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Copyright © 2020 Quality Machine Tools, LLC
PM-1440GT v9 2020-10
GIB ADJUSTMENT
Gibs on the cross-slide and compound, Figures 4-10, 4-11,
are gently-tapered lengths of ground cast iron held fast by op-
posing screws at each end. Adjusting them is a trial and error
process that takes time and patience. Aim for the best compro-
mise of rigidity and reasonably free table movement. Too tight
means accelerated wear on ways and leadscrews. Too free
means instability of the cutting tool, inaccuracies and chatter.
Both screw heads
must be tight against the gib ends. If you
loosen one, tighten the other.
The saddle gib, Figure 4-12, is not a tapered insert like those
on the cross-slide and compound. It is a three-part assem-
bly on the underside of the bed way at the back of the lathe.
It comprises a support bar, attached to the carriage, and two
separate gib strips each with two adjusting screws.
Figure 4-12
Saddle gib assembly
Figure 4-10
Cross-slide & compound front gib screws
Figure 4-11
Cross-slide & compound back gib screws
