Guide for mill sawing of timber

IS 9576: Scope & Key Specifications for Band Saw Blades

Scope (Clause 2.0)

• Defines terms related to band saw blades such as Clearance Angle, Kerf Width (Theoretical), and Sharpness Angle.
• Reference to IS 707-1976 for additional definitions.
• Rounding off test results per IS 2-1960.

Key Table: Specification for Teeth of Band Saw Blade (Clause 6.1.4)

• Pitch: Distance between teeth.
• Gullet Depth: Space between teeth for chip removal.
• Angles vary with wood density for optimal cutting.

Important Notes

• Use mechanical press and brazing fixture (Fig. 7) for blade maintenance.
• Final test values should be rounded per IS 2-1960 for compliance.

flowchart LR
    A[Wood Density] -->|<0.6| B[Use 25° / 15° Hook Angle]
    A -->|>0.6| C[Use 15° / 10° Hook Angle]
    B --> D[Select Thickness & Pitch from Table]
    C --> D
    D --> E[Set Gullet Depth accordingly]

This ensures correct blade geometry for efficient cutting and durability.

IS 9576: Terminology & Key Specifications for Band Saw Blades

Key Definitions (Clause 2.0)

• Clearance Angle: The angle between the saw tooth face and the workpiece, ensuring smooth cutting.
• Kerf Width (Theoretical): The width of the cut made by the saw blade.
• Sharpness Angle: The angle at the tip of the saw tooth affecting cutting efficiency.

Refer to IS 707-1976 and Fig. 1 for detailed tooth geometry.

Teeth Specification (Clause 6.1.4, Table 1)

• Hook Angle varies with wood density:
  • Low to Medium Density (Sp. Gr. < 0.6): 20° - 25°
  • Medium to High Density (Sp. Gr. > 0.6): 10° - 15°

Rounding Off (General Clause)

• Follow IS 2-1960 for rounding test results.
• Retain significant figures consistent with specified values.

flowchart LR
    A[Saw Tooth Geometry] --> B[Clearance Angle]
    A --> C[Kerf Width]
    A --> D[Sharpness Angle]
    B --> E[Ensures smooth cutting]
    C --> F[Width of cut]
    D -->

Types of Sawing Machines (IS 9576: Clause 4.3 & 4.3.4)

1. Circular Saw Machine:

• Frame: Heavy casting to hold all parts rigidly.
• Table: Cast iron with a central slot for blade movement and a mitre gauge slot.
• Arbor Shaft: Mild steel shaft rotating on bearings, driven by belt and pulleys.
• Collars: Two cast iron collars hold the blade in position on the arbor.
• Pulleys: Two cast iron pulleys transmit power from motor to arbor.
• Saw Blade: Circular steel plate with teeth, mounted on threaded arbor end and secured by collars and nut.

Key Specifications for Band Saw Blades (Clause 6.1.4, Table 1)

• Hook Angle: Varies with wood density; lower angles for denser wood.
• Pitch: Distance between teeth; larger pitch for softer wood.
• Gullet Depth: Space between teeth to clear chips.

Summary Diagram: Circular Saw Components

graph LR
A[Frame] --> B[Table]
B --> C[Arbor Shaft]
C --> D[Collars]
D --> E[Saw Blade]
C --> F[Pulleys]
F --> G[Motor]

Note: For detailed saw blade maintenance and saw doctoring, refer to Clause 6 of IS 957

IS 9576: Process of Conversion - Key Points

• Definition (Clause 2.1):
  Conversion is the process of sawing logs and flitches into smaller sections for further processing.

• Stages of Conversion (Clause 4.1):

  1. Break down of logs - Initial cutting of logs into manageable sections.
  2. Further conversion - Subsequent cutting of these sections into desired sizes.

• Quality Considerations (Clause 5.6):

  • Avoid logs with excessive taper, flutes, and shakes as they cause difficulties and increase wastage during conversion.
  • Conversion should be done judiciously to minimize wastage and maintain quality.

Typical Conversion Workflow

flowchart TD
    A[Log] --> B[Break down of logs]
    B --> C[Further conversion]
    C --> D[Final sections for use]

Practical Tips:

• Select logs with minimal taper and defects.
• Use optimized sawing patterns to reduce waste.
• Monitor moisture content for ease of conversion.

No explicit formulas or tables are provided in IS 9576 for conversion, but the emphasis is on quality control and efficient sawing processes.

IS 9576: Guide for Mill Sawing of Timber — Key Points

Though IS 9576 lacks explicit formulas, it emphasizes efficient sawing methods and timber handling to minimize wastage and improve quality.

Methods of Sawing:

• Plain Sawing (Flat Sawing): Logs are cut tangentially to the growth rings, producing varied grain patterns.
• Quarter Sawing: Logs are quartered and sawn radially, yielding more stable timber with vertical grain.
• Rift Sawing: Similar to quarter sawing but with more uniform grain, ideal for furniture.

Timber Handling Recommendations:

• Use proper log positioning to reduce defects.
• Employ sharp, well-maintained saw blades to ensure clean cuts.
• Handle timber carefully post-sawing to avoid damage and moisture absorption.

General Guidelines:

• Select sawing method based on timber species and end-use.
• Minimize kerf width to reduce wastage.
• Maintain saw speed and feed rate optimized per species hardness.

flowchart LR
    A[Log] --> B{Select Sawing Method}
    B --> C[Plain Sawing]
    B --> D[Quarter Sawing]
    B --> E[Rift Sawing]
    C --> F[Varied Grain, More Wastage]
    D --> G[Stable Timber, Less Wastage]
    E --> H[Uniform Grain, Premium Quality]

For detailed machine specifications and operational parameters, refer to machine manufacturer manuals and species-specific guidelines.

