PDF Publication Title:
Text from PDF Page: 018
RAYS. Keen-eyed observers will have noticed that there are light-colored stripes running perpendicular to the growth rings in Figures 8 and 9. These stripes are actually groups of cells called rays. Rays are groups of storage and conduction cells that run perpendicular to the fibers and the pores, outwards from the direction of the pith towards the bark. See Figure 10, where these earlier figures are repeated (with the rays labelled this time). RAYS RAYS RAYS Figure 10. A few of the rays are labelled on the end grain for each of these micrographs (of hard maple, red oak and white oak, shown above from left to right). The rays in the oaks are significantly wider than those in maple. These broad rays help to distinguish the oaks from other species. The size of each ray will vary, depending on how many individual cells are grouped into the ray. Sometimes the width of the rays can be used to help identify the species. Broad rays are noticeable to the naked eye and when combined with a ring porous structure positively identify lumber as coming from one of the oak species (refer to the oak micrographs in Figure 10). Ray cells run parallel to each other, and the number of ray cells that are stacked one on top of another will affect the ray height, while the number of rows of ray cells that run alongside each other will affect the ray width that is visible on the end grain. Ray heights and ray widths vary among species, so the rays will be easier to see in some species than in others. In some species there is a mix of both wide and narrow rays; in other words, all rays in a piece of wood are not necessarily going to look the same. Shrinkage around the rays often initiates localized defects called surface checks. Large, wide rays act like stress concentrators more than small, narrow rays, so species with broad rays (such as the oaks, beech and sycamore) are much more prone to checking than species with narrow rays (like yellow-poplar or maple). THE CROSS-SECTION AND THE SIDE GRAIN. You’ve probably noticed how the growth rings look different depending on where you look at a piece of lumber. Growth rings look a lot more like rings on the cross section than they do on the side grain. The appearance of the growth rings on the surface underneath the bark doesn’t resemble the growth ring appearance on the side of a pie-shaped wedge, either – how the growth rings look on a board surface depends on how the tree is sawn. Labels have been assigned to the different surfaces of a piece of wood so everyone can use the same terminology when we’re discussing how lumber looks or behaves during drying. The “cross section” surface is the same as the end of a log or the top of a stump; it’s sometimes referred to as the “transverse” surface. The “radial” and “tangential” names are related to geometry. The radius is a line extending from the center of a circle to its perimeter, like a bicycle spoke. Just as there are many spokes on a bicycle wheel, there can be an infinite number 18PDF Image | HARDWOOD DRY KILN OPERATION A MANUAL FOR OPERATORS OF SMALL DRY KILNS
PDF Search Title:
HARDWOOD DRY KILN OPERATION A MANUAL FOR OPERATORS OF SMALL DRY KILNSOriginal File Name Searched:
FOR128.pdfDIY PDF Search: Google It | Yahoo | Bing
5,000 BF Shipping Container Lumber Dry Kiln For Quality Lumber The 5,000 BF container kiln consists of one 40 foot high-cube aluminum shipping container... More Info
Shipping Container Lumber Dry Kilns by Global Energy Global Energy designed and developed the container kiln back in 1991. The purpose is to give access to portable sawmill owners, furniture makers, and small business the value added profit of dry kiln lumber and quality hardwoods... More Info
Vacuum Kiln Conversion Kit for Lumber and Wood Dry Kilns Convert your existing conventional dry kiln into a fast drying vacuum kiln. Similar to vacuum bagging in the boat building and aircraft industry, we have come up with a proprietary process which allows you to build a very simple vacuum kiln at a fraction of the price, and without the intensive conventional metal chamber structure... More Info
Vacuum Pump Cart System for Bagging Clamping Wood Drying and more Vacuum Cart with 2HP Pump and Dual Pistons with multiple multiplex vacuum ports and liquid reservoir... More Info
Vacuum Bagging Basics Vacuum bagging is a method of clamping, which has traditionally been used in the composites industry, but can also be used for vacuum drying materials, including wood products... More Info
| CONTACT TEL: 608-238-6001 Email: greg@globalmicroturbine.com | RSS | AMP |