Hex Adjusters, M6 x 0.25 Fine

  • M6 x 0.25 Hex Adjusters with Lengths from 10 mm to 50 mm
  • Exceed Class 3 Thread Tolerances
  • 250 µm Travel per Revolution


25 mm Long Hex Adjuster


Ø9.1 mm Bushing


Ø12.2 mm Barrel Adapter


Ø21.1 mm Removable Adjuster Knob


Lock Nut


Differential Adjuster Screw

2 mm Hex Socket

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  • Hex Adjusters Feature a 2 mm (5/64") Hex Socket
  • Differential Adjuster with 25 µm/rev Fine Adjustment Over ≥400 µm of Travel
  • Removable Adjustment Knobs Available for Hex Adjusters
  • Threaded Bushings and Lock Nuts for Threading Integration

These M6 x 0.25 Hex Adjustment Screws come lubricated for smooth mating with compatible components. The adjuster body is constructed of 303 stainless steel and the ball tip is constructed using 440 stainless steel that is fixed onto the adjuster using epoxy. Each screw is individually tested with a master gauge set that ensures the interchangeability of our adjuster screws and threaded bushings. The hex adjusters below are offered in lengths from 10 mm to 50 mm and can be adjusting using a 2 mm (5/64") hex key or balldriver. A differential adjuster screw, which provides 25 µm/rev of fine adjustment over ≥400 µm of travel, is also available.

Thorlabs also offers removable adjustment knobs which thread onto an M6 x 0.25 threaded adjuster and provides a means to make fine adjustment without a hex key. Threaded bushings, an adapter for Ø3/8" barrels, and lock nuts are available to further aid the incorporation of fine adjustment in your application.

If you are incorporating any of these components into larger optomechanical systems, please ensure that the specifications for any mating parts you are manufacturing have the appropriate tolerances. For more details, please see the Integration tab.

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. 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.

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:
user  (posted 2019-07-30 00:58:08.237)
Hello, I'm a university student in Korea. I want to buy Hex Adjusters, M6 x 0.25 sets. (F6MSS30, F6MSSK1, F6MSSN1P) But I don't know how to combine threaded bushing with Plate. How can I combine a bushing to a plate? Can you explain it to me?
llamb  (posted 2019-07-31 02:35:14.0)
Thank you for contacting Thorlabs. The F6MSSN1P bushing can be installed into a plate drilled out to a recommended bore diameter of 0.340" +0.001/-0.000". Please see the Integration tab for more details. I have reached out to you directly to discuss your application as well.

M6 x 0.25 Fine Hex Adjusters

  • Six Lengths Available from 10 mm to 50 mm
  • 2 mm (5/64") Hex Key Compatible
  • Max Load: 6.8 kg (15 lbs)

Our high-precision M6 x 0.25 Fine Hex Adjusters can be adjusted with a 2 mm (5/64") hex key or with our removable adjustment knobs (sold separately below). These M6 hex adjusters have a maximum load of 6.8 kg (15 lbs).

These adjuster screws are designed to be used with M6 x 0.25 threaded bushings, available below.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Metric Price Available
F6MSS10 Support Documentation
F6MSS10Fine Hex Adjuster, M6 x 0.25, 10 mm Long
F6MSS12 Support Documentation
F6MSS12Fine Hex Adjuster, M6 x 0.25, 12 mm Long
F6MSS20 Support Documentation
F6MSS20Fine Hex Adjuster, M6 x 0.25, 20 mm Long
F6MSS25 Support Documentation
F6MSS25Fine Hex Adjuster, M6 x 0.25, 25 mm Long
F6MSS30 Support Documentation
F6MSS30Fine Hex Adjuster, M6 x 0.25, 30 mm Long
F6MSS50 Support Documentation
F6MSS50Fine Hex Adjuster, M6 x 0.25, 50 mm Long

M6 x 0.25 Differential Adjuster Screw

DAS110 Mechanical Drawing
Click to Enlarge

Coarse Thread Length and Adjuster Length (L)
DAS110 Mechanical Drawing
Click for Details

A Cross-Section of a Differential Adjuster Screw,
Showing the Internal Components
  • 1.01" (25.6 mm) Adjuster Length (L)
  • Coarse Thread Length: 0.76" (19.3 mm)
  • Fine Adjustment: 25 µm/rev Over ≥400 µm of Travel
  • Ø0.49" (12.4 mm), 0.15" (3.8 mm) Thick Locking Ring
  • On-Axis Load Capacity: 11.25 lbs (5.1 kg)
  • Recommended Preload: 1 to 2 lbs (0.5 to 1 kg)

Thorlabs' DAS6M Differential Adjuster Screw comes pre-greased to ensure smooth mating into compatible components. To install the adjuster, screw the threads into the bushing by hand. Ensure that cross threading does not occur in order to avoid damage to the adjuster and bushing. Additionally, the screw includes a Ø0.49" (Ø12.4 mm), 0.15" (3.8 mm) thick locking ring with a knurled surface for improved grip. Four Ø0.09" (Ø2.3 mm) blind holes in the ring allow a hex key to be inserted to assist with tightening.