IS 9576: Maintenance of Machines and Saw Blades – Key Specifications

1. Teeth Specifications for Band Saw Blades (Clause 6.1.4, Table 1)

2. Sharpening Procedure (Clause 6.1.4.5)

• Use a saw sharpening machine with:
  • Platform supporting wheels for different blade lengths.
  • Adjustable grinder with angle control for gulleting.
  • Pusher mechanism to rotate blade tooth-by-tooth, adjustable by eccentricity based on pitch.

3. Maintenance Tips

• Joint blades before sharpening.
• Maintain correct hook and clearance angles for wood density.
• Regularly check gullet depth and pitch for optimal cutting.

flowchart LR
    A[Blade Jointing] --> B[Saw Sharpening Machine]
    B --> C[Adjust Grinder Angle]
    B --> D[Rotate Blade Tooth-by-Tooth]
    C --> E[Set Hook & Clearance Angles]
    D --> E
    E --> F[Sharpen

IS 9576: Saw Blade Sharpening and Setting Key Points

1. Teeth Specification (Table 1, Clause 6.1.4)

• Thickness, pitch, and gullet depth vary with saw width (10, 12.5, 15 cm).
• Clearance angle depends on wood density for efficient cutting.

2. Sharpening (Clause 6.1.4.5)

• Use a saw sharpening machine with:
  • Adjustable platform for different blade lengths.
  • Grinder with adjustable angle for gulleting.
  • Pusher mechanism to rotate blade one tooth per stroke (eccentricity adjusted per pitch).
• Teeth must be jointed and sharpened so all share equal cutting load.

3. Saw Doctoring (Clause 6.1.4)

• Operations include setting, leveling, tensioning, and sharpening.
• Proper set avoids timber binding and excessive kerf (waste).
• Saw body must be free from lumps and properly tensioned for speed.

flowchart TD
    A[Start: Saw Blade] --> B[Jointing Teeth]
    B --> C[Sharpening with Adjustable Grinder]
    C --> D[Setting Teeth for Proper Clearance]
    D --> E[Leveling and Tensioning Blade]
    E --> F[Ready for Cutting]

Summary: Follow Table 1 for tooth specs, use proper sharpening machines with angle and pitch adjustments, and ensure correct setting and tensioning for optimal saw performance.

IS 9576: Safety and Operational Guidelines for Band Saw Blades

Key Specifications (Clause 6.1.4, Table 1)

Safety & Operational Guidelines

• Hook/Clearance Angle: Adjust according to wood density for efficient cutting and reduced blade wear.
• Pitch & Gullet Depth: Larger pitch and deeper gullets for softer woods; smaller pitch for harder woods.
• Blade Thickness: Increase thickness with saw width for stability.
• Maintenance: Regular inspection and brazing (see Fig. 7 Brazing Fixture) ensure blade integrity.

Summary Formula for Hook Angle Selection:

[ \text{Hook Angle} = \begin{cases} 25^\circ \text{ to } 15^\circ & \text{for low to medium density wood (Sd. Sp. Gr. < 0.6)} \ 15^\circ \text{ to } 10^\circ & \text{for medium to high density wood (Sd. Sp. Gr. > 0.6)} \end{cases} ]

graph TD
A[Wood Density] -->|< 0.6| B[Use

Quality Considerations in Sawing (IS 9576: Guide for Mill Sawing of Timber)

Key Specifications for Band Saw Blades (Clause 6.1.4, Table 1)

Quality Control Tips:

• Hook Clearance Angle: Adjust according to timber density for smooth cutting.
• Pitch & Gullet Depth: Proper sizing prevents clogging and improves blade life.
• Blade Thickness: Must suit saw width and wood type for precision.

Maintenance:

• Regular sharpening and brazing (using fixtures like the Mechanical Press, Fig. 7) maintain blade quality.

flowchart LR
    A[Timber Density] --> B{Select Hook Angle}
    B -->|Low to Medium| C[20° / 15°]
    B -->|Medium to High| D[15° / 10°]
    C --> E[Choose Saw Width & Tooth Specs]
    D --> E
    E --> F[Adjust Pitch & Gullet Depth]
    F --> G[Perform Sawing]
    G --> H[Inspect Blade & Maintain]

This ensures efficient, high-quality sawing per IS

IS 9576: Annexures and Figures Key Details

1. Table 1: Specification for Band Saw Blade Teeth (Clause 6.1.4)

• Hook Clearance Angle varies by wood density:
  • Low to Medium Density (<0.6 Sp. Gr.): 20° and 15°
  • Medium to Greater Density (>0.6 Sp. Gr.): 15° and 10°

2. Key Definitions (Fig. 1):

• Clearance Angle: Angle between the tooth face and the workpiece to reduce friction.
• Kerf Width: The theoretical width of the cut made by the saw blade.
• Sharpness Angle: Angle defining the cutting edge sharpness.

3. Figures:

• Fig. 1: Diagram of saw tooth showing terms and angles.
• Fig. 7: Brazing fixture for blade maintenance.

Summary:

• Use Table 1 for selecting blade tooth dimensions based on saw width and wood density.
• Adjust hook clearance angles according to wood density for optimal cutting and blade life.
• Refer to Fig. 1 for tooth geometry understanding.

flowchart LR
    A[Wood Density] --> B{<0.6 or >0