DRO_Mill

Digital Read-Out (DRO) for the Rong Fu RF-25 Mill

RF-25 Mill & X Y Z Axes Scales. RF-25 Mill Tachometer & SFM

Taig Micro Mill Taig Micro Mill DRO & X Y Z Axes Scales. Taig CNC Mill DRO Taig Mill Tachometer & SFM
9x20 Lathe, 9x20 Lathe DRO X & Z1 Axes Scales. 9x20 Lathe Tachometer & SFM Taig Micro Lathe DRO
ShumaTech DRO

Rong Fu RF-25 with completed DRO & scales.
Scales directions & polarities must be correctly defined in the DRO setup for several of the functions to properly work.

Setup shown for milling the lathe DRO case. 1-2-3 "Johnny" blocks fixed at right angles to the table.
Plastic box sides slightly squeezed by the blocks. Toe clamps with protective tape gently secure the box.
The X & Y axes DRO scales were zeroed at the left, front corner (0, 0) using a Starrett wiggler center finder.
Then use the layout drawing of the (x, y) coordinates supplied to drill & cutout out all the holes.
I like to use a Unibit step drill to make holes in thin materials.

The US made Starrett wiggler set is far superior to imports.

To make the rectangular holes for the LED displays, I used the DRO's tool offset functions.
The offset function takes into account the end mill's diameter when cutting.
I used Function 5 (tool offset define) to first specify all the tool sizes where the
Tool # is always the numerator & 16 is always the denominator of a fractional size.
Tool #/16 of an inch. I find this a very easy nomenclature to remember, though it's of course, arbitrary.
I used 0 for the offsets. The DRO-350 will only allow three significant numbers input after the decimal point.

TOOL # TOOL SIZE
DIAMETER (INCH) EQUIVALENT
FRACTION
(INCH) EQUIVALENT
DECIMAL (INCH) CORNER
RADIUS (INCH)

1 1/16 1/16 0.0625 0.03125

2 2/16 ⅛ 0.1250 0.06250

3 3/16 3/16 0.1875 0.09375

4 4/16 Ľ 0.2500 0.12500

5 5/16 5/16 0.3125 0.15625

6 6/16 ⅜ 0.3750 0.18750

7 7/16 7/16 0.4375 0.21875

8 8/16 ˝ 0.5000 0.25000

9 9/16 9/16 0.5625 0.28125

Function 6 (tool offset use), followed by a Tool # (1~9), turns ON diameter compensation & selects the previously defined tool. First, select the tool size diameter being used. To cut a rectangular/square pocket or hole, move the cutter to the (x, y) coordinates of the front left corner but don't plunge, yet. If you are starting in a corner, you must compensate for two milling edges; e.g., both left & front. When you press a compensation key, you will see the scale offset by the appropriate tool radius. If 4, 6, 2 or 8 are pressed, the far left decimal of the corresponding scale lights indicating an offset was selected.

    Zero, Z-Axis depth (e.g., the part's top surface).
    Press 4 (left edge), set front left corner x coordinate.
    Press 2 (front edge), set front left corner y coordinate.
    Plunge to desired Z-Axis depth.
    Press 6 (right edge) & cut to front right corner x coordinate.
    Press 8 (rear edge) & cut to rear right corner y coordinate.
    Press 4 (left edge) & cut to rear left corner x coordinate.
    Press 2 (front edge) & cut to front left corner y coordinate.
    If necessary, remove any material in the center area.
    Continue cutting to desired depth or withdraw end mill.

Alternatively, you could start in the central cutting area, away from any edges. This approach can produce a more precisely sized pocket since it is a roughing cut followed by a finishing cut. To cut a protrusion, select the opposite cutter edge (direction) to which you are cutting. Practice on a piece of scrap. At first I was cutting protrusions instead of pockets because of my scale assignments. The pocket will, of course, have radii corners, but the protrusion will have square corners. Pressing 5 (center position) deselects any offsets (left LED's off). Selecting Function 6, 0 turns offset use OFF. Even if the power is removed, the numbered tool offset in use (1~9) is retained but not the selected cutting edge. See the ShumaTech site for additional details.

High RPM cuts using a two-flute, ⅛" end mill.

The DRO bracket is placed closer to the keys where pressure is applied.
I protected all exposed cables with spiral wrap. The 80/20 arm is mounted off a
triangular, Ľ" thick aluminum plate that is held under two of the motor-mounting bolts.
The Ľ-20 T-knobs are from Woodcraft. I use to tuck the DRO into the central quill-lever area.
SPC cables from LMS. All cable plugs are held in place with a spot of hot glue.
Black plastic (80/20) inserts are snapped into the channels to hold the cables in place &
to give the arm a nice, finished look. I have the DRO plugged into a line voltage surge protector.

Adding a deep red filter enhances the LED display contrast.
The five LED indicators have circular (punched) red filters, too.
Note: The blurred LED display is a photographic artifact.

I have now removed all of the quill levers so they do not contact the piece when working close to the vise.
This configuration allows much better access to the two column locks, belt tension lock & DRO.
I made two, ˝-12 threaded aluminum inserts to give it a finished look & keep the chips out
but kept the one back hole open if I want to screw in a lever for use like a drill press, if needed.
However, since I like the extra control afforded by the fine down feed, I have yet to use the levers.

RF-25 Mill X Y Z Axes Scales. RF-25 Mill Tachometer & SFM