Value Collection 230-4394 5C Emergency Collet 1/4 in

Product Description

The VALUE COLLECTION 230-4394 is a 5C emergency collet machined from steel for use in 5C collet chucks and closers on lathes and grinding machines. Emergency collets are supplied with a soft, unfinished pilot bore that the machinist bores to a custom diameter on-site, allowing the collet to grip non-standard workpiece sizes or odd-lot stock that standard collets cannot hold. This collet features a 1/4 inch pilot hole, an internal thread size of 1.041 inches at 24 threads per inch, and an external thread size of 1.242 inches at 20 threads per inch. Total indicated runout (TIR) is 0.00315 inches, providing reliable concentricity once the bore is finished to the final gripping diameter. Installation and finishing are performed by a qualified machinist.

This emergency collet is suited for machine shops, toolrooms, and production environments where a specific workpiece diameter does not correspond to a standard collet size. Typical applications include holding custom-diameter bar stock, stepped workpieces, and specialty tooling shanks in 5C-compatible spindles. The steel construction handles the clamping loads and cycle wear common in both short-run toolroom work and repetitive production turning or grinding operations.

Key Features

• Emergency-style design with soft, unfinished pilot bore that machinists bore to a custom gripping diameter on-site
• 1/4 inch pilot hole size (0.2500 inches decimal) for boring to final diameter
• TIR of 0.00315 inches for consistent concentricity after finish boring
• Internal thread size: 1.041 inches at 24 threads per inch
• External thread size: 1.242 inches at 20 threads per inch
• Steel construction for durability under production clamping loads

Compatibility

Designed as a standard 5C-pattern emergency collet compatible with 5C collet chucks, collet closers, and indexing fixtures that accept the 5C collet form factor.

Installation Notes

Emergency collets must be finish-bored to the required gripping diameter by a qualified machinist before use. The collet should be mounted in the spindle and the bore cut while the collet is under the same clamping pressure used in production to ensure true running after boring. Power down and lock out the machine spindle before removing or installing the collet in the chuck or closer. Follow shop safety procedures and applicable OSHA machining guidelines when operating collet-equipped lathes or grinders.