Ø1.5" Damped Posts

Overview
Ring Down Test
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Item #	Qty	Description
DP14A/M	1	Ø1.5" Dynamically Damped Post, 14" Long, Metric
C1511/M	2	Ø1.5" Post Mounting Clamp, 63.5 mm x 63.5 mm, Metric
POLARIS-K1	2	Polaris^® Ø1" Mirror Mount, 3 Adjusters

Periscope Constructed from a DP14A Damped Post, C1511 Post Clamps, and POLARIS-K1 Mirror Mounts

Click to Enlarge
Damped Posts Feature an Engraved Top Cap Indicating the Item # as well as a 1/4"-20 (M6) Tapped Hole

Features

Ø1.5" 1026 DOM Carbon Steel Posts Designed to Reduce Vibrations
Lead-Free Damping Weight Design for Shorter Damping Times Compared to Solid Stainless Steel Posts
8", 10", 12", and 14" Long Versions Available
Nickel-Plated Steel with Matte Finish for Long Life
Permanent Mounting Base with Four 1/4" (M6) Counterbores

These Dynamically Damped Ø1.5" Mounting Posts offer a vibration-limiting alternative to long lengths of Ø1.5" solid steel posts. Damped posts are ideal for applications where mechanical vibrations must be limited, such as beam steering and imaging. Ring down testing was performed to compare the damping times for damped carbon steel and solid stainless steel posts (see the Ring Down Test tab for a summary of the test results).

Damped posts are available in four lengths: 8" (203.2 mm), 10" (254.0 mm), 12" (304.8 mm), and 14" (355.6 mm). The damped posts are fabricated from steel with a nickel-plated matte finish and utilize internal damping weights containing no lead. Using an engineered passive vibration dampening design, an internal suspension system allows weights inside the post to move independently from the post's outer body, thus allowing vibrational energy to quickly be absorbed and dissipated. On imperial versions, the permanently attached mounting base has four 1/4" counterbores for breadboards with a 1.00" hole spacing, while the metric versions have M6 counterbores for breadboards with a 25.0 mm hole spacing. The top cap is engraved with the part number for identification. The posts also feature a top-located 1/4"-20 (M6) tapped hole to allow components to be secured to the top of the post.

Item #	DP8A(/M)	DP10A(/M)	DP12A(/M)	DP14A(/M)
Damping Time^a	20 ms	47 ms	61 ms	73 ms
Resonant Frequency (Theoretical)	780 Hz	435 Hz	300 Hz	~200 Hz
Length	8" (203.2 mm)	10" (254.0 mm)	12" (304.8 mm)	14" (355.6 mm)
Weight	1.56 kg (3.44 lbs)	1.91 kg (4.21 lbs)	2.14 kg (4.72 lbs)	2.4 kg (5.3 lbs)
Top-Located Tapped Hole	1/4"-20 (M6); 0.33" (8.4 mm) Deep
Mounting	Permanent Base with Four 1/4" (M6) Counterbores for Breadboards with 1.00" (25.0 mm) Hole Spacing

The post was struck with a 13 N force near the top of the post and the damping time (time for vibration amplitude to decrease to 1% of the initial value) was measured. Please see the Ring Down Test tab for details on the testing procedures and results.

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Initial Setup for Ring Down Test of DP10A Damped Post

Ring Down Test

A ring down test is performed on our damped and standard Ø1.5" posts to quantify the time needed to dampen vibrations to a minimum. To do this, a rig is set up (shown in the image to the right) that is designed to strike the test post with approximately 13 N of force (determined by measuring the peak force using a force gauge) by releasing a steel-ball-tipped lever arm that is held at a pre-determined height using a pin. A piezoelectric accelerometer, mounted flush to the top of the test post and aligned with the strike point of the lever arm, measures and records the acceleration of the post due to vibrations as a voltage signal. Because loads mounted to the post increase its vibration damping ability, no additional load is added during testing. Therefore, the results presented below represent the worst-case scenario for vibration damping.

In each set of test results shown below, both damped and standard posts are tested to compare the damping time (time it takes to reduce the amplitude of vibrations by 99%). For all post lengths tested, the damped posts dissipate the vibrational energy in a significantly shorter time frame than a standard post. See below for graphs from individual test runs.

Ring Down Test Summary (Average Over 5 Tests)
Post Length	Damping Time (Damped Posts)^a	Damping Time (Standard Posts)^a
8" (203.2 mm)	20 ms	81 ms
10" (254.0 mm)	47 ms	124 ms
12" (304.8 mm)	61 ms	144 ms
14" (355.6 mm)	73 ms	155 ms

Damping time is defined as the time required for the amplitude of the vibrations to reach 1% of the initial value after being struck.

