Hex Adjusters, M6 x 0.25 Fine

• Six Lengths Available from 10 mm to 50 mm
• 2 mm (5/64") Hex Key Compatible
• Max Load: 6.8 kg (15 lbs)
• Material: DFARS-Certified Stainless Steel
  • Traceable Material Certification Available (Must be Requested at Time of Purchase)

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).

Drilling and Tapping
While we recommend using our fine adjusters with the appropriately matched threaded bushing (sold below), it is also possible to incorporate them directly into a part or material by creating a threaded hole. For the adjusters on this page, the diameter of the pilot bore should be 5.575 mm ± 0.0165 mm. The corresponding metric drill bit size is 5.6 mm (0.2205") and the corresponding imperial drill bit is size #2 (0.2210"). The hole can then be tapped with TAPM6025. For fine pitch threads, it is especially important to tightly tolerance the pilot bore because of the shallow thread depth. For more information, see our taps and drill bit kit page.

Click to Enlarge
Coarse Thread Length and Adjuster Length (L)

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.

• 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.

• 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.

• 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.

• 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.