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Main » 2013 » November » 25 » Wood Panels and Humidity Charlotte Olympia Thanksgiving
6:01 AM Wood Panels and Humidity Charlotte Olympia Thanksgiving |
Wood Panels and Humidity Coping with wood movement All wood workers need to be
aware of wood movement when building furniture projects. Failure to consider
this important factor can cause wood panels to crack or split. My high school
biology teacher compared the structure of a piece of wood with a bundle of
straws. The straws represent the cells and capillaries of the wood. When a tree
is growing water and food are transferred up through the cells and are carried
throughout the tree.Once a tree is fell the free water in the wood is lost
rather quickly but the bound water trapped in the straw like cell is slower to
dissipate Charlotte
Olympia Black Friday. As the level of bound water is reduced these straw
like cells get narrower in diameter but maintain their length. This is the
fundamental reason that wood expands and contracts across its width but has
almost no expansion length wise.When working with wood it is very important to
allow the wood to expand and contract with changes in humidity. As humidity
rises the straw like cells expand in diameter with the opposite effect occurring
as the relative humidity falls. Ways to accommodate expansionLets use a cutting
board for the first example Charlotte Olympia
Thanksgiving. A solid wood cutting board with a bread board edge secured
with a tongue and groove joint. One edge has the bread board edge secured on
both ends with a dowel through the tongue The other bread board edge is secured
with the same tongue and groove joint but this end only has a dowel in the
center of the piece. The end secured with two dowels will develop a crack in the
main panel. Since the length of the edge piece doesn't change having it fixed
across the width of the main panel from expanding. Alternatively, the opposite
end of the cutting board is only fixed in the center. The main panel is free to
expand and contract towards the ends. The only visual difference would be that
the ends of the edge piece are no longer flush with the edge of the main panel.
The second example uses a large glued up panel such as a table top. If the table
top was fixed to the rails across the width of the panel the rise and fall of
humidity would undoudtable cause the panel to split.The best method to overcome
this is use wooden clip to attach the two pieces. A 1/4" x 1/4" dado milled on
the inside upper edge of the rails. This accepts a wooden clip that fits into
the dado and is then secures to the underside of the table top. This will
security hold the top hold the top onto the rails without restricting the
expansion and contraction of the large panel. Without this the table top would
slowly start to open up. In general anytime you are fixing one piece of stock
across a large glued up panel measures need to be taken to allow the panel to
move. Remember that it will expand across its width but not its length. Using
one of the two methods mentioned above you will be able to prevent your glued up
panels from splitting. huanghaiyan701 More information please visit:
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www.charlotteolympiaweb.com
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