Thursday, October 1, 2009
Day 2 Continued
Hardwood Comes from deciduous trees that drop their leaves every year.
broad Leaves, enclosed nuts, higher density, Mostly deciduous
Examples of Trees: Aspen, Poplar, Birch, Elm, Maple.
Applications: used for furniture but less frequently than softwood
Density: Higher density, which means the wood is harder
Found Where: Hardwood is found all around the world in the north and the Tropics
Softwood Comes from Trees that are conifer and have needless, which they do not normally lose each year
Leaves are less dense and less durable, High aslorific values, evergreen Cost: Less expensive Applications: Widely used as a structure for building, and furniture. Density: Lower density and most varieties are softer than hardwood. Found: In the northern hemisphere
Note: Even though Woodworker use more hardwood manufactured furniture is usually Softwood. Fine furniture is usually hardwood.
4/4 equals 1 inch
5/4 equals 1 and 1/4 inch
6/4 equals 1 and 1/2 inch
7/4 equals 1 and 3/4 inch
8/4 equals 2 inches
Bill of Materials
When we do our clock project we will complete a bill of materials. This will be used to help us calculate the amount of wood we will need to buy for our clock project. The measurement we will use will be board feet. Many will use this bill of materials to make a cut list, which determines what board we use to cut each of the project parts.
Calculating board feet uses a formula
thickness x length x width/divided by 144
all measurements are in inches, the 144 is the number of cubic inches in one board foot.
We will be adding about 20 to 30 percent to the number we get to account for any waste.
Our method also drops all fractions to the next full inch, so 4.5 inches is 5 in our formula.
A word about measurement and fractions
One area that has the potential for confusing new woodworking students (this student included) are fractions and what they mean. During the course we will be discussing how to understand and use fractions as our friend. (This I have to see, I am thinking I should have been born in England where they use the decimal system)
The modern moisture meter has a large Digital LCD readout. the range is 0 to 40 percent, with a plus or minus 1 percent. Use the moisture meter when purchasing different boards to make sure they are close in moisture content, or one could let them dry in the shop until they are closer to the same content. In either case we will give our purchase of new wood time to adapt to conditions in our shop by checking the moisture meter as they adapt to there new environment.
Different Types of Woodworking Joinery
For this common and simple joint the end of one piece of wood is simply placed against the adjoining piece, forming a right angle. The two pieces can be fastened with screws, glued or dry dowels, or sometimes staples. see illustration 1
Ina cross-lapped joint a rectangular channel is removed from both of the pieces of wood in the joint. The boards then interlock at right angles. The channels re cut to a depth that allows this joint to appear completely flush when properly constructed. The cross lapped joint is similar to the rabbet joint and uses the same general technique. see illustration 2
A dado is an adjustable blade used to create this simple joinery. Dado joints connect tow pieces of wood by cutting a groove (with a dado blade) in one piece of wood which is equal to the height and width of the second piece. Dado joints are often used to insert a drawer bottom. the dado joint is similar to the traditional rabbet joint and uses the same general technique. see illustration 3
This form of locking joint looks similar to an outspread bird’s tail. thus the name. One board has a flared extension which fits into matching flared cavity in the adjoining board. Use of a single dovetail is called a French Dovetail and multiple joints in the same corner are called and English Dovetail. Better drawers often use a multi-dovetail because of it’s strong holding power. see illustration 4
Two or more small holes are bored into two pieces of wood. The boards are then joined by inserting small round pegs into the holes of one board. The dowels are then inserted into the other board and the joint is glued. see illustration 5
Two pieces of wood are cut at 45 degree angle and the two beveled edges are placed end to end. They are usually connected with glue, nails or screws. see illustration 6
Mortise and Tenon
In this method of joinery, the mortised part has a recess cut into it. The tenoned part has a protrusion that matches the recess in the mortise. The pieces are sometimes glued together to strengthen the connections and sometimes a hole is drilled through both the mortise and the tenon and dowel inserted to further strengthen the joint. see illustration 7
for this joint, a groove is cut into one piece and a section of the other board fits into this groove. Similar to the lap but joint, only one board is cut.
Grooves are cut in ends of each piece of wood so that they will line up when joined. A small strip of wood called a spline is inserted into each groove to hold the two pieces of wood.
Tongue and Groove
Two pieces are joined by cutting and edge or shape on one piece of wood which fits into a mirror groove cut int he other board. The tongue and groove must be cut in such a way that the boards fit together tightly without gaps, and the tow surfaces remain flush. see illustration 8.
-- Woodworker in Progress, Oceanside CA