Granite is a hard material but its hardness varies for several reasons.
Base grade granite.
The minitech cnc mini mill gx is the most affordable precision ground granite frame micro machining system on the market.
Eley metrology s granite surface plates and tables are in accordance with bs 817 2008 and are graded at three levels.
Grade 0 plates and tables are typically used for laboratory environments where master artefacts are required.
Indicator arms have a throat depth of 1 75 and can be raised to a height of 6 depending on the type of mount used.
Level 1 granite has a very simple design and the colors are standard.
This low grade granite is usually imported from china and sold through granite liquidators big box stores or cut into tile.
The surface plate is often used as the baseline for all measurements to a workpiece therefore one primary surface is finished extremely flat with tolerances below 11 5 μm or 0 0115 mm per 2960 mm for a grade 0 plate.
Indicator arms are available in lug or stem mount.
An experienced granite plate technician can estimate the hardness by its color which is an indication of its quartz content.
Granite hardness is a property defined in part by the amount of quartz content and lack of mica.
6 x 6 x 2 grade aa 00005 these 6 x 6 x 2 granite bases are supplied with a 1 25 diameter 8 tall column and an indicator arm rigid or with a fine adjustment knob.
The granite properties determine the stiffness of the granite therefore accuracies can be guaranteed with less thickness than other types of granite.
Grade 0 granite surface plates tables.
A surface plate is a solid flat plate used as the main horizontal reference plane for precision inspection marking out layout and tooling setup.