After removing the surface
rust I set out to inspect the machine the best I could.
The machine has boxways on Y and dovetail ways on X and
Z. The ways and screws looked fine on all three axes.
Here's a couple of random photos:
This is the Y-axis ways and ballscrew, the red/brown
junk isn't rust it's just old oil and grease....
The next photo is a
closeup of the X-axis ballnut. The screws are 32mm in
diameter, 5mm pitch on all axes and are made by
As you hopefully can see
in the next photo I was able to get the rust on the
sides cleaned up pretty good:
Here's another shot of the
left side of the X-axis with the bearingplate removed.
You can see one of the manifolds for the central lubing
And here's a shot of the
spindle gearbox. The spindle, by the way, is a SK40
DIN2080, has 12 speeds between 44 and 2000rpm and the
motor is 4.5kW (6HP). It will eventually be controlled
by a Siemens Micromaster VFD.
Quite early in the process
I discovered a problem with the
Z-axis. The bevel gear that drives the Z-axis ballscrew
was slipping on the shaft so I had to take that apart
and fix it. I bought an engine hoist and started by
removing the table to gain better access as well as
reduce the weight of the knee a bit:
Once I got the knee lifted
(and supported) high enough I was able to slip down the
telescopic covers, loosen the ballscrew at the top end and
thread it down into the "leg" of the knee.
After that I could remove the whole
screw jack from the base of the machine. Once that was
done it was easy to spot the problem:
As you can see the only
thing holding the end of the shaft to the ballscrew was
a single set-screw. It was also burried so deep in the
shaft (in order for the gear to fit over it) that it more
or less became like hollow pin instead of a solid screw. I replaced the setscrew with a
conical dowel pin going thru the extensionshaft and
ballscrew from one side to
the other. Hopefully it will hold up much better than
Here's a shot of the sadle
with the table removed:
While having the table
removed I figured I might as well get some paint on that
bare metal on the sides of the machine, here's the
And here's the same view
with two out of three layers of paint. I brought one of
the bearingplates with me to the store for the guys to
match the new pain against. They did a pretty good job.