Lost in dimensions - bf, cbm, metres inches etc...

[Nerijus]

Hi everybody,

I'm new, and foreigner in this forum, form smal Europe country, named Lithuania.
In mobile sawmilling for seven years, and it is interesting to read some topics from the guys, doing the same, but in other side of the world.

So the first question which I want to ask - how do you count the amount of sawn lumber? as i understood, the unit is board foot, but how do you calculate it? For example how many bf is in log which is 20feet of lenght and the diameter in smaler end is 16 inches?

In various online  converters, bf >> cbm, the result is that 1000bf is about 2,35 cubic meters, but when I read the topics about the amounts of lumber sawn per day/hour/shift/etc, the numbers don't come together...

Or maybe in your coversations about the sawn board feet (per day, per hour, per galon of fuel, per earned dolar, per sharpened band blade, etc) you mean edged and stacked boards, not the logs lying on the ground?

[drobertson]

Nerijus, don't feel too bad, I get lost when I read post from you folks across the way too.   I always thought the conversion was 25.4 or just leave out the . and then figure the decimal in where it should be, but I am not sure, but it is good to  have you on, I am sure you can give us here plenty of insight as to the european way of doing things :christmas:  david

[WindyAcres]

Hey Nerijus, good luck with that  ;) I am living in Canada now for 2 years and I still don't know many yards there is to the mile or how many pounds to the ton (or how many onces to the pound?).. I know that there is 12 inches to the foot and that a bf is 12x12x1 inch. If you want to know the board footage from a baord that is 8 feet long, 6 inches wide and 1 inch thick.  Then you have to multiply 8 feet by 12 inches which is 96. Then you multiply 96 by 6 by 1 which is 576. Then you have to divide that by 144. So that board has 4 board feet...
For the board footage of logs, you have to look at a table.. There are many tables, which give different numbers I think.. As I said, still havent figured it out either :-)

Nerijus, it is very difficult if you are used to the metric system. 100 cm=1 m, 1 cm=10mm, 1000m=1km, 1l=1000ml, 1000g=1kg, 1l of water is rougly 1 kg. Wood is messured in cubic m.

MC

[tyb525]

When sawyers talk about how many board feet they've sawn, they are measuring the boards they have cut and stacked, not the logs on the ground before they milled them.

This forum has a section with all kinds of calculators for different things. click on "Tool Box" under the "Extras" tab.

And welcome to the forum!

[Ron Wenrich]

A board foot measures one square foot that is one inch thick.  A cubic foot has 12 board feet.  So, to figure out board feet in sawn lumber, you simply multiply the thickness (in inches) by the width (in inches) by the length (in feet) , and divide that by 12.  The formula would look like this:  (Thickness * width * length)/12

A 1" x 6" x 8' would have 4 board feet.

When it comes to trees, there are several ways to measure them.  You can use a cubic foot volume (not used much), a cord volume (which has 128 cubic feet on a standard cord), by the ton, or by the board foot.  None of these are really transferable in the mathematic sense from one to the other. 

To top things off, there are several types of scales used to determine the amount of board footage in a tree or a log.  You will see terms like Doyle, Scribner, and International scales used in various threads.  They estimate volume, and you can't say that so many feet in Doyle is equal to so many feet in Scribner.  Which scale is used varies from one place to the other. 

The next problem is that 1,000 board feet in tree scale will have more footage in log scale, even using the same scaling techniques.  And, you will normally cut more lumber out of a log than what it scales at.  They call that overrun.  If you go under, its called underrun. 

If you want to play around with different scales and volumes, we have several calculators that we developed that all you need to do is put in the length and the diameter, and it will give you the volume.  It might be a nice exercise for you, and probably make you more confused than what I just did. 

We have them in the Extras on the top bar or at the tool box on the left.  Or just hit this link:
https://forestryforum.com/board/index.php?action=toolbox

We have volume calculators for trees, logs and lumber.  We even have one for log weight. 

And welcome aboard.

[DanG]

Welcome Nerijus!  It's always nice to get new members from other parts of the world.

The easiest way for me to remember is that there are 12 board feet in one cubic foot.  Just convert the cubic feet to cubic meters and multiply by 12.

The Forestry Forum toolbox has several good calculators for different purposes.  You can find it under "Extras" at the top, or the toolbox icon below the ads at the left.

