Adjusting Gibs; Adjusting Leadscrew Backlash - Grizzly G0761 Owner's Manual

Adjusting Gibs

gibs are tapered lengths of metal that are sand-
wiched between two moving surfaces. gibs con-
trol the gap between these surfaces and how they
slide past one another. Correctly adjusting the
gibs is critical to producing good milling results.
tight gibs make table movement more accurate
but stiff. loose gibs make moving the table sloppy
but easier to do. the goal of gib adjustment is to
remove unnecessary sloppiness without causing
the ways to bind.
Tip: Some experienced machinists recommend
adjusting the gibs until there is a slight drag in
table movement.
screws on each end of the gib allow gib adjust-
ment to increase or decrease the friction pressure
between the sliding surfaces. Correctly posi-
tioning the gib is a matter of trial and error and
patience.
disConneCt MAChine
BeFore AdJusting the giBs!
Make sure all table locks are loose. then, loosen
one gib adjustment screw (see Figure 46) and
tighten the opposing screw the same amount to
move the gib, while at the same time using the
handwheels to move the table until you feel a
slight drag in that path of movement.
y-Axis gib screw
(1 of 2)
Figure 46. location of table gib screws.
Model G0761 (Mfd. Since 10/13)
FroM poWer
X-Axis gib screw
(1 of 2)
Adjusting Leadscrew
Backlash
leadscrew backlash is the amount of free-play
movement in the leadscrew (when changing the
direction of rotation) before the attached device
begins to move.
leadscrews must have a certain amount of back-
lash, but over time, this will increase with normal
wear. generally, 0.003"–0.006" leadscrew back-
lash is acceptable to ensure smooth movement
and reduce the risk of premature thread wear.
the X- and y-axis leadscrew backlash is adjusted
by using a long 5mm hex wrench to tighten/loosen
the cap screw on the leadscrew nut. this adjusts
the force the split leadscrew nut exerts on the
leadscrew threads.
the X-axis leadscrew nut shown in Figure 47
is accessed from underneath the left side of the
table.
the y-axis leadscrew nut is similar and is accessed
from underneath the machine base.
X-Axis leadscrew nut
Cap screw
Figure 47. X-axis leadscrew nut adjusting cap
screw.
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