Question
I would like a formula for calculating log volume in board feet to better estimate the production from a bandsaw mill. This formula would have as variables log length, small diameter, large diameter, and kerf with of course some assumptions. I’m looking for an actual formula with these variables which I can use in a spreadsheet (Excel or Numbers) to make my own calculators. Does anyone know where this formula has been worked out?
Forum Responses
(Sawing and Drying Forum)
From Gene Wengert, forum technical advisor:
The basic rule is the International 1/4" rule, which assumes a 1/4" kerf. I have seen an Internationl 1/8" rule in table form. You might have to use a table look-up. I have not seen a formula that incorporates 4/4, 5/4, 6/4, 8/4, cants, etc, all which will change the yield as well. And to be very accurate, sweep might also be included. If there is none in existence, it would be something that a university or government agency could fund and work on.
1. Take an accepted scale.
2. Modify it.
3. Test that against your actual sawmill return.
It all works in the end. I've been using the 1/4" scale, and have been tracking my production to determine how much over run I can expect from different logs. I too am doing this, partly, to better estimate how much I saw for customers.
To maximize the footage of the higher grade lumber, without losing overall yield, cut any good faces parallel to the bark. Take out the taper in the low grade. Also, turn the log to the next face when the faces adjacent to what you are now sawing promises higher grade. When selecting the faces, try and maximize the clear area in the faces and also put knots of the edges and not the center of a face. Finally, after opening the log, when it is time to go to the second face, turn the log 180 degrees, not 90 or 270. Following these suggestions will increase value by over 20% in many cases and increase yield by 2 to 5%.
Common Lumber Name | A | B | C |
Hardwoods | |||
Alder, Red | 9.9 | 19.2 | 2506 |
Apple | 10.9 | 31.7 | 4132 |
Ash, Black | 9.3 | 23.4 | 4132 |
Ash, Green | 14.3 | 27.6 | 3590 |
Aspen, Bigtooth | 10.3 | 18.7 | 2439 |
Aspen, Quaking | 10.3 | 18.2 | 2373 |
Basswood | 6.2 | 16.6 | 2174 |
Beech, American | 8.9 | 29.1 | 3793 |
Birch, Paper | 8.8 | 25.0 | 3260 |
Birch, Sweet | 11.9 | 31.2 | 4065 |
Birch, Yellow | 9.2 | 28.6 | 3723 |
Buckeye | 8.9 | 17.2 | 2235 |
Butternut | 11.3 | 18.7 | 2440 |
Cherry | 13.8 | 24.4 | 3184 |
Chesnut, American | 11.6 | 20.8 | 2708 |
Cottonwood | 8.5 | 16.1 | 2102 |
Dogwood | 6.8 | 33.3 | 4331 |
Elm, American | 10.2 | 23.9 | 3116 |
Elm, Rock | 12.2 | 29.6 | 3860 |
Elm, slippery | 11.5 | 25.0 | 3251 |
Hackberry | 11.8 | 25.5 | 3319 |
Hickory, Bitternut (Pecan) | 14.7 | 31.2 | 4062 |
Hickory (True) | |||
Hickory, Mockernut | 9.1 | 33.3 | 4332 |
Hickory, Pignut | 9.3 | 34.3 | 4332 |
Hickory, Shagbark | 10.9 | 33.3 | 4333 |
