ZHHIMG® Precision Granite Square | Black Granite Tri-Square Ruler for Metrology & Machine Assembly

Q: What is the difference between a granite square ruler and a granite surface plate? A: A surface plate provides a flat two-dimensional reference plane. A granite square ruler provides a right-angle (90°) reference between two precisely perpendicular faces. They are complementary tools: the surface plate establishes the datum plane, and the square ruler establishes perpendicularity to that plane.

Q: How do I verify the perpendicularity of a granite square in my own facility? A: The standard method uses a precision dial gauge or electronic probe on a height stand placed on a calibrated granite surface plate. The square is stood on the plate, the gauge is swept vertically along the reference face, and the reading variation gives the perpendicularity error. For Grade 00 verification, a laser interferometer or autocollimator system is required.

Q: Can granite squares be re-lapped if they go out of specification? A: Yes. Granite can be re-lapped to restore its surface and angular accuracy. This requires returning the square to a qualified facility with appropriate lapping equipment and reference standards. ZHHIMG® provides re-lapping and re-certification services.

Q: What is the recommended storage and handling practice? A: Store the square in its protective case when not in use. Before measurement use, allow the square to thermally equilibrate in the measurement environment for a minimum of 2 hours (longer for large squares). Avoid placing it on surfaces with significant thermal gradients. Clean with a lint-free cloth and neutral cleaner; never use abrasive materials.

Q: Do you provide custom sizes or special configurations? A: Yes. ZHHIMG® manufactures custom granite squares including non-standard sizes, special aspect ratios, squares with precision ground slots or holes, and squares designed to specific customer drawings. Contact our engineering team with your requirements.

Q: How long does delivery take, and do you ship internationally? A: Standard sizes are typically available within 15–30 business days depending on grade and size. Custom orders require additional lead time. We ship globally and have export experience to Europe, North America, Southeast Asia, the Middle East, and Africa. Export documentation and packing are handled in compliance with international freight requirements.

Q: Is a calibration certificate included with every square? A: A calibration certificate documenting grade compliance is included as standard. A full traceable calibration certificate with actual measured values and measurement uncertainty statement is available as an option or can be required at order placement. Please specify at time of order.