Standard Work · Lean Manufacturing

Drawer Box Diagonal Squareness Check

This standard operating procedure defines the single-point method for verifying the geometric squareness of drawer box assemblies after glue-up and before slide installation. Consistent squareness ensures flush panel gaps, smooth slide operation, and zero rework.

Estimated Time

5 min

Difficulty

Intermediate

Regulation

CSA Z434 / AWI

Version

1.0

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Purpose

The purpose of this procedure is to ensure every drawer box exits the assembly station with diagonals within ±1.5 mm tolerance. Square drawer boxes are critical to preventing binding, uneven face-frame gaps, and premature undermount slide failure. This check forms a key quality gate in the lean manufacturing cell.

Scope

This SOP applies to all drawer box assemblies produced on the CNC dovetail line and the manual assembly bench. It is performed by the assembly operator immediately after glue-up and clamp removal, before the unit is passed to the hardware installation station. It does not cover pre-glue-up fit checks or post-installation slide alignment.

Safety Precautions

LOTOLockout / Tagout: Verify pneumatic supply to clamps is isolated before reaching into the fixture zone for manual adjustments or cleaning. Follow plant-specific LOTO procedure Z-101.
PPEPersonal Protective Equipment: Wear ANSI A3 cut-resistant gloves when handling machined parts. Safety glasses are mandatory due to potential glue splatter and debris. Steel-toed boots required.
HANDSharp Corners & Pinch Points: Dovetail pins and sockets have sharp machined edges. Keep hands clear of clamp stroke zones. Use a brush, not compressed air, to clear sawdust and chips from the fixture.

Required Tools & Materials

Digital Caliper (300mm range, ±0.02mm accuracy) — Note: Ensure battery is charged and caliper is zeroed before first use.
Assembly Table (calibrated flat within 0.5mm over 2m span)
Pneumatic / Toggle Clamps (set to 80 PSI)
Dead-blow Mallet (for corrective tweaks)
ShopDocs Workflow Terminal (for delta sign-off)

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Procedure: Step-by-Step

1 Fixture Verification: Confirm assembly table surface is clear of debris, glue reside, and loose hardware. Engage all pneumatic clamps in a dry cycle to verify full stroke and pressure (80 PSI).

2 Part Staging & Glue Application: Insert back panel into domino slots. Apply Type II PVAc glue to all pin sockets and mating surfaces. Use a calibrated glue roller to maintain an even spread of 0.15–0.25 mm.

3 Assembly & Clamping: Assemble sides, top, and bottom panels onto the back panel. Secure all joints with clamps. Wipe excess glue immediately with a damp cloth to prevent surface contamination.

4 Diagonal Measurement: Using the digital caliper, measure from inside corner A to inside corner D. Record value. Repeat for corners B to C. Ensure caliper jaws contact the exact bottom of each internal corner for repeatability.

5 Squareness Calculation: Subtract the smaller diagonal from the larger diagonal. The resulting delta must be ≤ 1.5 mm. If delta is within tolerance, proceed to Step 7.

6 Corrective Action (if delta > 1.5 mm): Apply clamp pressure to the corners of the longer diagonal. Gently tap the long diagonal corners with a dead-blow mallet to rack the box into square. Re-measure. Loop until delta ≤ 1.5 mm.

7 Sign-off: Initial the QC traveler sheet. Log the final diagonal delta value directly into the ShopDocs quality checklist terminal for real-time SPC tracking and lot traceability.

Drawer Box Diagonal Squareness Check

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