Jour : 06/14/2026

Accuracy Grade Classification of Granite Parallel Rulers (Granite Straightedges)The domestic executive standard JB/T 7878-2017 “Rock Straightedges” divides them into three grades: Grade 00, Grade 0, and Grade 1, based on geometric tolerances such as straightness, working surface parallelism, and flatness. Grade 00 has the highest accuracy, and Grade 1 has the lowest.I. Core Determination Indicators…

Granite parallel bars (also known as granite parallel gauges / flat bars) are high-precision reference measuring tools made of natural granite (such as Jinan Green) through precision machining and manual grinding. Used in pairs, they are primarily used for parallelism, straightness, and flatness inspection, as well as equipment calibration. I. Core FeaturesStable Accuracy: Natural aging…