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1/4"-100 Adjusters

  • Adjuster Lengths Between 0.5" and 2"
  • 0.01" Travel per Revolution
  • Adjustment Knobs and Threaded Bushings
    Also Available


Lock Nut



5/64" (2.0 mm)
Hex Socket


Ø0.34" Bushing


Ø3/8" Barrel Adapter



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  • 100 TPI Fine Adjustment
  • Hex Adjusters Feature a 5/64" (2.0 mm) Hex Socket
  • Removable Adjustment Knobs Allow for Adjustment without Hex Key
  • Threaded Bushings, Lock Nuts, and Locking Collar for Fine Adjuster Integration
  • Barrel Adapters for Integration with Linear Translation Stages

Thorlabs offers 1/4"-100 hex adjusters that exceed class 3 standards. Each screw is individually tested with a master gauge set that ensures the inter-changeability of our adjuster screws and threaded bushings. A variety of 1/4"-100 threaded bushings, lock nuts, locking collars and barrel adapters are available to simplify the integration of fine adjusters in your application. The fine adjusters come lightly lubricated to ensure smooth mating into compatible components.

We also offer Polaris® Matched Adjuster/Bushing Pairs, which offer better adjustment stability and a smoother feel for smaller adjustment changes.

Threaded Bushing Application

Integrating Fine Adjustment Screws Into Optomechanical Systems

The assembly process begins by producing the appropriately sized mating hole for the threaded bushing. The recommended bore diamaters can be found with the product information for each bushing sold below. Given the close fit between the threaded bushing and the mating adjuster screw, we caution against using a press fit to assemble these products. For our own production needs, we use a permanent anaerobic adhesive that provides excellent long-term performance. Locking bushings with nuts do not require adhesive as they are held in place by the locking nut.

We recommend using Loctite Anaerobic Adhesive product number 680 or equivalent. In order to ensure maximum strength between the bonded parts, we strongly urge the user to follow carefully the instructions provided by Loctite, which specify the amount of clearance between the threaded bushing and the mounting plate. The most common source of failure is not allowing for the proper clearance between the parts being bonded since this clearance provides for the proper volume of adhesive.

When assembling, apply a small amount of the Loctite adhesive to the threaded bushing only. Rotate the bushing as it is installed to ensure a uniform distribution of the adhesive. After insertion, remove any excess adhesive from around the part.

As shown in the figure to the right, the flange on the mating bushing is designed to support the axial load of the screw and bushing assembly.

Volume Pricing Discount
Contact Thorlabs

OEM & Custom Precision Screws

Thorlabs manufactures custom and high volume OEM precision screws and bushings with various diameters, lengths, and threads. To inquire about custom or OEM precision screws, please contact Technical Support or use the "Contact Us" form to the right. A specialist will contact you within 24 hours or the next business day.

Precision Screw Capabilities

Thorlabs' in-house machine shop, located in Newton, NJ, gives us the ability to quickly produce large quantities of precision screws and bushings. We are equipped to manufacture screw diameters ranging from 2 mm to 20 mm with lengths up to 165 mm and a maximum thread pitch of 200 TPI. Our standard adjuster screw design has a hardened steel ball tip to provide a single point of contact; for other applications we are able to provide adjusters without the steel ball. Custom orders can be achieved on a case-by-case basis. For large orders of an item, Thorlabs passes on to the customer the cost savings associated with planned production of high volumes of that item. For more information on Thorlabs' discount pricing policy, click the "V" link to the right. We also offer a large variety of stock precision screws, which are available here.

Fast Turn-Around Times
Our experienced, highly skilled machinists are running our on-site Citizen Swiss Screw Machines 24 hours a day, allowing us to produce high-volume custom and OEM orders. Each machine is capable of running unattended, producing one screw every 30 to 120 seconds. This flexibility allows us to fulfill multiple orders at once without sacrificing quality.

High Quality
Thorlabs inspects all of our fabricated precision screws and bushings after the initial fabrication process and right before packaging. All inspections adhere to the ANSI AQL1.5 acceptable quality level, which states that if a certain percentage, based upon the amount of product in a certain lot, does not meet specification, then the entire lot is not sold. This ensures that all customers receive the highest quality product every time and that all items will be of equal performance.

