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 results.
Correctly positioning gibs is a matter of trial and error and patience. Tight gibs make table move- ment more accurate but stiff. Loose gibs make table movement sloppy but easier to do. The goal of gib adjustment is to remove unnecessary slop- piness without causing the ways to bind.
Many experienced machinists adjust the gibs just to the point where they can feel a slight drag in table movement.
Screws on each end of the gib allow gib adjust- ment to increase or decrease the friction between the sliding surfaces.
DIsCONnECT MACHInE FROM POWER BEFORE ADJUSting THE GIBS!
Make sure all table locks are loose. Then, loosen one gib adjustment screw (see Figure 53) and tighten the opposing screw the same amount to move the gib, while at the same time rotating the handwheel to move the table until you feel a slight drag in that path of movement.
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Figure 53. Location of table gib screws.
Model G0755 (Mfg. Since 1/13)
Adjusting Leadscrew
Backlash
Leadscrew backlash is the amount of freeplay movement in the leadscrew (when the leadscrew moves but the table does not) after changing the direction of rotation.
Leadscrews must have a certain amount of back- lash to rotate easily, but over time, it increases with wear. Generally,
The X- and
The
The
Cap Screw