I ain't untyping this just because Ron beat me to it! :D   :christmas:

[petefrom bearswamp]

welcome Nerijus.
Now take all of the board foot stuff in the previous post and convert it to metric!
And yes the board feet we are talking is in the lumber sawn not the logs
.
pete

[Nerijus]

Thank you guys for the one more converter  :D, now I'm finaly lost... like the first day in a sawmill :D. But it is interesting, which type of bf in the log - Doyle, Scribner or International, is the most popular in your talks?

And BTW - it is hard to believe, that, like somebody said, you are counting the boards and only then charging the customer... afterall, if you saw straight, long and thick logs, you can easy make up to 70 percent yield, and saw a quarter of 50ton timber truck, per day with a manual sawmil and two helpers. In other hand, if there will be short, curvy toptrees, you'll be happy that your SUV trailer will be filled up... but of course it is offtopic .

[Nerijus]

welcome Nerijus.
Now take all of the board foot stuff in the previous post and convert it to metric!
And yes the board feet we are talking is in the lumber sawn not the logs
.
pete

Now counted on calculator - result is the same like in online converters 1bf is about  0,0023 cubic meter, like in all converers. But for example, let's take a log - 20 ft lenght and 16,5 inches in smaler end inside the bark. In Europe we have, that this log is one cubic meter or 423bf. In toolbox, linked above this log is 180, 208, or 226...  :snowman: :snowman: :snowman: where has disapeared about a half of a log? :D

[Ron Wenrich]

A couple of things happen.  For one, there isn't a direct relationship between cubic foot volume in a log and the board foot volume coming out the sawmill.  You will have wood waste in the form of sawdust and slabs.  The cubic foot or meter volume would be the amount of wood fiber in the log.  The log scales that we use are primarily for the amount of 1" lumber coming out of that log.  Veneer buyers use Doyle, as do many sawmills.  Foresters often use International (its what they taught us in school).  Some mills that deal in smaller logs will buy Scribner or International. 

And to really mess things up, some guys buy logs by the ton.  But, the convert that over to board footage by an estimation of what it will saw out.  A lot of that is based on species.  I talked with one guy who bought black locust and figure 7½ tons per 1,000 bf of lumber.  Red oak is commonly figured at 6 tons per 1,000. 

Mills running on cubic volume have a lumber recovery factor.  Average seems to be about 6 bf/cu ft.  Really good mills will get 7, and poor mills will only get 5.  A lot would depend on what the product mix is going out the mill and what size of logs they are sawing.  So, that seems to be where there is a difference between the cubic volume and board foot volume. 

[Nerijus]

A couple of things happen.  For one, there isn't a direct relationship between cubic foot volume in a log and the board foot volume coming out the sawmill.  You will have wood waste in the form of sawdust and slabs.  The cubic foot or meter volume would be the amount of wood fiber in the log.  The log scales that we use are primarily for the amount of 1" lumber coming out of that log.  Veneer buyers use Doyle, as do many sawmills.  Foresters often use International (its what they taught us in school).  Some mills that deal in smaller logs will buy Scribner or International. 

And to really mess things up, some guys buy logs by the ton.  But, the convert that over to board footage by an estimation of what it will saw out.  A lot of that is based on species.  I talked with one guy who bought black locust and figure 7½ tons per 1,000 bf of lumber.  Red oak is commonly figured at 6 tons per 1,000. 

Mills running on cubic volume have a lumber recovery factor.  Average seems to be about 6 bf/cu ft.  Really good mills will get 7, and poor mills will only get 5.  A lot would depend on what the product mix is going out the mill and what size of logs they are sawing.  So, that seems to be where there is a difference between the cubic volume and board foot volume.

Thank you, it means that there different atitudes and traditions play the main role.... and there is no chance for direct comparison betwen European and US sawing results at the end of the day:).

[beenthere]

Nerijus
Welcome to the forum. You have good questions. Don't give up.

With your measure of log volume in cu meters, what portion of the log volume ends up in sawdust, slabwood, and lumber?   

Here, only the yield of sawn lumber is measured in board feet. And the Doyle, Scribner, and International rules only give an estimate of what that lumber yield is in board feet. No measurement of the sawdust or the slabwood.

[hackberry jake]

I like to use units of measure that are understood by all and easily converted. Like jag, load, whack, and "so much you can't shake a stick at".

