Overview
The Jacobs J912 rubber-flex collet is a precision workholding accessory designed for lathe chucks and tapping heads in CNC and manual machining environments. This collet accommodates workpieces and tool shanks ranging from 1/4″ to 3/8″ diameter (6.4–95mm metric equivalent). The rubber-flex design combines a synthetic rubber body with hardened steel jaw inserts to deliver superior grip force and repeatability compared to traditional split-steel collets, making it essential for high-precision machining operations.
Key Features
- Grip range: 1/4″ to 3/8″ (6.4–95mm) — accepts both decimal and metric diameters within capacity
- Gripping force up to three times greater than split-steel collets for secure, reliable workholding
- Parallel jaw insert surfaces ensure uniform clamping pressure and precise centering
- Synthetic rubber construction retains flexibility and resists heat, coolants, and cutting fluids
- Hardened steel jaw inserts precision-ground after molding for maximum accuracy and wear resistance
- Durable one-piece construction for long service life in demanding production environments
Technical Specifications
- Part Number: J912
- Manufacturer: Jacobs
- Grip Range: 1/4″ to 3/8″ (6.4–95mm)
- Body Material: Synthetic rubber (flexible core) + hardened steel jaw inserts
- Compatible Chuck Models: Jacobs Models 91, 92, 96
- Design Type: Rubber-flex with parallel jaw inserts
- Weight: Approximately 0.52 lbs (collet only)
Typical Applications
The Jacobs J912 is widely used in:
- CNC Lathes: Precision turning, threading, and facing operations requiring accurate centering and consistent grip
- Manual Lathes: Speed and setup convenience when handling multiple workpiece diameters within the 1/4″–3/8″ range
- Tapping & Reaming Heads: Secure tool shank retention for rigid, accurate hole operations
- Production Machining: High-volume runs where repeatability and tool life directly impact throughput and scrap rates
- Tool & Die Work: Fine finishing and precision grinding applications requiring minimal runout
Compatibility & Replacements
Compatible With
- Jacobs Models 91, 92, and 96 lathe chucks
- Jacobs tapping and reaming head chucks fitted for rubber-flex collets
- Any standard spindle nose or chuck designed for Jacobs rubber-flex collets
Replaces / Drop-In Replacement For
- OEM Jacobs J912 collets in worn or damaged condition
- Equivalent Jacobs factory-original J912 units
- Older J912 collets requiring refurbishment or replacement
Works With
- Jacobs chuck models equipped with rubber-flex collet pockets
- Standard CNC lathe control systems (no software or controller updates required)
- Manual lathe spindles with compatible chuck mounting
- Tapping and reaming machine spindles designed for Jacobs accessories
