Precision Roller Blocks

Low-runout bearing-based rollers for precision positioning.

Midnight Tools Precision Roller Blocks Render
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Designed, Machined, and Assembled in the USA

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High Precision for Inspection

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Full Part Support

Precision Low-Runout Positioning at Reasonable Prices

Low-runout Bearings

  • Our standard Precision Roller Blocks use deep groove ball bearings with a P5 (6 micron) runout tolerance.
  • Ultra-precision versions use bearings with a P4 (4 micron) runout tolerance.
  • Bearings are open type. If you require shielded or sealed bearings for your application please contact us before ordering.

Single Setup Machining of Critical Features

  • The profile of the roller body and the pin holes are machined in a single setup to minimize error.

Interference Fit Assembly

  • Blocks are assembled with interference fits to remove fit tolerance errors.
Roller Feature Render

Aluminum for Inspection?

Aluminum has numerous favorable properties but is not a typically used for inspection equipment due to its limitations. By understanding and designing for these limitations we can deliver roller supports that meet the precision needs of many inspection applications at lower prices. Details of common limitations of aluminum and our approach to mitigating them is provided below. If you have specific application questions contact us at


Design Mitigation


Low hardness

Low stiffness

High thermal expansion

Black anodize bodies

Minimize distance between pins and reference surface

Blocks are still susceptible to damage but anodizing provides a hard surface that resists scratches and minor damage and black color makes damage highly visible.

Thermal and loading dimension changes are proportional to the total dimension. Minimizing the distance to less than 1/4 that of competing steel products more than offsets the difference in material properties.


Supported Diameters

Small Size

1/2 to 3 in
13 to 76 mm

Medium Size

2 to 5-1/2 in
51 to 140 mm

Large Size

5 to 9 in
127 to 229 mm

Load Capacity

Per Block
(Assumes full support of base)

600 lbs
273 kg

Bearing Details

Bearing Number



30 mm


10 mm


9 mm

Runout Tolerance

Standard - P5
Ultra Precision - P4

Dimensions (LxWxH)

Small Size

3-3/4 x 1-1/4 x 1-3/8 in
95.3 x 31.8 x 34.9 mm

Medium Size

4-1/2 x 1-1/4 x 1-3/8 in
114.3 x 31.8 x 34.9 mm

Large Size

5-3/4 x 1-1/4 x 1-3/8 in
146.0 x 31.8 x 34.9 mm


Small Size
per block

0.63 lbs
287 g

Medium Size
per block

0.71 lbs
325 g

Large Size
per block

0.83 lbs
380 g



Anodized aluminum

Pins and Washers

Stainless Steel