[learner]

Nerijus One board foot equals 12 in² = 0.007741919999999999 m².  The Doyle, Scribner and International scale are Only used to Estimate how many board feet a log might contain.  Internal defects, bad cuts and other things affect what you actually get from a log.
There is No TRUE way to know what you can get from a log until you cut it up.  I make all my first cuts so that I can get a 1" x 4" minimum(after edged).  In other words each first cut leaves me a 4" flat surface.  You just have to decide how long you want the first cuts to be.  Is a first cut only leaving 3 foot of 4" surface  worth it?  From there the boards just get wider and your board footage just goes up. 
You will allways have some amount of waste from any log.  The first four cuts to square a log are generally waste(unless you can process it into firewood etc.).  After that, each cut is a usable board once edged.
This is the best way I have found to maximize the board footage you get from each log.
I hope this helps and Wellcome to the Forestry Forum!

[customsawyer]

Welcome to the forum. What kind of mill and other equipment are you using?

[Brucer]

And here in BC we buy and sell logs using the BC Metric Scale. It calculates the volume of the firm wood in the log. The principle is to calculate the area at each end of the log, average the two numbers, and then multiply by the actual length.

That means I'm paying for everything in the log: the lumber, the timbers, the slabs, the edgings, and the sawdust. It's up to me to decide how many Board Feet I can saw from a log, and how much money I will earn from that wood. I've found over the years that I can recover about 200 BF as timbers and 100 BF as lumber from every cubic metre of wood -- roughly 70% recovery.

[Ianab]

Part of the confusion may be that logs and boards may both be measured in Cubic Metres.  In either case this  is the volume of wood you are talking about. As Brucer explained, the difference is the sawdust, slab and any other waste. You should recover 60 - 70%?

When logs are sold by the Board Foot, a "scale" equation is used to estimate how much sawn wood will be recovered.  So a log that scales as 100 bd/ft should produce 100-110 brd ft of sawn wood. Depending on the mill, the sawyer, sizes being sawn, luck etc.

What gets really confusing when you are buying on one scale, and selling on another. A ton of small logs wont produce near as much as a single one ton log. Proportionally more gets thrown out as slabs and edging when sawing small logs....

Ian

[Nerijus]

Welcome to the forum. What kind of mill and other equipment are you using?

oy
Me ow two, localy manufactured mobile bandmills, with electric 3 phasis 400V 7,5KW (11hp)  motors. We don't prefer gas or diesel, because fuel in europe is twice more expensive than in US, but sawing and labour rates in our country is about twice lower than at yours:). 3 phasis electricity we can find almost in every site, so that is no necessity to have diesel or gas. For log loading we use whinch for heavy logs or hands and cant hooks for light ones. Blades are the same like yours - .055 x 1-1/4" WM or similar - I did't find any difference between the manufacturers. For sharpening I use cbn wheel grinder and dual tooth setter.

[Nerijus]

Part of the confusion may be that logs and boards may both be measured in Cubic Metres.  In either case this  is the volume of wood you are talking about. As Brucer explained, the difference is the sawdust, slab and any other waste. You should recover 60 - 70%?
Ian

Ok, that is the difference, that we count and charge everyting what is in the log - sawdust, firewood, and boards, you count only those, money worth, 50-70 percent of lumber in the log:)

[Ron Wenrich]

Question for you cubic meter guys.  When you're cutting lumber, is there any overrage in the dimensions of your lumber?  For example, when I cut 4/4 hardwoods, I have to give 1 1/8" of wood, but scale it at 1". 

How are your softwood dimension stocks cut?  I don't cut much dimension stock, but when we do, its all cut to full size.  A 2x4 is actual dimensions.  But, mills cutting for the retail and construction trade will cut their lumber scant and measure it full scale.  An automatic overrun of 25% from softwood vs hardwood measurement. 

[John Bartley]

Nerijus One board foot equals 12 in²

I hate to be a picker of nits, but .... one board foot = 144 cubic inches  (12" x 12" x 1")

cheers

John

[harrymontana]

1m2 = 10,7m2
1m3 = 424BFT
measuring a board = thick " x width " x length ' / 12 = BFT

Not just the USA works like this, we (in Bolivia) also work like this..
Selling to overseas clients we convert BFT into m3 (or m2)

[Ron Wenrich]

I've also noticed that you guys use something like 10,7 in your numerals.  What does that mean?  10.7? 

[Brucer]

Ron, the National Lumber Grades Authority (in Canada) specifies that for softwood lumber, a board foot is calculated using the nominal width in inches, the nominal thickness in inches, and the nominal length in feet. The US National Grading Rule for Softwood lumber follows the same criteria. In fact the two documents are co-ordinated so they say virtually the same thing.

This means a 2x4x12', whether it is rough sawn to full dimension, or dried and planed to 1-1/2" x 3-1/2", contains 8 board feet.

