Spi 21-257-1 Flat Button Contact Point Dial Indicator

Product Description

The SPI 21-257-1 is a flat button contact point designed for use with dial indicators in precision measurement applications. Threaded at 4-48 and machined from black oxide steel, this contact point measures 0.094 inches in contact point length and 0.75 inches in diameter. It is a direct-threaded replacement tip used when a broader, flat contact surface is needed to measure flat or nearly flat workpiece surfaces. Machinists, tool and die makers, and quality control technicians install this type of contact point when the standard pointed tip is not appropriate for the surface being gauged. The black oxide finish provides corrosion resistance in typical shop environments.

This contact point is suited for residential machine shops, manufacturing floors, and toolrooms where dial indicators are used for setup, inspection, and runout measurement. The flat button style is commonly specified in AGD Group 1 applications, making it compatible with a wide range of standard dial indicator bodies that accept 4-48 threaded contact points. It is a single-piece consumable item packaged individually and ordered in single-unit quantities.

Key Features

• Flat button contact style provides broad, stable contact surface for flat workpiece measurement
• 4-48 thread size matches standard AGD Group 1 dial indicator stems
• Black oxide steel construction for durability and corrosion resistance in shop environments
• 0.094 inch contact point length for precise, low-profile tip engagement
• 0.75 inch diameter button face for stability on flat and near-flat surfaces
• Meets AGD Group 1 industry designation for standardized fitment

Compatibility

Designed for use with dial indicators that accept 4-48 threaded contact points and conform to AGD Group 1 specifications.

Installation Notes

Contact point replacement is performed by machinists or metrology technicians using a standard wrench or contact point tool to unthread the existing tip and thread in the replacement. Zero the indicator after installing a new contact point to confirm proper seating and accurate readings. Do not overtighten, as the 4-48 thread is fine-pitch and the stem on the indicator body can be damaged by excessive torque. Verify the indicator is secured in its holder and not under load before swapping contact points.