Product Description
The CMT C-Spanner for ER40 Precision Collets is a dedicated clamping nut wrench engineered to tighten and loosen ER40 collet nuts with accuracy and ease. Designed specifically for ER40 clamping nuts used in CNC machining applications, this spanner delivers a secure, positive grip on the nut profile - helping machinists achieve consistent, repeatable clamping performance on precision collet chucks. Whether you are setting up high-speed spindle work or performing routine collet changes, having the correct spanner means proper torque transfer and protection of both the collet nut and the chuck body.
Key Features
- Designed for ER40 clamping nuts - matches the exact nut geometry of ER40 precision collets, ensuring a flush, stable fit that prevents rounding or slipping during tightening and loosening
- C-spanner configuration - the open-hook profile wraps securely around the collet nut, giving you controlled leverage without obstruction, even in confined spindle areas
- Purpose-built for precision collet systems - using a dedicated ER40 spanner rather than a generic tool protects delicate collet nut threads and preserves the accuracy of your clamping setup over repeated use
Why This Product
- Matched to the ER40 standard - this spanner fits ER40 clamping nuts precisely, eliminating the guesswork and potential damage that comes with using an ill-fitting or improvised wrench on a precision collet system
- Supports proper torque application - when used alongside a calibrated torque wrench such as the CMT TW-200, this spanner enables accurate clamping torque delivery, which is critical for tool runout control and spindle performance
- Protects your investment - the correct spanner prevents wear on the collet nut shoulders, extending the service life of your ER40 collets and clamping hardware
- Part of CMT's precision collet accessory line - designed as a companion tool within the CMT 991 series of c-spanners for precision collets, ensuring compatibility and consistent quality across your collet tooling setup
Specifications
- Order Number: 991.184.00
- Description: C-Spanner for ER40 Collet Nuts
- Brand: CMT Orange Tools
- Series: 991 - C-Spanners for Precision Collets
- Compatible Collet Size: ER40
- Country of Origin: Made in Italy
Frequently Asked Questions
What size collet nut is this spanner designed to fit?
This c-spanner is designed specifically for ER40 clamping nuts. It is not intended for use with other ER sizes such as ER16, ER20, ER25, or ER32 - each of those requires a spanner matched to its own nut diameter.
Can this spanner be used to apply proper clamping torque on its own?
The c-spanner is used to hold or turn the ER40 clamping nut. For proper clamping torque, it should be used in combination with a calibrated torque wrench such as the CMT TW-200, which ensures the collet is tightened to the correct specification for safe and accurate tool holding.
Why is it important to use the correct spanner for ER40 collet nuts?
Using the correct c-spanner for your ER40 clamping nut ensures a precise fit on the nut profile. An ill-fitting or improvised tool can round off the nut shoulders, making future tightening and loosening difficult, and can also introduce uneven clamping forces that affect tool runout and machining accuracy.
Is this spanner part of a larger CMT collet accessory series?
Yes - the CMT 991.184.00 belongs to the CMT 991 series of c-spanners designed for precision collets. This series provides correctly sized spanners for various ER collet nut standards, allowing users to build a consistent, matched set of collet tooling accessories.
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