1. #1

    Thank you for reading

    I was taught that minimizing run-out is essential for successful drilling
    I can see machinists making dowel holes with HSS drills in collets, and sometimes these drills run even more than 0.1mm out, on steel and aluminium.
    I know the spot drill defines the position of the holes, however drilling with a drill which runs more than 0.1 out, I would not use it even to make a normal tapped hole for a high precision job
    What’s your experience about run out

    Thank you in advance for your support

  2. #2
    Relative to the job - 0.1mm is fine for a hole that is to be tapped, for dowel holes, they must be reamed to fit.

    Drills are only ever treated as a way to get an approximate sized hole, the accuracy is added later by machining or reaming or boring etc.

    If the spot-drill is used correctly then the drill can be quite bad and still drill in the correct place.

  3. #3
    Collets come in different tolerances. If your vender does not mention tolerance you can probably assume they are from the cheap end of the pile

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