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Products Home / Optomechanical Components / Optical Post Assemblies / Bases / Table Clamps / Base Adapters and Clamping ForksBase Adapters and Clamping Forks
- Base Adapters and Clamping Forks for Our Post Holders and Posts
- Flexible Positioning on an Optical Table or Breadboard
- Slots with Lengths from 0.38" to 2.11" (9.5 mm to 53.5 mm)
0.38" (9.5 mm)
Counterbored Slot
1.24" (31.5 mm)
Counterbored Slot
with Captive Screw
CF125C
CF038-P5
1.30" (33.0 mm)
Clearance Slot
POLARIS-CA1
2.11" (53.5 mm)
Counterbored
Slot
PF175
Contact Pads
Maximize Overall
Clamp Stability
Post and
Base Not
Included
Underside of
CF125C
0.63" (15.9 mm) Clearance Slot
MSC2
MSC3
0.59" (14.9 mm) Counterbored Slot
Please Wait
Click to Enlarge
Our Ø1" and Ø1.5" posts can be secured to an optical table using post base adapters and clamping forks.
Features
- Clamping Forks Secure Pedestal-Style Mounts to the Optical Table or Breadboard
- Rigid One-Piece Construction with Relief Cuts to Maximize Clamping Stability
- Versions of Clamping Forks Available with Captive Screws
- Polaris® Non-Bridging Clamping Arm with Flexure Clamping Mechanism
- Base Adapters Convert Posts and Post Holders to Pedestal-Style Mounts
Thorlabs offers clamping forks to secure our pedestal-style Ø1/2" post holders, Ø1" post holders, Ø1" pedestal posts, Ø12 mm pedestal posts, or Mini-Series post holders to breadboards and optical tables. With slots ranging from 0.38" to 2.11" (9.5 mm to 53.5 mm) in length, each fork can swivel around the pedestal-style post holder or post to access the most convenient mounting holes on the optical table or breadboard. Thorlabs also manufactures Polaris® Non-Bridging Clamping Arms for Ø1" or Ø25 mm posts, which provide high holding force with minimal torque.
Our base adapters thread onto the bottom of our standard Ø1/2" post holders, Ø1" post extensions, or Ø1.5" posts to convert them into pedestal-style posts. The clamping forks can then be used to hold the posts or post holders in place by clamping over the base adapter.
Please note that significant overtightening of clamping forks can deform the surface of an optical table, which can cause misalignment of components. This effect is minimized with the use of Polaris Clamping Arms; see below for details.
An alternative method for securing Ø1" and Ø1.5" pedestal posts is a pair of CL8 table clamps. These compact pieces are part of our larger selection of table clamps and allow users to secure posts to breadboards and tables with limited space.
| Posted Comments: | |
Nicholas Breslin
(posted 2019-10-28 11:21:50.487) Is there any consideration to make a CF model between the CF038 and the CF125. For compact optical setups using a CF038 is preferable, but sometimes the range just isn't enough to find a good screw hole but the CF125 has too large of a footprint and starts to remove the ability to be compact. It would be nice to have some options between 038 and 125. Like a 075 or a 100 even llamb
(posted 2019-10-28 05:20:47.0) Hello Nicholas, thank you for your feedback. I have added this idea for a more mid-sized clamping fork to our internal product forum for further review. avnerf
(posted 2017-05-07 00:50:26.64) Dear Sir/Madam
Is the CF175 clamping fork made of a solid bar of 303 stainless steel (CNC processed) or from sintered stell powder ( as it used to be for the last 10 years or so)?
