Lesson 4 - Log Scaling Flashcards
(15 cards)
What is scaling
involves the measurement of log volumes
What is the most precise way to measure scaling
Volume is the most precise method for obtaining an indication of quantity in scaling
what is log grading
consists of assigning logs to particular classes
What is a scaling stick and what is it used for
instrument used for measuring the diameter (or radius) of a log
What is a loggers tape and what is it used for
a metal measuring tape wound onto an open-edged metal spool, used to measure log length
How do you calculate log volumes without a calculator?
using a scaling stick and the scaling stick table
- go to the column with the top radius, then go up the column until you reach the length (max 12m), write that number down
- repeat for the bottom radius, write that number down
- add the numbers together, divide the sum by 1000
what is the scaling stick factor
one associated with each radius class, factor is the volume in dm3 of a 1m long cylinder of that radius
principle use of the factor is for reducing the dimensions of logs to account for the volume of decay present
what is sap rot and heart rot
sap rot is the rot around the outside portion of the log
- the volume of firmwood when sap rot is present is simply the volume of the solid central core of the log
heart rot is decay that is present as a central core in the log and is surrounded by a solid shell of wood
How measure volume with when heart rot is present
If the heart rot extends all the way through then the length is the same, but we now include a a rot vector to our calculation (dimensions of the rot)
find the volume of both then subtract the rot volume from the log volume to get the exact firmwood volume
What is radii reduction and what are the steps?
this is reducing the radii to find the log volume
1. compute the net factor for each end of the log
2. find the radii which most closely corresponds to each of these factors
(ex. net top factor = factor for RT = 19cm which is: 113
- factor for RDT = 8 cm which is: 20
= 93
radii that most closely corresponds to a factor of 93 is 17cm)
3. rewrite the dimensions for the reduced volume using your new information
What is length reduction and what are the steps?
consist of reducing length
- compute the average rot factor (average the factors found for top and bottom)
- compute the average log factor (average the factors found for top and bottom)
- compute the ratio average rot factor to average log factor and multiply by log length
- subtract this quantity from the original log length to obtain the reduced log length
reduced length = L - (average rot factor/average log factor) x L
the reduced length found becomes the new length in the reduced dimensions (radii stay the same since a reduced length)
What to do if the heart rot does not extend all the way through?
use length reduction
replace average rot factor with rot factor and L with LD
what is butt rot and how is it calculated
butt rot is heart rot in the butt log of a tree, if it extends through the log it is treated identically to heart rot,
if the rot is visible only at one end assume it is a conical shape, use the reduced length equation for heart rot that does not extend through the log and divide LD by 3
What is ring rot and how is it calculated
rot that looks like a ring in the cross section
three radii need to be defined
R1 = total log radius
R2 = denoting the radius out to the outer edge of the ring of rot
R3 = denoting the radius out to the inner edge of the ring of rot
if it extends through the log either radii reduction or length reduction can be used
Revised factor = R1 Factor - R2 Factor + R3 Factor
What is log grading
process of assigning logs to various classes on the basis of surface characteristics and the amount of defects present, the grade of a log should reflect the quality of the log in terms of possible end use, and hence the log’s value
