Design World

  • Home
  • Technologies
    • ELECTRONICS • ELECTRICAL
    • Fastening • joining
    • FLUID POWER
    • LINEAR MOTION
    • MOTION CONTROL
    • SENSORS
    • TEST & MEASUREMENT
    • Factory automation
    • Warehouse automation
    • DIGITAL TRANSFORMATION
  • Learn
    • Tech Toolboxes
    • Learning center
    • eBooks • Tech Tips
    • Podcasts
    • Videos
    • Webinars • general engineering
    • Webinars • Automated warehousing
    • Voices
  • LEAP Awards
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
    • 2021 Winners
  • Design Guides
  • Resources
    • Subscribe
    • 3D Cad Models
      • PARTsolutions
      • TraceParts
    • Digital Issues
      • Design World
      • EE World
    • Educational Assets
    • Engineering diversity
    • Trends
  • Supplier Listings
  • Advertise
  • Subscribe

Taper shank test fixture provides mill productivity, tool performance

By Paul Heney | August 16, 2018

JM PerformanceAn important part of CNC milling is the v-flange toolholder–which impacts the performance of the cutting tools and the machine itself. A critical factor in toolholder performance is the surface area contact between the large end of the toolholder and the spindle, which is essential for tool rigidity. A higher percentage of taper contact with the spindle at the large end and moving up the taper toward the small end results in improved cutting performance and over-all milling results. Less than 75% taper contact with the spindle results in poor T.I.R. (runout), poor tool life, poor tolerances, vibration and chatter, poor finishes, and excessive spindle wear and tear.

In an effort to ensure optimal mill productivity and tooling performance, JM Performance Products Inc. developed the Taper Shank Test Fixture, to check toolholders and test for taper deformation.

A growing area of concern with use of modern CNC machines with upwards of 500 tools, is tooling cost containment and optimal tooling performance. Unfortunately when a standard retention knob is installed into a toolholder, it can expand the small end of the taper of the toolholder. This expansion can reduce toolholder to spindle contact by 70% or more, resulting in loose tool situations.

The end result is that it will no longer meet ISO 1947 angular taper tolerance (AT) specifications “AT3 or better” for toolholders. Retention knob expansion prevents toolholders from properly seating within the spindle, which can result in vibration and chatter issues that negatively impacts tool life, especially expensive carbide tools. It also impacts milling at the actual production level; most companies are running machines 20-40% slower than they should in order to preserve their tools and get required accuracy and finishes.

An often over-looked safety hazard also exists. As the tool is rotating in excess of 8,000 rpms, the movement of the holder within the spindle is applying enormous stress to the retention knob that is holding it in the spindle. What many shops don’t realize is that stress can cause failure of the retention knob, resulting in the toolholder and tool breaking loose from the spindle during a cutting operation.

Besides damage to the spindle, tool, holder, and workpiece, the velocity of the tool when it breaks loose also represents a real injury threat to the operator.

Additional considerations for toolholder expansion include:
▪ Carbine tool life is diminished by 50% for every .0005” distance short of full engagement between the
toolholder and spindle.
▪ Toolholders may begin to expand with as little as 15 ft/lbs of torque. ▪ Toolholders showing more than .0002” growth have not been hardened adequately and should not be used!

The Taper Shank Test Fixture quickly checks toolholders for distortion caused by retention knob installation.
Development of the patented product was key to identifying the inherent flaw design in v-flange tooling. This discovery was ultimately the driving force for the creation of their patented High Torque retention knobs, which are longer than traditional knobs and feature a precision pilot to increase rigidity, and a relief below the flange that forces threads into a deeper cross section of the toolholder. This eliminates the toolholder expansion responsible for costly and ongoing CNC milling and boring issues.

Key integrated design features include:
▪ Precision gages that read in increments of 1/10,000 of an inch.
▪ Ground to mirror a machine spindle.
▪ Three top dial indicators read the height off the flange and two side dials read taper movement.
▪ Sizes: 30 / 40 / 45 / 50 / 60 Taper

Proper retention knob installation is crucial to toolholder performance. Overtightening the retention knob may damage and unnecessarily stress the knob leading to premature failure. It also exacerbates the effects of toolholder expansion. A quick, simple test using the Taper Shank Test Fixture can be performed on a toolholder with a retention knob already installed.