Precision Screw Production

Posted Comments:
Ben Garber  (posted 2019-07-18 19:28:41.613)
Hi, I'm hoping to use your 1/4"-100 set screw and bushing for fine angle adjustment of a heavy optics mount for which weight would be borne along the set screw. What is the maximum recommended compression load for a fully-engaged set screw and bushing? Thank you, Ben
llamb  (posted 2019-07-19 01:47:01.0)
Hello Ben, thank you for contacting Thorlabs. We would recommend a maximum load of 15 lbs (6.8 kg).
user  (posted 2015-04-15 15:32:46.71)
It would be nice to have a metric equivalent (e.g. M6-0.25) to the 3/16"-100 fine adjustment screw.
cdaly  (posted 2015-04-28 07:04:56.0)
Response from Chris at Thorlabs: Thank you for your feedback. We will look into the possibility of adding metric equivalents to out imperially threaded fine adjuster screws.

1/4"-100 Hex Adjusters

  • Five Lengths Available from 0.5" to 2"
  • 5/64" (2.0 mm) Hex Key Compatible
  • Max Load: 15 lbs (6.8 kg)

Our high precision 1/4"-100 Fine Hex Adjusters can be adjusted with a 5/64" (2.0 mm) hex key, F25USK1 removable adjustment knob (sold below), or HKTS-5/64 hex key knob (sold below). The F25US series have a maximum load of 15 lbs (6.8 kg). The adjuster body is constructed of 303 stainless steel and comes pregreased to ensure smooth mating into compatible components. The ball tip is constructed using 440 stainless steel that is fixed onto the adjuster using epoxy.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
F25US050 Support Documentation
F25US050Fine Hex Adjuster, 1/4"-100, 1/2" Long
F25US075 Support Documentation
F25US075Fine Hex Adjuster, 1/4"-100, 3/4" Long
F25US100 Support Documentation
F25US100Fine Hex Adjuster, 1/4"-100, 1" Long
F25US150 Support Documentation
F25US150Fine Hex Adjuster, 1/4"-100, 1 1/2" Long
F25US200 Support Documentation
F25US200Fine Hex Adjuster, 1/4"-100, 2" Long

1/4"-100 Threaded Bushings

  • Ideal for Slip Fit
  • Two Lengths Available
  • Material: 510 Phosphor Bronze (Vacuum Rated for 10-6 Torr)
  • Recommended Bore Diameter: 0.3395" +0.0005"/-0.0000"

Our 1/4"-100 Threaded Bushings are commonly used in slip fit applications where fine adjusters are needed. Due to the tolerances of our fine adjusters, we discourage press fitting this bushings. The recommended bore diameter for our 1/4"-100 bushings is 0.3395" +0.0005"/-0.0000". To learn more about the use of fine adjustment screws and bushings in optomechanical systems, please see the Integration tab above.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
F25USN1P Support Documentation
F25USN1PThreaded Bushing, Phosphor Bronze, 1/4"-100, 0.63" Long
Lead Time
F25USN2P Support Documentation
F25USN2PThreaded Bushing, Phosphor Bronze, 1/4"-100, 0.57" Long
Lead Time

1/4"-100 Thread to Ø3/8" Barrel Adapters

Click to Enlarge

LNR25M Stage Fitted with
F25USA1 Adapter, F25US200 Adjuster, and F25USK1 Knob
  • Material: 510 Phosphor Bronze (Vacuum Rated for 10-6 Torr)
  • Adapts 1/4"-100 Adjusters to Ø3/8" Barrel Size
  • Recommended Bore Diameter: 0.375" +0.002"/-0.000"

These 1/4"-100 threaded to Ø3/8" barrel adapters are made from 510 Phosphor Bronze (vacuum rated for 10-6 torr). They allow our 1/4"-100 adjusters to be used with linear translation stages that accept actuators with Ø3/8" (Ø9.5 mm) barrels. The photo to the right shows an adjuster screw used as a replacement for the actuator included with the translation stage. For vacuum applications, we recommend a thorough ultrasonic cleaning to remove any grease or particulates prior to use.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
F25USA1 Support Documentation
F25USA1Mounting Barrel Adapter, 1/4"-100 to Ø3/8"
Lead Time

1/4"-100 Lock Nut

  • Knurled Outside Diameter for Easy Tightening
  • Material: 510 Phosphor Bronze
  • Vacuum Compatibility: 10-6 Torr

The LN25100 lock nut features a knurled outside diameter, which helps when tightening or loosening the nut. This lock nut is made from 510 Phosphor Bronze, which is vacuum rated for 10-6 Torr. Each nut features blind holes that allow a hex key to be used to help tighten the lock nut.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
LN25100 Support Documentation
LN251001/4"-100 Lock Nut

1/4"-100 Locking Collar, Stainless Steel

  • Compact Locking Collar: Ø0.33" (Ø8.4 mm), 0.08" (1.9 mm) Thick
  • Use One Collar To Lock an Adjuster to a Bushing
  • Use Two Collars to Create a Hard Stop on an Adjuster
  • Install and Remove with the POLARIS-T2 Spanner Wrench

