Thorlabs offers 1/4"-100 hex adjuster 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 components 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.
When assembling, apply a small amount of the Loctite adhesive to both threaded bushings and the mounting plate and ensure a uniform distribution of the adhesive around the perimeter of the parts before assembly. After insertion, remove any excess adhesive from around the part.

The assembly process begins by producing the appropriate 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.
As shown in Figure 1, the flange on the mating bushing is designed to support the axial load of the screw and bushing assembly.
Five Lengths Available from 0.5" to 2"
5/64" 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" 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)
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
F25US050 |
Ultra-Fine Hex Adjuster, 1/4"-100, 1/2" Long |
$6.10 |
Today |
F25US075 |
Ultra-Fine Hex Adjuster, 1/4"-100, 3/4" Long |
$6.60 |
Today |
F25US100 |
Ultra-Fine Hex Adjuster, 1/4"-100, 1" Long |
$7.10 |
Today |
F25US150 |
Ultra-Fine Hex Adjuster, 1/4"-100, 1 1/2" Long |
$8.80 |
Today |
F25US200 |
Ultra-Fine Hex Adjuster, 1/4"-100, 2" Long |
$10.40 |
Today |
Ideal for Slip Fit
Two Lengths Available
Material: 510 Phosphor Bronze (Vacuum Rated for 10-6 Torr)
Recommended Bore Diameter: 0.340" +0.001/-0.000Our 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 0.340" +0.001/-0.000.
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
F25USN1P |
Threaded Bushing, Phosphor Bronze, 1/4"-100, 0.63" Long |
$7.70 |
Today |
F25USN2P |
Threaded Bushing, Phosphor Bronze, 1/4"-100, 0.57" Long |
$7.70 |
Today |
Knurled Outside Diameter for Easy Tightening
Material: 510 Phosphor Bronze
Vacuum Compatibility: 10-6 TorrThe 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.
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
LN25100 |
1/4"-100 Lock Nut |
$8.20 |
Today |

| Item # | Knob Diameter |
|---|---|
| F25USK1 | 0.58" |
| F25USK2 | 0.925" |
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.
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
F25USK1 |
Ø0.58" 1/4"-100 Removable Adjuster Knob |
$7.00 |
Today |
F25USK2 |
Ø0.925" 1/4"-100 Removable Adjuster Knob |
$9.00 |
Today |

These 5/64" Hex Key Adjuster Thumbscrews allow for quick adjustment of many 5/64" (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 also offer hex key thumbscrews in other sizes from 0.050" to 3/16" and 2 mm to 5 mm.
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
HKTS-5/64 |
NEW! Customer Inspired!5/64" (2 mm) Hex Key Thumb Screw (4 Pack) |
$22.50 |
Today |