Thanks nbayconich
(posted 2017-05-18 12:35:48.0) Thank you for contacting Thorlabs. The CF175 clamping fork is made from sintered 303 stainless steel. A techsupport representative will contact you directly. user
(posted 2017-02-24 17:38:35.58) new large quantity pack for BE1 bases:
BE1-P5 jlow
(posted 2017-03-01 04:55:34.0) Response from Jeremy at Thorlabs: Thank you very much for the suggestion. We will look into carrying this. chenav
(posted 2016-11-16 14:42:23.88) I am sorry to say the design of the captive-screw clamps is really terrible. The idea is great, but in practice when the screw is turned the whole clamps slides back and forth as a result. It's funny at first, but very soon you realize you need three hands to use these clamps: one to hold a screwdriver, another to hold the optic being clamped, and a THIRD to hold the clamp from sliding away from the post base. Unfortunately, most people in our lab indeed do not have three hands available. Sadly we've ordered a large quantity of these clamps without testing them first, and had to give them all to a graduate student so they can remove the captive screw. We now use them as standard clamps and all is well. tmorgus
(posted 2016-11-16 10:01:22.0) Hello Chenav, It is true that one disadvantage to the captive screw is that the clamping fork will move if not restrained as the screw is tightened. My technique for using the captive screw clamping forks is to use two fingers on the hand holding the post to pull the clamping fork into the post as I am tightening the screw with the other hand. I tend to do this even for the non captive screw version because I feel that without the restraining force on the clamp a small shift is possible just as the clamping screw gets tight. I will contact you directly as I would like to make the situation right for you. Tyler, Mechanics Business Unit Leader piksarv
(posted 2014-11-27 17:06:24.95) It would be nice if the hex socket on the bottom of PB4/M for tightening the pedestal base adapter to a post would be also metric. cdaly
(posted 2014-12-02 04:00:48.0) Response from Chris at Thorlabs: According to our internal machine drawings, which the PB4/M is produced from, the hex socket on the bottom accepts a 3mm hex. The drawing online is mislabeled and I will have this updated as soon as possible. Jurgen.Stampa
(posted 2014-07-25 17:26:59.97) I had to laugh. These captive screw forks have been around for a long while - like I used them in grad school 15 years ago. Is it customer-inspired innovation or some one just recycling an old design? cdaly
(posted 2014-08-06 06:23:34.0) Response from Chris at Thorlabs: Customer inspired indicated it was requested by our customers and as a result of their input we now offer it as a product in our catalog. cbrideau
(posted 2014-05-09 13:17:44.31) I am constantly struggling with aligning the screws in the 'classic' forks. The new captive screw forks look much better. Great innovation! cdaly
(posted 2014-05-22 10:28:59.0) Response from Chris at Thorlabs: Thank you for your feedback. We're glad to hear you like the newer version. |
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Click to Enlarge
An MSC2 Clamping Fork secures a Ø12 mm pedestal post to a breadboard with 1/4"-20 tapped holes.
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An MSC3 Clamping Fork secures the MSP1 Ø12 mm pedestal post to a Mini-Series breadboard with 8-32 tapped holes.
- Secure Any of Our Ø12 mm Pedestal Posts or Pedestal-Base Post Holders to Breadboards or Optical Tables
- MSC1 Has a 0.63" (15.9 mm) Long Counterbored Slot for a 4-40 (M3) Cap Screw
- MSC3 Has a 0.59" (14.9 mm) Long Counterbored Slot for an 8-32 (M4) Cap Screw
- MSC2 Has a 0.63" (15.9 mm) Long Slot for a 1/4"-20 (M6) Cap Screw
- Swivel Fork 360° to Select the Most Convenient Mounting Hole
Our clamping forks are designed to provide exceptional clamping force when used with our Ø12 mm pedestal posts or our pedestal-base post holders. These clamping forks provide flexibility for building setups that combine Mini-Series components and our larger range of optomechanics offerings. The MSC1 and MSC2 are made from anodized aluminum, while the MSC3 is made from precipitation hardened 17-4PH stainless steel to provide a more uniform clamping force.
Designed to be used with the Mini-Series breadboards, the MSC1 and MSC3 are compatible with a 4-40 (M3) and 8-32 (M4) cap screw, respectively. The MSC2 slot accepts 1/4"-20 (M6) cap screws, thus enabling the inclusion of Mini-Series posts and components into setups on standard breadboards and optical tables in addition to mini-series breadboards.
