I previously determined that in order to remove the ballscrew / ballnut assembly for cleaning and inspection, I'd need to remove the front (thrust) bearing, as it's too long to clear the rea of the saddle .
So firstly I had to remove the 4 screws holding the cross slide bracket (ballnut yoke) to the ballnut. This was a PITA, as the only access to the bottom screws was through the gap between the ballnut and the saddle casting. Luckily it didn't fight me. Luckily because if I'd managed to mess up the socket on the screw, progress could have become rather tricky. PITA because the socket was full of brass swarf that had to be cleared out before I could get the hex key far enough in to break and drive the screw safely.
Naturally, the bearings didn't want to just fall off, so a pulley puller was needed. This is the same one that did sterling work on the pulleys.
Ready to come out?
Here it is finally. It's an NSK double ballnut and looks almost identical to the ones in The Shiz - perhaps not surprising, given that they are almost the same age.
The markings say
NSK
W2802-142D-SPZ
1NX-046
Careful measurement shows that this is a 5TPI thread rather than a 5mm pitch. Over 20 threads I'm seeing 101.6mm rather than 100mm. I suppose that's not surprising for a US machine and isn't really a problem, as I can set up the servos with whatever ratio I like.
Cleaned up nicely.
This is the thrust bearing (operator) end
And the drive (pulley) end. The little extension is for the encoder drive, although I won't be trying to use them with my Acorn system. If there's any backlash in the belt system, I'll have to live with it.
Let's put it all back together again:
The encoder spindle extension is handy for working the grease into the ballscrew / ballnut.
All lubed up with grease (ballscrew) and way oil (slides)
Back together finally.
No comments:
Post a Comment