• 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: IMTS Showstoppers
      • Print: Buyers Guide
      • Print: Manufacturing sMart
      • Print: Specifications
    • 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: Custom, White Papers & Webinars
      • E-mail: Specifications
    • Special Promotions
      • Print: IMTS Showstoppers
      • Print: Buyers Guide
      • Print: Manufacturing sMart
  • 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 » In Search of True Helical Action

Gear Talk With Chuck
Gear Talk With Chuck RSS FeedRSS

Design / Contact Ratio / Helix / 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.

In Search of True Helical Action

April 5, 2018
Charles D. Schultz
No Comments
I was trained in the cult of the integer face contact ratio. A few adherents to this belief are still above ground, but the introduction of personal computers has made it difficult to attract new recruits. We were not quite “flat-earthers” — but close. It started off simply enough: if you wanted true helical action, you needed a face contact ratio of more than 1.00. If 1.00 was the minimum, 2.00 ought to be even better. And if 2.00 was the goal, why not select helix angles that got you exactly 2? Or if your helix angle was fixed by the cutting machine, change the face width to get that magic “2.” Lengthy technical papers were written supporting this philosophy. Elaborate charts were prepared to aid our company’s design teams. So, imagine my shock when I left that firm and discovered that the industry was full of heretics who just used seemingly random helix angles; and their gears worked just fine. Not that I did not encounter other strongly held beliefs which, upon later examination, were not truly necessary. Among the “commandments” I heard about were: 1. Helix angles over 20° must be avoided. 2. Helix angles must be integer values like 8°; 10°; 12°; 16°; 18°; 20°; 23°; or 30°. 3. Face contact ratios over 2 are bad. 4. Face contact ratios under 1.0 are nothing but distorted spur gears. Each of these commandments originally had some basis in science; most likely some well-intentioned student either misunderstood, misremembered, or took something out of context and had it carved in granite so they wouldn’t forget it. Actually, they inscribed it in the company’s computer code and future designers did not know their output was compromised. Once the gear trade became international and computer programs were commercially available, it became impossible to ignore the biases trained into your designers. Many things our system said should be avoided worked well in competitors’ machines. With regard to helix angles, I learned that most values will function just fine provided the mounting system is sufficient.

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
  • Laser Gear Inspection with Douglas Beerck of Gleason
February 28, 2022
RECOMMENDED
  • LPC Carburizing: The Affordable Alternative to Gas Carburizing

    April 25, 2022
    Nitrex2.jpg
  • Hardness Testing Gears — Know Your Options for Best Results

    April 25, 2022
    Starrett1.jpg
  • Kapp Niles Examines Intelligent Rolling Grinding for E-mobility

    April 25, 2022
    Opening Image.jpg
  • Making Gear Grinding Transparent

    May 19, 2022
    Picture6.png
  • The Numbers Game

    May 19, 2022
    Toolx7-featured.jpg
  • Making Gear Grinding Transparent

    May 19, 2022
    Picture6.png
  • The Numbers Game

    May 19, 2022
    Toolx7-featured.jpg
  • LPC Carburizing: The Affordable Alternative to Gas Carburizing

    April 25, 2022
    Nitrex2.jpg
  • Subscribe
  • Advertise
  • Contribute
  • AGMA
Powered byAGMA
Copyright © 2022 Gear Technology
  • Privacy Policy
  • Contact