Sherline 5000 Mill Assembly Instructions

-11-
BACKLASH
ADJUSTMENT
(Lathe and Mill)
Backlash is the
amount the hand-
wheel can be
turned before the
slide starts to move when changing directions. This is a
fact of life on any machine tool, and on machines of this
type it should be about .003" to .005" (.08 mm to .12 mm).
Backlash must be allowed for by feeding in one direction
only. Example: You are turning a bar to .600" diameter.
The bar now measures .622" which requires a cut of .011"
to bring it to a finished diameter of .600". If the user
inadvertently turns the handwheel .012" instead of .011",
he couldn’t reverse the handwheel just .001" to correct the
error. The handwheel would have to be reversed for an
amount greater than the backlash in the feed screws before
resetting the handwheel to its proper position.
Backlash on the X- and Y-axes of the mill may be reduced
to a minimum by adjustment on the anti-backlash nuts.
These nuts are located on the handwheel ends of the mill
saddle. The nuts are secured by button head screws that
hold a star gear that interlocks with teeth on the nut.
To adjust backlash, simply loosen the button head screw
that locks the star gear. Rotate the anti-backlash nut
clockwise on the X-axis and counterclockwise on the Y-
axis until snug. Retighten the button head screw while
pushing the gear toward the nut. With the anti-backlash
nuts properly adjusted, the leadscrews should turn smoothly
and have no more than the proper .003" to .005" of backlash.
HANDWHEEL ADJUSTMENT (Lathe and MIll)
The handwheels are secured to their corresponding
leadscrew shafts by a small set screw in the side of the
handwheel base. Check them periodically to make sure
they have not been loosened by vibration. On the adjustable
“zero” handwheels, you must first release the rotating collar
by loosening the locking wheel. Then rotate the collar until
you can see the set screw through the small hole in the
side of the collar and adjust the screw as necessary.
FIGURE 13—
Adjusting the gibs
GIB LOCK
GIB
BED
SADDLE
belt guard housing. Loosen the two nuts that hold the motor
to the motor mounting bracket and take the tension off the
belt. With your finger, push the belt off the larger diameter
groove of the pulley and into the smaller one. (Depending
on which way you are changing it, this could be either the
motor or spindle pulley.) Then move the belt to the larger
diameter groove on the other pulley, and rotate the headstock
by hand to get it to seat. Push the motor outward on the
motor mounting bracket to put the proper tension on the
belt, and retighten the two motor mounting screws. Now
you can replace the mounting plate, pivot the speed control
back down, and refasten it. Moving the belt back to the
other position is simply a reverse of the above procedure.
SPINDLE PRELOAD ADJUSTMENT
If any end play develops in the main spindle, it can be easily
eliminated by readjusting the preload nut. (See part number
40160 in the exploded view.) When the headstocks are
assembled at the factory, the preload nut is adjusted to .0002"
(.005 mm) of end play. This is controlled by the outer races
of the bearing being held apart by the headstock case and
the inner races being pulled together by the preload nut.
This setting was determined through experience, and, like
everything in engineering, it is a compromise. If the machine
is only to be run at high-speed, this setting may be too
“tight.” The headstock will run fairly warm to the touch
normally, but extended periods of high speed operation may
bring about excessive temperature. The headstock should
not be too hot to touch. If this is your case, the preload
tension may be reduced slightly.
To change the adjustment, remove the spindle pulley, loosen
the set screw in the preload nut and back the preload nut
off 4° of rotation (counterclockwise). The bearings are lightly
pressed into the case, so the inner race will not move
without a sharp tap with a plastic mallet to the end of the
spindle where the pulley is attached.
If you find your bearings are set too loose, you may want
to take up on the end play. You can check them with an
indicator or by spinning the spindle without the motor belt
engaged. If the spindle spins freely with a chuck or faceplate
on it, it is too loose for normal work. Adjust the preload nut
until it turns only about one and a half revolutions when
spun by hand.
GIB ADJUSTMENT (Lathe and Mill)
Tapered gibs are fitted to the mill headstock, saddle and
table and to the lathe saddle and crosslide. Correct
adjustment of the gibs will ensure smooth and steady
operation of the slides. The gib is effectively a taper with
an angle corresponding to the one machined into the saddle.
It is held in place by an “L” wire gib lock that is secured
with a locking screw. It is adjusted by loosening the gib
locking screw and pushing the gib inward until “play” is
removed. After adjusting, retighten the locking screw.
Milling operations require a tighter adjustment of the gibs
than lathe operations.
LEADSCREW
SADDLE
SET SCREW
NUT
ANTI-
BACKLASH
NUT
FIGURE 14—Mill Backlash Adjustment
(NOTE: Older mills use a “pointer” type lock instead
of the star gear.)