9x20 Lathe DRO Z1-axis Scale
Last updated on Sunday, September 07, 2014 06:03:01 AM Eastern 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, -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
 align

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 100F 10v 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 gage blocks to get longer distances. A DRO is a better solution.

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

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