View Full Version : "Phasing" a CNC Lathe

11-21-2003, 11:35 PM
Got this CNC Lathe, Naka-Tome Slant 2 lathe I have written about before. Got it in July. FINALLY got the power to it Wednesday, our shop maint man a bit slow and a bit irritated by this all...but I digress

The electrician hooks the power up, then says i need yet ANOTHER electrician to come in and "Phase" the machine. I know he is talking about setting the legs of power correctly to get the spindle running in the right direction, but my school maint man says that if I am NOT phased right, I will blow the machine right up, the servos will "run away", the control will burn out ASAP, and pumps will blow, the world will end.......

So, the end result. I had an electrician picked out who does industrial work, I had to go with a guy who does not (but in defense, he is the best residential electrician in three states, and I would hire him in a heartbeat for my home or a normal business), but NOW, I have to pay again to get an electrician, the guy I wanted the first time, to come in and "Phase" the machine.

The question, is this something I can do by being cautious, switching the "three phase legs" if needed, and will I blow the heck out of the machine if I switch it on just to check?

Am I being fed a load of malarky, or is this a valid concern?

Rich Carlstedt
11-22-2003, 01:08 AM
What does your manual say ?
Is it a new machine ?
Any wires disconnected and reconnected internally?
Normally, Phasing in is done by the installing electrician with a person who can tell him the proper direction of the motors...IF THEY ARE NOT MARKED..
If marked, then he should be able to do it alone...
If he was hired to just drop power to the machine, then he was correct and advised you to phase it so nothing wrong would occur ...also "relieves him" of liability if something goes amuck.
If this is a used machine, all the motors should be phased together already....as long as nothing was disconnected internally at any time !
If your spindle is DC drive or AC VFD, then the drive system should not need anything in my opinion, but any Hydralic pump ( and coolant!) must run right, or you could damage something...I believe..
The manual and the manufacturer are your best source for answers.

11-22-2003, 01:17 AM
The correct answer is probably "It depends."
Three phase machines are typically 240 or 480 volts, or something close depending on local power supply.
If a machine wired for 240 is powered up with 480, large quantities of smoke will result. If the reverse, there will be less smoke, and it will take longer to develop. If you do not know for sure that the machine is wired for the power at hand, a qualified electrician should check it out as the motors and transformers will have to be rewired, and changes made to fuses and starters to accomodate the house voltage.
If you do know for sure that the voltages are compatible, probably the worst case is that it will run backwards. That is easily rectified by switching two of the incoming power legs.
I can tell you by experience that it is not a good idea to rely on stickers or signs to determine voltage on a used machine, the only way to be sure is to check the physical connections.

11-22-2003, 01:59 PM
ANother worry..

If the lathe uses 120 without a stepdown transformer but off the 3-phase.. sometimes you have a hot leg that floats from 90 volts to 180 to the neutral.. Known as the stinger leg. It'll smoke 120 volt devices, thou measuring to the other phases with a voltmeter it is rock steady. I guess that just showes what you always should have been taught, voltage is according to Forward or reverse flow potential.

Check the motor wiring, the transformer taps to make sure it is set up for the right voltages. That would smoke some expensive parts..

You got 240 3 phase?

I am in North georgia, a old grey electrician who has specialized in industrial controls and robotics. I'll help you anyway I can.

I installed a single phase in-3phase out inverter to run my cnc' bridgeport head. I had to install a new transformer for the stepper drives.

Mine works great now, I just have WINDOWS problems..

What software you using? I have Qstep on mine, Love to machine using the joystick thou. We did some Visual basic software on here a while back..

Really a lot of fun.. if you plan on keeping the machine, become familiar with it, get schematics, manuals, all the data you can find on YOUR model. Otherwise plan on spending money each little bitty problem. Just like owning a harley if you don't do your own work. Prepare to have sex, and not the fun kind, electricians can be mean when we hand bills for labor..

Sorry about the long post. Going to take a nap now..

11-22-2003, 08:38 PM
A machine I purchased new had instructiions how to "phase" easily. The machine had three main three phase motors which all came from the factory wired for the correct phasing between them. They advised testing the hookup for direction by only powering the coolant pump. Once that was correct, the others would be too.

Their concern was running the hydraulic pump backwards.

The electronics and servos ran off 120V so phasing wasn't an issue.

Bill Neufeld
11-22-2003, 10:13 PM
Ditto all of the above.Have the electrician call the service dept of the distributor for any information that is not in the manual and for any start up precautions.
If the manual has instructions for phasing the incoming power an electrician can hook up a phase indicator and check that it is per the manual.(You did get manuals with the machine?)
Is the voltage incoming per the manufacturers specification on the name plate? Are all the correct fluids in the reservoirs? Hydraulics, way lube,coolant?. Do not run any fluid motor without fluid in the reservoir.
Before powering on for the first time ensure that any/all E-stops are engaged. Pull fuses/trip breakers; overloads to the spindle drive and servo drives.This should confine any loss of smoke to the control section. The control should have a power supply which is fused or has a breaker. Close the doors on the machine and turn on the power. Assuming all is ok the control may display a test sequence at the end of which it will likely display some error messages, E-stop; phasing incorrect,lack of power to spindle;servos.If the control does not start up check for blown fuses tripped breakers.At this point I would try to run the coolant pump for 1 second while having someone watching for the rotation on the motor.If there is any indicator on the motor this should give an indication if the phasing is correct.
Assuming that phasing is correct I would restore fuses/reset breakers/overloads for 1 section at a time and power up to check that each does not lose smoke.After each section is restored you should have less error messages on the screen. At the end of which all E-stops are taken off. Then try to manually jog the axes at a slow speed. All is good? Home all axes and you are ready to make chips.
Happy chip making.

Bill Neufeld
11-22-2003, 10:23 PM
For fluid motor read pump motor. Sorry about that.