Y AXIS MATSUURA MC 760 BALLSCREW REPLACE

I've replaced a number of ballscrews in my days, Never this machine in particular though. Y axis is two doors down so to speak, so not that you have to start there, but be ready for the fact that you MAY have to remove the table and saddle both to get the Y screw out. Maybe not, and don't start out that way.

Keep the machine operational as long as possible. Completely remove the Y axis way covers to start. Move the saddle to both extremes of travel and see if you can discern a path for the screw and nut to be extracted with the saddle still in place. Pay attention to the size of the flange on the ball nut compared to that of the main support bearings housing. Pulling the screw straight out depends on if the ball nut flange is smaller then the main bearing mount bore. Depending on the bearing arrangement, you may have a simple floating bearing or bearing set on the end opposite the fixed end. These bearings will typically have a close sliding fit. If the secondary housing is small enough, you can just remove it with the bearings still inside and extract it as a unit. Watch for pull pins as they're likely there aligning the bearing block.

My memory is clearing a little and I recall that there is typically not enough room under the ball nut housing that's either part of or attached to the underside of the saddle, to slide the screw out from under it if the free end housing is still attached. And may be the sole reason you have to pull the table and saddle. I think your chances are best overall if you can extract the fee end bearings out of their housing while leaving the housing in place. Long Y travel machines are going to have a better chance of getting the screw out without removing everything above it.

Telescoping screw covers add another degree of complexity to removing AND replacement. At some point you have to pull them away from the nut and secure them leaving the screw thread bare. This is because the slot cut in bottom of the ball nut housing on the saddle is too small for the screw to pass through with the telescoping cover in place. A good tool for holding a telescope cover in a retracted position is a small Kant-Twist clamp lightly clamping on the screw.

Again you may have to remove the table and saddle to get this done. Don't forget to remove the oil lines from the ball nuts before yanking them out.

Be prepared to re-grid your machine's Y axis. If there is some Y reference measurement you can make against a fixed object that you can repeat to once you're all back together again that would be good to have recorded. Especially if loosing an exact position will mess with saved programs that use with this type of relationship. Also if you replace your screw with new, your screw compensation numbers will be worthless and should be zeroed out. Set up to have your screw re-laser shot after running it in for a little while.

Cleanliness is king when reassembling. No forcing anything. Parts books diagrams are your friend to see what you're getting into.

Dave