Swiss Precision Since 1961 

How Does It Work?

The DEFA tool cuts a pre-adjusted chamfer diameter. The blade force keeps the DEFA blades out to the predetermined setting, thereby defining the chamfer diameter. The blade’s upper and lower cutting edge permit machining in both forward and reverse directions. As the DEFA blades enter the material, the force occurring through the feed on to the chamfer definition surface causes the blades to retract radially along the axis of the chamfered surface. The cutting width is constantly reduced. The definition surface angle determines the chamfer angle. Damage to the hole or thread surface is prevented by the sliding surface geometry of the DEFA blades.

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DEFA adjustable outside diameter chamfering tool


The Adjustable Chamfering Tool

  • Controlled chamfers over a range of adjustments
  • Chamfering thickness can be infinitely adjusted directly on the tool, depending on the bore dimension
  • No reversing the spindle or indexing the work piece saves cycle time
  • Front and back or only back chamfering of bores in hard-to-machine or highly burr-forming materials 
  • Ideal for Inconel and other exotic materials
  • Dual cutting system for machining bores with longitudinal grooves, cross-bores and open bores with discontinuous cut
  • Exchangeable carbide blade with material-specific coating 
  • Blade geometry has a sliding surface that allows cutting chamfers without damage to the bore surface or of the thread during penetration
  • Widely used by the world's leading aerospace manufacturers

Available from stock for immediate delivery in sizes
from 4 mm-36.2 mm (.157"-1.425")
for front and back cutting or back cutting only geometry 

DEFA chamfering tool catalog

How Do I Order a DEFA Chamfering Tool? 

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1.To select the correct tool you must know the hole size and chamfer size required. Cutting blade options also include front & back cutting and back only cutting.

2. Use the minimum hole column in the DEFA catalog to choose the tool holder best matching your drill hole size. Check to make sure the chamfer diameter requirement does not exceed the maximum chamfer.

3. Calculate the ØD2 (over the blade) diameter (ØD2 = ØD + .080”) and add this dimension as a suffix to the order number. 

4. Add “p” to the order number if you need the tool with an End Plug. Leave blank for tool with straight shank.

View Application Data Sheet for DEFA

For more assistance, see our online Tool Selector.

Questions? Contact Your Local Sales Agent

DEFA Case Study

 Replacing Manual Deburring of Inconel in the Machining of Aircraft Components

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A major manufacturer of jet engine and aircraft components wanted to replace the manual hand benching to deburr an Inconel part. Their goal was to automate that process to save both labor and time. 

close up picture of chamfers on an inconel jet engine part

Application Details

  • Bore: Ø.345 and Ø.401 requiring front/back break edge 0.005-0.015”
  • Chamfer: 0.010"x 90 degrees
  • Material: Inconel 718
  • Volume: 2 parts/wk (360 holes/part)
  • Machine: NC 
  • Machining: horizontal
chamfering tool for deburring inconel on a jet engine part


  • Tool: DEFA11-34-339 and DEFA13-30-390
  • Blade life: 800-2000 holes 

Machining parameters:

  • Speed: 60 SFM
  • Feed: 0.002 IPR


Customer successfully reduced a 2 1/2 hour manual operation to only 10 minutes. They reduced time, production and labor costs, and the  machinist's physical risk of repetitive motion which was involved in hand benching. 

Need help selecting a tool? Visit our online Tool Selector and go to the Locate Agent page on our website to find your local technical sales representative. For more assistance, contact us at or 513-860-9900 and we'll be happy to point you in the right direction.