Southbend SB1023 manual Column & Table Gib Adjustment, Handwheel Backlash Adjustment

Model SB1023 M A I N T E N A N C E For Machines Mfg. Since 8/09

Handwheel Backlash Adjustment

Backlash is the amount of play found in a leadscrew. Without moving the table, the amount of backlash can be determined by lightly turning the handwheel with your fingertips in one direction until the handwheel stops, noting the location shown on the handwheel scale. Then the handwheel is turned in the other direction until it stops. The distance between both stopping locations is the amount of backlash. If the backlash exceeds 0.007", adjust it back into range the of 0.003" to 0.006".

The backlash adjustment is made by tightening or loosening the cross-feed leadscrew halfnut cap screws shown in Figure 42. These screws draw two halves of the halfnut together against the leadscrew placing pressure on the threads. If this fit is too tight, loosen the cap screws, tap the table a few times with a rubber or wooden mallet, and turn the handle slowly back-and- forth until the handle turns freely. To readjust the backlash, rock the handle back-and-forth and tighten the screws slowly until the backlash is correct.

Note: Avoid the temptation to overtighten the cap screws at the leadscrew halfnut. Overtightening will cause excessive wear to the halfnut and leadscrew. Reducing backlash to less than 0.003" is impractical and reduces the life of the gib and the ways.

Gib

Cap Screws

	Leadscrew
Gib Screw	and Halfnut

Figure 42. Table gib and leadscrew.

Column & Table Gib Adjustment

The gib is a tapered piece of steel that is held in position by a gib screw. When the screw is turned clockwise, the gib will be moved to fill the loose void in the way, thus, removing the play. If more play is needed, adjust the screws the opposite direction.

When adjusting the table or column gib screw (Figure 43), keep in mind that the goal is to remove sloppiness in the ways without causing the dovetailed ways to bind or prematurely wear. A loose gib can cause dimensional problems or a poor finish on the workpiece.

Figure 43. Column gib and leadscrew.

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