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TOOL GEOMETRY. MACHINING WOOD. A Stress Failure Process With Three Objectives. Severing – To make two or more pieces from one Shaping – To impart a shape or contour on a piece of wood Surfacing – Sanding, jointing or planing an edge or surface. MACHINING WOOD. The tools. MACHINING WOOD.
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MACHINING WOOD • A Stress Failure Process With Three Objectives. • Severing – To make two or more pieces from one • Shaping – To impart a shape or contour on a piece of wood • Surfacing – Sanding, jointing or planing an edge or surface
MACHINING WOOD • The tools
MACHINING WOOD • The tools
MACHINING WOOD IDEAL CUTTING ACTION
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.
TYPES OF CUTTING ACTION • ORTHOGONAL CUTTING • PERIPHERAL MILLING
TYPES OF CUTTING ACTION • 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
TYPES OF CUTTING ACTION • Peripheral Milling – A rotary cutter head with one or more cutting edges intermittently coming in contact with the work piece • Jointer • Router • Planer
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
TYPES OF ORTHOGONAL CUTS • 90° to 90°Cutting (Planing End Grain) • Requirements for a good cut • Low cutting angle • Sharp edge • High clearance angle
TYPES OF ORTHOGONAL CUTS • A closer look at 90 to 90 cutting
TYPES OF ORTHOGONAL CUTS • The Effects of Skewing
TYPES OF ORTHOGONAL CUTS • O° TO 90° CUTTING VENEER SLICING
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°
TYPES OF ORTHOGONAL CUTS • Type II Chip • Smaller rake angle • Compression rather than upward lifting • Failure occurs right at the cutting edge
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
TYPES OF ORTHOGONAL CUTS CUTTING QUALITY
TYPES OF ORTHOGONAL CUTS When you can’t cut with the grain the chip breaker can help
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
PERIPHERAL CUTTING • Jointer • Planer • Router • Refer to pages 166, 167 & 168 for peripheral cutting problems.
MACHINING WOOD • The tools
MACHINING WOOD • www.technologystudent.com/equip1/planes1.htm www.fine-tools.com/rauh.htm
MACHINING WOOD • Bench Chisels
MACHINING WOOD • Paring Chisel
MACHINING WOOD • Cranked Paring Chisels
MACHINING WOOD • Mortising Chisel
MACHINING WOOD • Mortising Chisels
MACHINING WOOD SAW BLADES
MACHINING WOOD • 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
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
MACHINING WOOD • Dado blades
MACHINING WOOD • Cutter Heads
MACHINING WOOD • Plywood Blade
MACHINING WOOD • Forrest Blades Plywood/Laminate
MACHINING WOOD • Combination Blade
MACHINING WOOD • Rip Blade
Triple Chip MACHINING WOOD