• TOPICS
    • Design
    • Manufacturing
    • Inspection
    • Heat Treating
    • Lubrication
    • Materials
    • The Gear Industry
    • Gears by Type
  • MAGAZINE
    • Current Issue
    • Departments
    • Archives
    • Subscribe
    • Advertise
  • NEWSLETTER
    • Subscribe
  • VIDEO
    • Gear Technology TV
      • Ask the Expert Live
      • Revolutions
    • Industry Videos
  • BLOGS
  • BUYER'S GUIDE
  • NEWS and EVENTS
    • Product News
    • Industry News
    • Events
  • ADVERTISING
    • Brand Awareness
      • Print: Display Advertising
      • Online: Web Banners & Keyword Banners
      • Online: Native Advertising (Sponsored Content)
      • E-mail: Custom, White Papers & Webinars
      • E-mail: Newsletter Sponsored Content (Native Advertising)
    • Response & Lead Generation
      • Online: Sponsored Content (Native Advertising)
      • E-mail: Newsletters
      • E-mail: Newsletter Sponsored Content (Native Advertising)
      • E-mail: Custom, White Papers & Webinars
      • Online: Buyers Guide
    • Print Advertising
      • Print: Display Advertising
      • Print: MPT Expo Showstoppers
      • Print: Buyers Guide
      • Print: Manufacturing sMart
      • Print: Specifications
      • MPT Expo Show Guide Advertising
    • Online Advertising
      • Online: Web Banners & Keyword Banners
      • Online: Native Advertising (Sponsored Content)
      • Online: Buyers Guide
      • Online: Specifications
    • E-mail Advertising
      • E-mail: E-Newsletters
      • E-mail: Newsletter Sponsored Content (Native Advertising)
      • E-mail: AGMA Industry News
      • E-mail: Custom, White Papers & Webinars
      • E-mail: Specifications
    • Special Promotions
      • Print: MPT Expo Showstoppers
      • Print: Buyers Guide
      • Print: Manufacturing sMart
      • MPT Expo Show Guide Advertising
  • CONTACT US
  • AGMA
    • Membership
    • Events
    • Education
    • Emerging Technology
    • AGMA Media
    • Standards
Subscribe
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Home » Blogs » Gear Talk With Chuck » How Many Teeth Do You Want?

Gear Talk With Chuck
Gear Talk With Chuck RSS FeedRSS

Design / Manufacturing / Bending Strength / Contact Ratio / Helix / Pressure Angle / Profile / Strength / Tooth Profile / Undercut / Cutting Tools / Processes / Hobs / Grinding / Helical Gears / Spur Gears
Charles schultz
Chuck Schultz is a licensed engineer, Gear Technology Technical Editor, and Chief Engineer for Beyta Gear Service. He has written the "Gear Talk with Chuck" blog for Gear Technology since 2014.

How Many Teeth Do You Want?

April 17, 2018
Charles D. Schultz
No Comments
Designing gears is somewhat of a mathematical puzzle. You have lots of interconnected factors to play with in hopes of finding the “best” overall solution to the problem. Among the fundamental “variables” is the number of teeth on each component. As with helix angle, many of our “tribes” have adopted rules on how many teeth can be used in their products. All of these rules are valid in certain circumstances, but may not reflect the full range of possibilities. Back when they were first carved into granite, the rule makers were hoping to save future generations some of the pain they went through discovering what did not work. Take the typical “low limit” on pinion teeth of 18 for spur gears and 14 for helical gears; if you ever see a severely undercut tooth, you can appreciate what they were trying to avoid. Those rules are not “wrong,” but they simplify the problem in a way that prevents designers from understanding modern manufacturing techniques that allow almost any number of teeth to be made without undercutting. Before you start typing comments suggesting that I have gone off the deep end, I once had a “desk widget” which featured a ONE-tooth helical pinion driving a fifty-tooth gear. Many things are possible — but not practical; design rules save time but stifle innovation. Many very successful gear systems employ relatively low numbers of teeth on the pinion. The advent of short lead hobs — generating the tooth profile with a cutting tool having a lower pressure angle than the finished part — made undercutting something that is routinely worked around, rather than avoided. The number of “spaces” factors heavily into grinding cycle times, so there is an economic incentive as well as a bending strength argument for reducing tooth counts. There is also an excellent counter argument that looks at profile contact ratios and insists upon much higher numbers of teeth. We will cover that in another posting. So to once again paraphrase Mr. Ray Drago’s mantra: the correct answer to “how many teeth?” is “It depends.”

Recent Comments

Thank you for this - Happy Saint Patrick's...

Post a comment to this article

Report Abusive Comment

Free Gear Technology Subscriptions
Subscribe
Free Gear Technology Subscriptions
Subscribe
FEATURED VIDEO
  • Helios1
    Forest City Gear Taps Helios Gear for Custom Cutting Tools
January 18, 2023
RECOMMENDED
  • Precision Equals Performance at ZPE GripTec

    October 12, 2022
    gt0922_Page_28_Image_0003.jpg
  • State of the Powder Metal Industry

    October 12, 2022
    gt0922_Page_30_Image_0001.jpg
  • The Afterglow of Furnaces North America 2022

    October 12, 2022
    gt0922_Page_20_Image_0001.jpg
  • Reigniting the Educational Infrastructure

    December 5, 2022
    gt1122_Page_20_Image_0001.jpg
  • Profile: Continuing Education and Training with the AGMA

    December 5, 2022
    gt1122_Page_26_Image_0001.jpg
  • Reigniting the Educational Infrastructure

    December 5, 2022
    gt1122_Page_20_Image_0001.jpg
  • Profile: Continuing Education and Training with the AGMA

    December 5, 2022
    gt1122_Page_26_Image_0001.jpg
  • Precision Equals Performance at ZPE GripTec

    October 12, 2022
    gt0922_Page_28_Image_0003.jpg
  • Subscribe
  • Advertise
  • Contribute
  • AGMA
Powered byAGMA
Copyright © 2023 Gear Technology
  • Privacy Policy
  • Contact