Product Description

521-B Spherical Mount

For alignment telescopes and targets

Mounting flexibility is what you get with the 521-B spherical mount. It is compatible with any 2¼” alignment telescope or collimator, allowing you to position your telescope in the many orientations your application may require. The spherical mount also functions as a target holder for alignments requiring precision target fixtures. It has three radial setscrews at approximately 120 degree intervals, as well as three “axial” setscrews in a line along the length of the sphere. This allows for accurate and flexible target positioning. Often used with our cup mount 560-2. Conforms to all A.I.A. standards. The 2022 is classified as National Stock Number (NSN) 4920-01-013-0448.

Although it may be used in many different mounting configurations, the 521-B Spherical Mount at left is shown holding a 2022 Alignment Telescope in a 5170 base. The highlighted portion shows a 521-B Spherical Mount, a 565 Spring Clamp, and a 560-2 Adjustable Cup Mount.


Outside diameter:
3.5000″ +0.0005″, −0.0000 (88.9mm, +0.013mm −0.000)
Inside diameter:
2.2500″ +0.0005″ −0.0000 (57.2mm, +0.013mm −0.000)
Concentricity of I.D. to O.D.:
0.0005″ (0.013mm) TIR maximum. Distance from center of sphere to squared face: 1.000″ +0.005″ -0.000″ (25.4mm, +0.127mm – 0.000mm)
Material: Heat-treated steel
Finish: Black oxide
Approx. weight:
Sphere, 3 lbs. (1.4 kg)
Shipping, 4 lbs. (1.8 kg)



May Be Used With

560-2 Cup Mount with 565 Spring Clamp
705, 705-1, 707 family, 714, and 6130 disk targets
5150 and 5170 Alignment Telescope Bases
5180 Alignment Telescope Base (discontinued)




English (PDF)