Servo Turret Issue

[Tom Slick]

I've got a 4020 with a 30 tool servo turret ATC that has had intermittant carosel positioning issues for a couple of years. 2 years ago it was having an issue with picking up the wrong tool, fadal replaced everything (literally) in the ATC's control system and the problem went away. now it has had an interrmittant issue with the carosel lining up about 1/2" off to the spindle comes down knocks my $750 custom ground end mill (amoung others) out. it has gone as long as 3 days with no issue then it drops a tool but when it started it would drop a tool at least once per cycle.
details:
it faults moving cw or ccw
it's always misaligned with the carosel too far to rear.
new $900 servo turret motor-- didn't solve it.
new eprom on the controller card-- didn't solve it
medium fast speed on the carosel speed-- didn't solve it
medium slow may have solved it, that is the latest try and it's been 3 days, but what kind of "fix" is that? the benefit of the servo turret is gone when it is slow speed.
all voltages look good 5v and 160v
has the newest power supply

Fadal's techs have looked at it and I've had numerous calls to fadals tech support. at this point we are throwing hail marys and hoping it catches one for a touchdown.

has anyone else delt with a problem like this and what fixed it?

[IN2GLAMISGIRL]

I was having a off position problem with my 30 tool servo umbrella style changer. It happened when I had a heavy load of tools in the machine. Fadal service replaced the e-prom but that did not help.
The problem was the 30 tool holder plate was slipping on the mount. There are six bolts on a 2 1/2 washer that squeze the plate to hold position. Make sure this interface is clean and dry and torque those bolts down hard! A tiny slip at the center is huge at the o.d. of the tool plate.

By the way I have some machines with the side arm changer and they are rock solid no problems. (knock on wood)

[Tom Slick]

Update;
Machine is still overshooting (as fadal calls it). I have replaced all of the relays in the ATC system. today it likes to drop T27 during a tool change from T14 to T27 but only at random intervals, maybe twice in a row, maybe once every 2 hours. I have slowed the servo motor down to "slow" (dip switch 1 and 2 are both off) and we'll see if that makes a difference. slowing the motor to medium-slow lessened the serverity of the overshoot.

It's not the turret plate alignment, after an overshoot it will realign properly if you hit turret cw or turret ccw. the servro turret motor is "dead" when it overshoots. during a normal tool change it is always "live". it acts as if it looses signal from the encoder and doesn't turn the last 1/3 of a revolution.

a little more info; this machine always has the same 30 tools in it, so the "load" on the ATC is always the same.

just to add to the frustration it won't malfunction when the fadal tech is here, of course!

[dango]

for understand your problem
is it some time trying to make tool change and when it change or
befor the motor stop moving
and then you got the problem
if it is like this I will try to help you
make some tool change and go to the back open the door of the electric
and look on the card during tool change
there is two red lamps if the current lamp flashing during the tool change
then your motor type not fit
try to change the 3,4, switches this might solve the problem
switch 1,2 is for speed

[Tom Slick]

Dango, the turret has stopped when Z comes down to grab the tool. I have already adjusted the turret motor speeds and all it has done is lessen how far the machine overshoots.

Update;
I pulled the gearbox out and the worm gear had some scoring on it's tooth faces and the spur gear had corresponding grooves. New parts are a month lead time from Fadal so I blended out the high spots and re-polished the gears until I can get new parts. these grooves may have caused just enough binding to fault the turret motor

[Tom Slick]

It looks like the grooves in the worm and spur gear were causing the problem. after blending them out and cleaning / regreasing the gear assy. we have had zero problems. certainly one of the more challenging problems I've had with these machines.

[rickyt]

Glad to hear you figured it out, I hope it stays fixed this time. What controller do you have? We have some 4020's and one has the fanuc controller on it, it really leaves much nicer surface finish's compared to the Legacy. The only gripe is, we have to do a tool change with M6 T#, other than the standard T# M6. We also have a 6535 50taper VMC, man is that thing fun to run. Talk about a workhorse, you can push most tools to the breaking point and the spindle load hardly moves.

[Neal]

rickyt--
The problem of the M6T? or T?M6 has been solved. You need a ladder update. Have ladder 97 installed and the code order will not matter.
Neal

[Neal]

x

[Tom Slick]

We have 3 4020s and 2 5020s varying in age from 1987 to 2001. 2 are CNC88, 2 are CNC88HS and the machine that had the turret issue has a 32mp. none of them have issues with T#M6 or M6T#.

[Neal]

Tom--
The tool change coding was only an issue on the Fanuc 18i MB5 control. It has since been corrected with the latest ladder update.

Neal

[rickyt]

Im going to call Flint Machine and see about the ladder update, we are now having an issue with setting fixture offsets. I set the offset for x0. then y0., move the table away from that position, then go to mdi and type in G0 G90 G54 X0. Y0. and the table goes off somewhere and stops. It is way off from the fixture offset that I just set. I've powered down, sent to home position, and still same thing.