Hex Adjusters, 3/8"-100

  • Hex Adjusters, Knobs, Bushings, and Lock Nuts
  • Tolerances Better Than Class 3
  • 0.01" Travel per Revolution

Hex Socket


Lock Nut


Ø0.5" Bushing






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  • 100 TPI Fine Adjustment
  • Hex Adjusters Feature a 3/16" Hex Socket
  • Removable Adjustment Knobs Allow for Adjustment without Hex Key
  • Threaded Bushings and Lock Nuts for Fine Adjuster Integration
  • Barrel Adapters for Integration with Linear Translation Stages

These 3/8"-100 adjuster screws have a thread depth (peak to valley) of 0.006", achieving 0.01" travel per revolution. These adjusters exceed the industry class 3 thread tolerance standard and are also DFARS (Defense Federal Acquisition Regulation Supplement) compliant. 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.

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 outside of 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

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3/8"-100 Fine Hex Adjusters

screw diagram
  • Four Lengths Available from 0.75" to 2.0"
  • 3/16" Hex Key Compatible
  • Max Load: 25 lbs (11 kg)

Our high precision 3/8"-100 Fine Hex Adjusters can be adjusted with a 3/16" hex key or 3/8"-100 removable adjustment knob (sold below). The F38SS series adjusters have a maximum axial load capacity of 25 lbs (11 kg). The adjuster body is constructed of 303 stainless steel and comes pre-greased to ensure smooth mating into compatible components. The ball tip is constructed using 440 stainless steel that is fixed onto the adjuster using epoxy. These adjuster screws are designed to be used with 3/8"-100 threaded bushings, available below.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
F38SS075 Support Documentation
F38SS075Fine Hex Adjuster, 3/8"-100, 0.75" Long
F38SS100 Support Documentation
F38SS100Fine Hex Adjuster, 3/8"-100, 1.0" Long
F38SS150 Support Documentation
F38SS150Fine Hex Adjuster, 3/8"-100, 1.5" Long
F38SS200 Support Documentation
F38SS200Fine Hex Adjuster, 3/8"-100, 2.0" Long

3/8"-100 Removable Adjustment Knobs

  • Use with 3/8"-100 Hex Adjusters
  • Clearance Hole Allows Access to Adjuster's Hex Socket
  • Available in 2 Sizes
  • Knurled Knob Increases Adjustment Sensitivity

The F38SSK1 and F38SSK1L Removable Adjustment Knobs thread on to our 3/8"-100 F38SS series 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 (Ø0.60") and large (Ø0.85").

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
F38SSK1 Support Documentation
F38SSK1Ø0.60" 3/8"-100 Removable Adjuster Knob
F38SSK1L Support Documentation
F38SSK1LØ0.85" 3/8"-100 Removable Adjuster Knob

3/8"-100 Threaded Bushings

  • Ideal for Slip Fit Applications
  • Two Lengths Available
  • Made From 510 Phosphor Bronze (Vacuum Rated for 10-6 Torr)
  • Recommended Bore Diameter: 0.5000" +0.0005"/-0.0000"

Our 3/8"-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 these bushings. The recommended bore diameter for our 3/8"-100 bushings is 0.5000" +0.0005"/-0.0000". These bushings are made of phosphor bronze, which offers advantages over brass, including vacuum compatibility. For vacuum applications, we recommend a thorough ultrasonic cleaning to remove any grease or particulates prior to use. 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
F38SSN2P Support Documentation
F38SSN2PThreaded Bushing, Phosphor Bronze, 3/8"-100, 0.57" Long
F38SSN1P Support Documentation
F38SSN1PThreaded Bushing, Phosphor Bronze, 3/8"-100, 0.63" Long

3/8"-100 Lock Nuts

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

The LN38100 lock nut features a knurled outside 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. These nuts feature blind holes that allow a hex key to be used to help tighten the lock nut.

The POLARIS-LN4 lock nut has a hexagonal profile which accepts 13 mm wrenches. The stainless steel nut comes pre-greased with ultra-high-vacuum-compatible, low-outgassing PTFE grease. For applications that require frequent tuning of the adjusters, the lock nuts only need to be lightly tightened by hand 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 (sold below). POLARIS-LN4 lock nuts have a 13 mm hex. To avoid cross threading the lock nut, place it against the adjuster and "unscrew" the lock nut until you feel a slight drop; then thread the lock nut onto the adjuster.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
LN38100 Support Documentation
LN381003/8"-100 Lock Nut, Knurled, Phosphor Bronze
Lead Time
POLARIS-LN4 Support Documentation
POLARIS-LN43/8"-100 Lock Nut, 13 mm Hex, Stainless Steel
Lead Time

Torque Wrench for Polaris® Lock Nuts

Coaxial Connector Wrench
Click to Enlarge

TW13 Torque Wrench Used to Secure POLARIS-LN1 Lock Nut on POLARIS-K2S2 Mirror Mount
Coaxial Connector Wrench
Click to Enlarge

The TW13 wrench is engraved with its preset torque value and item #.
  • 13 mm Hex for Use with POLARIS-LN4 Lock Nut, as well as
    POLARIS-LN1 Lock Nut and POLARIS-T2 Spanner Wrench
  • Preset Torque Value of 32 oz-in (0.23 N•m)
  • Break-Over Design Ensures Proper Torque is Applied
  • Ideal for Applications Requiring Long-Term Locking

This torque wrench has a preset torque value of 32 oz-in for use with the
POLARIS-LN4 lock nut used on Polaris® mounts. The wrench is also compatible with the POLARIS-LN1 lock nut and POLARIS-T2 spanner wrench. When the preset torque value has been achieved, the break-over design will cause the pivoting joint to "break," as shown to the right. The wrench's hex head will move back into place once the force is removed. This design prevents further force from being applied to the lock nut. Engraved guidelines indicate the angle the wrench should pivot in order to apply the specified torque; pivoting the handle past these guidelines will over-torque the lock nut. The wrench is also engraved with its preset torque value, torque direction, wrench size, and item # for easy identification in the field.

This wrench is designed to be compatible with cleanroom and vacuum chamber applications. It is chemically cleaned using the Carpenter AAA passivation method to remove sulfur, iron, and contaminants from the surface. After passivation, it is assembled in a clean environment and double vacuum bagged to eliminate contamination when transported into a cleanroom. The wrench has a bead blasted finish to minimize reflections when working with setups that include lasers.

Please note that these wrenches are not intended for use in applications where adjusters are frequently tuned, as these applications typically require torque values of 4 to 8 oz-in (0.03 to 0.06 N·m).

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
TW13 Support Documentation
TW13Customer Inspired! 13 mm Preset Torque Wrench for Polaris Lock Nuts, 32 oz-in
7-10 Days