Spi 20-641-7 Contact Point Extension 1.5 in 4-48 Thread

Product Description

The SPI 20-641-7 is a drop indicator contact point extension designed to increase the reach of a dial indicator contact point for dimensional measurement work. Manufactured from steel, this extension measures 1.5 inches in length and features a 4-48 threaded connection, the standard thread size used on most dial and test indicator contact points. It allows technicians and machinists to access recessed bores, deep shoulders, and hard-to-reach measurement surfaces without repositioning the indicator setup. At 0.15 pounds, it adds negligible mass to the spindle assembly, helping to maintain measurement accuracy and stylus force consistency during use.

This extension is suited for use in machine shops, toolrooms, and on the production floor wherever a dial indicator or test indicator requires extended contact reach. It is appropriate for dimensional inspection tasks including surface runout checks, bore alignment, and part setup on mills, lathes, and surface plates. Any application requiring a 4-48 threaded contact point replacement or extension is a valid use case for this part.

Key Features

• Steel construction provides durability and dimensional stability under repeated use
• 4-48 thread matches the standard contact point thread on most dial and test indicators
• 1.5-inch extension length increases stylus reach into recessed or deep features
• Lightweight at 0.15 pounds to minimize added mass on the indicator spindle
• Single-piece quantity allows individual replacement or addition without bulk purchase

Compatibility

Designed for use with any dial indicator or test indicator that accepts a standard 4-48 threaded contact point.

Installation Notes

Installation requires no special tools beyond finger-tightening or a small wrench suitable for the contact point flat, if present. Remove the existing contact point from the indicator spindle before threading on the extension. Avoid over-tightening, as the 4-48 thread is fine and can be damaged by excessive torque. Verify indicator stylus force and travel are not compromised after adding the extension, as increased lever arm length can affect measurement sensitivity.