[jmullett]

Have a ~1999 Torqcut 30 with low hours for its age. Dx32 Control, Parvex Servos on all 3 Axis.

My guys ran the mill a couple of days ago and ran fine. Upon start-up Friday morning we received a "Following Error" when we tried to home. Z-Axis and carousel homes fine then get the "Following Error" when it tries to home the Y-Axis. We can see the Following Error value by viewing the parameter in the MaintPage and the Y-Axis and Z-Axis are on the home limit switces and are indicated as such on the MaintPage. We can see the Y-Axis following error build in either direction as we turn the jog wheel up to 0.050 or down to -0.050 following error and then drives fault out.

Pulled the lower inspection plate to get a look at the Y-Axis motor and can see the motor pulley actually turn a small amount (though I think it is just compliance in the belt, torsion ect) either direction when we try to jog it then it springs back when the drives kick out. We cannot turn the motor pulley by hand with the drived de-energized. And we cannot push the table with brute force and backdrive the ball screw. At this point I'm thinking that somthing is mechanically blocking the Y-Axis travel.

It doesn't make sense though because it just happened while the machine was idle. This is a linear rail machine and everything looks pristine. No chips or oxidation on the linear rails or ball screw. Good coating of way oil on both as well.

Looking for any ideas from the more experienced out there. Anyone else have similar experience. Unfortunatley, the Y-Axis is all the way to the front of the machine and it looks as the only way to remove the Y-Motor is out the bottom an I have to remove the chip pan enclosure to do that. Bridgeport has made that look dificult. I looks like I have to remove the contol pod to be able to slide the enclosure forward.

I have a full set of manuals with the exception of the mechanical part drawings in the maintenance manual. Is there anybody that would be willing to share. I'm interested in knowing if I can can get access to ballscrew nut for the Y-Axis through the top so I can push the table to the back of the machine to see if that opens things up in the front of the machine. Diagrams or pictures would help. I think this is pretty much the same as a Torqcut 22 as well just longer X-Axis.

Thanks for any suggestions.

[machintek]

Remove the belt and try turning the ball screw by hand. If you can rock the ball screw back and forth even a couple of degrees, then the issue may be the linear ways. If not the problem may be the ball screw bearings or ball nut.
Probably at that point it would be best to remove the ball screw pulley and the nut behind it. Now see if the screw can move or the table can.
BTW, I have never seen Parvex motors on anything but the Z axis.
Obviously you have the piece of sheet metal off between the Y axis ways to expose the belt and such. I thought there was a piece of sheet metal along the front bottom of the machine as well that allows removal of the motor out the bottom front. I have done this but it has been a while.

George

[jmullett]

Got the Y-Axis Belt off and I can turn the ballscrew screw a few degrees. I put a dial indicator on the table and I am able to move the table back in forth by turning the ball screw pulley with 0.013-0.014" total table travel. And it is very easy to turn and move the table in this range. Then its like hitting a brick wall at the end of travel in either direction.

I cant see anything janky with the limit switch plunger that coule be causing this either

Trying to figure out if I should attempt to remove the ball screw or try to slide the linear rail trucks out one at a time from underneath the table. Do you know if these trucks have captive balls or are they gonna spill out all over the place if I slide them off the end of the rail?

[jmullett]

I blew a little compressed air in the rear ballscrew bearing ansd had one of my guys work the pulley back and forth at the same time and she progessivley freed itself up. I noticed some orange dust blow out of the bearing. So I think I will be looking for some replacement bearings. I notice the lack of an oil line and the absence of a grease zerk. Hmm, go figure.

If I'm in for a penny, I'm in for a pound. What else should I do whils I got the thing apart?


***EDIT***
Whoa, Priced the bearings from a few sources $500 to $800 each. Even Chinese crap knock-off is still $220. Where's the best place to get these? I'll probably just change the one bad one for now.

[jmullett]

I'm looking fot the amount of preload that is put on the ballscrew by the support bearings. INA documentation calls out a locknut torque variable Ma that should be obtained by the ball screw manufacturer. I can see that the screw is a 40 mm dia/12mm pitch made by Kuroda P/N 40-12C55 KGC1762.

I can't see any info on the Kuroda website and thought that someone might have a spec on it or could tell me how tight these these locknuts should be.

[machintek]

What the factory had us do is stretch the ballscrew about .003 inch.
Put a dial indicator against the end and tighten the nut until it is stretched that amount.

George