Following the manufacturer’s instructions to fit the fixture and zeroing out the indicators for a base reading, and then loosening the knob for a second reading, will return an immediate indication of whether or not the holder has experienced expansion. The good news is that an expanded toolholder does not need to be removed from service and scrapped. Once the retention knob has been removed, the toolholder should return to its original state and can be used with a High Torque knob tightened to the correct torque spec.

When the toolholder taper is deformed, it prevents the toolholder from properly seating within the spindle. The ‘elastic zone’ at the small end makes contact with the spindle before the large end of the taper is engaged. This reversal of contact allows the toolholder to move at the gage line. Ultimately, this movement at the gage line is what produces fretting marks found on the toolholder and a laundry list of milling issues.

According to JMPP President, John Stoneback, “It’s important to note that all v-flange tooling is designed to fit the spindle taper within tolerances of twenty-nine-millionths of an inch (0.000029-in.). Tests performed using the Taper Shank Test Fixture revealed a significant advantage for our High Torque retention knobs vs. standard knobs. In fact, most of our clients experience a 20-80% performance advantage.”

JM Performance Products Inc.
www.jmperformanceproducts.com

You Might Also Like


Filed Under: MOTION CONTROL

 

About The Author

Paul Heney

Paul J. Heney, the VP, Editorial Director for Design World magazine, has a BS in Engineering Science & Mechanics and minors in Technical Communications and Biomedical Engineering from Georgia Tech. He has written about fluid power, aerospace, robotics, medical, green engineering, and general manufacturing topics for more than 25 years. He has won numerous regional and national awards for his writing from the American Society of Business Publication Editors.

LEARNING CENTER

Design World Learning Center
“dw
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for Design Engineering Professionals.
Motor University

Design World Digital Edition

cover

Browse the most current issue of Design World and back issues in an easy to use high quality format. Clip, share and download with the leading design engineering magazine today.

EDABoard the Forum for Electronics

Top global problem solving EE forum covering Microcontrollers, DSP, Networking, Analog and Digital Design, RF, Power Electronics, PCB Routing and much more

EDABoard: Forum for electronics

Sponsored Content

  • Widening the scope for machine tool designers with FORTiS™ enclosed encoder
  • Sustainability, Innovation and Safety, Central to Our Approach
  • Why off-highway is the sweet spot for AC electrification technology
  • Looking to 2025: Past Success Guides Future Achievements
  • North American Companies Seek Stronger Ties with Italian OEMs
  • Adapt and Evolve
View More >>
Engineering Exchange

The Engineering Exchange is a global educational networking community for engineers.

Connect, share, and learn today »

Design World
  • About us
  • Contact
  • Manage your Design World Subscription
  • Subscribe
  • Design World Digital Network
  • Control Engineering
  • Consulting-Specifying Engineer
  • Plant Engineering
  • Engineering White Papers
  • Leap Awards

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy | Advertising | About Us

Search Design World

  • Home
  • Technologies
    • ELECTRONICS • ELECTRICAL
    • Fastening • joining
    • FLUID POWER
    • LINEAR MOTION
    • MOTION CONTROL
    • SENSORS
    • TEST & MEASUREMENT
    • Factory automation
    • Warehouse automation
    • DIGITAL TRANSFORMATION
  • Learn
    • Tech Toolboxes
    • Learning center
    • eBooks • Tech Tips
    • Podcasts
    • Videos
    • Webinars • general engineering
    • Webinars • Automated warehousing
    • Voices
  • LEAP Awards
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
    • 2021 Winners
  • Design Guides
  • Resources
    • Subscribe
    • 3D Cad Models
      • PARTsolutions
      • TraceParts
    • Digital Issues
      • Design World
      • EE World
    • Educational Assets
    • Engineering diversity
    • Trends
  • Supplier Listings
  • Advertise
  • Subscribe
We use cookies to personalize content and ads, to provide social media features, and to analyze our traffic. We share information about your use of our site with our social media, advertising, and analytics partners who may combine it with other information you’ve provided to them or that they’ve collected from your use of their services. You consent to our cookies if you continue to use this website.