1. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Unit 22 Sharpening Tools

2. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Tools Used for Sharpening Sharp tools are safer than dull ones Tools used –files –bench stones and hand stones –sanders and grinders Fine-toothed files used for sharpening –flat –round –triangular –auger bit –chain saw

3. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Cutting Edges Always observe the design and shape of cutting edges when they are new Tools used to cut steel must have thick, strong edges Tools used to cut wood must have fine, sharp edges Tool edges are usually designed with single or double inclined planes

4. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Sharpening Knives and chisels are sharpened to a very fine edge Remove all burrs or rough spots before sharpening To check for sharpness: –Place tool flat on soft wood –Raise back slightly and push cutting edge across wood –If sharp, the edge will shave off a fine sliver

5. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Sharpening Tips Smooth-edged knives may be sharpened in the shop Serrated knives should be brought to manufacturer Wood chisels are only sharpened on one side to an angle of 29 degrees When sharpening a cold chisel, use a medium grit grinding wheel To sharpen a center punch, hold it to the grinding wheel at an angle and twirl it until sharpened to a 60- to 75-degree angle

6. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Sharpening Tips (continued) Can be easier to sharpen an ax on a grinding wheel mounted on a belt-driven arbor Axes can also be sharpened with a large, sharp, medium-cutting, flat file Twist drills should be sharpened with a special jig to obtain the correct angle Be sure that the drill tip is exactly centered When sharpening blades, maintain the original angle and keep the blade balanced All shovels are sharpened on the inside edge

7. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Important Terms Bench stone: sharpening stone designed to rest on a bench Hand stone: designed to be held in the hand Inclined plane: a surface that is set at an angle to another surface Convex: curved out Concave: curved in Hollow ground: teeth are wider at their points than at their base Tool steel: steel with specific carbon content for annealing and tempering Anneal: heating and cooling to make the steel soft and malleable

8. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Important Terms (continued) Temper: to heat and cool quickly to control the degree of hardness Draw the temper: excessive heating that makes the steel soft and useless Whet: sharpen by rubbing on a stone Serrated: notched surface Ax stone: small round stone for sharpening in the field Field: the area where an operation takes place High-speed drill: a twist drill made and tempered to drill steel Balance: weight is equally distributed on both sides of center