RF-25 Mill DRO X-axis Scale
Last updated on Sunday, September 07, 2014 05:46:13 AM Eastern US Time Zone

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Scales, Brackets, Over-travel Switch, Cables, Handle Animations

Scales

18" scale, hardened SS.
This style scale has a good (enclosed) SPC plug receptacle (manual).


Trimmed scale scrap with plastic cover removed.


2" x 2" aluminum L-channel cover mounted using front dove-tail slot. Six, -20, flat-head screws hold the
 L-channel for a very rigid configuration. Machined steel dovetail nuts for mounting. Retained access to the
center oilier hole. The L-channel serves as the scale mount & protects it from impact, fluid & debris.

Brackets


OEM over-travel switch & bracket configuration.


Scale transducer mounted on back of power-feed over-travel switch bracket. Used transfer screws
(M3-.5 threads)
for accurate alignment. Soldered a 100F 10v tantalum capacitor across the battery leads on each of the scales.

 

New spacer bracket replaces original.

Over-travel Switch

This mount protects scale's front (which is not needed) & places the SPC output on the bottom, back, right.
Only hardened SS scale surfaces are exposed.


Power feed end-of-travel mechanical stops mounted on top/inside bracket surface. These are the original
stops with the stepped end (fly) cut flat. The -20 mounting bolt is flush with the top of the L-channel bracket.
The electrical stop turns the power feed motor off about four full crank turns (for this machine) before reaching
the lead screw mechanical end-of-travel; just enough distance to allow a safe stop from full speed.
This is a machine-dependent distance that needs to be empirically determined.


This area was relieved (both sides) to allow the scale's lower bracket edge
to clear the table locks. A lock nut will be used in the final installation.


The scale rests on pairs of self-aligning, spherical washers. Installed rubber washers
on all the scale mounts to allow a little floating to reduce the 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.

Cables
 

Drilled & tapped the front right carriage corner to mount a cable strain relief. It is the cradle/nylon
 tie type of fastener. All cable plugs are held in place with a spot of hot glue.


Mounted a cable strain relief on the front left corner of the Y-axis bracket to hold the over-travel switch cable.

Handle Animations

Revolving, chrome plated carbon steel handle, animation.


Left: OEM plastic handle table locking levers interfered with DRO brackets.
Right: Replacement die-cast zinc alloy/steel locking adjustable levers.


Animation of the replacement locking levers for the table.
Kipp (USA) adjustable handle (ball style) 5/16-18 with a 1.97" (50mm) long threaded stud.
Levers now more accessible, clamp much tighter, clear the scale & are away from the mechanical end of travel.

Scales, Brackets, Over-travel Switch, Cables, Handle Animations

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