Ø1½” Post Basics


Ø1.5" Post Basics

  • Solid Stainles Steel Construction
  • Stackable Design Provides Flexibility for Rigid Structures
  • Wide Range of Accessories Available

Our Ø1.5" Mounting Posts, which are fabricated from nonmagnetic 303 stainless steel, offer a wide range of basic building blocks for assembling large, rigid, 3D structures. The post products detailed on this page are the most essential construction elements onto which a host of accessories can be fastened. The solid stainless steel construction of our posts, post spacers, and post bases are complimented by large-diameter relief cuts at end interface points to provide exceptional strength and rigidity.

The stackable P-Series Posts and Post Spacers can be combined to offer a wide range of achievable mounting heights, while the P-Series Bases offer versatility when fastening posts to an optical table. A 1/4"-20 (M6) tapped hole in each post end provides sufficient clamping strength to join to posts, effectively making them one longer rigid post.


Ø1.5" Posts


  • Solid Nonmagnetic Stainless Steel Construction
  • Ideal for Large, Rigid, 3D Structures

These solid stainless steel Ø1.5" (Ø38 mm) P-series posts, offered in heights ranging from 1" (25 mm) to 14" (350 mm), are designed for constructing extremely rigid assemblies with demanding structural integrity requirements. The stackable design, which has 1/4"-20 (M6) tapped holes on both ends, allows the joining of multiple mounting posts to achieve an array of lengths. Using a 3/16" (5 mm) balldriver inserted through the side clearance hole, sufficient torque can be achieved to securely tighten stacked posts. These posts also feature a large-diameter relief cut on both ends for mounting stability.

For ease in distinguishing between the imperial and metric versions, the tops and bottoms of the metric posts have a ring engraved on them, while the imperial posts have no such engraving (see images above on the right).

Post spacers are also available below to provide greater flexibility in height. Please note that if your application requires tighter tolerances than those offered by the P-series [±0.005"(±0.127 mm)] or height adjustability, we recommend using the BLP01 Adjustable Height Post.


Ø1.5" Post Spacers

 * Solid Nonmagnetic Stainless Steel Construction
 * Ideal for Achieving "In-Between" Post Lengths

These solid stainless steel Ø1.5" (Ø38 mm) post spacers are designed to achieve post heights that are between those offered by any two P-Series posts. For example, a post height of 28 mm is achieved simply by attaching a PS3M (3 mm post spacer) to a P25/M (25 mm post). The spacer provides a center-located 1/4" (M6) clearance hole for access to the P-series posts as well as a large-diameter relief cut on both spacer ends for mounting stability. Please note that for applications requiring tight height tolerances, we recommend using a BLP01 Adjustable Height Post.


Ø1.5" Post Pedestal Base Adapter and Clamping Fork


Each PB4 (PB4/M) Pedestal Base Adapter has a threaded 1/4"-20 (M6) stud that is designed to thread onto the bottom of our P-Series Posts. For instance, the image to the right shows a P2 post with a PB4 Base. The PB4 adapter allows our PF175 clamping fork to be used to position the post assembly conveniently on your optical bench. This clamping fork creates three points of contact with the table for high stability.

Please note that significant overtightening of clamping forks can deform the surface of an optical table, which can cause misalignment of components and decrease stability of the clamping fork


Ø1.5" Post Bases


This universal post base has a 1/4" (M6) Counterbored hole in the center that allows the base to be attached to a Ø1.5" mounting post using a 1/4"-20 (M6) caphead screw. Four 1/4" (M6) counterbored holes on 2" (50 mm) centers are provided for mounting the post base to an optical table or optical breadboard.

PB2 and PB2/M
These post bases have counterbored slots that allow for additional freedom in the placement of Ø1.5" mounting posts. The PB2 has a center-tapped 1/4"-20 hole while the PB2/M has a center-tapped M6 hole. The PB2/M has an identifying ring engraved around the tapped hole on the bottom face of the base. Use a 1/4"-20 (M6) setscrew to attach the PB2 (PB2/M) base to a Ø1.5" mounting post


Ø1.5" Pedestal Post Clamp


  • Compatible with Ø1" and Ø1.5" Posts
  • Two-Point Contact with Pedestal Post Perimeter
  • Line Contact on Table for More Secure Clamping Force

Thorlabs' CL8 pedestal post clamp secures our Ø1" and Ø1.5" pedestal posts to an optical table or breadboard. Its V-shaped tip provides two-point contact with the post perimeter and its rounded edge increases the contact area along the table.


Post Position Retainer


  • Re-Position Ø1" and Ø1.5" Posts within an Optical System
  • Re-Alignment Based on Two Contact Points
  • Third Contact Point for Realigning Square Components
  • 1.73" (43.8 mm) Long and 0.13" (3.2 mm) Thick

Thorlabs' RSPC Post Position Retainer is used to realign posts that have been removed from an optical system. It acts as a marker on the breadboard or optical table in the event that you need to remove a post from your setup. The two white dots engraved on the top surface of the outer arms of the retainer mark the two points of post contact. The RSPC was specifically designed for use with the Ø1" Pedestal Posts. The third dot, located within the V-groove, is for retaining the position of a square base or other squared-off component. For more information on using the RSPC with a square component.

Note: The RSPC Post Position Retainer can also be secured to an optical table or breadboard via the CL6 clamp. This clamp is useful in situations where the RSPC cannot be placed directly over a hole in the table. The photos below illustrate the RSPC being secured to an optical table both with an 8-32 cap screw and with the CL6 clamp.


Our Mission is to accelerate the advancement of optical technology for precision measurements and their applications from the table tops of research laboratories to standard use in communication and high technology industries. Our aim is to serve our customers. Our hope is to create a place for highly skilled people in an open environment

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