# Possible electrical issue with new G9972Z lathe



## Road_Clam (Mar 12, 2022)

So i'm observing an odd issue with my new lathe. When I power up the lathe pushing the green power button, I then attempt to rotate the spindle  "L - R"  switch to either rotation position and I see the spindle rotate a tiny bit and then nothing. I have to put the spindle switch in either L or R position FIRST then press the green power button for the spindle rotation to start. Seems like some type of internal circut breaker keeps tripping off when I try to use the spindle switch.  Are you supposed to be able to flip the spindle switch back and fourth between L and R  while the lathe is powered up ? If I continue to press and hold the green power button then I can switch back and fourth with spindle rotation and the spindle turns as it should.  I'm confused as to what's going on. Sounds like by reading the manual you should be able to switch rotation direction under power via the spindle switch.


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## Jim F (Mar 12, 2022)

Page 19 of the manual says to wait for spindle to stop before changing direction.....
Good practice with a threaded chuck.


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## Mitch Alsup (Mar 12, 2022)

Only machines on 3-phase power can reverse while the major component is spinning.


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## WobblyHand (Mar 12, 2022)

Have an earlier Grizzly.  G0752Z.  I push the green button to start.  Wait a little and turn the F/R switch to either F or R, but not flipping one to the other.  Spindle rotates in the correct direction.  To stop, can push the STOP button, or turn the F/R switch in the middle.  If turned to the middle (neutral?) the lathe spindle rotation can be started again by changing the F/R switch position.

My lathe will not start up if the F/R switch is not in neutral.  Safety.  This is a good thing.  Read the manual, there is a lot of stuff hidden in there!


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## Road_Clam (Mar 12, 2022)

OK, let me further clarify, i'm clear on the fact you need to wait until the spindle is completely stopped before reversing the switch direction. My issue is happening when the spindle is completely stopped.


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## WobblyHand (Mar 12, 2022)

Ok.  Let's' start over again.  Lathe power is on.  Switch is in neutral.  You turn the switch to F(orward)  normal rotation.  What happens?
The spindle rotates a little then stops rotating?  Or what?  If it stops, is the power to the lathe still on, or do you have to turn it back on again?  The more succinct your description, the easier it is to help.

By any chance does your lathe have a VFD?  Are you plugged into a GFCI outlets?  Might as well ask the question.


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## Road_Clam (Mar 12, 2022)

WobblyHand said:


> Ok.  Let's' start over again.*  Lathe power is on.  Switch is in neutral.  You turn the switch to F(orward)  normal rotation.  What happens?*
> The spindle rotates a little then stops rotating?  Or what?  If it stops, is the power to the lathe still on, or do you have to turn it back on again?  The more succinct your description, the easier it is to help.
> 
> By any chance does your lathe have a VFD?  Are you plugged into a GFCI outlets?  Might as well ask the question.


The spindle won't power up and turn with this sequence of conditions. And if I keep the switch in the "F" position and push the green power button the spindle then starts as it should. It's becoming clear to me there is some type of internal circuit interrupt fault that keeps tripping and seems to be associated with the "on/off" main switch. Lastly  no VFD and no GFCI outlet power supply. The circuit is adequate as I also run my air compressor off the same circuit. I'm going to give Grizz tech support a call and see what they say. I just want to make sure that i'm not incorrectly operating the power controls. 

small world, we are practically neighbors...


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## WobblyHand (Mar 12, 2022)

Road_Clam said:


> The spindle won't power up and turn with this sequence of conditions. And if I keep the switch in the "F" position and push the green power button the spindle then starts as it should.


Does the spindle stay on?  You haven't explicitly stated that in this description.  We aren't in the same room, so we need to make sure we understand.  It starts then quits after a while?


Road_Clam said:


> It's becoming clear to me there is some type of internal circuit interrupt fault that keeps tripping and seems to be associated with the "on/off" main switch.





Road_Clam said:


> Lastly  no VFD and no GFCI outlet power supply. The circuit is adequate as I also run my air compressor off the same circuit. I'm going to give Grizz tech support a call and see what they say. I just want to make sure that i'm not incorrectly operating the power controls.



I just downloaded the manual.  It seems the operating procedure is different from my lathe.  

You are quite correct that you turn the spindle direction first, then the power.  Are you saying if you do this the motor stops after a second or so? 

Schematic looks simple.  Maybe a bad run capacitor or faulty switch?  Don't see any interlocks.


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## Bi11Hudson (Mar 12, 2022)

What he is asking about is the speed control vs power on circuit. It is common on small lathes and milling machines where they *must* start at lowest speed. That has to do with the design of the controller board. Presetting direction before starting is preferred even on three phase. Presetting speed before starting is akin to starting an auto. The speed control must be at the lower end to start. I have a mini-mill that is used as a drill press for small drills where speed must be below 60 RPM to prevent melting through plastic. I had given some thought to eliminating that start-speed function but realized that most of my work is at low speed anyway so why bother. It may have some relation to safety or making the board with a lower component count, I don't know. . . or care. I don't like it but can't create the gumption to do anything about it.

