Vlier SSPH55A Threaded Spring Plunger 1/4-28 Stainless Steel

Product Description

The VLIER SSPH55A is a threaded spring plunger designed to provide repeatable, spring-loaded positioning and indexing force in precision assemblies. Featuring a 1/4-28 thread with a 1 inch thread length and a stainless steel body and nose, this standard-length plunger delivers an initial end force of 1 pound and a final end force of 4 pounds. The plunger tip diameter measures 0.118 inches with a 3/16 inch projection. Its stainless steel construction makes it well suited to environments where corrosion resistance and durability are required. Licensed machinists, tooling technicians, and assembly mechanics typically install this type of component during fixture builds or production line setup.

This spring plunger is used in tooling fixtures, jigs, machine housings, and precision assemblies where controlled detent or positioning force is needed. The 1/4-28 fine thread allows for accurate depth adjustment and secure installation in tapped holes. Applications include workholding equipment, dial or selector mechanisms, and any assembly requiring a compact, internally threaded spring-loaded element. With no locking element present, installation torque can be adjusted freely during setup without the resistance of a friction-lock feature.

Key Features

• 1/4-28 fine thread with 1 inch thread length for precise depth control
• Stainless steel body and nose for corrosion resistance in demanding environments
• Initial end force of 1 pound, middle end force of 2.5 pounds, final end force of 4 pounds
• 3/16 inch plunger projection with tip diameter range of 0.117 to 0.118 inches
• No locking element, allowing unrestricted torque adjustment during installation
• Standard plunger length type for straightforward drop-in replacement or new builds

Compatibility

Designed as an OEM-style or new-installation threaded spring plunger for use in any tapped 1/4-28 bore requiring a standard-length stainless steel spring plunger with a 3/16 inch projection.

Installation Notes

Installation is typically performed by machinists or assembly technicians using a hex key sized to the 0.079 inch hex drive. Always ensure the receiving tapped hole is clean and dimensionally correct for the 1/4-28 thread before installation. Do not over-torque the body, as this can compress the spring beyond its rated travel and reduce detent performance. Verify plunger projection and force requirements against the assembly specification before final seating.