The Four Place Turret System

This system is our part number FPT-150 that is designed to utilize existing off the shelf components which provides very economical and sophisticated Coordinate Measuring Machine ( CMM ) evaluation and legal calibration. This rugged Turret is one and one half inch ( 1 1/2", 1.5", 38.1 mm ) in diameter. It is one and three eights of an inch ( 1 3/8", 1.375", 34.93 mm ) thick.

It has a ten millimeter ( 10 mm, 0.40 inch ) diameter hole through the center, of the cylinder, so that it can be indexed the full 360° around. This hole provides the method of mounting the four place turret on its mating part, and locking it rigidly in place. There are four counter bores machined, at 90° increments on the one and one half inch ( 1 1/2", 1.5", 38.1 mm ) outside diameter that are 0.770 inch ( 19.6 mm ) in diameter. Each flat has a five sixteenths inch ( 0.3125”, 5/16” 7.9 mm) diameter hole, with 18 threads per inch, machined in it.

This machining is done to facilitate mounting up to four Adjustable Ball Bar ends, with or without extensions. The standard off the shelf adjustable Ball Bar end is our part number ABB-PB-100 (which has a 1.00” [ 25.4 mm ] master sphere) or ABB-PB-75 (which has a 0.750” [ 19.05 MM ] master sphere).

Two adjustable Ball Bar ends mounted 180 degree apart, on the Four Place Turret will form a short Ball Bar, that may be used to calibrate your C.M.M. probe. This approach to probe calibration is quite unique in that the inter ball dimension can be subtracted, and you are substantially measuring all 360 degrees of a ball suspended in space.

By adding Adjustable Ball Bar extensions of various lengths, other Ball Bar lengths are generated that can actually used as a calibration artifact, (ABB-50 which is 50mm long, ABB-100 which is 100 mm long, and ABB-200 which is 200 mm long). See Figure #2. This Four Place Turret device will mount directly on, any one of the three facets, of the standard Tri-mount Collar (FS-3) used with the Heavy Duty Stand or with an Anchor. See Figure #3.

This Four Place Turret works very well, with our Two by Two Block (BLK-2) and with probe calibration extensions, part P-EP-3 which is three inches (76.2mm) tall, or our part number P-EP-6 which is six inches (152.4mm) tall. This Four Place Turret is a low budget accessory of the highest quality. It forms the back bone of a family of C.M.M. calibration and evaluation equipment that you can custom tailor to your specific needs. See Figure #4.

It is the most economical approach to providing a complex calibration artifact for articulating or star probe arrays. Individual calibration spheres can be placed at any angle and at any elevation using off the shelf adjustable ball bar extensions of different lengths. When you have several Adjustable Ball Bar Ends, it will open new opportunities for you to better calibrate and evaluate your machine.

Four or more of the adjustable Ball Bar ends placed at different elevations and positions along a diagonal of the C.M.M. table are all the hardware that is needed to perform a temperature drift test. See A.N.S.I. B89.4.1-1997 for full details.