Spi 20-644-1 Drop Indicator Contact Point Extension

Product Description

The SPI 20-644-1 is a contact point extension designed for use with drop-style dial test indicators. It extends the reach of the contact point to allow measurements in recessed bores, deep cavities, and hard-to-access features where the standard contact point cannot make direct contact. Machined from steel, the extension measures 2.5 inches in length and uses a 4-48 threaded connection to mate with compatible indicator contact points. At 0.15 pounds, it is a lightweight accessory suited for precision measurement setups on the shop floor or in the field.

This extension is used in metrology and inspection applications wherever a dial test indicator needs additional reach. Common scenarios include checking runout or bore alignment on lathes, mills, and surface plates, as well as inspection of deep counterbores or stepped features. Machinists, tool and die technicians, and quality control inspectors working with dial test indicators will find this extension useful for maintaining accurate contact geometry at depth.

Key Features

• Steel construction provides rigidity and durability for repeated precision measurement use
• 2.5-inch extension length increases reach into deep or recessed features
• 4-48 threaded connection compatible with standard dial indicator contact point threads
• Lightweight at 0.15 pounds, minimizing added mass on the indicator stylus
• Single-piece package, sold individually

Compatibility

Designed for use with any test indicator that accepts a 4-48 threaded contact point, making it a broadly compatible accessory for standard drop-style dial test indicators.

Installation Notes

Thread the extension into the indicator contact point port by hand until snug, taking care not to overtighten and damage the 4-48 threads. Verify that the extension is fully seated and does not introduce lateral play before taking measurements. When swapping extensions on sensitive indicators, handle the indicator body to avoid altering calibration. No special tools are required for installation.