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Fanuc 6t Turret Indexing Issue

mm00361

Plastic
Joined
Dec 14, 2021
Hello everyone,

I've purchased my first CNC lathe and have been spending the last couple months getting it setup in my shop. This is a 1981 Takisawa TS20 with the Fanuc 6T. I've spent the last couple weeks getting it tooled up, setting up dnc with rs232, and getting the turret aligned. Everything was looking good until I done my first project. I noticed that when the turret would go by tools six through ten there was clunking noise. After several more tool cycles when it went to clamp it skipped the tool it was aiming for and went to the next tool. So I noticed if kept upward pressure taking out the backlash radially it's smooth as silk. I had previously removed the curvic pins to align the turret also so I thought that could be the issue, but everything looked fine. The turret is back off with gear box lid off also. It's worse without the weight of the turret. I also I think having the weight of the tool blocks hanging on that operator side making the issue worse which is why when I pull up on the during a change it goes away. I can see on the cam shaft the servo is over shooting where it's supposed to be when the fault happens. Could this be backlash be adjusted mechanically somehow or does the servo need to be zeroed to know where to seat. I will mention the hydraulic solenoid for clamping has an adjustable locking bolt that someone has definitely moved previously.
 
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I will also mention the turret sounds like it's clipping the curvic coupling on those couple tools when making a full revolution. Maybe the turret isn't unclamping and clamping all the way. Low hydraulic pressure maybe?...I do know the timing is off. Just not sure why.
 
Sounds like the prior owner tried to adjust the hydraulic solenoid for clamping to get it to index properly.
30 years of operation surely wore the gears, if your upward pressure taking out the backlash radially causes it to work, you have found the problem.
What adjustment is available remains a question.
The 1981 turrets mostly relied on switches, or encoder for stopping position.
One could change their location to try to get it to position better.
Have you tried balancing the weight of the tools?
 
Thanks for the reply. It's funny that you say that, because as I was typing that I realized I had just taken the tool blocks off the opposing side as it had them all the way around. I took them off off to gain more room....if I can't figure this out I guess they will be going back on. Sigh....
 
Try to find where the lash is hiding. Is it in the mesh of some gears? Is it in the fit of a gear to a shaft? Gear and shaft and a keyway? How about the bearing that supports the unclamped tool disc?

I have found loose setscrews on top of keys to be the problem a couple of times on geneva type turrets.
 
Hello everyone,

I've purchased my first CNC lathe and have been spending the last couple months getting it setup in my shop. This is a 1981 Takisawa TS2 with the Fanuc 6T. I've spent the last couple weeks getting it tooled up, setting up dnc with rs232, and getting the turret aligned. Everything was looking good until I done my first project. I noticed that when the turret would go by tools six through ten there was clunking noise. After several more tool cycles when it went to clamp it skipped the tool it was aiming for and went to the next tool. So I noticed if kept upward pressure taking out the backlash radially it's smooth as silk. I had previously removed the curvic pins to align the turret also so I thought that could be the issue, but everything looked fine. The turret is back off with gear box lid off also. It's worse without the weight of the turret. I also I think having the weight of the tool blocks hanging on that operator side making the issue worse which is why when I pull up on the during a change it goes away. I can see on the cam shaft the servo is over shooting where it's supposed to be when the fault happens. Could this be backlash be adjusted mechanically somehow or does the servo need to be zeroed to know where to seat. I will mention the hydraulic solenoid for clamping has an adjustable locking bolt that someone has definitely moved previously.

My problems with hydraulic turrets kind of making me going is removing the curvic plates both
clening those they wore thru the years, they build rust, specially if coolant is fed to tool by
center shaft, orings let coolant in, then adjusting the speed and clamping selenoids, and balancing
by adding tool blocks as counterweights and not let machine set for weeks, try to cycle tool changer
otherwise dia. would not be consistent because tool changes centerline , and fools me adjusting offset
but they are still good, you may need to adjust cam by rotary switch and diagnostic parameter until is
right on the money, also the switch the controls clamp unclamp.
 
Well I tried.... I tried to adjust that Jack screw on the solenoid and it jammed up the servo. I can't figure out how to get it unlocked now. Anyone know the m code to reverse the turret direction?
 
Its usually up to the MTB to assign M codes, but M17 and M18 works on Mori lathes of that era to reverse turret rotation. Do you have a programming manual?
 
Just a little update. I got it unlocked. The hydraulic lock pin isn't extending everytime. The solenoid is looking like the issue. Does cleaning these typically have a high success rate or should I be trying to find a replacement?
 
I have a TS15. You may have checked but worth asking IMO: what is your main system hyd pressure? Tank is full/no cavitation sounds on chucking clamp/unclamp?
 
I looked earlier and there was only one gage back there aside for the one for the chuck and tailstock on the side, and it was broke. I plan to get one tomorrow. The level was about 3/4 full. Should I top it off to be sure? It does look like a weak system on the side. The chuck pressure seems to work fine, but I do remember it fluctuating when I first powered the machine a couple weeks ago. Hadn't seen it do that much since, but could be related. I'll check more into it tomorrow.
 
It's definitely not hydraulic. Whether it's induction or servo I'm not sure. Idk how an induction motor would stop at specified point like it does so I'm leaning towards a servo.
 
Induction motor will stop when it is no longer being energized.
I don't think that there are servo turrets on that age machines.
Easy to check as it would need to have a servo drive, do you have an schematic?
 
It's definitely not hydraulic. Whether it's induction or servo I'm not sure. Idk how an induction motor would stop at specified point like it does so I'm leaning towards a servo.

3/4 tank level should be fine, wild idea how about checking the hyd motor, bottom tank strainer was suggested by a mechanic when i had problems, some those tanks have only one gage, they need volume oil
if hydraulic they need to see tool #1,in diagnostic page, otherwise don't work, and that thing is controlled by rotary switch, it may have a switch in a cam if that thing gets loose, they only attempt
to pull forward.
 
So I took a day off from working on this, but I'm back with a fresh set of eyes. If I supply resistance to the hydraulic motor that turns the worm gear, the paddle with the lock pin seats perfect eveytime. You see can in the video. There are two scallops for the oin to seat at a 180 degrees. When it doesn't seat its always on the same scallop. There was an adjust on the side of the motor solenoid I tried adjusting. It didn't seem to make much difference so I put it back. It was actually all the way out for whatever reason.
 








 
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