Circular Saw

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Circular Saw

• Not used as headrig in softwood sawmills
• Less throughput than band saw
• Blades rigid, saw kerf is 1/4 to 3/8
• Relatively wide saw kerf high waste factor

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Circular saw
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Circular saw video
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Waste Factor Comparison
Band Saw
Circular saw
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Sawmill generic overview
Log yard
Bucking
Debarker
Headrig
Cants
Side boards
Gang Saw
Trimmer
Edger
Sorter, Stacker
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Gang Sawing
cant
gang saw blades
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Gang saws

• Fixed, oscillating blades
• Little flexibility
• Intermediate kerf
• Single pass
• High throughput

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Gang saws
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Log breakdown patterns
1. live sawing 2. cant
sawing 3. sawing for grade
4 5. sawing for edge grain
6. dimension lumber
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(No Transcript)
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Optimization software
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Scanning of the log to optimize the yield
Bottom profile
Mid-length profile
1x4 14 2
Top profile
2x4 16 2
2x4 16 2
Product mix selected
2x4 16 2
2x4 16 2
2x4 16 2
1x4 16 2
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Sawmill optimization
(Halco Software Systems)
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Sawmill generic overview
Log yard
Bucking
Debarker
Headrig
Cants
Side boards
Gang Saw
Trimmer
Edger
Sorter, Stacker
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Wane
http//www.wdscapps.caf.wvu.edu/lumberrtk/
http//www.decks.com/article197.aspx
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6. Edger

• The edger will rip the rough sawn board to width
  and remove the wane and other defects. Uses
  circular saws.

wane
wane
saw cuts
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Edger optimizer
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7. Lumber Grading - Trimming
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Lumber Grading

• Different grades systems for hardwoods and
  softwoods
• Different grades depend mainly on
• natural defects
• size, number and location of knots
• size, location and type of stain or rot
• amount of wane
• machine defects
• skip
• snipe

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Lumber Grading
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Trimming

• The trim saw is used to cut the boards to length

Lumber is trimmed to lengths of 2 foot
multiples. Uses circular saws.
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Trimming
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Multi-saw trimmer
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Sawmill generic overview
Log yard
Bucking
Debarker
Headrig
Cants
Side boards
Gang Saw
Trimmer
Edger
Sorter, Stacker
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The Green Chain
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Descrambler
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J-bar sorting

• The lumber is scanned and sorted into bins
  depending on
• species, grade, dimensions

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Multiple sort bins
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Stacking
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Drying kilns
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Reasons for drying lumber

• Increase strength of lumber
• Reduces later dimensional changes
• Increases decay/insect resistance
• Decreases weight of lumber

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Drying
Sticker
Lumber

• Drying factors
• Temperature
• Relative humidity
• Air circulation

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Planermill
Planermill
Kilns
Sawmill
Logyard
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Planer
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Planer
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Planer
4 knifes per planer head
24 knifes per planer head
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Waste Management

• Trim ends
• Chips
• Sawdust
• Planer shavings
• Bark
• Hog fuel