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 device offers improved accuracy, convenience and significant time savings when compared to the traditional method of tramming with a dial test indicator, according to the company.

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

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.