log rythems, log scale, myth or math

[mitchmaine]

We were standing around at lif the other day comparing the load of logs and pulp on a scoot, and a friend said a cord of wood was 500’ of logs. That was the old standard but I was told by a trucker once it was closer to 600’ so I said so. But I never did actually try and figure it out so..the easy way was volume, and 128 cubic feet is a cord, and 500’ feet of lumber is about 41 cubic feet. That makes about 320 feet to the cord and of course can’t be, so I started figuring the volume of a saw log. It takes a 16 foot log 26 inches on the short end to scale 500’. Multiply the radius squared by pi by the log length gives us almost 59 cu. Ft. that’s better. The whole log is there almost including kerf wood and some slab.but it would take 1110 feet of saw log to make a full 128 foot cord and that’s not right. So we added to the log and now have to whittle a little off the cord seeing that it is full of air. I drew three two foot squares on the wood pile out here. One in big wood and one in small and figured out the area of the wood inside the squares and it came out anywhere between 2/3 and ¾ solid wood so I used 70 % of 128 or about 90 cubic feet for the cord of wood. With those numbers it takes about 762 feet of logs to make a cord of wood. I can live with that.
Wood trucks used to haul about ten cord loads of pulp or 5000 feet of logs and the price was $10 per cord or $20 per thousand. Either way it was a rough way of scaling and easy to see why 500 feet equaled a cord of wood. Useless system now that pulp is bought by weight and logs are still stickscaled. And truckers offer you a roadside price disguising the cost of the trucking.
Good to see you all at low impact forestry. I liked the new format. Thanks for letting me come along.

Joke for the day: the kid comes home from school, and his father askes “what did you learn in school?” the boy said “teacher said pi r squared.” Father said “that’s the dumbest thing I ever heard. Any fool knows pie is round. Cake are squared. Pie is always round!”

mitch

[Scott G]

Mitch,
All bf scales are based on supposed recoverable volume, not total volume. Whether its Scribner, Scribner Decimal C, Doyle, or International the same principle applies – it is what is produced (recoverable) after the headrig is done with it. Problem is that all of these scaling formulas were calculated back when mills weren’t even close to being as effecient as they are now. One of the small local mills I’ve sold to typically gets a 15% overrun and they are running an older circular headrig. Bandmills, locally, can have upwards of a 35-40% overrun (on Scribner decimal C – the scale we use) on the average size timber we have.

I am not a fan of the weight system although it is used fairly routinely out here. If you are running a large mechancal operation and hot-logging it can work out OK for you as long as you agree on an average moisture content. For small guys like me, who might build up a deck of a specific sort at the landing over an extended period of time, it doesn’t work well due to the dry climate we have. We can routinely run 15% or lower RH which draws moisture out of wood quickly. With the weight system (out here) you are literally losing money the longer it sits on the landing.

My favorite method of scaling/measuring wood is by solid CCF (as opposed to loose cf as measured in a cord). Solid CCF, for the most part, is an absolute. The USFS cruises & bids out its timber sales locally by CCF exclusively now. Western Canada, the same although it is expressed as cubic metre. Unfortunately, the mills aren’t buying by CCF yet. My preferred method of measuring is the Smalian formula. You can then take an average of your deck and end up with an accurate scale. If I’m selling sawlogs, I’ll scale everything myself (Scribner Decimal C) and then haggle with the mill owner over their scale if need be. Post & Pole material is all by the piece, basically based on diameter and linear ft. This is a really nice way to go as I just build a load, grab my tally counter and crayon and come up with (X x $2.45 (or whatever the current price is)). I have over two decades with the fellow I sell posts to, he trusts me, so when I give him the number he cuts me a check on the spot. Yet another reason I love logging for posts & poles.

[mitchmaine]

Hey scott,
Its international rule around here. It gains slightly on scribner. We used to have maine or bangor scale, a 42’ scale stick measuring logs 12 to 30 feet by 1 foot increments. A fair rule, but expensive for the mill. I can’t see why. All they had to do was adjust the price. In the end the scale means nothing. It changes drastically as the wood yard fills and emptys. Take good care of your pole scaler. Friends in this business are hard to find.
Actually what I was trying to say was that I gave a piece of advice to someone that I had never challenged. And wondered instantly if it was accurate or not and ran the numbers to see. It would be like telling you I drove three abreast with single lines on the middle one and just let the others follow along. If you didn’t know better and passed it along till someone actually tried it with the expected results, well, I try to make sure I have done or tried something before I pass it on. That’s all. Good luck in athol next week. Wish we could make it down. We’re heading for Oregon for thanksgiving. probably pass you in mid-air. mitch

[Author]

Posts