Eye-ballin'n Bushels

[Metals406]

I know that a lot of old saws are good at eying bushels in a tree, and getting pretty close. Busheling has mostly been replaced by a day-wage, so it's an under utilized skill. Most probably just do it to keep track for themselves, and not for pay.

I was using an online calculator for MBF, and found out a little something. Without going by "form class", and just multiplying 3 numbers, I found I could get a fairly close number that was a "happy medium" between all three common scales. . . Doyle, Scribner, and International.

What I did was, multiply DBH in inches, times how many 16' logs you could get, times that number again.

Like so: A 20" DBH tree (form class 78) with (4) 16' logs, averaged 419.333 between all three scales.

When I take 20 X 4 X 4, I get 320. (Doyle was 346)

If I do a 14" DBH (form class 78) times (3) 16' logs, I get and average of 138.6666.

When I take 14 X 3 X 3, I get 126 (a happy medium between Doyle and Scribner).

Anyone else have a simple formula besides fancy-pantsy scale sheets?

 

[madhatte]

I like that method, but it's got some flaws you need to be aware of. DBH x Logs ^2 will give you an approximate volume based on an idealized cylinder. Form Class represents deviation from that ideal due to taper. Also, all of the formulas you can use to derive FC are based on the whole tree, whereas volume estimates (be they Scribner, Doyle, or International) are based on the log. A 16' log will scale better on paper because of geometry, but how many 16' logs do you cut? 33' or 41' is more likely, and will change both theoretical and actual volume numbers. Best way to get an accurate volume estimate is to fall/buck/scale a sample of logs from every site in order to generate a local correction factor based on the actual trees being measured and cut. That way you'll know for sure what a MBf looks like HERE as well as THERE if you've done the work in both locations. I had a long discussion with the guy who generated the equations for Westside DF volumes awhile ago and he told me to be more worried about height and diameter than taper -- taper has too many complicated causes and effects to be a useful metric other than as per-log deductions.

 

[Metals406]

I like that method, but it's got some flaws you need to be aware of. DBH x Logs ^2 will give you an approximate volume based on an idealized cylinder. Form Class represents deviation from that ideal due to taper. Also, all of the formulas you can use to derive FC are based on the whole tree, whereas volume estimates (be they Scribner, Doyle, or International) are based on the log. A 16' log will scale better on paper because of geometry, but how many 16' logs do you cut? 33' or 41' is more likely, and will change both theoretical and actual volume numbers. Best way to get an accurate volume estimate is to fall/buck/scale a sample of logs from every site in order to generate a local correction factor based on the actual trees being measured and cut. That way you'll know for sure what a MBf looks like HERE as well as THERE if you've done the work in both locations. I had a long discussion with the guy who generated the equations for Westside DF volumes awhile ago and he told me to be more worried about height and diameter than taper -- taper has too many complicated causes and effects to be a useful metric other than as per-log deductions.

I was hoping you'd reply!! I know it has flaws, but I was looking at it as a "shoot from the hip" kinda deal. Sure, there's gonna be some plus minus to it.

A guy can also use frustum of a cone calcs, but it's more math.

I was surprised that I was even as close as I was just multiplying three numbers.

I like the eye-ball and scale thing, and that's probably how the old-timers got good at it.

Just thought I'd throw this out there for guys curious when they fall a 3' tree, and think "I must have 4 MBF here!"

I'd say another easy way to do it is the pretend you're at the mill, and turn it into a square in your mind (usable BF). Measure small side, vertical and horizontal, and times that by length. Now you have a real good idea what's waste and what's not.

I have too much time on my hands. Hahahaha

 

[Sport Faller]

I was hoping you'd reply!! I know it has flaws, but I was looking at it as a "shoot from the hip" kinda deal. Sure, there's gonna be some plus minus to it.

A guy can also use frustum of a cone calcs, but it's more math.

I was surprised that I was even as close as I was just multiplying three numbers.

I like the eye-ball and scale thing, and that's probably how the old-timers got good at it.

Just thought I'd throw this out there for guys curious when they fall a 3' tree, and think "I must have 4 MBF here!"

I'd say another easy way to do it is the pretend you're at the mill, and turn it into a square in your mind (usable BF). Measure small side, vertical and horizontal, and times that by length. Now you have a real good idea what's waste and what's not.

I have too much time on my hands. Hahahaha

Damn, were you watchin Bill Nye The Science Guy this morning with the kids :hmm3grin2orange:

that is a pretty cool way to scale tho (now all my pics will have an estimated board footage footnote) yesterday's Larch was about 270 as it had the top out of it

EDIT: wait I must have been wrong as hell because I've heard that the average cord of wood is about 500bf and that one log was waaaaaay more than a cord

 

[forestryworks]

Scale on the small end.

 

[madhatte]

Also: USFS prefers to scale by Cubic Foot, rather than Board-Foot. The conversion factor is 12: divide Bf by 12 to get Cf, multiply Cf by 12 to get Bf. Cf is also useful in converting to cords: 128 Cf/cord. I realize that these numbers make no allowance for kerf, and that's OK for estimation purposes. It's the scaler's job to fix those errors.

 

[slowp]

In this area, since most sales are second growth without a lot of defect, the USFS prefers to weigh trucks and sells wood by the ton. Now I hope you are really confused.

In da old days, ve cruised timber using the 3P method, and there was a pocket card that we carried and it would give an estimate of the volume of the tree by diameter and height. It also took taper into consideration.

A 3P cruise is a 100% cruise. Each tree is estimated. Trees are randomly measured to get a coefficient of variation?? and that is figured into the cruise. We found out that you could not get an accurate cruise if the crew members changed every day. Ooops, thread drift.

Although cruising is different from scaling, the end result should be close.

 

[hammerlogging]

"should" is a very important word there. Lots of the cruisers don't know #### about logging or selling wood and the cruises can be over. I this hardwood, its like "you think I'm going to get a log out of that????"

You're going to get real close just writing down the stump diameter and your height or logs and putting it into excel with the right equation at the end of the week or day, of you really want to know. After a few times, you can start guessing and check yourself, then you'll just guess and be pretty right on.

 

[madhatte]

3P is the way to go. It doesn't have to be 100%, and, in fact, the statisticians are saying now that smaller samples coupled with good local variation data will produce better results faster because the math is doing all the work. I was in Placerville, CA this May for training on this very subject. The most important thing in designing a 3P cruise is selecting the right proportion of measure trees vs estimate trees -- variations in forest type and canopy complexity mean that a boilerplate value is useless. Also, the policy we use where I work is to exclude the 30 feet at the top from volume or defect estimates. That way we miss a lot of the "you think I'm going to get a log out of that????" conversations altogether.