Each clamping fork features landing pads on the bottom surface to maximize stability when using a washer and cap screw to lock down a post with the fork. Please note that significant overtightening of clamping forks can deform the surface of an optical table, which can cause misalignment of components.
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Click to Enlarge
The BE1R has a magnet in the base for stability in temporary setups.
Click to Enlarge A CF125 fork is used to secure a Ø1/2" post holder to an optical table with a BE1 base.
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Clamping forks are available with three slot lengths.
- BE1(/M) and BE1R(/M) Adapters Convert Standard Ø1/2" Post Holders and Ø1" Post Extensions into Pedestal-Style Mounts
- Clamping Fork or CL8 Table Clamp Secures Pedestal-Style Mount to a Breadboard or Optical Table
- Three Sizes Provide Clamping with 1/4"-20 (M6) Cap Screws
- 0.38" (9.5 mm) Long Counterbored Slot (CF038-P5)
- 1.24" (31.5 mm) Long Counterbored Slot (CF125)
- 1.76" (44.8 mm) Long Counterbored Slot (CF175)
- Swivel Fork 360° to Select Most Convenient Mounting Hole
- BE1(/M) Adapter and All Clamping Forks Available in Packs of Five (CF038-P5 Not Sold Individually)
Pedestal Base Adapters
The BE1(/M) and BE1R(/M) pedestal base adapters feature 1/4"-20 (M6)-threaded studs that fit into the bottom of our standard Ø1/2" post holders or Ø1" post extensions (see photos to the right), converting them into pedestal-style mounts for added stability. The BE1R(/M) adapter has a magnet in the base that is sufficiently strong to securely hold the base in place without clamping to an optical table (see photo at the top right). Made from solid 303 stainless steel with a 1.25" (31.8 mm) outer diameter, these adapters allow Ø1/2" post holders and Ø1" pillar posts to be used with the CF series of clamping forks, and can be tightened onto the post or postholder using a 1/8" (3 mm) hex or ball driver.
The BE1(/M) base adapter is available in a pack of five for ease of ordering.
Clamping Forks
The CF038-P5, CF125, and CF175 clamping forks are designed to provide exceptional clamping force when used with our Ø1/2" post holders and Ø1" post extensions that have been adapted using the BE1(/M) to pedestal-style mounts. These clamping forks can also be used with our pedestal-style Ø1/2" post holders or Ø1" pedestal posts without any need for the BE1(/M).
Made from solid 303 stainless steel, the CF038-P5, CF125, and CF175 clamping forks create three points of contact with the table for high stability. For flexibility in the positioning of post assemblies, three sizes are available: the CF038-P5 fork offers a 0.38" (9.5 mm) long counterbored slot, the CF125 fork offers a 1.24" (31.5 mm) long counterbored slot, and the CF175 fork has a 1.76" (44.8 mm) long counterbored slot. All three counterbored slots are designed for 1/4"-20 (M6)-threaded cap screws. Please note that significant over tightening of clamping forks can deform the surface of an optical table, which can cause misalignment of components and decrease stability.
These clamping forks are available with a 1/4"-20 (M6)-threaded captive screw. For more information, please see below. Clamping forks are also available in packs of five for ease of ordering (note: the CF038-P5 clamping fork is only available in packs of five).
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Click for Details
Bottom view of the captive screw held in the slot by a retainer.
- Same Design as CF038, CF125 or CF175 with Added 1/4"-20 (M6) Captive Screw
- Secures Pedestal-Style Mount to a Breadboard or Optical Table
- Three Sizes Provide Clamping with 1/4"-20 (M6) Cap Screws
- 0.38" (9.5 mm) Long Counterbored Slot [CF038C(/M)-P5]
- 1.24" (31.5 mm) Long Counterbored Slot [CF125C(/M)]
- 1.76" (44.8 mm) Long Counterbored Slot [CF175C(/M)]
- Position Fork Over 360° to Select Most Convenient Mounting Hole
- Clamping Forks Available in Packs of Five [CF038C(/M)-P5 Not Sold Individually]
Our Clamping Forks offer the convenience of 1/4"-20 (M6) captive screws, while still providing the same exceptional clamping force for our pedestal-style posts and post holders as our standard forks, sold above. The screws can be tightened into the breadboard using a 3/16" (5 mm) hex key or balldriver. Please note that significant over tightening of clamping forks can deform the surface of an optical table, which can cause misalignment of components.
