DO NOW

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DO NOW

• LESSON

11/10/2009

• What are the

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Focus Point What are the Types of Punches?

• Instructional Objectives
• 1. List the purpose of various punches.
• 2. Describe the different types.
• 3. Use a specified punch.

LESSON
November 10, 2009
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I) Punches
punch is a hard metal rod (carbon steel) with a
shaped tip at one end and a blunt butt end at the
other that is struck by a hammer.

• made of hardened tool steel
• The part held in the hand is usually octagonal
  shaped or it may be knurled, in order to prevent
  the punch from slipping in the hand.

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A) Center Punch
II) Types

• A sharp pointed tool which is used to provide an
  indentation in sheet metal prior to drilling.
• If the indentation is too deep, the metal will be
  distorted from the blow of the hammer. However it
  shall be deep enough to provide a rest

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Various Center Punches
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Automatic Center Punch

• Spring loaded
• No ball peen hammer required

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B) Pin Punch

• Used to remove rivet shank from the hole of a
  rivet being replaced.
• Pin punches come in the exact sizes as the rivets
  being removed.
• Common set of punches 3/32 1/8, 5/32 3/16
  1/4

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Pin Punch Contd.

• May also be used to align holes in the skin for
  faster installation. (Aligning punch)
• This differs from the pin punch in its length
  (6-8 inches) It tapers from 1/8 at the point to
  3/8 at the shank.

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C) Transfer Punch

• A special punch used to mark rivet holes when
  using an old skin as a template for laying out a
  new skin.
• The diameter of the punch is the same as that of
  a rivet hole, and the end is ground so that the
  mark on the new skin will be in the actual center
  of the hole.

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Transfer Punch
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D) Prick Punch

• primarily used for the purposes of layout.
• By design it produces a smaller indentation than
  a center punch, which acts as a useful datum
  point in layout operations.

• indentation made with a prick punch can be
  enlarged with a center punch
• A prick punch usually has a tip, that when viewed
  on a profile, has sides at a 30-60 degree angle
  to one another.

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PRICK (PUNCH)
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E) Hollow Gasket Punch

• Used to make gaskets for engines/carburetors -
  (rubber, cork, leather)
• Gasket punches come in sets for various sizes to
  accommodate standard bolts and studs.
• The cutting end is tapered to a sharp edge to
  produce a clean, uniform hole.

Glossary Word
Gasket Stationary seal between two (2) flat
surfaces.
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Gasket Punch

• Must be placed on a wood or lead plate to prevent
  damage of the cutting edge.
• Now the punch is hit with a hammer, driving it
  through the gasket material where the holes are
  required.

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F) Drift Pin (Punch)

• Commonly referred to as drift pins and starting
  punches. Has a long taper from tip to body.
• Made to withstand the shock of heavy blows.

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DRIFT PIN

• May be used to free pins or bolts that are
  frozen in their holes. After the pin or bolt
  has been loosened the drift pin may be to large
  to finish the removal, then use a pin punch.

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What must you wear when using punch?
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SAFETY TIP

• Always use the proper punch for the proper job,
  in order to prevent injury!

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Focus Point What are the Types of Punches?

• SUMMARY (PEP TALK)
• 1. What are 3 punches used in Sheet Metal?
• 2. Compare the Prick Punch to the center Punch.
• 3. Why do we use a gasket punch.