Lead-screw Conversion
Last updated on Tuesday, September 19, 2023 04:03:57 PM Mountain US Time Zone


Lead Screws, Split Nut, Anti-backlash Nut Adjustment, Stepper Motor Couplers


Converted the mill's lead screw, nut, & bearing assemblies
to those for CNC & NEMA 23 stepper motor mounts.

Lead Screws

The Taig CNC conversion kit: lead screws with bearings &
bosses, adjustable bronze nuts, couplers, &
NEMA 23 stepper-motor mounts. The nylon tubing is
cut diagonally (45 deg) into 3/4" long coupling pins.
There are 4 pins per coupler. The diagonal
cuts can assist in assembly.

Leftover parts from the conversion provided a precision
ground 1/2-20 left-hand lead screw with bearing plate &
bronze nut assembly thus allowing the implementation
of a very useful upgrade to the 9x20 lathe cross slide.

The NEMA 23 motor mount screws onto the finely threaded
boss & is clamped into place by a ring & set screw.

The bronze, zero-backlash nuts have two (outside)
clamping screws & one (center) locking set screw.

Split Nut

X-axis install. The bronze split-nuts work much better than
expected. White lithium grease is a good lubricant.

Anti-backlash Nut Adjustment

X-axis nut. To adjust the anti-backlash nuts, first
remove the stepper, unbolt the bearing plate &
push the slide until the nut is exposed. Loosen the
center set screw, then one at a time, tighten the
outer screws until the lead does not turn, then
back-off a 1/4-turn. Re-tighten the center set screw.

Y-axis anti-backlash nut.

I used a wrench to feel the lead screw tightness.

Stepper Motor Couplers

X-axis boss & coupler. Do not over tighten
the lock nut as it can bind (break)
the bearings that are inside the boss.

Y-axis boss & coupler. Note the four
holes for the 3/4" long nylon coupling pins.
A simple yet effective coupler.

Z-axis boss & coupler.

X, Y, & Z-axes lead screws now converted for CNC.

Lead Screws, Split Nut, Anti-backlash Nut Adjustment, Stepper Motor Couplers