Unanodized, Circular, Solid Aluminum Optical Breadboards, Double Density Holes

  • Unanodized Finish for Use in Vacuum Applications
  • Acid Etched and Vacuum Sealed for Immediate Use
  • Through-Tapped Mounting Holes
  • Custom Sizes Available


Ø12.00" Aluminum Breadboard

Counterbored Ø1/4"
(M6) Mounting Holes


Ø5.87" Aluminum Breadboard

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Diagram of the MBR6U Breadboard. For similar diagrams of the other circular breadboards, please see the Weights & Dims tab.
Specification Imperial Boards Metric Boards
Material C250 Aluminum
Finish Precision Ground, Matte Finish
Cleaning and Packing Acid Etched and Vacuum Sealed
Size Ø5.87" and Ø12" Ø149 mm and Ø300 mm
Breadboard Thickness 0.5" 12.7 mm
Flatness ±0.006" over 1 ft2 ±0.15 mm over 0.3 m2
Holes 1/4"-20 Taps M6 Taps
Hole Spacing 1" Centers
Double Density Pattern
25 mm Centers
Double Density Pattern
Counterbores Four 1/4" Holes Four M6 Holes
Vacuum Compatibility as Packaged 10-6 Torr
Preparation and Packaging Chemically Cleaned and Vacuum Bagged
Aluminum Outgassing Rate at 20 °C 7.6 x 10-9 Torr-Liters/s/cm2


  • Precision Manufactured Unanodized Surface for Vacuum Applications
  • Acid Etched and Vacuum Sealed for Immediate Use
  • Electrically Conductive for Applications Requiring a Common Ground
  • Counterbored Mounting Holes for Attaching to an Optical Table or Breadboard Feet
  • Circular Geometry Saves Space
  • Same Hole Pattern as Our Double-Hole-Density Breadboards

Thorlabs' circular, unanodized, double-density breadboards are constructed from a 1/2" (12.7 mm) thick aluminum plate; this thickness is sufficient to maintain flatness over the full area (see the table to the right for flatness specifications). These nonmagnetic breadboards feature 1/4"-20 (M6) tapped holes at twice the density of our standard 1" (25 mm) hole pattern to provide a convenient platform for assembling prototype optical assemblies, conducting experiments, and mounting small subsystems. Please see the Weights & Dims tab for breadboard diagrams that call out the hole spacings.

Each breadboard offers four 1/4" (M6) counterbored mounting holes for attaching the breadboard to an optical table, another breadboard, mounting posts, brackets, breadboard feet, or other surfaces and mounts.

Vacuum Compatibility Information
These vacuum-compatible breadboards are chemically cleaned and prepared for vacuum applications before packaging. They are compatible directly out of the packaging with vacuum environments down to 10-6 Torr. With additional cleaning and processing, they can be used at even lower pressures, only limited by the outgassing rate of the aluminum (see the table above). The material properties of the aluminum and the cleaning methods completed by the end user should be used to determine the appropriateness of these products and materials in a specific vacuum system.

Thorlabs also offers rectangular double-hole-density optical breadboards, as well as rectangular standard-hole-density breadboards and unanodized, vacuum-compatible breadboards. Custom sizes of all breadboards are also available. Please contact Tech Support for more information.

Item # Dimensions Unpackaged Packaged Shipping
Mass (kg) Weight (lb) Mass (kg)a Weight (lb)a
MBR6U  Ø6.00" x 0.50" 0.56 1.23 0.57 1.26
MBR12U  Ø12.00" x 0.50" 2.34 5.16 2.59 5.71
MBR150U/M  Ø150.0 mm x 12.7 mm 0.56 1.23 0.57 1.26
MBR300U/M  Ø300.0 mm x 12.7 mm 2.27 5.00 2.66 5.86
  • These weights are approximate and are subject to change. The information is only to be used as a guideline.

Below are diagrams calling out the dimensions on each breadboard. Please note that the breadboards are not shown proportionally to one other.

Posted Comments:
j.travers  (posted 2016-08-02 14:32:04.22)
Do you do custom sizes? I'm looking for a diameter of around 200 mm to 250 mm, with metric mounting holes.
bwood  (posted 2016-08-03 04:17:32.0)
Response from Ben at Thorlabs: Thank you for your question. I am pleased to say we have a wide array of custom capabilities within our breadboard ranges, including these circular, anodised breadboards. Once you have finalised the specifications of your required breadboard, please contact your local Thorlabs technical support office to being the quoting process.

Unanodized, Solid Aluminum Circular Breadboards, Double Density (Imperial)

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
MBR6U Support Documentation
MBR6UUnanodized, Circular, Aluminum Breadboard, Ø5.87" x 0.50", 1/4"-20 Double-Density Taps
Lead Time
MBR12U Support Documentation
MBR12UUnanodized, Circular, Aluminum Breadboard, Ø12.00" x 0.50", 1/4"-20 Double-Density Taps

Unanodized, Solid Aluminum Circular Breadboards, Double Density (Metric)

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Metric Price Available
MBR150U/M Support Documentation
MBR150U/MUnanodized, Circular, Aluminum Breadboard, Ø149.0 mm x 12.7 mm, M6 Double-Density Taps
Lead Time
MBR300U/M Support Documentation
MBR300U/MUnanodized, Circular, Aluminum Breadboard, Ø300.0 mm x 12.7 mm, M6 Double-Density Taps