Introduction

1. Introduction : The hammer is a very simple striking tool. It is just a weighted head and a handle which directs its course. Your toolbox is not complete unless it contains at least two or three types of hammers. Machinists’ hammers are made of steel, hardened and tempered. They are made in different sizes (weights) from 6 oz. to 2 ½ lb.; those weighing over 1 ¼ lb. are not much used. The top of the hammer head is called the PEEN and the bottom is called the FACE.

2. Classification of Machinist Hammer • HARD HAMMER • Is one that is made of carbon steel and forged to shape and size. • A hard hammer is use for striking punches, cold chisels, steels, and figures, etc. • SOFT HAMMER • May have the entire head made of a soft metal such as lead, Babbitt, copper, or brass. • Used when striking finished or semi finished work piece to prevent marring the finished surfaces.

3. A ball-peen hammer is also known as an engineer's hammer or a machinist's hammer and may be graded by the weight of the head. It is the mechanic's hammer of choice when making gaskets or driving drift pins. • It is distinguished from a point-peen hammer or chisel-peen hammer by having a spherical or hemispherical peening head.

4. - A cross peen or machinists hammer has a flat face, which is either square or octagon and a wedged shaped face. They are often used in blacksmithing where the wedge or cross peen face is used in shaping, cutting or folding the metal.

5. SLEDGE HAMMER Used for the heavier jobs, such as driving in stakes or to break up concrete, stone or masonry. For lighter jobs just the weight of the head may be used for blow's, but for heavier work, the hammer is swung like an axe. Wear suitable protective clothing, including safety glasses. Weights 7, 10 and 14 lb.

6. PLASTIC HAMMER • May have the entire head made of a soft metal such as lead, Babbitt, copper, or brass. • Used when striking finished or semi finished work piece to prevent marring the finished surfaces.

7. ADVICE IN USING A HAMMER • Always use the right hammer for the job, it will make the job easier and avoid possible damage to the hammer/workpiece. • When assembling delicate work, use a piece of scrap wood between the work piece and the head of the hammer. This will prevent damage to the workpiece.

8. Never use a hammer with dents, cracks, chips, mushrooming, or excessive wear. Replace the hammer-redressing is not recommended • When striking a chisel, punch, or wedge, the striking face of the hammer should be 3/8 “larger than the struck face of the tool”. Both the striking hammers face and the struck face of the tool should be free of oil.

9. Where the handle is held in the hammer head by steel wedges, check regularly to ensure the wedges are tight. Timber handle can shrink in dry conditions. • If a timber handle does start become loose, place the head in water overnight, the water will cause the handle to expand and tighten in the head. • Always wear safety glasses.

10. PUNCH A punch is a hard metal rod with a shaped tip at one end and a blunt butt end at the other that is usually struck by a hammer. A variety of punches are used in engineering, but often the purpose is to form an impression of the tip on a work piece.

11. PRICK PUNCH • Is made of hardened tool steel and ground to a slender point having a 30 to 60 degrees included angle. • It is use to mark lightly or indent the intersections to layout lines.

12. DRIFT PUNCH • is a long, tapered punch • Used for loosening straight pins, taper pins, rivets and other small parts being disassembled.

13. DRIVE PIN PUNCH Are used to set in place or remove straight and taper pins and some types of small parts requiring a drive fit.

14. CENTER PUNCH • Similar to a prick punch in appearance except for the point, this is ground to a 90 degree included angle. • Used to enlarge a prick-punch mark so a drill can be started in the exact location.

15. Also known as letter stamps or number stamps. These are used to emboss the impression of a letter or number into a workpiece. They are most common in the reverse image, this allows the end result to be immediately readable, however they may be made as a positive image. This is essential in the case of die or mold making and ensures that the finished product will in fact be readable, a die is in fact a negative image already.