What is this drill bit for?

  1. Ali

    Ali Member

    Messages:
    955
    Location:
    Cheshire
    ????

    Got a few of them.

    D95D5E63-AD72-4001-8753-C007CA2BD64B.jpeg 81564670-8DCD-4515-9F3E-27609668B3D1.jpeg

    Special application?

    Made by Guhring but the part numbers etched in give me nothing on google.
     
  2. mechman Member

    Messages:
    1,980
    Location:
    great britain n.e.lincs
    Seen them with 4 flutes and were called core drills, they were mainly used for drilling rough casting bores etc.
     
  3. Paul.

    Paul. Moderator Staff Member

    Messages:
    6,639
    Location:
    Northampton. UK
    Three flute drill, used for drilling hard stuff, also useful for opening out existing holes without them going a funny shape
     
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  4. northwest

    northwest Member

    Messages:
    2,042
    Location:
    Manchester UK
    I will buy them if you are selling?

    Great on sheet metal and plastics.

    Edit: And keeping holes round as ^^^^
     
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  5. fizzy Member

    Messages:
    6,806
    uk
    I used something similar for phosphor bronze. Normal bits would snag.
     
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  6. Ali

    Ali Member

    Messages:
    955
    Location:
    Cheshire
    Thanks. I think they’re all 7.5mm or 8.5mm so I can’t see myself reaching for them too often. Not sure how many I have, if more than 5 I might sell the rest. I’ll have to try them out on a few bits.
     
  7. Seadog

    Seadog Forum Supporter

    Messages:
    6,968
    Location:
    NE London - UK
    +1 for core drill.
     
  8. whm_fab

    whm_fab Motorsport fabrication

    Messages:
    387
    Location:
    ireland
    theyre great for drillinng perspex / lexan etc
     
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  9. outofthefire

    outofthefire Member

    Messages:
    2,427
    Leeds
    I used to grind a steeper angle for drilling stainless and 8.5 is drill size for tapping 10mm x1.5 so a useful drill to have in your box.
     
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  10. Morrisman

    Morrisman Forum Supporter

    Messages:
    2,697
    Location:
    Staffordshire, England
    Yes, usually used in a jig to open up holes in castings without deflecting too much.
     
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