9x20 Lathe
DRO Z1-axis
Scale
Last updated on
Friday, December 14, 2018 03:18:29 PM
Mountain US Time Zone
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Bracket, Alignment,
Mechanical Linkages &
Cables,
Low-cost Z1-axis Travel Dial
Bracket
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.
Alignment
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 placements.
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.
Click on linked thumbnails
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 gage blocks to get longer distances. A DRO is
a better solution.
Click on linked thumbnails
Bracket,
Alignment,
Mechanical Linkages &
Cables,
Low-cost Z1-axis Travel Dial
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