Ø1" (Ø25 mm) Post Holders

Figure 1.1  Top View of Ø1" Post Holders Showing the Flexure Lock and Relief Cuts

Features

• Post Holders with Flexure Locking Mechanism for Ø1" Posts
  • Bottom-Located Tapped 1/4"-20 (M6) Mounting Hole
  • Pedestal Base Compatible with PF85B, PF125B, or PF175B Clamping Fork
• Available Lengths: 1.5" (38 mm), 2" (50 mm), 3" (75 mm), and 4" (100 mm)
• Imperial and Metric Locking Options Available

These Ø1" (Ø25 mm) Post Holders are the ideal solution for mounting optical components with maximum stability and an adjustable height. They are designed to be used with our stainless steel Ø1" Posts, which are offered in a range of fixed heights. These post holders provide the same level of stability as a pillar post directly threaded into an optical table or a pedestal post secured with a clamping fork. When using a longer post, a taller post holder should also be used to ensure the greatest stability. Please see the Stability tab for more information and the results of an experiment comparing various mounting options.

The flexure design of the post holder supports the post in a clamping mechanism that is secured with an 8-32 (M4) cap screw using a 9/64" (3 mm) hex key. The circular groove in the central bore allows the metal to flex and clamp the post's position without breaking. When locked, the square groove provides two fixed contact lines with the post to maximize the clamping force. The RSHT post holders have a base with a bottom-located 1/4"-20 (M6) tapped hole for mounting. This allows these post holders to be used with our Post Holder Bases, such as the BA2. This design does not allow a post to pass all the way through the post holder and always leaves the post resting at least 0.24" (6.1 mm) above the table surface. By contrast, the RSH post holders have a pedestal base and can be easily secured to a breadboard or optical table using the PF85B, PF125B, or PF175B clamping fork. The central bore of these post holders goes through the base, allowing Ø1" posts to pass all the way through the post holder and rest on the optical table surface for minimum beam height.

We also offer Ø1" post mounts, which mount a Ø1" post to an optical table without the use of a clamping fork.

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Figure 2.2  Stability Test Apparatus

The stability of a Ø1" post mounted in an RSH flexure post holder was compared to that of a post directly threaded to a breadboard and a post with a pedestal base secured to a breadboard with a clamp. The experimental apparatus consisted of an RS6 post held in an RSH post holder that was clamped to a breadboard with a PF175 clamping fork. A 2" moment arm was clamped to the post, and a variable load was applied to the end of the arm. As different loads were applied to the moment arm, the deflection of the post was measured with a dial indicator. The experiment was then repeated with the post threaded directly into the breadboard and with a pedestal post secured by a clamping fork. The results are shown in Figure 2.1.

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Figure 2.1  Results of an Experiment Investigating the Deflection of a Ø1" Post Under a Variable Load for Different Mounting Conditions

The test results indicate that, within the accuracy of the measurements, the RSH post holder is just as stable as the other two mounting options. However, instabilities can be introduced when a shorter post holder is used with a longer post. We recommend that you use a taller post holder with taller posts to avoid any loss of stability.