Unimat SL spindle bearing replacement.

I recently stripped and re-greased the spindle bearings in my Unimat. On re-assembly I found the spindle to be running out, so I ordered new bearings. Here's how I fitted them.

The first job is to remove the spindle end nut with a 19mm spanner. Mine came undone easily using a tommy bar in the spindle nose;

Now the belt pulley can be slid off the spindle;

The motor bracket and, if fitted, the return spring can now be removed (for convenience only) by undoing the clamping screw with a 5mm allen key;

 The feed lever, headstock clamping screws and set screw in the headstock can now be undone and the spindle sleeve carefully slid out, taking care as the internals are now loose;

The main spindle can be slid out of the sleeve;

And stripped down;

On the left is the pulley end bearing, which is loose in the sleeve, followed by 2 cup washers, then the main spindle. Underneath is the distance bush, nose end bearing inner with ball race (the outer is still in the sleeve) and washer. Note that the chamfered end of the distance bush is towards the pulley.

The nose end bearing outer needs to be gently drifted out of the sleeve, I used a length of brass rod and a copper + hide mallet;

Assembly is a straightforward reversal of the above. New bearings need checking for swarf before greasing, I found a little brass on mine. I used Emco Unimat #1 Synthetic grease.

Nose end bearing in place, not yet greased, note the washer;

And the pulley end, at this stage the spindle assembly is ready to be fitted back into the headstock;

The two cup washers sit behind the rear bearing, back to back with the concave faces outermost.

When re-fitting the motor bracket I used a steel rule to align the spindle and motor pulleys;

Checking the spindle with a lever type DTI;

I found the spindle to be out slightly in both planes, under a thou. on the back face and about 2 thou. on the diameter (3 thou. in the bore). I'm not sure if the diameter run-out is a machining fault or if its in tolerence, more investigation needed. The back face is easily machined true however;

At some stage I'd like to try a different spindle in this machine, just to see if there is a fault with mine.

Any comments from other Unimat users most welcome!

Paul.

Update 17/05 - new spindle fitted, run-out within .0005" on the outer diameter, but .002" inside the bore. Much better.