How Much Lumber is on this Log Deck? How much money this load is worth depends upon your answer. Let’s assume the trailer is 40’ long.

Introduction to Log Scaling In the example of the load of logs, we can’t come up with a common answer. How many boards can we make out of one of these logs? How many can we make out of the whole log deck? We need a unit of measurement that we can use that will be consistent from tree to log to board

In the forest industry we use a unit of measurement called a “board foot” (BF) We will use this unit for “Cruising” standing trees or “Scaling” logs. We will use BF to determine the volume of “logs”. We can use BF to determine the volume of finished boards. A “board foot is equal to a board that is 12”wide X 12”long X 1” thick or 144 cubic inches.

In forest management, we need to estimate the value of both standing trees and logs that we ship to the mill. This value is based on the quality of the trees or logs. Quality refers to knots vs. clear wood. Value is also based upon the species i.e. Pine, Cedar or Fir The value also increases with the size or volume of the tree/log in board feet because we can make more boards out of it

What is the Difference Between Log Scaling and Timber Cruising? Timber Cruising is estimating the volume in board feet of standing trees, live or dead. We would need to know the height, diameter, and species of the tree. We then look it up on the appropriate chart or table to determine the volume of the tree in board feet. When timber cruising we are estimating how many finished boards we can get at the mill from the standing tree. We use the same volume bdft. We need to determine the height usually with a tool called a clinometer. The diameter is also needed. Using a Biltmore stick on the left and a diameter tape on the right. We also need to know the species of the tree. All of this information is recorded for each tree that is cruised. Any defects such as scars, rot or fungus that can be seen are noted and deducted from the total volume that is determined from a table.

Scaling Log scaling is determining the volume in board feet of down trees and logs cut to length. We need to know the length, diameter, and species of the log. We then either look it up on a table/chart or on the scaling stick. These logs are scattered out on the rail logs underneath so that they scaler can easily see the logs and measure them. Before they go to the log deck behind him. These are second growth Douglas fir logs as can be seen by the bark and the pink color of the heart wood. It is easier for the scaler to see certain defects than it is for the timber cruiser.

Log Scaling Equipment Loggers tape for measuring the length of the log Scaling stick, tape measure, or folding rule for measuring the diameter of the log I would have these tools out so that they can manipulate them and pass them around. You could have them compare a value on the stick with a value on the table as you move through the program. A data logger is just a hand held computer that has software for recording the information and using formulas to look up on a table a give the volume of the log and allow the scaler to deduct defect. The information can then be downloaded in the office and put into spread sheets and reports. The modern scaler would not use a scaling stick except as a measuring stick. Data sheet or data logger for recording data

Scribner Log Rule Provides how many 1” thick boards can be made from a log using the volume of a cylinder projected the length of the log from the small end. When Scribner made the log rule he actually drew out the boards with the kerf on a circle of the small end of the log. Kerf = the material removed by the saw blade. At the turn of the last century the blades were ¼” thick. Modern blades are much thinner. The log scaling rules do not account for potential product (boards) that could be made from the tapered portion of the log. Volume is only calculated from the straight sided scaling cylinder that starts on the small end of the log. Modern manufacturing (Milling) methods allow the mill to actually get more product out of a sound log with no defect than it scales.

Diameter Diameter is measured inside bark at the small end. Two measurements are taken at right angles, with the short axis measured first and fractions of an inch are dropped. The resulting values are averaged and any fraction is dropped. This final result is the scaling diameter. There are many different log rules. Even the Scribner log rule has many different variations on the west coast of the U.S. there is the west side rule (coastal) and the east side rule ( east of the cascade mtns.) and others. Other common log rules are the Doyle and the International ¼” rule. This is what makes it difficult when teaching log scaling is that rules all developed across the U.S. and around the world. The East side Scribner is common for Washington, Oregon, and California in the interior and serve as a good basis for learning about log scaling.

When making diameter measurements, always remember the following:   ·        Diameters are measured on the smallest point on the log. ·        Measurements are taken inside the bark. ·        Measure through the true center of the log. ·        Disregard all abnormal bumps and depressions (such as knot clusters, swells, or broken ends). 12"+ 15" = 27" 27"2 = 13 ½" Drop the final ½" Scaling diameter = 13 inches   Any thing can be used to measure the diameter. The stick works well still because it is stiff and you don’t have to bend over a lot to use it. If a tape measure is used a 1” wide tape is good because of it’s stiffness.

Log length Acceptable log lengths are generally in two-foot multiples, plus 6” for trim allowance per segment. The Minimum length is 8’ The maximum scaling length for a single segment log is 20’ plus trim. On a butt-cut, measure from the shortest side on the small end to the point where the scaling cylinder emerges on the butt. Second cut logs are measured from short side to short side. When measuring length always measure from the edge closest to the center or shortest length of the log. You can’t make boards out of wood that’s not there.

Let’s Scale Some Logs #1 small end diameter 15” length 12’ 4” #2 small end dia. 13” length 14’ 5” #3 small end dia. 18” length 18’ 6” #4 small end dia. 14”X 16” length 20’ #5 small end dia. 21”X 24” length 16’ Use either a scaling stick or the chart to determine the gross scale for each log in board feet Use either the scribner log tables or scaling sticks. The sheets are easier at first. Walk them thru the 1st couple of problems and move about the room checking for understanding and giving assistance where needed. There is a work sheet attached that they can use. The last three logs can be used as a homework assignment or scored assessment. The next three slides are the three pages need to scale the logs listed. They can be used to help get thru the 1st couple of logs or skipped. The answers as determined from the printed table are on the slide after the table slides they will come up one at a time.

#1 small end diameter 15” length 12’ 4” Gross Scale = 110 board feet (bdft.) #2 small end dia. 13” length 14’ 5” Gross Scale = 80 bdft. #3 small end dia. 18” length 18’ 6” Gross Scale = 240 bdft. #4 small end dia. 14”X 16” (15”) length 20’ Gross Scale = 180 bdft. #5 small end dia. 21”X 24” (22”) length 16’ Gross Scale = 330 bdft.