These are aluminum oxide stones in various shapes that are ground to a high degree of flatness. They are sold as a pair (See application notes). Their main use is to check and repair precision surfaces – The flatness of the stones does not allow the stones to cut into a flat surface, the surfacepressure is to low, but if there is raised material like a burr, the reduced area of contact will make the stone cut and remove the material that’s raised above the surrounding surface.
This process will not alter milled, ground and lapped surface finishes if done with care.
Main applications are magnetic chucks, v-blocks, vices, parallels, precision parts during assembly, external spindle tapers (Hardinge tapernose, DIN shorttaper or the tapernose of a surface grinder).
Especially useful for deburring a freshly scraped surface.
The stones come in a pair, and before each use they are rubbed against each other to remove any metal or abrasive particle that is sticking out the ground surface.
Then they can be applied to any clean precision surface and used like a regular stone to remove burrs and raised material.
They will – if used properly – Not scratch surfaces, remove material or create a grind lay.