When used with a compatible component, coarse adjustment is provided by the external threads on the main screw body, labeled B on the diagram to the right. The screw can be actuated using the attached knob, labeled A, or the 5/64" (2 mm) hex socket. The knob can also be removed if needed due to space constraints.

The fine-adjustment mechanism provides a highly de-magnified displacement of 25 µm per revolution and can be actuated using a 1/16" hex accessible through the center of the 5/64" (2 mm) hex for coarse adjustment.

As illustrated in the diagram to the right, an intermediate actuator, labeled C, is threaded into the main body screw (B) and onto a push rod (D) that terminates with a ball tip. A pin on the push rod fits into a slot on the main body screw and prevents these two components from rotating relative to each other. As a result, when the intermediate actuator is rotated, it will be translated along the main body screw at a rate determined by the intermediate actuator's external thread pitch while the push rod is translated in the opposite direction at a rate determined by the intermediate actuator's internal thread pitch. Thus, differential movement is achieved between the intermediate actuator and the push rod.

The DAS6M differential adjuster screw has an intermediate actuator with an external thread pitch of 400 µm and an internal thread pitch of 375 µm. When the intermediate actuator is rotated clockwise, it advances in the main body by 400 µm per revolution. At the same time, the push rod, which is restricted from rotating by the main body, retreats by 375 µm per revolution, providing a total displacement of 25 µm per revolution.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Metric Price Available
DAS6M Support Documentation
DAS6MNEW!Differential Adjuster Screw, 25 µm/Rev Fine Adjustment, M6 x 0.25 Coarse Adjustment Threads

M6 x 0.25 Removable Adjuster Knobs

  • Use with M6 x 0.25 Hex Adjusters
  • Clearance Hole Allows Access to Adjuster's Hex Socket
  • Available in 2 Sizes
  • Knurled Knob Increases Adjustment Sensitivity

The F6MSSK1 and F6MSSK1L Removable Adjustment Knobs are manufactured using anodized aluminum and thread onto our M6 x 0.25 hex adjusters to allow adjustment without the use of a hex key. This provides quick and easy adjustments for a broad range of applications. The adjuster knobs are available in two sizes: standard (Ø14.7 mm) and large (Ø21.1 mm). To install, loosely screw the knob onto the adjuster end and then use a hex key to hold the adjuster in place while using tightening the knob further.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Metric Price Available
F6MSSK1 Support Documentation
F6MSSK1M6 x 0.25 Removable Adjuster Knob
F6MSSK1L Support Documentation
F6MSSK1LLarge-Diameter M6 x 0.25 Removable Adjuster Knob

M6 x 0.25 Threaded Bushing

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

Our F6MSSN1P M6 x 0.25 threaded bushing is commonly used in slip fit applications where fine adjusters are needed. Due to the tolerances of our fine adjusters, we discourage press fitting these bushings. The recommended bore diameter for our M6 x 0.25 bushings is 0.3395" +0.0005/-0.0000". Please see the Integration tab for more information. 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 - Metric Price Available
F6MSSN1P Support Documentation
F6MSSN1PThreaded Bushing, Phosphor Bronze, M6 x 0.25

M6 x 0.25 Thread to Ø3/8" Barrel Adapters

  • Material: 510 Phosphor Bronze (Vacuum Rated for 10-6 Torr)
  • Adapts M6 x 0.25 Adjusters to Ø3/8" Barrel Size
  • Recommended Bore Diameter: 0.3740" +0.0005"/-0.0000"

These M6 x 0.25 thread to Ø3/8" barrel adapters are made from 510 Phosphor Bronze (vacuum rated for 10-6 torr). They allow our M6 x 0.25 adjusters to be used with linear translation stages that accept actuators with Ø3/8" (Ø9.5 mm) barrels. 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 - Metric Price Available
F6MSSA1 Support Documentation
F6MSSA1Mounting Barrel Adapter, M6 x 0.25 to Ø3/8"

M6 x 0.25 Lock Nut

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

The LN6M25 lock nut features a knurled outer diameter to make gripping the nut easier when loosening or tightening. The 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 - Metric Price Available
LN6M25 Support Documentation
LN6M25M6 x 0.25 Lock Nut