Hickory, Shellbark | 6.6 | 32.2 | 4195 |
Holly, American | 8.3 | 26.0 | 3387 |
Hophornbeam, Eastern | 7.9 | 32.8 | 4266 |
Laurel, California | 15.1 | 26.5 | 3456 |
Locust, Black | 21.2 | 34.3 | 4470 |
Madrone, Pacific | 7.8 | 30.2 | 3925 |
Maple (Soft) | |||
Maple, Bigleaf | 12.8 | 22.9 | 2980 |
Maple, Red | 13.1 | 25.5 | 3318 |
Maple, Silver | 12.4 | 22.9 | 2981 |
Maple (Hard) | |||
Maple, Black | 12.3 | 27.0 | 3523 |
Maple, Sugar | 12.3 | 29.1 | 3793 |
Oak (Red) | |||
Oak, Black | 11.7 | 29.1 | 3792 |
Oak, California black | 16.4 | 26.5 | 3455 |
Oak, Laurel | 6.3 | 29.1 | 3791 |
Oak, Northern red | 13.6 | 29.1 | 3793 |
Oak, Pin | 13.0 | 30.2 | 3928 |
Oak, Scarlet | 13.2 | 31.2 | 4065 |
Oak, Southern red | 9.6 | 27.0 | 3520 |
Oak, Water | 10.4 | 29.1 | 3793 |
Oak, Willow | 6.4 | 29.1 | 3790 |
Oak (White) | |||
Oak, Bur | 15.4 | 30.2 | 3928 |
Oak, Chestnut | 10.1 | 29.6 | 3858 |
Oak, Live | 17.5 | 41.6 | 5417 |
Oak, Overcup | 10.7 | 29.6 | 3860 |
Oak, Post | 11.0 | 31.2 | 4063 |
Oak, Swamp chestnut | 10.7 | 31.2 | 4063 |
Oak, White | 10.8 | 31.2 | 4062 |
Persimmon | 7.0 | 33.3 | 4332 |
Sweetgum | 8.9 | 23.9 | 3115 |
Sycamore | 10.7 | 23.9 | 3115 |
Tanoak | 9.0 | 30.2 | 3926 |
Tupelo, Black | 10.4 | 23.9 | 3116 |
Tupelo, Water | 12.4 | 23.9 | 3115 |
Walnut | 13.4 | 26.5 | 3454 |
Willow, Black | 8.6 | 18.7 | 2438 |
Yellow-poplar | 10.6 | 20.8 | 2708 |
Common Lumber Name | A | B | C |
Softwoods | |||
Baldcypress | 13.2 | 21.9 | 2844 |
Cedar, Alaska | 14.4 | 21.9 | 2844 |
Cedar, Atlantic white | 10.9 | 16.1 | 2100 |
Cedar, eastern red | 16.4 | 22.9 | 2981 |
Cedar, Incense | 13.1 | 18.2 | 2371 |
Cedar, Northern white | 11.1 | 15.1 | 1964 |
Cedar, Port-Orford | 12.6 | 20.2 | 2641 |
Cedar, Western red | 12.2 | 16.1 | 2100 |
Douglas-fir, Coast type | 12.3 | 23.4 | 3049 |
Douglas-fir, Interior west | 13.2 | 23.9 | 3116 |
Douglas-fir, Interior north | 14.0 | 23.4 | 3048 |
Fir, Balsam | 9.9 | 17.2 | 2236 |
Fir, California red | 10.6 | 18.7 | 2437 |
Fir, Grand | 10.7 | 18.2 | 2371 |
Fir, Noble | 10.1 | 19.2 | 2507 |
Fir, Pacific silver | 10.4 | 20.8 | 2711 |
Fir, Subalpine | 10.5 | 16.1 | 2101 |
Fir, White | 12.2 | 19.2 | 2506 |
Hemlock, Eastern | 12.6 | 19.8 | 2573 |
Hemlock, Western | 11.5 | 21.8 | 2847 |
Larch, Western | 11.3 | 25.0 | 3251 |
Pine, Eastern white | 12.3 | 17.7 | 2303 |
Pine, Lodgepole | 11.5 | 19.8 | 2576 |
Pine, Ponderosa | 12.6 | 19.8 | 2573 |
Pine, Red | 12.2 | 21.3 | 2777 |
Southern yellow group | |||
Pine, Loblolly | 12.9 | 24.4 | 3183 |
Pine, Longleaf | 15.0 | 28.1 | 3658 |
Pine, Shortleaf | 12.9 | 24.4 | 3183 |
Pine, Sugar | 12.6 | 17.7 | 2302 |
Pine, Western white | 10.0 | 18.2 | 2370 |
Redwood, Old growth | 14.9 | 19.8 | 2573 |
Redwood, Second growth | 13.2 | 17.7 | 2302 |
Spruce, Black | 11.3 | 19.8 | 2575 |
Spruce, Engelmann | 10.0 | 17.2 | 2234 |
Spruce, Red | 10.6 | 19.2 | 2506 |
Spruce, Sitka | 10.8 | 19.2 | 2506 |
Tamarack | 12.0 | 25.5 | 3318 |