The Starrett 659BZ magnetic base assembly set is used to mount dial indicators for taking precise and repeatable measurements. The dial indicator has a 0-0.125" measuring range and 0.0005" graduations. The 0-25-0 balanced dial reading enables the operator to determine at a glance when the measurement is out-of-tolerance. The hardened stainless steel contact point provides durability and long life. The base has an on/off switch that releases the magnetic field when positioning the base. When turned on, the magnetic base has a holding power of 100 to 150 lb. The v-shaped base attaches to flat surfaces or round surfaces up to 5"/125mm in diameter. A threaded adapter on the base makes it possible to use Starrett Series 657 magnetic base posts and attachments. Both the upright post and gage rod are approximately 9-3/8" (238mm) long and 3/4" (19mm) in diameter. The post snug has two 3/4"/19mm holes that position the dial indicator at any height and vertical angle, and provides 360-degree rotation of the gage rod. The arm assembly can be finely adjusted to position the indicator as required. The set includes the magnetic base, upright base post, gage-holding rod with clamp assembly and fine adjustment, and a swivel post snug.
Magnetic bases are magnetic fixtures commonly used in metalworking to hold dial indicators, and are also used in other fields, such as optics. Magnetic bases can assist the user with setting up a workpiece in a milling machine, surface grinder, or other machine tool. The vertical post and rod in a magnetic base connect using swiveling connectors, or snugs. This allows free motion of the arm so that the dial indicator can be moved into position on the workpiece. Many magnetic bases have a V-step, which is a V-shaped notch in the base for holding the base to arbors, shafts, and other cylindrical items. The magnetic base has a circular hole through the center. A round permanent magnet is inserted into this hole, and a handle or button is attached to allow the user to rotate the magnet. Rotating the magnet turns the base on and off as this causes the position of the magnetic field to rotate as well. In the on position, the iron is acting as an extension of the magnet, while in the off position, the magnet is acting as a keeper, preventing the magnetic field from extending through the base.
The L.S. Starrett Company manufactures precision measuring tools, metrology and testing equipment, and saw blade products. The company, founded in 1880, is headquartered in Athol, MA.