BLOCK-HEAD® Air Bearing Spindle Specifications

(at 150 psi)

The BLOCK-HEAD® family of air bearing spindles (named for their short, blocky shape) combine rotational accuracy with extremely high stiffness comparable with that of heavy-duty ball bearing headstocks. These spindles are suitable for accurate support of overhung loads, and their unique combination of accuracy and stiffness makes possible direct machining to optical tolerances and finishes.

BLOCK-HEAD® spindles have been used successfully from less than 50 psi up to 200 psi, and have shown no signs of instability. They will operate equally well in any position, over a wide speed range, and in a variety of environmental conditions. Add-ons such as motors, chucks, mounting plates, and custom tooling benefit from the correct nature of the BLOCK-HEAD® design. Accessories can be close-coupled, tightly-held, and non-distorting.


 
Load Capacity
Radial
Axial
Tilt
Stiffness
Radial
Axial
Tilt
Error Motion
Radial
Axial
Tilt
Total Weight
Rotor Weight
Rotor Inertia 
Maximum Speed
Air Consumption

Model 3R BLOCK-HEAD®

Ultimate Working
65 lb 32 lb
170 lb 85 lb
140 in-lb 70 in-lb
0.5 lb/microinch
1.5 lb/microinch
1.6 lb-in/microradian
< 1 microinch
< 1 microinch
< 0.3 microradian
7.25 lb
3.2 lb
0.16 oz-in-sec2
15,000 rpm
< 2 scfm


Model 4R BLOCK-HEAD®

Ultimate Working
100 lb 50 lb
400 lb 200 lb
400 lb-in 200 lb-in
0.67 lb/microinch
2.0 lb/microinch
4.0 lb-in/microradian
< 1 microinch
< 1 microinch
< 0.1 microradian
19 lb
7.7 lb
0.73 oz-in-sec2
7,500 rpm
< 2 scfm


Model 4R 2.25 BLOCK-HEAD®

Ultimate Working
125 lb 63 lb
175 lb 88 lb
150 lb-in 75 lb-in
0.8 lb/microinch
1.0 lb/microinch
1.7 lb-in/microradian
< 1 microinch
< 1 microinch
< 0.1 microradian
16 lb
7 lb
0.77 oz-in-sec2
7,500 rpm
< 2 scfm


Model 4B BLOCK-HEAD®

Ultimate Working
100 lb 50 lb
400 lb 200 lb
400 lb-in 200 lb-in
0.67 lb/microinch
2.0 lb/microinch
4.0 lb-in/microradian
< 1 microinch
< 1 microinch
< 0.1 microradian
18 lb
7.7 lb
0.73 oz-in-sec2
7,500 rpm
< 2 scfm


Low-Profile 4R & 4B BLOCK-HEAD®

Ultimate Working
100 lb 50 lb
400 lb 200 lb
400 lb-in 200 lb-in
0.67 lb/microinch
2.0 lb/microinch
4.0 lb-in/microradian
< 1 microinch
< 1 microinch
< 0.1 microradian
16 lb
5 lb
0.40 oz-in-sec2
7,500 rpm
< 2 scfm




 
Load Capacity
Radial
Axial
Tilt
Stiffness
Radial
Axial
Tilt
Error Motion
Radial
Axial
Tilt
Total Weight
Rotor Weight
Rotor Inertia 
Maximum Speed
Air Consumption

Model 10R BLOCK-HEAD®

Ultimate Working
400 lb 200 lb
2,400 lb 1,200 lb
6,000 lb-in 3,000 lb-in
2 lb/microinch
10 lb/microinch
100 lb-in/microradian
< 1 microinch
< 1 microinch
< 0.1 microradian
154 lb
72 lb
36 oz-in-sec2
1,800 rpm
< 3 scfm


Model 10B BLOCK-HEAD®

Ultimate Working
400 lb 200 lb
2,400 lb 1,200 lb
6,000 lb-in 3,000 lb-in
2 lb/microinch
10 lb/microinch
100 lb-in/microradian
< 1 microinch
< 1 microinch
< 0.1 microradian
146 lb
72 lb
36 oz-in-sec2
1,800 rpm
< 3 scfm


Model 10R-606 BLOCK-HEAD®

Ultimate Working
600 lb 300 lb
1,000 lb 500 lb
2,800 lb-in 1,400 lb-in
3 lb/microinch
5 lb/microinch
60 lb-in/microradian
< 2 microinch
< 2 microinch
< 0.1 microradian
104 lb
42 lb
27 oz-in-sec2
1,500 rpm
< 4 scfm


23R BLOCK-HEAD®

Ultimate Working
1,500 lb 750 lb
15,000 lb 7,500 lb
50,000 lb-in 25,000 lb-in
4 lb/microinch
40 lb/microinch
1,500 lb-in/microradian
< 1 microinch
< 1 microinch
< 0.1 microradian
2,200 lb
1,400 lb
245 oz-in-sec2
Application Dependent
< 10 scfm



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.