Spindle locks up when I power up my RPC

skeeks · Oct 12, 2017

Hey guy, I just got done wiring up the American Rotary AR-10 for my Romi 13-5 lathe. It’s a 5.5 hp motor on the lathe. The idler motor starts right up and the lathe shows it’s getting power (via the light for the e stop). However before I turn on the power switch on the back of the lathe, I can spin the spindle by hand. Once it shows it’s getting power I can no longer spin the spindle by hand even when it’s not in gear.

Lathe worked perfectly when plugged into 3 phase before it was transported.

Any help would be much appreciated.

SAF · Oct 12, 2017

Make sure that the wild leg from your RPC, is not connected to the two legs that power the control power circuits in the machine.

SAF Ω

skeeks · Oct 12, 2017

SAF said:
Make sure that the wild leg from your RPC, is not connected to the two legs that power the control power circuits in the machine.

SAF Ω

Wild leg? I’m extremely electrically “special.” Gotta really walk me through it.

JST · Oct 12, 2017

skeeks said:
Wild leg? I’m extremely electrically “special.” Gotta really walk me through it.

The "wild leg, or "generated leg" is the one that is NOT passed through from the source.... The wire that starts at the RPC.

If that powers controls, it can cause problems if, as is nearly certain to happen, the voltage on that "generated leg" drops lower than normal line voltage as a motor is started on the machine that the RPC powers. Motors pull many times their normal current as they start. Anywhere from 4 to 8 times normal current, depending on the motor design.

The voltage drop can cause controls to misbehave.

That said, what do you mean by "spindle locks"? What spindle, and what do you mean by "locks"?

Do you mean it stops? Do you mean it cannot be turned? Please explain further.

Monarchist · Oct 12, 2017

skeeks said:
Hey guy, I just got done wiring up the American Rotary AR-10 for my Romi 13-5 lathe. It’s a 5.5 hp motor on the lathe. The idler motor starts right up and the lathe shows it’s getting power (via the light for the e stop). However before I turn on the power switch on the back of the lathe, I can spin the spindle by hand. Once it shows it’s getting power I can no longer spin the spindle by hand even when it’s not in gear.

Lathe worked perfectly when plugged into 3 phase before it was transported.

Any help would be much appreciated.

An E-stop didn't perchance get pushed during the move, did it?

Many require a manual pull-out and/or twist to reset.

skeeks · Oct 12, 2017

JST said:
The "wild leg, or "generated leg" is the one that is NOT passed through from the source.... The wire that starts at the RPC.

If that powers controls, it can cause problems if, as is nearly certain to happen, the voltage on that "generated leg" drops lower than normal line voltage as a motor is started on the machine that the RPC powers. Motors pull many times their normal current as they start. Anywhere from 4 to 8 times normal current, depending on the motor design.

The voltage drop can cause controls to misbehave.

That said, what do you mean by "spindle locks"? What spindle, and what do you mean by "locks"?

Do you mean it stops? Do you mean it cannot be turned? Please explain further.

When the lathe is not under power the spindle spins freely (in gear or not). When I turn on the power switch and breaker the lathe locks up. Almost like the brake is on and will not turn off.
Someone in another thread said something about adjusting the “adjustment pot” (no idea what this is or what he was talking about) for the electric brake.

On this specific lathe the apron power lever has 5 positions- forw, off, brake, off, rev. When I disengage the spindle form any gearing it is still stuck in place. However spins freely by hand when power is turned off.

skeeks · Oct 12, 2017

Monarchist said:
An E-stop didn't perchance get pushed during the move, did it?

Many require a manual pull-out and/or twist to reset.

Nope. Didn’t get touched... well unless a bird or something nailed it on the drive home haha (which did not happen).

skeeks · Oct 12, 2017

Here is a wiring diagram.

motion guru · Oct 12, 2017

The image you posted doesn't have enough resolution to be helpful.

skeeks · Oct 12, 2017

motion guru said:
The image you posted doesn't have enough resolution to be helpful.

Posted it from my phone. I’ll try to get a better picture up later.

JST · Oct 12, 2017

If the spindle locks as you say, then...

1) Sounds like the brake is indeed on. It may be on whenever the spindle is not supposed to be turning. Have you tried to RUN the machine? You only said "turned breaker and power switch on".

