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Precision Bearings

Precision Bearings


Professional Instruments

authorized distributor

Professional Instrument products are the world’s most accurate air bearing spindles and slides for customers who require millionth-inch precision, high stiffness, and zero friction. 



BLOCK-HEAD® Spindles

BLOCK-HEAD® Spindle family combines ultra-high accuracy with extremely high stiffness in a very compact package making possible direct machining to optical tolerances and finishes.

Model 3R  - 15,000 rpm                      

Model 4R, Model 4R 2.25, Model 4B , Low-Profile 4R & 4B - 7,500 rpm

Model 10R, Model 10B, Model 10R-606 - 1,800 rpm

Model 23R  - Application Dependent rpm

Motorized Spindles

Motorized Spindles

Motorized Spindles integrate motors with air spindles for unmatched smoothness combined with high power and precision. Optional features include water cooling, optical encoders, metrology brakes, and non-influencing rotary unions. Typical applications include memory-disk research, generate aspheric optics, or build liquid-mirror telescopes.

4R Twin-Mount - high-power brushless-DC motor

4R Foot/Flange, A.C. Cube  - 1hp AC induction motor  

Motorized 10R – 10hp brushless-DC motor ,

Motorized ISO


ISO spindles

ISO Spindles

The ISO spindles offer high accuracy and stiffness along with high speed  capability and redial load capacity. Radial, axial, and tilt errors are specified to be better than 25.4 nanometers (one-millionth of an inch).Typical applications include Single point diamond turning, flycutting, internal grinding, and HDD servo track writing/head testing.

ISO 2.25 -60,000 rpm

ISO 5.5 -10,000 rpm



Rolling-Element Bearings

Rolling-Element Bearings

Rolling-Element Bearings lists ball bearing, roller bearing, and tapered-roller-bearing spindle assemblies. Typical applications include memory-disk testing, machine tools, coating rolls, precision pivots, and bearing testers.

Model 4R-T - radial and axial error motions of less than ten-millionths of an inch.



Oil hydrostatic spindles

Oil Hydrostatic Spindles

Oil hydrostatic spindles deliver high accuracy and stiffness in a smaller package than a comparable air bearing where space is at a premium. Our liquistatic bearings are all captured-thrust-style structures and typically have six radial pockets.  With designs ranging from one to two inch diameter rotors up to rotors seven inches in diameter, we have the capability to customize a liquistatic bearing to suit your application



D4-A Dryer-Filter-Regulator

Humidity Alarm

GF-5 Precision-Ground Flatstones

Magnetic Bases & Indicator Mounts