Fabricated from solid 303 stainless steel, all of these clamping forks create three points of contact with the table for high stability. For flexibility in the positioning of post assemblies, Thorlabs offers three sizes: the CF038C(/M)-P5 fork has a 0.38" (9.5 mm) long counterbored slot, the CF125C(/M) fork has a 1.24" (31.5 mm) long counterbored slot, and the CF175C(/M) fork has a 1.76" (44.8 mm) long counterbored slot. When used with the BE1(/M) base adapter (sold above), these clamping forks can position our standard Ø1/2" post holders or Ø1" post extensions. Alternatively, the clamping fork is directly compatible with our pedestal-style Ø1/2" post holders or Ø1" pedestal posts.
These clamping forks are also available in packs of five for ease of ordering (note: the CF038C(/M)-P5 clamping fork is only available in packs of five).
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- PB4(/M) Adapter Converts Ø1.5" Posts to Pedestal-Style Mounts
- Clamping Fork Secures Pedestal-Style Mount to a Breadboard or Optical Table
- One Fork Size: 2.11" (53.6 mm) Long Counterbored Slot
- Swivel Fork 360° to Select Most Convenient Mounting Hole
Pedestal Base Adapter
The PB4(/M) pedestal base adapter features a 1/4"-20 (M6)-threaded stud, which fits into the bottom of our Ø1.5" posts to convert them into pedestal-style mounts. Made from solid 303 stainless steel with a 1.85" (47.0 mm) outer diameter, this adapter allows these posts to be used with our PF175 clamping fork.
Clamping Fork
The PF175 clamping fork is designed to provide exceptional clamping force when used with our Ø1.5" posts that have been adapted using the PB4(/M) to pedestal-style mounts. This clamping fork can also be used with our Ø1" post holders or BLP01 adjustable-height post without any need for the PB4(/M).
Made from anodized aluminum, the PF175 clamping fork creates three points of contact with the table for high stability. The 2.11" (54 mm) long counterbored slot for 1/4"-20 (M6) cap screws allows the most convenient mounting hole to be selected and creates flexibility in the positioning of post assemblies. 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.
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Click to Enlarge
Click for POLARIS-CA1/M Holding Torque Results*
The Polaris clamping fork design has undergone extensive testing to ensure high-quality performance. See the full presentation for more details.
*It is important to note that the 1/4"-20 and M6 x 1.0 clamping torque values have been adjusted to provide the same clamping post and table forces. Also note that the maximum recommended tightening torque for an 18-8 stainless steel screw is 75.2 in-lbs for a ¼-20 screw and 8.8 N-m for an M6 x 1.0 screw. Higher mounting torques can cause the screw to fail.
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Side-Located 1/4"-20 (M6) Screw Actuates Clamping Bore
- 3-Point Contact Bore with Flexure Clamping Mechanism for Ø1" or Ø25 mm Post Mounting
- Three Options Available:
- POLARIS-CA1: Ø1" (Ø25.4 mm) Bore and 1/4"-20 Screw
- POLARIS-CA1/M: Ø1" (Ø25.4 mm) Bore and M6 x 1.0 Screw
- POLARIS-CA25/M: Ø25.0 mm (Ø0.98") Bore and M6 x 1.0 Screw
- 0.60" (15.2 mm) Deep Mounting Bore for Height Adjustments and 360° Rotation
- Heat-Treated, Stress-Relieved Stainless Steel Provides Large Clamping Force
- Flippable Design Supports Left- and Right-Handed Orientations
(See Image Below Right) - High Stability Ideal for Use with Our Fixed and Kinematic Polaris Mirror Mounts
- Vacuum Compatible to 10-9 Torr at 25 °C with Proper Bake Out
- ±0.001" (±0.02 mm) Surface Flatness
- 1/4"-20 or M6 x 1.0 Clamping Screw
The Polaris Clamping Arm is the ideal solution for stably mounting any Ø1" or Ø25 mm post. Each clamping arm, which is constructed from heat-treated, stress-relieved stainless steel, provides extremely high holding forces with minimal torquing of the mounting screws.
