[snascar2424]

I just bought a chnc II super precision gn10 control basically a fanuc control.
When i first fired the machine off i tried to start the spindle speed around 200 rpm's but the position page showns only 184 rpm's. Now i think the problem may be that the machine needs 230 volts and i have approx 214-217 volts a little low. What i think i need to do is get a step up transformer to get it around 230 volts +- 5%. This seems to be what i was told in the past. The spindle when it is running almost seems to hit the brake just for a split second. If any one has had this problem please let me know I think I'am correct that i need at least 219 volts for the machine to operate correctly.

[Al_The_Man]

That does not appear too low to cause you problems, the spindle operates on frequency, so especially on no load, I doubt raising the voltage will make a difference.
Normally Japanese/Fanuc machines have a ±10% tolerance for supply, and most Fanuc use 100vac and 200vac for control voltage.
Measure some point in the cabinet where the 200v is distributed, that should tell you how much you are out.
Al.

[snascar2424]

I was told that the voltage will not cause what is happening but i just had the machine moved and think maybe the brushes need to blown out or changed. maybe dirt has got on the armature and is the source of the problem. I ran the spindle up to full rpm before no problem or thing different is voltage and moving the machine. The only other thing i have done is clean the machine from top to bottom.

[Al_The_Man]

I didn't realize you had a DC spindle motor, but I still think the voltage is not a problem.
Is the spindle % error the same across the speed range?
Al.

[jabernowl]

try making a threaded part...if it works you should have no problem. had my machine for years and it always been a little off on the rpms.

[Al_The_Man]

try making a threaded part...if it works you should have no problem. had my machine for years and it always been a little off on the rpms.

Shouldn't make alot of difference, the Z usually follows (geared off) the spindle encoder on threading and tapping.
Al.

[snascar2424]

The thing is that the motor is jerking like a loss of power talked with a fanuc repair guy out here and he saids voltage not a problem. I just got the machine so if there is a problem then i want to deal with it now. I'am not to worried about the difference in rpm as much as the motor cutting in and out. thanks for the info.

[Al_The_Man]

Considering the age of the machine, it could be likely that the motor has not seen any maintenance in a while, DC motors accumulate alot of carbon and brushes and comm wear, as well as tachometers.
It might pay to give it a good inspection as well as the servo's, which assume would also be DC brushed.
Al.

[snascar2424]

I had loose connection from moving machine.