Bearing Preload - Promac 941A Operating Instructions Manual

Bearing Preload

This lathe is shipped from the factory with the
spindle bearing preload properly adjusted. If
the spindle ever develops excessive end-play
and the workpiece finish suffers, you can adjust
the bearing preload to remove the unnecessary
end-play and improve the workpiece finish.
To adjust the spindle bearing preload:
1. Run the lathe for approximately 20 minutes
on high speed to bring the lathe to normal
operating temperature.
1. DISCONNECT LATHE FROM
POWER!
Loosen the two Spindle lock nut one
2.
full turn counterclockwise.
36)
Note: Use the Wrench 42-52.
3. Place a wooden block over the outboard
end of the spindle, and hit it soundly with
the heavy dead blow hammer (see Figure
37).
Your goal is to slide the spindle forward
just enough to introduce spindle end-play
that you can feel by hand.
Figure 36
(see Figure
4. Clockwise to tighten the Spindle Lock
Nut, Rotating the 3-Jaw Chuck with
spindle, Check the spindle bearing preload,
Spindle should be no gap, rotating with
slight resistance. The need to repeatedly to
loosen or tighten the Spindle Lock Nut
adjustment.
To confirm that the spindle
bearings are correctly preloaded:
1. Reattach all removed lathe components
and prepare it for operation.
2. Install the chuck and tighten the jaws
into the center.
3. Set the spindle speed to a medium setting.
4. Connect the lathe to power and turn the
lathe spindle ON.
5. Let the lathe run for 20 minutes.
6. Turn the spindle OFF, disconnect the
lathe from power, then check the
temperature of the spindle.
— If the spindle nose is slightly warm to
the touch, you have correct bearing preload.
— If the spindle nose is hotter than you
can comfortably keep your hand on, the
preload is too tight and you must repeat
24
Figure 37