Model 3R BLOCK-HEAD®

The model 3R BLOCK-HEAD® air bearing fits well in high-speed applications like dicing saws or I.D. grinders. Its sub-millionth-inch accuracy and high central stiffness enable controlled material removal even in tough or brittle materials.

Specifications (at 150 psi)

Load Capacity Ultimate Working
Radial 65 lb 32 lb
Axial 170 lb 85 lb
Tilt 140 in-lb 70 in-lb
Stiffness Radial 0.5 lb/microinch
Axial 1.5 lb/microinch
Tilt 1.6 lb-in/microradian
Error Motion Radial < 1 microinch
Axial < 1 microinch
Tilt < 0.3 microradian
Total Weight 7.25 lb
Rotor Weight 3.2 lb
Rotor Inertia 0.16 oz-in-sec2
Maximum Speed 15,000 rpm
Air Consumption < 2 scfm
Metric Specifications


Load capacity and stiffness are approximately linear with air pressure.

Ultimate load capacity is measured when metal-to-metal contact is made across the bearing surfaces. Working load capacity is half of the ultimate load capacity. Rotor weight must be included as part of total spindle load.

Axial and tilt loads are supported by the same bearing surfaces. Consequently, a load applied in one mode reduces the other mode proportionally.

High speed or high inertia applications require rotor containment. Maximum speed is dependent on application. Consult Professional Instruments for further information with regard to speed.