FANUC Servo motor synchronisation

[deetech]

i have a rotary table fitted with a FANUC alpha i 2000 series motor.

some accident lead to breakage of the motor shaft. We have made a new shaft and have fitted the shaft and now the motor is ready.

but, when we are trying to give a pulse to it to rotate, it is rotating suddenly. we've been told that when shaft is changed, the coupling needs synchronisation.

can some tell me how to synchronise the motor so that the encoder will give correct pulse the motor will run properly.

[Al_The_Man]

You cannot change the commutation point as the encoder is keyed into the shaft?
It depends what you did to the rotor when repairing?
If it is the type with the 3 ears on the encoder body, you may have it in the wrong point. rotate it.
Al.

[tc429]

alphas are all red type encoders with the oldham coupler... I took a old dead red encoder(dont matter type, long as it bolts up) pull the board off of it, time it on a known good motor (+ to A, - to B and C), put a magic marker line on the disk, rotate about 90, hit it again, remark it, repeat for all 4 positions...while at it, remove C (just + to A, - to B) hit the battery again and put another mark in a different color...should be a few degrees CCW on the disk, use this on repaired/rewound motors after timing to verify rotation- if it jumps CW instead, then swap B/C leads. I'll try to get a picture tomorrow if i think about it, just retimed one yesterday, its still laying on my box.

to check your repaired motor, youll need to release the brakes(if it has one) then hit the 'time' position of +A, -BC to the motor connector (a couple size D batteries will move it uncoupled), then mount the marked up disk- if the lines arent in time, then take a wrench across both tangs and rotate the key on the motor shaft as necessary to get the magic marker lined up. those keys usually can be twisted pretty easily

if you have a older quadrature encoder laying around, you can use it by making up a LED box, the +A, -BC position should light up C1,C2,and C4 (C8 ideally right at its on/off toggle position), verify rotation by floating C, and hitting again, proper rotation should light C2,C4 only.

on the serials, I just use my old dummy disk to retime the rotor key- they knock them around all the time when replacing servo bearings...if you have anyone besides Fanuc or TIE rebuild your servos, checking timing AND rotation before installing might be a good idea...we had several motor shops send us servos that were screwed up, if called theyd say, just swap the rotation till it works...or pops a amp, no thanks.

btw, you can replace bearings in the red encoders the same way- put wide tape across the disk, press the shaft out (POP when it breaks free will shatter the disk unless face is taped) press the new bearings in the housing, press the disk/shaft back in using like a 3/4 carbide button tool on top of the tape to press it in, to realign, theres 2 little marks on the outer track that line up at the reference position, press the encoder key back on parallel to any flat side of the encoder...realigning the phototransistors/board should probably be done with a scope on the phototransistor outputs to show that lissajous circle or whatever they call it, but usually Ive had luck just moving it around/centering it up with the LED box...