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Question on Wiring Old Nakamura CNC Lathe

the average Joe

Aluminum
Joined
Nov 16, 2022
I recently acquired an older Nakamura Tome CNC lathe from 1981. I looked through the manuals and the only thing they mention about wiring is to have a power source with 3 phase 230 volt connections. I put the lathe in a spot where we used to have an old Vulcan CNC mill(gone before I started working here), and it has a fused disconnect from a 30 amp breaker that is set up with 10 gauge THHN stranded wire.

All of our HAAS mills, including our VF-8, are wired this same way.

Can I wire the lathe to the disconnect box using the same 10 gauge wiring? I read some other posts on the forum, and it seems like CNC lathes pull more amps than mills dues to the initial draw to spin up the chuck, but other than that there wasn't a lot of consensus on the wiring size.

Also, the main switch on the back of the cabinet is 100 amps, but I don't know if that factors into actual amps that the machine draws.

The breaker panel nearby used to support 3 older cnc mills, so I can probably get something going if I need to modify things.
 
Thats probably a little light for a lathe. If its a fused disconnect, what is feeding it? What is the capacity of the disconnect- it should be printed on the inside of the door. If the feed to the disconnect is large enough, swap out the fuses and rewire from the disconnect to the machine with correct larger wire. The full load amps or KVA should be on a tag on the machine somewhere. In real life, you can probably get away with 60-75% of the nameplate requirements- possibly slightly less.
 
The fused disconnect is fed by the same 10 gauge wire, but there isn't a number on the corresponding breaker back at the panel. I wasn't able to find anything on the inside of the machine. I'll check again and see.

I do have a pic of the main spindle motor's plate though. I assume that would be doing a majority of the power consumption?
 

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The spindle motor has an intermittent rating of 7500W. That alone is near 30A. Then you have servos, coolant, hydraulics to add to the mix. That 30A service will be hurtin a bit. It’s enough to get you started, but spindle accel is where you will likely first have trouble.
 
Okay, so I finally got the lathe up and going, sort of.

The control is giving me a 400 "servo" alarm, which according to my research is indicative of either electrical overload or the lathe being against the hard limits. I can't get it to clear. It just continues to say "not ready". I wiggled the two e stop switches and still nothing.

The hydraulic pump isn't turning on either, but I don't know if that's related to my current problem or if it's a fun separate issue. My plan was to power it up, check the hydraulic pump rotation and switch the power leads as needed to get it running in the right rotation.

There's a sound like a relay or contactor that makes a clunking sound in the back of the machine every five minutes too.

A few days before we moved the lathe, the guy sent me a video of it powering up and homing in the x and z. I'm suspecting that maybe while we were moving it around, it jammed against a hard limit(s) and it needs to be manually inched away from it to clear the alarm. I guess if that's the issue, I'll have to uncover the ballscrews and manually turn them until they're far enough away from the limits?

Machine is hooked to a 3 phase panel, and has 240v incoming on all three legs as far as I can tell. According to the manual, that should be fine.

Any help would be appreciated!
 
I’ve cleared 401 and 400 servo alarms on Fanuc 6T’s by replacing the Daito fuses on the servo VCU of the offending axis. There’s a little window on the fuse to show it’s blown.

I’d be rectifying that servo alarm then hearing/watching the open cabinet to determine exactly what contactor is tripping in and out. If you have a coolant pump/coolant in the machine you can verify correct phase rotation by turning the coolant on.
 
I’ve cleared 401 and 400 servo alarms on Fanuc 6T’s by replacing the Daito fuses on the servo VCU of the offending axis. There’s a little window on the fuse to show it’s blown.

I’d be rectifying that servo alarm then hearing/watching the open cabinet to determine exactly what contactor is tripping in and out. If you have a coolant pump/coolant in the machine you can verify correct phase rotation by turning the coolant on.
Until he gets the Not Ready status cleared he won't be able to turn on the coolant pump unless he manually actuates the contactor.
 
I figured it out!

Turns out, I had to push the power button until the hydraulic pump kicked on. After that, I was able to get it into MDI and do a zero return. Everything seems to work (both, axes spindle, tool turret etc) I can't test the coolant pump yet, because the cable for it seems to be missing(previous owner never used it after their move) but they said last they recall it works.

However, I found out that if I moved the z axis manually too far, it goes past the limit switch and alarms out. I don't know if this is just a quirk with older Fanuc NC lathes, or if it's something that I'll have to work around.
 
A few of us run older Nakamura slant turning centers here, if you post the model and some more info about the control I'm sure you will get better info on its operation. My Slant Jr. and Slant 1 run Fanuc 10 and 11 T controls. On these there is a stroke end release button you use to fire up the machine and jog it if it is past the limit switch. You likely have an even older control like 6T
 
Ah right.

The Lathe is a Nakamura Tome TMC-2. It was made back in 1981, and has a Fanuc 6T-B control. It's the one with the turret that runs perpendicular to the chuck.
Also, will the machine go to the limit switches without alarming out while running parts? For instance, if my program has the tool change happening at x z zero it'll be able to go there without any issues or will I have to account for that in the post processor?


Sorry for the dumb questions, I'm new to CNC turning : )

Here's pic of the machine too.
1678927829627.png
 
It will not alarm if you go to the home position, and in operation it usually will have a small amount of over travel in x and z.
There are a few different ways to do the tool offsets on the 6T control.
This video might get you headed in the right direction: (and its also a Nakamura)
 
Thanks, I finally got around to reading the instruction manual too so that helped a lot.

I use Gibbs, and they have a default post processor for the 6T that seemed to work pretty well(haven't run it yet, I still have to set up the DNC computer for it). Since I'm new to all of this, I think I'll stick with the original G50 offset arrangement so I can use the wear comps at the control. From what I've read, the main difference is that the tool offsets act as the part origin as well since the older machines didn't have enough memory to handle that.

Also, the stroke release button for my machine is key protected, and someone broke the key off in the "off" position so I had to jimmy it with a flathead screwdriver to get it to turn on.

For 500 bucks I'm not complaining ; )
 








 
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