MOUNT THE DATUM RAIL AND VERIFY X0/Y0

HARDWARE — FINAL QUANTITY AND LOCATIONS FOLLOW THE CLEARANCE TEST
- Removable 1/4-20 flat-head machine screws, seated flush with the maple.
- Matching threaded inserts or captive nuts installed in structural deck locations.
- Two removable alignment pins per rail for repeatable location; screws clamp, pins locate.
- Suggested starting spacing: one fastener 3–4 in. from each rail end, then no more than
  12–16 in. apart. Move any position that conflicts with a track, rib, clamp, or machine.

A. MAP THE SAFE MOUNTING ZONE
1. Fit the permanent MDF modules and T-tracks. Lock the tilt table horizontal and level it.
2. Place the assembled L at the front-left, with both crisp inside faces toward the work area.
3. Set the rail only slightly above the MDF—just enough to register stock. Confirm the
   final proud height cannot contact the collet, dust shoe, gantry, clamps, or cutter.
4. With power off and Z safely raised, move the complete LowRider carriage through every
   X/Y extreme. Repeat with the dust shoe and the largest planned cutter/clamp combination.
5. Mark T-tracks and torsion-box ribs on masking tape. Choose fastener positions only in
   confirmed structural zones, clear of the full moving and cutting envelope.

B. INSTALL REPEATABLE LOCATORS AND CLAMPS
1. Square the front/Y0 rail to the LowRider's Y travel—not merely to the deck edge. Sweep
   a dial indicator along its inside face and adjust until variation is acceptably small.
2. Clamp the front rail without moving it. Drill one alignment-pin hole near each end through
   a drill guide so the holes are square. Install removable pins; do not glue the rail down.
3. Position the left/X0 rail at the half-lap. Use the largest reliable square, then compare
   diagonals of a large test rectangle. Adjust until both diagonals match.
4. Drill and install the left rail's two alignment pins while clamped in place.
5. Transfer the approved screw locations. Drill clearance holes through maple; countersink
   until every screw head is flush or below the top face. Install inserts/captive nuts below.
6. Tighten screws from the corner outward only enough to seat the rail. Recheck straightness;
   over-tightening can bow a 97 in. wooden reference edge.
7. Remove and reinstall both rails twice. They must seat on the pins without force and return
   to the same indicator reading. If they do not, correct the locator holes before calibration.

C. ESTABLISH MACHINE ZERO
1. Home the LowRider using its normal machine-homing procedure. Use a clean, known-diameter
   end mill or precision pin in the collet; measure its actual diameter.
2. Approach the left rail's inside face from the work area at low jog speed. Touch off with
   a feeler strip or probe. The spindle center is one tool radius inside X0, so set the work
   X coordinate to the measured tool radius (plus any feeler/probe compensation).
3. Approach the front rail's inside face the same way. Set the work Y coordinate to the tool
   radius (plus compensation). The intersection of the two inside faces is physical X0/Y0.
4. Retract, approach both faces again, and repeat the readings. Record machine-to-work X and
   Y offsets, tool diameter, touch-off method, rail proud height, and the date.

D. VERIFY THE ZERO AND SQUARENESS
1. Clamp scrap against both rails. Program a shallow 4.000 x 4.000 in. square with its lower-
   left corner a known distance—such as 1.000 in.—from X0/Y0. Do not cut into the rails.
2. Measure the square's sides and diagonals. Equal diagonals confirm squareness; side errors
   expose scale or backlash. Measure its offsets from both rail faces to confirm zero.
3. Run a longer diagonal check across the usable field before trusting the 97 in. datum.
4. Remove and reinstall the rails, re-home, reload the recorded offsets, and repeat the test.
   The result must return within the tolerance required by the work you intend to cut.
5. Recheck after a hard carriage strike, deck-module change, seasonal movement, or whenever
   a test cut no longer lands at the recorded offset.

SAFETY HOLD
Do not drill from assumed coordinates. Every hole is transferred after inspection because
safe positions depend on the completed deck. Keep the rails removable and never let either
rail enter the cutter, dust-shoe, clamp, or carriage envelope.
