Q. What are the characteristics of different color granite surface plates?A. Color alone does not always determine what a particular color of granite is like. Not all black granites are alike and neither are all pink granites. Generally Black granite has very good density and stiffness. This means it will bend or warp less under load. It also means it absorbs less moisture that can distort accuracy. Black granite varies more in hardness with some having a good wear resistance and others not. Pink and Gray granites are less dense making them not as stiff as black granite, which is why they need to be thicker. They can also absorb more moisture. Pink and Gray granites tend to be harder and more wear resistant. All of these granites can make excellent surface plates, they just have different characteristics that can be matched up to the type of work and environment they will be used in.
Q. Can a surface plate be moved without being recalibrated?A. Under certain circumstances you can move a plate without recalibration. As long as the supports or the environment are not changed the plate can be moved without recalibration. If the plates is transported it is always a good idea to recalibrate.
Q. What is the proper way to support a surface plate?A. Surface plates are supported on three points. The location is determined with a 20% formula. Place them at 20% of the length and width in from the edges, with the third at 20% of the length and centered on the width. See installation instructions on the forms page of our web site.
Q. What causes surface plates to go out of tolerance?A. Wear from use is the most common cause. Other factors are improper supports, fluctuation in temperature, or the plate not being allowed to normalize completely to room temperature. A heat source (sun light or heater) directly on a plate will cause temporary distortion. Plates will also change from thermal expansion due to changes in gradient temperature. Thermal gradient is the difference in temperature between the top and the bottom of the surface plate.
Q. What is the best way to clean a granite surface plate?A. There are a number of ways to satisfactorily clean your plate. A cleaner that removes the dirt and does not leave a residue or excessive moisture behind is desirable. A glass cleaner will accomplish this for most situations. A waterless hand cleaner is recommended periodically for a deeper cleaning of the pores in the granite. It is very important to keep your plate clean which will reduce wear greatly.