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Published byRayna Chenery Modified over 9 years ago
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TOOL GEOMETRY
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MACHINING WOOD A Stress Failure Process With Three Objectives. 1.Severing – To make two or more pieces from one 2.Shaping – To impart a shape or contour on a piece of wood 3.Surfacing – Sanding, jointing or planing an edge or surface
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MACHINING WOOD The tools
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MACHINING WOOD The tools
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MACHINING WOOD
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CIRCULAR SAW BLADE GEOMETRY
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MACHINING WOOD IDEAL CUTTING ACTION
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MACHINING WOOD HERE IS WHAT HAPPENS Wood fails when ultimate stress is reached. Stress is accompanied by strain. The work piece deforms ahead of the cut and both work piece and chip spring back.
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TYPES OF CUTTING ACTION ORTHOGONAL CUTTING PERIPHERAL MILLING
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TYPES OF CUTTING ACTION 1.ORTHOGONAL CUTTING The tool edge is more or less perpendicular to its direction of travel The cut is parallel to the edge or surface of the board Examples: Pushing a hand plane across the surface of a work piece Using a cabinet scraper
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TYPES OF CUTTING ACTION 2.Peripheral Milling – A rotary cutter head with one or more cutting edges intermittently coming in contact with the work piece Jointer Router Planer
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TYPES OF ORTHOGONAL CUTS 90° TO 0° - Planing along the grain 90° - Relationship of the cutting edge to grain 0° - Relationship of the direction of cut to the direction of grain
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TYPES OF ORTHOGONAL CUTS 90° to 90° Cutting (Planing End Grain) Requirements for a good cut Low cutting angle Sharp edge High clearance angle
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TYPES OF ORTHOGONAL CUTS A closer look at 90 to 90 cutting
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TYPES OF ORTHOGONAL CUTS
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The Effects of Skewing
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TYPES OF ORTHOGONAL CUTS O° TO 90° CUTTING VENEER SLICING
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TYPES OF ORTHOGONAL CUTS Type I Chip Large rake angle Small chip Grain failure occurs out in front of the knife Cutting angle ~ 45° sharpness 30° clearance 15°
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TYPES OF ORTHOGONAL CUTS Type II Chip Smaller rake angle Compression rather than upward lifting Failure occurs right at the cutting edge
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TYPES OF ORTHOGONAL CUTS Type III Chip 0° to small rake angle Uses compression to produce failure Snow plow effect Not an acceptable chip type
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TYPES OF ORTHOGONAL CUTS CUTTING QUALITY
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TYPES OF ORTHOGONAL CUTS When you can’t cut with the grain the chip breaker can help
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TYPES OF ORTHOGONAL CUTS
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PERIPHERAL CUTTING Revolving cutterhead operating along an edge or face of a board Creates knife marks which should number between 12 and 25 per inch
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PERIPHERAL CUTTING
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Jointer Planer Router Refer to pages 166, 167 & 168 for peripheral cutting problems.
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MACHINING WOOD
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The tools
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MACHINING WOOD www.technologystudent.com/equip1/planes1.htm www.fine-tools.com/rauh.htm
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MACHINING WOOD
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Bench Chisels
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MACHINING WOOD Paring Chisel
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MACHINING WOOD Cranked Paring Chisels
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MACHINING WOOD Mortising Chisel
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MACHINING WOOD Mortising Chisels
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MACHINING WOOD SAW BLADES
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MACHINING WOOD
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Types of saw blades Plywood or cross cut blade 60 to 80 teeth large top bevel small gullets Rip blade 20 to 60 teeth no top bevel larger gullets
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MACHINING WOOD Combination blade 40 teeth Square tooth followed by beveled teeth Large gullets Laminate blade or “triple chip” blade 80 teeth typical Small gullets
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MACHINING WOOD Dado blades
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MACHINING WOOD Cutter Heads
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MACHINING WOOD Plywood Blade
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MACHINING WOOD Forrest Blades Plywood/Laminate
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MACHINING WOOD Combination Blade
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MACHINING WOOD Rip Blade
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MACHINING WOOD Triple Chip
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