Smithy GN1300 - Manual (Page 46)

Step 2: Unscrew the handwheel from the end of the feed screw.
Step 3: Using a punch and a small hammer, tighten the spanner nut about one-eighth
of a turn and recheck the backlash in the leadscrew.
Step 4: If backlash is acceptable, replace the handwheel, washer, and retaining screw.
If more adjustment is needed, repeat step 3 above.
Half-Nut to Leadscrew Backlash
Worn threads on the half-nut can cause excessive backlash in the longitudinal direction.
Half nuts are made of a brass-like material and do wear out over a period of time. The
only fix for a worn half nut is to replace the worn nut with a new one.
Adjusting Mill Feed Backlash
Excessive backlash in the vertical fine feed can come from two places.
• The fit between the worm gear and the pinion gear shaft
• The fit of the quill gear to the quill rack
Adjusting the Fit Between the Worm Gear and
Pinion Gear Shaft
Follow the procedure below to adjust the fit between the worm gear and pinion gear.
Step 1: Remove the fine-feed handwheel and dial.
Step 2: Loosen the two setscrews that hold the left and right worm gear bearing sup-
ports in place. They are located on top of the vertical feed housing at the left and right
end of the worm gear.
! NOTICE !
The longitudinal handwheel (Rack & Pinion) is intended for rapid,
coarse feed and is not calibrated for fine measurement. There is no
backlash procedure for this mechanism.
5: Preparing Your Machine For Operation
5-16 Or Visit www.smithy.com
! NOTICE !
The bearing housing has two holes in the outside surface
to allow a punch or spanner wrench to turn the housing.