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Counterbore Tool Issue

Discussion in 'QUESTIONS & ANSWERS (Get Help Fast Here!)' started by petertha, Jan 3, 2017.

  1. petertha

    petertha Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    I bought some mixed brands of HSS capscrew counter bores & its becoming obvious some are not cutting well. First I thought it was a 3-flute vs 2-flute thing. But upon closer inspection, the cutting edge is not consistent. Viewing from the side, some have what would form a flat bottom hole. Others have a slope meaning they would cut deeper out near the edge & shallower in where the pilot stub is. Not like an outer pip either, its a linear taper. The better quality (happen to be 3-flute euro) are all flat bottom. What makes me suspicious is the angle &straight are from the same set - almost like they messed up the grinding relief. Correct me if I'm wrong but isn't the whole objective of a capscrew counterbore to be flat across the bottom, not tapered?
     
  2. woochucker

    woochucker United States Active Member Active Member

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    yep. sounds like a quality control issue, or lack of it.
     
  3. EmilioG

    EmilioG United States Active User H-M Supporter-Premium

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    They're pricey but well made; Alvord Polk.
     

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