Both rules also say that for any lumber less than 1" thick, the number of board feet is the nominal width multiplied by the nominal length. In other words, the thickness is always rounded up to 1".

In many countries that use the metric system, the comma is used as a decimal point, and a period is used to separate groups of 3 digits. When Canada adopted the decimal system we kept the period as a decimal point, but specified that groups of three digits should be separated by a space instead of a period or a comma. Not that anyone follows the rule  :D.

[harrymontana]

I've also noticed that you guys use something like 10,7 in your numerals.  What does that mean?  10.7?

10,7 I guess it refers to 1m2 = 10,7 sqft

[drobertson]

can we just use the good ole whack, jag, good load, and a pile for future reference? :christmas:

[SwampDonkey]

Ron, the comma used in the numbers is a language thing. Member Isawlogs here is of French heritage and they use a comma instead of a period as well. ;)

Here is New Brunswick and probably the rest of the Maritimes, but mostly NB, we have to use 3 systems: imperial, US and metric. Being a bilingual province is not just about language, but  measurements and written numbers. :D

On another note, we use NB Log Rule here, so none of those log rules work here. Over in Maine, we always sold wood to them on another rule, the Bangor Rule. But both rules are very similar to International log rule. Doyle tends to favor the buyer when logs are small <40" and closer to International when above that. A lot of times it makes little difference what rule is used, because the price will be adjusted accordingly. :D

10,7 I guess it refers to 1m2 = 10,7 sqft

10.764 ft² ;D Usually this only refers to tree basal area not lumber.

1m3 = 424BFT

Only if your talking a solid block or cant , not when sawed to 1" stock. The 1 m³ includes the sawdust and the slab wood. It would take an 80 foot maple tree with 16' diameter to get 424 BFT, but as far as lumber you'll probably only recover 200 bf from that tree because of limbs and crotches, above the second or third 16' log.

Also those conversion factors change by length and species. When we used them it was based on 8 foot wood like pulp and studs.

[GeneWengert-WoodDoc]

There are several postings that indicate one bf = 1/12 cubic foot (0.63 cubic foot).  However, in practice, that is seldom true. 

For softwoods, as Brucer stated, a piece 1-1/2" x 3-1/2" x 12' is 8 bf, but it is only (1.5 x 3.5 / 144) x 12 cubic feet =.4375 cu ft for 8 bf and not 0.666 cu ft.  The cubic feet per bf changes for different sizes, especially at 2x10 where the width is only 9.25".  Note that for softwood lumber, the bf is given to two decimal places.

For hardwoods, the thickness for one inch pieces is often 1-1/8, but this extra thickness is not counted when measuring the bf.  also, with hardwood lumber, the bf is given to the closest foot.  This means that a 12' long piece that is just a tiny bit over 7-1/2" wide and 1-1/8" thick is 8 bf and so is a piece 8-1/2" wide.  So, the cubic footage for these two pieces is 0.70 and 0.80 and not 0.66.   If this isn't confusing enough, the actual thickness can be 1.00" up to 1.24" which will change these numbers by 10%.  And then there is the kiln dried rule for thickness which is another can of worms.

Bottom line is that you can use 1000 bf = 2.36 cubic meters = 83.3 cu ft, but if you go and measure a pile of lumber, you will find considerable variation.

Incidentally, although a cord is 128 cubic feet in overall size, the amount of wood is only 70 to 80 cubic feet.  Then, not everyone used a cord that is 4' x 4' x 8', so the 128 cf number will vary.  Sometimes we hear that one cord = 500 bf of lumber when sawn.

When measuring logs, we find 1/4 International scale to be the closest estimator, but most use a scale based on a 1/4" thick saw (saw kerf).  There is a 1/8" International that is closer for bands but it is not widely used.  In the Southern U.S., Doyle scale is popular and it tends to greatly underestimate logs under 16" in diameter, inside bark, small end.  This underestimate means that the saw miller gets the benefit, but small logs require more handling cost per bf, so it is a fair thing to do if the log cost is the same for all size logs.  Scrivener scale sems to be used out West a lot...it is,very close to Doyle.  There are over 100 log scales in North America.

What a mixed up situation, but it works.

[GeneWengert-WoodDoc]

Correction....Scribner, not Scrivner.

[Dan_Shade]

I think its good to understand these things, but its probably only necessary if you are dealing in a wholesale market.  None the less, good deals require both parties to understand what the terms are.

When I saw for somebody and they say 5/4, I ask if they would like  1.25 or 1.31 thick (our something else).