The POLARIS-CA1 and POLARIS-CA1/M are designed to hold a Ø1" post, such as our fixed Polaris mount, while the POLARIS-CA25/M is designed to hold a Ø25 mm post or Ø1/2" post holder using a flexure clamping mechanism. The POLARIS-CA1 and POLARIS-CA1/M are not compatible with Ø25 mm posts; the bore diameter is too large and will not contact the post when clamping.
The side-located clamping mechanism, as shown in the photo to the above left, is actuated using a 1/4"-20 cap screw for the POLARIS-CA1 or an M6 x 1.0 cap screw for the POLARIS-CA1/M and POLARIS-CA25/M. Because the side-located clamp and mounting slot are tightened separately, the user can set the position of the fork and adjust the rotational alignment independently. The clamping arm has a compact 3.33" x 1.60" (84.5 mm x 40.6 mm) footprint for tight laser cavity setups, with a thickness of 0.60" (15.2 mm) for increased stability. A 1.30" (33.0 mm) long clearance slot allows for a variety of mounting solutions using a 1/4"-20 or M6 cap screw and washer.
Both the imperial and metric clamping arm have been tested for holding strength. Based on the test results, recommended torques have been determined for both the flexure clamp and for tightening the slot to the table. The scales for these measurements, as seen in the figure above, are not direct conversions due to an efficiency difference between 1/4"-20 and M6 x 1.0 screws. The efficiency of M6 x 1.0 screws is about 5% less than that of 1/4"-20 screws due to differences in diameter and pitch. For optimal performance we recommend tightening this screw of the POLARIS-CA1 with 15 to 25 in-lb of torque and the screw of the POLARIS-CA1/M and POLARIS-CA25/M with 1.75 to 3 N•m of torque. When mounting the clamping arm to the platform we recommend using 40 to 65 in-lb of torque for the POLARIS-CA1 and 4.75 to 7 N•m of torque for the POLARIS-CA1/M and POLARIS-CA25/M. For best results, use the maximum recommended torques from each range. These torque values can be dialed in using a torque driver.
The flat, non-bridging (see drawing below) top and bottom allow the clamping arm to be used on either side depending on the needs of the application. This allows optical components to be placed in near contact to one another while minimizing the footprint, as shown in the image to the bottom right. A relief cut is included around the top and bottom slot; this protects the ±0.001" (±0.02 mm) flat surface that contacts the optical table from any marring due to the screw and washer. Minimizing damage to this surface of the fork allows for more stable mounting of components using the clamping arm.
Note: The POLARIS-CA1 requires a 3/16" hex key and the POLARIS-CA1/M and POLARIS-CA25/M requires a 5 mm hex key.
Click to Enlarge
The Top and Bottom of the Fork can be Used for Mounting, Minimizing the Overall Footprint and Distance Between Components
Non-Bridging Design
Industry-standard clamping forks are designed with a bridge, as shown in the below diagram, for clamping to pedestal style posts or post holders. This design will slightly damage the laser platform during each use by pulling up the part of the platform located under the bridge. The Polaris clamping arm is designed with a flat top and bottom to eliminate this problem.
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A Bridge is Created When an Industry-Standard Clamping Fork is Used with a Pedestal Post
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The POLARIS-CA1 Eliminates the Bridge Created by an Industry-Standard Clamping Fork
Clamping Forks
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