Starrett 649 Spindle Square Simplifies Tramming

The L.S. Starrett Company has introduced its patented 649 Series Spindle Square for tramming the head of a vertical milling machine. Tramming must be done regularly to ensure squareness and perpendicularity between the spindle and work surface. This innovative device offers improved accuracy, convenience and significant time savings when compared to the traditional method of tramming with a dial test indicator.

The 649 Series Spindle Square comes fully assembled with two AGD Group 2 dial indicators. It has a solid steel body construction, durable black wrinkle finish, and ground gaging surface. The unit weighs approximately 4 lb. and is approximately 6¾" (172mm) wide and 5½" (140 mm) long from the top of the shank to the end of the contact points. 

Machinists report that the 649 Series Spindle Square is easy to use. After setting the spindle square indicators to "0" on a surface plate, the Spindle Square is placed into the collet of the milling machine. The head is brought down to the table until both indicator needles have rotated approximately one full rotation. The needles do not need to point in the same direction. Identical numerical readings, not the needle positions, indicate squareness. Normal tramming procedures are used until both indicators read the same numerical value. After setting the X-axis, the same procedure is repeated for the Y-axis.