  I already have a phase converter that is being used on my drill press that sits next to the lathe.

I'm looking to run the lathe at a slower speed than what the reeves drive provides.  The current motor looks to have a 56 frame.  There isn't a lot of extra space but I would prefer a 1.5 or 2 HP versus the current 1 HP.

[Arlin Eastman]

Karl

I am thinking someone has done this before but I do not remember for sure.  Also if you do take off the reeves drive and put on a normal pulley since you have the phase converter to turn the speed up or down, or maybe I am not thinking right on that part.  I know I do not like the reeves drive and think it is a pain and heard of them breaking down all the time.

I know someone will be along to correct me or suggest a better way.

Looking forward to seeing it when it is done. 

[TDKPE]

Find a 1200 rpm 3-phase motor (usually 1140 rpm nameplate).  They're not nearly as common as 1800 and 3600 rpm motors, but there are at least a few (sometimes a bunch) on ebay all the time, so not that difficult to find.  That will put the 'normal' speed range down to 2/3 of the original to start with, and makes it easier to slow it down from there as you won't be losing torque as fast as you will with an 1800 rpm motor (you're starting with 1-1/2 times as much as the 1800 for the same hp rating).  

Go up in hp if you want.  I would recommend you do anyway with a VFD, as they run in constant-torque mode below 60Hz output, so running the motor at half-speed will give you half-power for instance.  Lathes available with either fixed-speed motors and belt speed variation, or with a VFD for variable speed, are normally sold with the VFD version having a much larger motor.  For that reason.

So starting with a slower motor right out of the gate, say 1 hp at 1200 rpm for example, would be essentially the same as having a 1-1/2  hp 1800 rpm motor and VFD and slowing it down to 2/3 speed.  Go up in motor power and lower in speed, and you'll have a tractor.

But do watch the frame size.

[MichaelMouse]

Find a 1200 rpm 3-phase motor (usually 1140 rpm nameplate).  They're not nearly as common as 1800 and 3600 rpm motors, but there are at least a few (sometimes a bunch) on ebay all the time, so not that difficult to find.  That will put the 'normal' speed range down to 2/3 of the original to start with, and makes it easier to slow it down from there as you won't be losing torque as fast as you will with an 1800 rpm motor (you're starting with 1-1/2 times as much as the 1800 for the same hp rating).  

In case you're confused, the 1200/1800/3600 are nominal rpm @ 60Hz. "Slip" makes them into 1140/1725/3450 you see on the nameplate.

[measure once cut remeasure]

Find a 1200 rpm 3-phase motor (usually 1140 rpm nameplate).  They're not nearly as common as 1800 and 3600 rpm motors, but there are at least a few (sometimes a bunch) on ebay all the time, so not that difficult to find.  That will put the 'normal' speed range down to 2/3 of the original to start with, and makes it easier to slow it down from there as you won't be losing torque as fast as you will with an 1800 rpm motor (you're starting with 1-1/2 times as much as the 1800 for the same hp rating).  

Go up in hp if you want.  I would recommend you do anyway with a VFD, as they run in constant-torque mode below 60Hz output, so running the motor at half-speed will give you half-power for instance.  Lathes available with either fixed-speed motors and belt speed variation, or with a VFD for variable speed, are normally sold with the VFD version having a much larger motor.  For that reason.

So starting with a slower motor right out of the gate, say 1 hp at 1200 rpm for example, would be essentially the same as having a 1-1/2  hp 1800 rpm motor and VFD and slowing it down to 2/3 speed.  Go up in motor power and lower in speed, and you'll have a tractor.

But do watch the frame size.

Thank you for the advice on motor speed.  Space is going to be the major limiting factor. Going to have to measure what little excess space is around the current motor and then remove it.  There is more space below the motor, in the storage area under the headstock.  Jury rigging a motor mount in the storage area could be an option.