Granite Right Angle Square 00 Grade 300 x 200 x 40mm - Triangular Machinist Square

Solid black granite triangular right-angle square, grade 00, for checking squareness of machine axes, columns and setups.

Granite right angle square - 300 x 200 x 40 mm

A solid black granite right angle square, 300 mm x 200 mm x 40 mm, for inspection and machine setup work. Triangular right angle square with single through-hole for lifting and clamping.

Stand the square on a surface plate or machine table and bring the blade up against the column, the spindle nose or the workpiece. Because both legs are ground to the right angle, either leg can be the reference - turn it round and the square checks the other direction. Granite is preferred over steel here: no rust, no burrs from knocks, and much lower thermal movement when the workshop warms up.

Specification

• Type: Triangular right angle square
• Size: 300 x 200 x 40 mm (length x width x thickness)
• Material: black natural granite, fine grained, lapped working faces
• Grade: 00 (supplier stated)
• Stated accuracy: within 0.005 mm on the working faces (supplier stated, not certificate-verified)
• Working faces: ground working faces on both legs of the right angle
• Handling: single through-hole for lifting and clamping
• Packaging: wooden case (supplier stated)
• Lead time: 15 working days

What grade 00 actually means

The supplier states grade 00 with accuracy within 0.005 mm on the working faces. That figure comes from the supplier's own specification card, not from a calibration certificate - we have not verified it and we do not include a certificate with the item. Treat it as the supplier's claim, and if you need a documented accuracy for acceptance testing or customer sign-off, have it calibrated on arrival. We would rather say that plainly than print a tolerance we cannot stand behind.

Choosing the right size

The leg lengths are 300 x 200 mm, so the square will check a feature up to 200 mm tall with the long leg as the base, or up to 300 mm tall stood on its short leg. As a rule take the largest square that will physically fit the space you are working in: the further the blade extends past the feature being checked, the more of the error you can actually read.

Handling and care

Granite is hard and stable, but it chips rather than dents. Do not let it slide across a machine table with swarf under it, and never lift it by the blade - use the handling holes. Keep it in its case when it is not in use. Wipe the faces with a clean cloth before a check; a single chip of swarf under the face is bigger than the tolerance you are trying to measure.

What is and is not supplied

One granite right angle square, 300 x 200 x 40 mm, in a wooden case. No calibration certificate or inspection report is supplied, and no stand or surface plate is included. The tolerance is the supplier's stated figure only.

Photographs

The two photographs show a right angle square of this type from the same supplier range. They are representative of the product - the unit pictured is not the exact size listed here, and the size supplied is the size in the title. Granite is a natural material, so the colour and speckle of the stone will vary slightly from the photographs.