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The model 89 is a precision mounting base designed to accommodate almost all of our 2¼" diameter alignment telescopes and collimators. The instrument is supported by two wyes which are 8.375" (212.7mm) on center, and are mounted to a channel-sectioned bar. (Special wye spacings are available on request.) The wyes provide stable support of the instrument barrel. For added protection, adjustable metal clips secure the telescope to the base.

Precise rotation in a horizontal plane is controlled by the patented Brunson ball bearing spindle, similar to that of all Brunson transits.  The mounting base has a standard 3½" x 8 internal thread for attachment to any compatible optical tooling stand.  A fine motion tangent screw allows easy azimuth control, and incorporates a wobble pin for tension relief and a stable setup.  Four large-headed leveling screws in nylon bushings make tilt adjustment easy.  A level vial may be ordered as extra equipment.

Note:  The original Brunson 89 had a wye spacing of 9½" (as shown in photo above), but was modified for the somewhat smaller spacing of 8.375" in order to fit all of the K+E design alignment telescopes.