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Tuesday, 26 November 2013

Procedure for Sharpening a Drill by Hand

Procedure for Sharpening a Drill by Hand Points : Procedure for Sharpening a Drill by Hand Sharpening drills by hand on the off-hand grinding machine is a common operation in many shops. Many hand sharpening techniques have been developed. The following is suggested:
  1. Put on goggles. Do this even when the wheel is protected with a shield.
  2. Examine the grinding wheel to make sure the face is straight and true. If it is not dress it with a wheel dresser.
  3. If a coolant is used, see that there is sufficient liquid in the reservoir then start the machine.
  4. Examine the angle at which the drill was last ground. Check with a drill point gauge.
  5. Assuming the angle is correct, hold the drill shank with the right hand and the rest of the drill with the left hand.
  6. Place the fingers of the left hand that are supporting the drill on the grinder tool rest. The tool rest should be slightly below center (about 1 in. on a 7. in. wheel)
  7. Stand so the centerline of the drill will be at a 59° angle with relation to the center line of the wheel and lightly touch the drill lip to the wheel in approximately a horizontal position.
  8. Use the left hand as a pivot and slowly lower the shank with the right hand. Increase pressure as the heel, is reached to insure proper clearance.
  9. Repeat the operation on each lip, until the drill is sharpened. Do not quench high speed steel drills in water to cool. Let them cool in calm air.
  10. Check the drill tip frequently with the drill point gauge to assure a correctly sharpened drill. Secure a drill that is properly sharpened and run through the motions of sharpening it. When you have acquired sufficient skill, sharpen a dull drill. To test, drill, a hole in soft metal and observe the chip formation. When properly sharpened, the chips will come out of the flutes in curled spirals of equal size and length. The tightness f the chip spiral is governed by the Rake Angle.
The standard drill point has a tendency to stick in the hole when it is used to drill brass. When brass is to be drill, the, drill should be sharpened.

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