9x20 Lathe DRO Z1-axis Scale
Last updated on Tuesday, September 19, 2023 04:31:56 PM Mountain US Time Zone


Bracket, Alignment,
Mechanical Linkages & Cables,
Low-cost Z1-axis Travel Dial


L-channel bracket mounts on the back of lathe bed to
hold & protect the Z1-axis scale. The 10-32 bolt to the

 far right is for mounting the electronic scale bracket. The
bed is cast & therefore, uneven. To enable adjustment,

jack screws where placed below each of the three, 1/4-20
mounting bolts & then used a 2" dial readout to iteratively

adjust the entire 26" long bracket until it was even in both
dimensions. Due to the inside corner radius, the bracket was
spot milled to flatten the 3 areas under the hex bolt heads.
The reach of the 2" dial readout allowed measurement

 the entire length & depth of the Z1-scale bracket runout.
Self-centering spherical & shim washers aid alignment.

Of all the DRO scale mountings, this one was the hardest
to mount & align due to the uneven cast base surface.

The L-bracket does not touch the motor housing as this
would transmit extra vibration to the transducers.


An old X-axis L-bracket shown.

Measured scale runout & shimmed as necessary.

Mechanical Linkages & Cables

X & Z1 axes scale linkages. New X-axis L-bracket now
matches the overall design. Transfer screws, both

imperial & metric, were essential for accurate hole
I soldered a 100-mF10v tantalum capacitor
across the battery leads of the scale
. All cable
plugs are held in place with a spot of hot glue.

Installed rubber washers on all the scale
mounts which allows a little floating
to reduce strain on the transducers.

The RF-25 mill's free-floating Z-axis design works
so well that now all of my mill & lathe scales

are attached at only one end while the other end
remains captured but loosened to allow floating.

This approach greatly reduces minor out of
alignment induced stress on the transducer. This

design also helps to reduce DRO jitter as does a
clean, deburred transducer with NR capacitors.

Everything shown here, the X scale & Z1 linkage
bracket, is mounted to a single block that is attached

 to the back of the carriage. The single pivot point
of the connecting rod allows easier final alignment.

Low-cost Z1-axis Travel Dial

Before the lathe DRO, I sometimes used a dial indicator
with 2" travel range mounted to the back rail

by a Mighty Mag magnet. Use gauge blocks to get
longer distances. A DRO is a better solution.

Bracket, Alignment,
Mechanical Linkages & Cables,

Low-cost Z1-axis Travel Dial