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Model G0758 (Mfd. Since 2/14)
Adjusting Gibs
Gibs are tapered lengths of metal sandwiched
between two moving surfaces to control how
much friction they have when they slide past one
another. Correctly adjusting the gibs is critical to
producing accurate milling results.
Tight gibs make table movement more accurate
but stiff. Loose gibs make table movement sloppy
but easy. The goal of gib adjustment is to remove
unnecessary sloppiness without causing the ways
to bind.
Tip: Many experienced machinists adjust the gibs
until there is just a slight drag in table movement.
Screws on each end allow gib adjustment to
increase or decrease the friction between the slid-
ing surfaces of the ways.
DISCONNECT MACHINE FROM POWER
BEFORE ADJUSTING THE GIBS!
Make sure all table locks are loose. Then, loosen
one gib adjustment screw (see Figure 44) 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.
Figure 44. Location of gib screws.
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 45
is accessed from underneath the left side of the
table.
Figure 45. Example of X-axis leadscrew nut cap
screw for adjusting backlash.
X-Axis Leadscrew Nut
Cap Screw
Y-Axis Gib Screw
(1 of 2)
X-Axis Gib Screw
(1 of 2)
The Y-axis leadscrew nut is similar and is accessed
from underneath the machine base.