Cedar Log Yield

dad2nine · July 14, 2006, 11:50:38 PM

I'm having a heck of a time trying to accurately calculate cedar log yield. With all the face defect, taper and heart rot in the bigger logs, cedar is really throwing me for a loop.

Is there a formula for calculating cedar log BF yield?

Thanks much...

Furby · July 14, 2006, 11:52:36 PM

Guessing you want the cedar scale.
Um, where is that........

Try these:
https://forestryforum.com/board/index.php?topic=5399.msg73621#msg73621
https://forestryforum.com/board/index.php?topic=11695.msg163397#msg163397
https://forestryforum.com/board/index.php?topic=10112.msg138100#msg138100
https://forestryforum.com/board/index.php?topic=2645.msg35059#msg35059

Jeff · July 15, 2006, 12:19:15 AM

The scales do not take into account face defects and heart rot. That's an inpossible infinite that can not be formulated into a scale. You have to know a whole lot about your local growing conditions and whether a paticular stand is on a good site or poor site and history of past cedar harvests to even consider guessing on such variables on standing trees. You still have to weigh in possibilities of local instances of butt rot fungi.

Taper can be calculated if you know the correct form class for your growing region.

extrapolate85 · July 15, 2006, 11:11:26 PM

For a ball park estimate: ((diameter in inches +1) squared) x length of log in feet x 0.005454 x 8 = approximate BF of lumber. reduce diameter to account for surface defects; and reduce length to account for lineal defects. This is an over simplified formula but should give you in the ball park. Example:

Log is 12' long and 13" in diameter on the small end. It has some sap rot that affects the outer inch of the circumference, so diameter is reduced to 11": log also has a crook which will cause the loss of 1/4th of 4" so length is reduced to 11': (11+1)^2 x 11 x 0.005454 x 8 = 69.1 BF.

The "8" constant from the formula assumes a 10" - 15" small end diameter; if less than 10" use a constant of 7, if small-end diameter is greater than 15 use a constant of 8.5. This formula approach can be fine tuned to many of the variables such as defects, taper, product made and sawing efficiency.

Cedarman · July 16, 2006, 08:26:28 PM

Cedar logs can grow round, oval, squarish, rectanglish and trianglish. I have gotten perfect 6" square cants that were measured at 7". Actual measurement was right at 7 3/4" and the log was very squarish. So that is paid for 14, sawed 24.

The best way is to do them as a group of logs since there is so much a wide variation in log shape and ingrown bark.

Measure 20 or 30 logs, saw them, measure the good lumber and the low grade lumber. Now you will have an average yield. It is almost impossible to get an accurate estimate of what any individual log will saw out.

Remember a 7" log can have almost 14 per cent difference based on diameter measure alone. It may measure exactly 7" all the way to 7 15/16" and be called a 7" log. Cedar log measure calls a 7" log at 14 feet and an 8" log at 19. (Some cedar scales call a 7" at 15 feet). So that is a 36 per cent change in footage using the scale.

Have fun sawing cedar.