[redman_80us]

I have a Tongtai Topper lathe with fanuc OITC control. We had a hit the other day where our new operator hit a boring bar on the chuck in the process of a tool change. After resetting and taking back off, we noticed the turret was setting down hard on a counter clockwise tool change. Before I get ahead of myself, this is a slant turn machine with V.D.I. tooling. I pulled all of the holders out of the turret and started with loosening the face bolts to allow for some manual manipulation of the disc. I can get the "thump" from clamping lessened, but can't get rid of it completely. My next step was going to be to loosen the coupler on the servo and call up a tool, then call up t0101 for the original zero point. My thinking was that with the turret in the clamped position and the coupler being disengaged, this would allow for the servo to go to "home or start position", without having a load on it. Once this was done, I would tighten the coupler back down and everything would be timed correctly again. Unfortunately, this is a direct drive servo with a taper lock on the drive pulley. A little more of a tear down than what I was initially planning on. Next, I went into the PMM and reset zero point for the encoder while in the clamped position. I was sure that this would fix my problem because each tool change position would be exactly the same distance, 30 degrees for 12 stations, from one another and being as I zeroed a new clamped position, each movement would be in the correct position for a smooth seat. I still have the hard seat! One thing that confuses me is that with the face bolts loosened on the turret, I have smooth seating a no "thump". Once I tighten the face bolts, there's the thump again. I'm thinking this has something to do with the turret putting load on the pressure plate and loading up the mechanics of everything, but not sure. Also, the directions I have for resetting the turret servo zero point says to have hydraulics on but CNC off. This confuses me because how can I have the CNC off but still have hydraulics? Any help would be greatly appreciated in working through this problem.

[fomaz]

I have a Tongtai Topper lathe with fanuc OITC control. We had a hit the other day where our new operator hit a boring bar on the chuck in the process of a tool change. After resetting and taking back off, we noticed the turret was setting down hard on a counter clockwise tool change. Before I get ahead of myself, this is a slant turn machine with V.D.I. tooling. I pulled all of the holders out of the turret and started with loosening the face bolts to allow for some manual manipulation of the disc. I can get the "thump" from clamping lessened, but can't get rid of it completely. My next step was going to be to loosen the coupler on the servo and call up a tool, then call up t0101 for the original zero point. My thinking was that with the turret in the clamped position and the coupler being disengaged, this would allow for the servo to go to "home or start position", without having a load on it. Once this was done, I would tighten the coupler back down and everything would be timed correctly again. Unfortunately, this is a direct drive servo with a taper lock on the drive pulley. A little more of a tear down than what I was initially planning on. Next, I went into the PMM and reset zero point for the encoder while in the clamped position. I was sure that this would fix my problem because each tool change position would be exactly the same distance, 30 degrees for 12 stations, from one another and being as I zeroed a new clamped position, each movement would be in the correct position for a smooth seat. I still have the hard seat! One thing that confuses me is that with the face bolts loosened on the turret, I have smooth seating a no "thump". Once I tighten the face bolts, there's the thump again. I'm thinking this has something to do with the turret putting load on the pressure plate and loading up the mechanics of everything, but not sure. Also, the directions I have for resetting the turret servo zero point says to have hydraulics on but CNC off. This confuses me because how can I have the CNC off but still have hydraulics? Any help would be greatly appreciated in working through this problem.

It seams that you are working on the right direction and you have the necessary will to solve it. The issue is probably too difficult / small / intrinsic to someone help you without being physically present there.

To have the hydraulic working you can manually force the contactor of the hydraulic to be on. If you can't (depending on the contactor type), you probably have to use a voltage directly applied to the contactor coil to turn it on (you can make it pass though a button for easy of operation). Normally the contactor voltage is 24VDC or 110VAC (make sure of the needed voltage before using it).
You probably will have to do the same to "force" the valves to work in the desired direction.

[underthetire]

Never seen that brand. Guessing you knocked the curvic coupling off center.

[redman_80us]

Thanks for the info. I have a couple of other things that I want to check out in the morning, mechanical side, but good info for the manual manipulation of the hydraulics. I am a CNC Machinist and programmer with 13 years experience in the field. Only dabbed at the machine tech side when necessary. No maintenance department at this job, so as you can imagine, the last 6 years at this job has been a learn as you go with the maintenance side of things.

[redman_80us]

Now that you mention it, I did notice that on the clamping movement, the inward movement of the pressure plate, the curvic coupling appeared to rotate slightly and move just a smidge backward upon seating. I just assumed this small movement was a built in allowance for the mechanics of the machine. This particular machine has a hydraulic driven clamp and unclamp function with a servo driven, belt and pulley drive for the turret. There are four pins that run through the curvic coupler and bolt on the outside face of the pressure plate. I was thinking that if I unbolted the pins from the pressure plate and pulled it off, I would have access to the coupler. From there, I don't know what to expect. I don't know if this coupler is hard bolted or pinned, and I was afraid of really screwing up the alignment. I have 13 years experience in CNC machining and programming but only in the last few years have I dabbled in the tech side of the field. The shop I am currently working for has no maintenance department and the CNC Mill guy and myself are the only ones in the whole shop with CNC experience. I'm really glad I stumbled upon this forum as it has helped me out of some hard spots, and appreciate the help thus far and anything else that comes to mind in helping me with this situation, please let the suggestions fly.