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DP14A Packaging

Item #	% Weight Reduction	% CO₂ Reduction
DP8A(/M)	66%	74%
DP14A(/M)	66%	74%

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Thorlabs' Green Initiative is aimed at reducing waste. To that end, we have begun to re-engineer our product packaging. Products listed above are now shipped in re-engineered packaging that minimizes the use of non-recyclable materials.

Over the course of a year, the re-engineered packaging across our product line is projected to reduce our CO₂ footprint by more than 16,184 kg and reduce packaging by over 13,893 pounds! As we move through our product line, we will label re-engineered packages with our green Smart Pack sticker (above).

Posted Comments:

user (posted 2019-06-13 13:06:56.7)

Is it possible to add to the DP14A/M an extension post of 50mm on top (P50/M)?

YLohia (posted 2019-06-13 04:11:22.0)

Hello, since both have M6 threads, the P50/M can be added to the DP14A/M using an M6 setscrew.

michael.rappaport (posted 2017-11-15 22:43:21.883)

The 1.5" dia. damped posts are described as follows: --------------------------------- Ø1.5" Stainless Steel Posts Designed to Reduce Vibrations Lead-Free Damping Weight Design for Shorter Damping Times Compared to Solid Stainless Steel Posts 8", 10", 12", and 14" Long Versions Available Nickel-Plated Steel with Matte Finish for Long Life ---------------------------------- Why Ni-plate stainless steel? Are they really stainless steel and if so, what type? Thank you.

nbayconich (posted 2017-12-14 10:27:49.0)

Thank you for contacting Thorlabs. These posts are actually made of carbon steel 1026 DOM not stainless steel. The nickel plating is meant to prevent corrosion of the steel. We will update our webpage to display the correct steel used in these parts.

jjean (posted 2017-04-02 16:00:51.247)

Would it be possible to provide a custom version of the DP8A post with mirror finish instead of matte finish? Thanks!

tfrisch (posted 2017-04-18 04:45:48.0)

Hello, I will reach out to you directly about your application. I would not recommend using a post as an optical mirror.

stump (posted 2015-11-23 12:53:48.407)

I was thinking of mounting a solid aluminum breadboard on top of 4 DP8A's instead of the standard 1.5 inch posts but wondered if I would still get the desired damping? The measurements (and pictures showing various uses) all use post mounts anchored along the cylinder--not sitting on top. Thank you.

besembeson (posted 2015-11-25 02:31:41.0)

Response from Bweh at Thorlabs USA: In the configuration you describe, the posts will be locked both at the top and the bottom which presents a more complex rigid system than the configuration we have tested for damping times we show on the website. It would seem you might gain little by using the damped posts in this manner but overall it will be a coupled system that we don't have damping time data for. The resonant frequency will also depend on the size/weight of the breadboard and setup that you have. In our tests, the top end of the posts are free standing.

urbancic (posted 2015-09-17 12:20:56.087)

Dear Sir or Madam, I'm interested in the Ø1.5" Damped Posts but I was wondering if is possible to get them other custom lengths. Best regards, Jurij

besembeson (posted 2015-10-05 01:18:15.0)

Response from Bweh at Thorlabs USA: Yes we can provide this. We will follow-up with you.

john.chiaverini (posted 2014-04-24 09:26:19.37)

What are the masses (or weights on earth) of the DP8A and the DP14A? Thanks. John C.

bsanii (posted 2013-11-22 11:17:54.79)

We bought the DP14A as a replacement for the DP14, because the base was welded on. Unfortunately we missed that you also removed the 1/4-20 thread on the top of the post, which we need. A couple questions: Can we tap the top of the DP14A, or will that release sand or the like? Alternatively, any strategies for keeping the base attached to the post on the DP14? I was about to buy some locktite. Thanks, Babak

cdaly (posted 2013-12-04 01:54:46.0)

Response from Chris at Thorlabs: Thank you for your inquiry. There's no reason you cannot tap the bottom of the DP14A. As long as you do not go further than an inch in depth, you will not even make it through the base plate piece. We can provide a custom version of the DP14A with a tap on the top if you would like though. If you would like to epoxy the base on the DP14, I would suggest Loctite 2760.

tcohen (posted 2012-07-03 10:10:00.0)

Response from Tim at Thorlabs: These posts are sealed with Loctite 2760 on the threads. I have contacted you to further discuss the suitability of this post.

jonathan.newport (posted 2012-06-27 15:32:10.0)

Are these posts sealed sufficiently to operate in vacuum at ~10^-6 torr? Thanks!

tcohen (posted 2012-05-22 10:25:00.0)

Response from Tim at Thorlabs: Thank you for your feedback! We are testing this and will provide you with an answer shortly.

user (posted 2012-05-16 16:25:01.0)

What is the first natural frequency of vibration for the damped post DP14?

View All »Matching Part Numbers

Ø1.5" Damped Posts

Features

Ring Down Test

8" (203.2 mm) Long Posts

10" (254.0 mm) Long Posts

12" (304.8 mm) Long Posts

14" (355.6 mm) Long Posts

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