Tech Tip #8 - Reamer Guidelines

Kennametal can recommend a drill size that will leave an appropriate amount of material for the reamer to efficiently size the finished hole.

General guidelines for drill sizes are:

  • <1/4” = .010”
  • ¼” to ½” = .015”
  • ½” to 1-1/2” = .025”

A common misconception is to leave too little material for the reamer to remove. The reamer needs enough material to make its cut. Too little material will cause the reamer to rub or burnish and results in accelerated wear and poor surface finish.

Cutting speeds should be about two-thirds that of drilling SFM for similar material and feeds should be two to three times higher. 

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