.


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## WobblyHand (Mar 12, 2022)

Bi11Hudson said:


> What he is asking about is the speed control vs power on circuit. It is common on small lathes and milling machines where they *must* start at lowest speed. That has to do with the design of the controller board. Presetting direction before starting is preferred even on three phase. Presetting speed before starting is akin to starting an auto. The speed control must be at the lower end to start. I have a mini-mill that is used as a drill press for small drills where speed must be below 60 RPM to prevent melting through plastic. I had given some thought to eliminating that start-speed function but realized that most of my work is at low speed anyway so why bother. It may have some relation to safety or making the board with a lower component count, I don't know. . . or care. I don't like it but can't create the gumption to do anything about it.
> 
> .


This lathe doesn't have a speed control circuit.  The speed is controlled only by the pulleys and the base 1725 rpm motor speed with internal centrifugal switch.  There is no rheostat or pwm circuit to change speed.  There are 6 spindle speeds, 150, 300, 560, 720, 1200, and 2400 RPM. Page 65 of the manual shows the wiring diagram.  Has an on off switch, a spindle switch, a start capacitor and a run capacitor, that's it for electronics.


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## Road_Clam (Mar 12, 2022)

WobblyHand said:


> You are quite correct that you turn the spindle direction first, then the power.  Are you saying if you do this the motor stops after a second or so?


If I set the spindle  switch to L or R position first, then press the power button the spindle starts are runs as it should.  I also re-read the "test run" pp 19 proceedure of the manual and i'm still confused as the manual seems to call out performing both spindle startup methods. I'll post a Youtube vid tomorrow and it will show you exactly how i'm working the power switches.


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## WobblyHand (Mar 12, 2022)

Road_Clam said:


> If I set the spindle  switch to L or R position first, then press the power button the spindle starts are runs as it should.  I also re-read the "test run" pp 19 proceedure of the manual and i'm still confused as the manual seems to call out performing both spindle startup methods. I'll post a Youtube vid tomorrow and it will show you exactly how i'm working the power switches.


I just read that page.  My take on the test procedure

1. Set direction switch to R
2. Press power on button.  Spindle should rotate in correct direction.
3. Set direction switch to O position.  Wait for the spindle to stop.
4. Set direction switch to L.  Spindle should rotate in the opposite direction.
5. Push Red off power button.  Spindle should stop.  This is a test of the Emergency stop

If you can do all the steps as above, the lathe is fine.


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## markba633csi (Mar 12, 2022)

Sounds normal, I believe the system won't allow an incorrect startup sequence- it's trying to protect itself (and you)


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## WobblyHand (Mar 12, 2022)

markba633csi said:


> Sounds normal, I believe the system won't allow an incorrect startup sequence- it's trying to protect itself (and you)


I just read the steps out of the manual, attempting to paraphrase them.  The OP was unsure how to interpret the procedure.


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## Road_Clam (Mar 13, 2022)

And to make the situation even more weird I actually had more success today moving the spindle switch between L and R  and the spindle responding as it should powering up in each direction. This seems to be a random issue.


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## WobblyHand (Mar 15, 2022)

Bad switch contacts?  Tarnish from the container ship ride to the US?  Seems that it sometimes works as stated in the manual.
Also could be rough shipment.  Might want to open it up and check if the connections are on tight.  Maybe the connectors  need to be slightly tightened a tiny bit.  Seems pretty odd.  It should work the way the manual states.  

By the way, you probably shouldn't spin the chuck that way with nothing in the jaws. You could tighten the jaws to meet in the center.    They don't need to be ridiculous tight, but at least snugged.  Would really be a bad thing if a jaw decided to go flying.  Machines won't care or weep if they kill you.


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## Mitch Alsup (Mar 16, 2022)

When I got my G4004G 12×36 lathe, the forward/reverse switch on the skirt did a few "wierd" things. 
I traced it down to the cam near the Norton Gearbox housing, got out some allen wrenches, and adjusted the position of the cam to match the positions of the detents on the skirt.
Has worked ever since.

Perhaps you should dig into the switch (with power off of course) to see if there is anything you can see akilter, or measure with a A/C volt meter.


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## Road_Clam (Mar 28, 2022)

Update. Since i  moved my lathe down into my basement workshop AND added a 20A dedicated power circuit my above described occurrence has disappeared. When i was having all my issues was trying to run the lathe out in my shed on a 15a circuit with an extension cord,  and in cold weather. Ill bet the lathe internal on/off switch circuit breaker is very sensitive to amp draw. The lathe rotational switching functions perfect now.


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