successfully added to cart
View Cart


Mark all as read

Tech Tip: Chamfer Length vs. Tool Life in Threading

It is important to use the longest chamfer possible for the tapped hole condition. Sometimes this includes purchasing a special. An increase in chamfer length will result in an increase in tap life!

To determine the longest chamfer for blind holes, subtract the full thread length required plus one pitch from the drill depth. The extra pitch enables clearance at the bottom of the hole for spindle over-spin and chips. Then divide this figure by the number of threads per inch (TPI). The resulting number is the recommended chamfer length. Select a tap with a chamfer length no longer than this figure.


  • Size: ¼-20 NC
  • Full thread length: .250
  • Drill depth: .473
  • Pitch: 1/ 20 = .050
  • .473 -.250 -.050 = .173
  • (drill depth minus full thread length and one pitch)
  • .173 ÷ .050 = 3.5
  • (new drill depth divided by threads per inch (TPI)
  • 3.5 = recommended chamfer length

In this case, select a standard tap with thread chamfer no longer than 3.5.
For a safety margin, a 3-thread chamfer may be preferable.

A 4-flute semi-bottoming tap has 12 working teeth; a bottoming tap has 8. The semi-bottoming tap has 50% more tap teeth to dramatically improve tap life!
By selecting a tap with a longer chamfer length, you will reduce chipload per tooth and tapping torque, enabling increased tapping speeds and tool life. When tapping harder steels and space-age alloys such as nickel, titanium and stainless, a longer chamfer length may determine success or failure.
Specifying the proper chamfer length will ensure greater tool life. For each chamfer tooth added, the tap life will increase exponentially.

Please adjust the following properties from

ISO Catalog Number

ANSI Catalog Number

to find similar products.
If you create a new solution, you will lose any solutions you were working on already. How would you like to proceed?
You are about to create a duplicate . Do you want to proceed?
You are about to delete Do you want to proceed?
What would you like to rename your to?
Please enter a valid name
Please enter a name for the duplicate
Please enter a valid name
You are about to add to your My Solutions page. Do you want to proceed?
Please enter a valid name
Send a copy of

Please enter a valid Email
Please enter a valid name

We have found the following CAD Drawings

Select the files you are looking for and download them all at once

You should be logged to see your dashboard information
The product/s () you were trying to add to the cart is/are not available, please contact customer service.
item(s) successfully added to the cart
View Cart