The POLARIS-LNS1 locking collar is a compact alternative to the lock nut sold above. This locking collar is compatible with all of the 1/4"-100 adjusters sold on this page, as well as those used in many of our mirror mounts and stages. This locking collar is compatible with Polaris mounts that have 1/4"-100 adjusters, excluding the piezo-driven mounts and mounts with low-profile adjusters (Item #s POLARIS-K1-H and POLARIS-K1-2AH). Each collar is only 0.08" (1.9 mm) thick and constructed of stainless steel. We recommend the POLARIS-T2 Spanner Wrench to install or remove these locking collars. A center through hole allows a 2 mm ball driver to pass through the spanner wrench, so that the adjuster can be held in position while the locking collar is engaged.

The locking collar can be used to lock an adjuster in a desired position or to create a hard stop at any position to prevent overdriving an adjuster. For applications that require frequent tuning of the adjusters, the locking collar only needs to be lightly tightened to a torque of approximately 4 to 8 oz-in (0.03 to 0.06 N·m). For long term stability, we recommend tightening to a torque of 32 oz-in, which can be achieved by using our TW13 preset torque wrench in combination with the POLARIS-T2 wrench. To avoid cross threading the locking collar, place it against the adjuster and "unscrew" the collar until you feel a slight drop; then thread the collar onto the adjuster.

Cleanroom and Vacuum Compatibility
This locking collar is compatible with cleanroom and vacuum applications. The locking collar is chemically cleaned using the Carpenter AAA passivation method to remove sulfur, iron, and contaminants from the surface. After passivation, it is double vacuum bagged to eliminate contamination when transported into a cleanroom.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
POLARIS-LNS1 Support Documentation
POLARIS-LNS11/4"-100 Locking Collar, Stainless Steel
+1 Qty Docs Part Number - Universal Price Available
POLARIS-T2 Support Documentation
POLARIS-T2Spanner Wrench for POLARIS-LNS1 Locking Collar
5-8 Days

1/4"-100 Removable Adjustment Knobs

100 TPI Knobs
Click to Enlarge

F25USK1 and F25USK2 Knobs Shown Attached to a POLARIS-K1 Mirror Mount
Item # Knob Diameter
F25USK1 0.58"
F25USK2 0.925"
  • Use with 1/4"-100 Hex Adjusters
  • Clearance Hole Allows Access to Hex Socket
  • Knurled Knob Increases Adjustment Sensitivity
  • Available in 2 Sizes (See Table to the Right)

These removable adjustment knobs are compatible with our 1/4"-100 adjusters, including those used in the Ø1" Polaris Kinematic Mounts. These knobs enable quick and easy tweaking of an actuator without needing a hex key.

We offer two sizes of adjustment knobs. The Ø0.58" standard size (F25USK1) is similar in size to the stainless steel knobs included with our Polaris mount, while the larger Ø0.925" size (F25USK2) provides additional angular resolution.

Please note that these knobs are not compatible with Polaris mounts that use side-hole adjusters. The recessed bore of knob is not deep enough to allow the knob to engage the threads on the side-hole adjuster.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
F25USK1 Support Documentation
F25USK1Ø0.58" 1/4"-100 Removable Adjuster Knob
F25USK2 Support Documentation
F25USK2Ø0.925" 1/4"-100 Removable Adjuster Knob

5/64" Hex Key Adjusters

POLARIS-K12AH with HKTS-5/64 Adjuster
Click for Details

POLARIS-K1-2AH with HKTS-5/64 Adjuster
  • For Convenient Adjustment of 5/64" and 2 mm Hex-Driven Actuators
  • Red Anodized Adjustment Knob with Engraved Hex Size
  • Replaceable Hex Tip
  • Sold in Packages of 4

These 5/64" Hex Key Adjuster Thumbscrews allow for quick adjustment of many 5/64" and 2 mm hex-driven actuators (or standard actuators with the knobs removed). These temporary knobs can be left in the screw's hex socket between adjustments for convenience (see photo to the right). An 8-32 setscrew (5/64" hex) secures the replaceable hex bit, which can be reversed if the tip is stripped. Contact Tech Support to order replacement hex key bits.

We offer hex key thumbscrews in sizes from 0.050" to 3/16" and 2 mm to 5 mm.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
HKTS-5/64 Support Documentation
HKTS-5/64Customer Inspired! 5/64" (2 mm) Hex Key Thumbscrew, 4 Pack
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