Variable Speed on Lathe

Rich Aldrich

Member
Messages
296
Location
Manistique, Michigan
I am considering a lathe and of course going through the whole gamet of research. I started thinking....

One of the issues with the Griz and ShopFox lathes is that the low end speed is not low enough. Even on the Nova 1624-44 or Jet 1442, variable speed would be nice.

At the paper mill where I work, we are installing a lot of ABB variable speed drives on equipment. These are 3 phase, 460V. I asked one of our electrical engineers if ABB makes a single phase variable speed 110V. He checked into it. ABB makes single phase, 220V in 1 HP, 2 HP and 3 HP. The price for a 2 HP is about $170 and a reostat for about $12. If you had a tach on the lathe, you could get a digital controller instead of a reostat. I think, no guarrantees, one of these drives would work on a lathe as long as the motor can be rewired for 220V.

Ideally, the motor should be rated for variable speed, but we have not had much trouble with motors with variable speed drives. Most of ours are not rated for variable speed drives.

The drive has the capability of spinning backwards and can run the motor a bit overspeed.

Any thoughts?
 
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Rich, I used to be an application applications engineer of variable speed drives and have written several paper on using them on lathes. If applied right they can be very nice tools but if done wrong they can be a PIA. I'll try to find some of the info I have psoted previously.
 
I responded to you with a PM on several issues.
The low end speed issue is a matter of cost vs. versatility. Yes, Reeves drives generally have a fairly high low end speed. But, consider that most of those lathes cost a fraction of what a good EVS would sell for. It is a matter of what you want vs. your budget.
 
I am trying to come up with an option that is lower cost than the OEMs. One issue is that although the input is single phase, the output is 3 phase. You would have to replace the motor with a 3 phase motor. I am not sure, but this probably changes the frame size, which would require motor mount modifications, belt changes (possibly length), etc.... probably not worth it.

The do have an option for DC output, but that requires similar changes as 3 phase.

Oh well, back to the standard commercially available stuff.

I will probably buy a Nova 1624-44 when I can.
 
I am trying to come up with an option that is lower cost than the OEMs. One issue is that although the input is single phase, the output is 3 phase. You would have to replace the motor with a 3 phase motor. I am not sure, but this probably changes the frame size, which would require motor mount modifications, belt changes (possibly length), etc.... probably not worth it.

The do have an option for DC output, but that requires similar changes as 3 phase.

Oh well, back to the standard commercially available stuff.

I will probably buy a Nova 1624-44 when I can.

craft supply has them on sale with free bed ext. and free chuck for around 1000.00 plus fright fright will be lower if you can send it to a com loading dock
thats what i did last week talk to roger at csusa
 
I am trying to come up with an option that is lower cost than the OEMs. One issue is that although the input is single phase, the output is 3 phase. You would have to replace the motor with a 3 phase motor. I am not sure, but this probably changes the frame size, which would require motor mount modifications, belt changes (possibly length), etc.... probably not worth it.

The do have an option for DC output, but that requires similar changes as 3 phase.

Oh well, back to the standard commercially available stuff.

I will probably buy a Nova 1624-44 when I can.

My Grizzly, and I presume the Jet clone, converts to 3 phase. There is a box full of electronic black magic on the back of the headstock that does this. And, the instruction manual warns "hands off".
 
Rich,

Another option would be to pick up a DC motor and DC drive. On eBay, I've picked up a number of DC motors and a couple KB Electronics drives to run them. The KBIC Series use a plug in resistor to match the HP rating of the motor. http://www.kbelectronics.com/catalog_chassis.htm That gives a bit more leeway when trying to match parts.

Just food for thought.

Wes
 
I wound't ever use a DC motor on a Lathe due to the loss of HP. They are constant torque device and Horse power is what you want especialy when turning at low speeds. There are a number of 3 Phase inverter (variable speed) AC Drive that run on 1 Phase.

Here is one source that I've used in the past.
http://www.driveswarehouse.com/

I don't understand everthing you say. But, wouldn't this by why DC motor lathes (many/most, at least) use a dual-range step pulley and belt arrangement?
 
I don't understand everthing you say. But, wouldn't this by why DC motor lathes (many/most, at least) use a dual-range step pulley and belt arrangement?
Yes it is and also they have to over size the motor.
If you have a large diameter piece you need more torque to remove the same amount of material then you need with a small diameter material. Generaly speeking you will turn the larger diameter material at a slower speed them you turn a small dia mater. HP is Torque x RPM/K Therfore low speed more torque = higher HP.
 
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