Spi 21-271-2 Radius Needle Contact Point Dial Indicator

Product Description

The SPI 21-271-2 is a radius needle contact point designed for use with dial indicators in precision measurement applications. Machined from black oxide steel, this contact point features a 1/32-inch diameter tip and a 5/8-inch contact point length. It threads directly onto AGD Group 1 dial indicators using a 4-48 thread, providing a secure, repeatable attachment point. Metrology technicians, tool-and-die machinists, and quality control professionals install this type of contact point when measuring radii, grooves, slots, or recessed features that a standard ball-tip point cannot reach accurately.

This contact point is suited for shop-floor and inspection-room environments where AGD Group 1 dial indicators are in service. The radius needle tip geometry concentrates contact on small or contoured surfaces, making it appropriate for checking bore edges, undercuts, and fine detail features on machined parts. Its black oxide steel construction resists corrosion in typical shop environments without adding significant mass to the indicator spindle assembly.

Key Features

• Radius needle tip geometry for measuring grooves, slots, and recessed surfaces
• Black oxide steel construction for corrosion resistance and durability
• 4-48 threaded shank compatible with AGD Group 1 dial indicators
• 5/8-inch contact point length (0.6250 inches decimal equivalent)
• 1/32-inch tip diameter for access to small or tight features
• Lightweight at 0.1 pounds — minimal effect on indicator spindle feel

Compatibility

Designed for use with dial indicators requiring a 4-48 thread contact point, conforming to AGD Group 1 industry designation standards.

Installation Notes

Installation is performed by metrology technicians or machinists. Before changing contact points, remove the dial indicator from any active fixture and ensure the spindle is in a neutral, unloaded position. Thread the contact point onto the indicator spindle by hand and snug gently — do not use excessive force, as the 4-48 thread is fine-pitched and the tip material can be damaged by overtightening. Verify the contact point is fully seated and the indicator reads correctly against a known reference surface before returning the instrument to service.