2) It is possible with a machine that is getting only two out of three phases, for the motor to not turn, and not be "turnable" but usually it will be obvious that power is applied, humming, vibration, etc, even if motor does not turn. This does not seem like your problem, though.

Big B · Oct 12, 2017

I'm wondering if you have a hot and ground switched. Just a wild ass guess but worth checking.

I had a South Bend lathe that I bought wired for 240 3 phase. It already had a plug on it so I figured it was ready to plug in. After considerable time and frustration I got my meter out and found that a hot and ground had been switched. Once I switched them back it ran fine for years.

skeeks · Oct 12, 2017

JST said:
If the spindle locks as you say, then...

1) Sounds like the brake is indeed on. It may be on whenever the spindle is not supposed to be turning. Have you tried to RUN the machine? You only said "turned breaker and power switch on".

2) It is possible with a machine that is getting only two out of three phases, for the motor to not turn, and not be "turnable" but usually it will be obvious that power is applied, humming, vibration, etc, even if motor does not turn. This does not seem like your problem, though.

I have tried to run it. Nothing happened- didn’t make a sound or anything. The power light under the e stop came on when under power until I switched the leads, which did nothin. So I switched them back and now the power light will not come back on so I’m guessing I blew a fuse? I’m not sure to be honest. I have a friend coming later with a multimeter. Hopefully that will help point me in the right direction.

I’ve checked the wiring time and time again for the RPC and it seems that everything is correct from the idler motor to the box, single phase input to box and box to plug.

JST · Oct 12, 2017

You likely need to verify that the voltages are present inside the machine at the connection block.

If that is OK, the problem must be inside the machine.

If it was converted from a higher voltage, the control transformer (I saw it on the diagram) may be wired for the higher voltage still, and as a result none of the contactors will close because they are getting low voltage..

Or a fuse could be blown.

Or, frankly, for any number of other reasons. Need more data, Pics of machine control box, good circuit diagram, pics of wiring..... etc.

mksj · Oct 12, 2017

A larger version of the schematic is attached. The RPC generated or wild leg should be attached to L3 per the schematic, the two leads L1 and L2 going to the power transformer should be the non-generated leg. The lathe motor is equipped with a brake solenoid, which is activated in the stop position. It will also remain locked if the Master Relay CR1 is tripped, this will result in the solenoid brake remaining engage and the motor rotation contactors to be inactivated. Double check to make sure the emergency stop button is not pressed (the power light remains on independent of the E-Stop). Check that the gear box cover and Klixon limit switches are not tripped. Check to see if the coolant pump works.

The spindle looks to have 5 positions, center brake on next position off and turns on CR1 then run. Also check if there is not a start or reset button that has to be pressed at when powered up.

You can map out voltages at the control terminal strip outlined in the manual.

JST · Oct 12, 2017

Yes, the E Stop and the gearbox door can stop everything, as can the motor overtemp switches. Also check the motor overload, OL1. It might need to be reset. .

Those are what stops CR1 from closing, which should release the brake. If that does not fix it, the apron switch needs checked, because it closes CR1. Once CR1 is closed, it is "sealed" in closed position by it's latch contact, until power is removed.

probably you need to check that CR1 gets closed. Once that happens, everything should work. It appears that you need to move the apron control out of "brake on" to make CR1 close, after which it should stay closed on its own.

72bwhite · Oct 12, 2017

and is it properly phased?

skeeks · Oct 13, 2017

Got it figured out. The center pin was punched out on the selector switch. Got that fixed, then discovered the motor and transformor were wired for 480v instead of 230v like we were told. The brake was engage and now works perfectly

JST · Oct 13, 2017

Super.

I hope our suggestions helped

skeeks · Oct 14, 2017

JST said:
Super.

I hope our suggestions helped

They definitely did. I had a buddy come over that owns a car audio business and understands electronics. He sorted it all out in a couple hours. So i definitely can't take credit for it. You guys will be seeing some of my barrel work and probably questions in the gunsmithing section here in the coming months.

Now comes the fun part... tooling this thing up. I'm looking for turning, parting and laydown threading tools (that hold carbide inserts) with 1/2" or 5/8" shanks. If you guys know of any place in particular, point me in the direction!

Spindle locks up when I power up my RPC

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