Vlier SL312 Knob Handle Spring Plunger 5/16-18 Thread

Product Description

The VLIER SL312 is a knob handle spring plunger with a knurled knob design, intended for indexing, positioning, and light-duty holding applications in industrial assemblies and tooling fixtures. The plunger is non-locking and operates with an initial end force of 1 pound and a final end force of 6 pounds, giving technicians and assemblers a controlled, repeatable engagement feel. The body is steel with a zinc gold chromate finish for corrosion resistance. The 5/16-18 thread size and 0.625-inch thread length allow installation into standard threaded housings without additional hardware. Maximum plunger diameter is 0.154 inches.

This spring plunger fits standard threaded bores in jigs, fixtures, machine components, and tooling plates where a knob-adjustable, hand-operated plunger is required. The knurled knob allows tool-free manual adjustment, making it suitable for production environments where frequent repositioning is needed. Body length is 0.76 inches, and the length under head or shoulder is 0.625 inches, keeping the installed profile compact. Plunger projection is 0.188 inches, providing positive ball or pin engagement without excessive protrusion.

Key Features

• Non-locking plunger design with 1 lb initial end force and 6 lb final end force
• Knurled knob handle allows tool-free manual adjustment
• Steel construction with zinc gold chromate finish for corrosion resistance
• 5/16-18 thread size for compatibility with standard threaded bores
• Compact body length of 0.76 inches with 0.188-inch plunger projection
• Plunger diameter tolerance of +0.001 / -0.000 inches for precise fitment

Compatibility

Designed as a standard-thread spring plunger for use in threaded housings or tapped holes sized for 5/16-18 inch fasteners in industrial fixtures, jigs, and positioning assemblies.

Installation Notes

Installation is performed by threading the SL312 into a properly tapped 5/16-18 hole using the knurled knob. Ensure the mating bore is clean and free of burrs before installation. Do not use power tools to drive the plunger, as over-torquing can damage the spring mechanism. Verify plunger projection clearance in the assembled position before placing the assembly into service.