General Woodworking Units 2 & 3

Wood Properties

Mr. Bartels

Monadnock Regional H.S.

Wood Properties

Crown: – Photosynthesis occurs here (CO2 + H2O + SUN= Sugar + O2– Provides some raw materials (for wafer /particle board etc.)

Trunk: – Supports the crown -Provides us with lumber

Roots:– Anchor the tree -Absorb Water & Minerals– Prevent Erosion

Crown

Roots

Trunk

Parts of the Trunk–Outer Bark: Protection against Fire, insects & Disease.–Inner Bark: (Called Bast or Phloem) Cells carry food (SAP) made in leaves downward.–Cambium Layer: 2 cells wide, allows the tree to increase in girth. New wood forms on inside(Xylem); New bark on outside(Phloem).–Sapwood: Newer, lighter colored, Springy growing part of the wood which carries sap from roots upward.–Heartwood: Older, less alive, darker colored part of the wood. Was sap wood. More Ridged.–Pith: soft, Center of the tree. Allows for vertical growth. Considered a defect.–Medullary Ray Cells: Channels which carry food/sap horizontally.–Annual Rings: New Ring Each Year

Springwood: Lighter colored, less dense part of each ring (Spring growth).Summerwood: Darker colored, more dense part of each ring (Summer growth).

Wood Classifications

Softwoods– Conifers: Cone or needle bearing trees

Examples: Spruce, Fir, Hemlock

Hardwoods– Deciduous: Broad leaf trees - shed leaves in winter– Examples: Oak, Birch, Beech

Sawing Methods

Plain Sawing: •Most common, easiest method•Called “Flat Grained” on softwoods•Produces “U Shaped” face grain•Least expensive method•Wood warps the most

Quarter Sawing:• Called edge or Vertical

Grained on softwoods• Produces straight

almost parallel face grain

• More Expensive • More difficult, log is 1st

“quartered”, then sawed tangent to rings (65-90 degree angle)

Rift Sawing:•Logs “quartered” then sawed at a 35-65 degree angle•Yields more, wider boards with pronounced rays•Most expensive

Surface Condition: •Rough lumber: straight off the saw blade•Dressed: Surfaces planed S1S, S2S or S4S

•“NOMINAL SIZE”= Before Planing : “2 X 4”•“ACTUAL SIZE”= After Planing: “1 1/2” x 3 1/2”

Drying / Seasoning Lumber Moisture Content : Percentage of moisture to

wood cells Green Lumber (GR):

– Can contain 30-300% moisture content– a green 2 X 4 X 8 can have up to 3 gallons of h20

Air Dried (AD):– One month to a year. yields a 12-15% MC (in some

species)

Kiln Dried (KD):– One to four weeks yields a 10% or less MC

Lumber Grades

Softwoods Best& Most Expensive Grade

– Select Grade A: “Clear”– Select Grade B Few Knots– Select Grade C More Knots– Select Grade D Most Knots

2nd Best Grade- Less Expensive– Common # 1-5– House Trim is Common #2

Hardwoods Best& Most Expensive Grade

– F.A.S. (Firsts & Seconds) 85-90% clear 2nd Best, Less Expensive Grade

– Select: Good for Furniture, At least 1 good face 3rd & 4th best Grades

– Common # 1 & #2 : 66% clear, narrow boards Grading done from worst side of board Lumber sold in “Random widths & Lengths”

Purchasing Lumber

Linear or “Running” Foot– Price per foot of material– Molding, dowel

Square Foot/age– Sheet Goods: Plywood, Wafer Bd., Paneling,

Particle Bd.– Calculate Area (Length X Width)

The Board Foot– How Lumber is sold– Volume measurement – 1 Board Foot = 1” X 12” X 12” – Formulas For Board Foot Calculation– “C”=100 Bd. Ft., “M”= 1000 Bd. Ft.– All Fractions get rounded UP to next inch

for calculation– Must Carry out answer 2 decimal places– A) Use If LENGTH is given in INCHES

T” X W” X L”144

– B) Use If LENGTH is given in FEET

T” X W” X L’12

Sample Board Foot Problem

Example: 2” X 4” X 8’Step 1

2 X 4 X 812

Step 28 X 8

12Step 3

6412

12 .64.00

12 5 .64.0060.00 4.00

12 5 .364.0060.00 40 36 4

12 5 .364.0060.00 40 36 4

12 5 .3364.0060.00 40 36 4 36 4

Answer= 5.33 BD. FT.

Sample Board Foot Problem

Example: 3/4” X 4” X 16’’Step 1

1 X 4 X 16144

Step 24 X 16

144Step 3

64144

144 .64.00

144 .4640576 640

Answer= .44 BD. FT.

144 .44640576 640 576 64

Putting It All Together…..A Complete Lumber Order

Should Include :– Species– Lumber Grade– Sawing Method– Amount (Board Footage)– Size Pieces (Nominal T x W x L )– Surface Condition

(Rough/Dressed s2s, S1s, S4S)– Drying Method