Lumber grading - the very basics GUESS THE GRADE

[lottathought]

Threads like this are gold to many of us newer WWr's.
Frankly, this is one of the few places we can go and have faith that the info is accurate.

[Ivey]

Kyle, thanks for posting this information. I am going to try to make the Raleigh short course.
Jeff, looks like you're getting a handle on this grading thing. I wish that I had the softwood certification so that I could stamp some of this nice looking pine and cypress that I'm sawing. It would nice to see a house built from it along with all of the horse barns...

[jeff...]

Originally Posted by Ivey

Kyle, thanks for posting this information. I am going to try to make the Raleigh short course.
Jeff, looks like you're getting a handle on this grading thing. I wish that I had the softwood certification so that I could stamp some of this nice looking pine and cypress that I'm sawing. It would nice to see a house built from it along with all of the horse barns...

Ivery check the hardwood grade book - http://www.natlhardwood.org/pdf/2007_Rules.pdf
It's got rules for Cypress but not for pine. I haven't looked at the Cypress rules in detail, but it would give you a very good idea what's coming off your mill.

I was going to attend one of those 3 day classes, seems like they pop up just about everywhere, till I found out from NHLA there is no certification required to be a hardwood inspector / grader. So I ordered the Grade book and decided I would try and figure it out for myself instead.

Thanks

[jeff...]

6) To understand FAS1Face (F1F) and Select grades, first an understanding of #1 common basic requirements is needed. Both F1F and Selects must contain #1 grade on their poorest face and FAS on their better face. There are specific grade which rule allowances for minimum board size, wane and other characteristics for both FAS and Select grades which I’ll cover later. If there is money to be made cutting lumber it’s in the #1 common grade, a company that can produce a lot of #1 common can be in a good financial situation. A saw mill company that can maintain a steady stream of 14” diameter and larger logs and be able to turn the logs frequently during sawing in order to get the best grade possible can produce quite a bit of #1 common. The grade rules for #1 common are not near as stiff as they are for the upper grades.

Width - Lumber must be at least 3 inches or wider.

Length – Boards must be no less than 4 foot long or no greater than 16 foot long.

Size of cuttings - A #1 common clear cutting can be no smaller than 4 inches wide by 2 foot long or 3” wide and 3’ long. A cutting can be larger, but must be at least be these sizes.

Number of allowable cuts - is SM +1 divided by three with a maximum of 5 cuts. The result is rounded down to the nearest whole number (drop any fractions).
SM + 1
--------- = #1 common allowable cuts (Max 5).
3

#1 Common cutting unit (CU) Yield - is surface measurement (SM) times eight. This is the minimum allowable clear wood form the piece of lumber. For a board to make #1 Common eight twelve’s of it’s wood must be in clear cuttings and be contained within the minimum #1 common clear cutting size and be cut in the #1 Common number of allowable cuts

Pith - The amount of pith allowed for #1 common is no more that one half the length of the board.

7) #1 Common example - The example below represents a piece of lumber that is 8 3/4" wide, 2 1/8” thick and 8' 2" long. The black areas represent it’s poorest defective face. The shaded area is considered waste because of defect and the dashed line are where the board would be cut to yield it’s greatest number of clear cutting units. Does it qualify for a #1 common grade?




7-1) First calculate Board Foot (BF) Remember to round width and length down

Thickness 2 * Width 8 * Length 8
---------------------------------- = 10.67 BF
12

7-2) Calculate the surface measure (SM) Remember to round width, length down and the resultant down

Width 8 * Length 8
--------------------- = 5.3 SM (5 rounded)
12

7-3) Calculate the number of cutting units contained in the example, ) Remember to round width and length down

Width 8 * Length 8 = 64 CU


7-4) Calculate number of allowable #1 common cuttings to make grade. Remember to drop the fraction

SM (5) +1
------------- = 2 #1 common allowable cuts
3

7-5) Calculate #1 common CU Yield required

SM (5) * 8 = 40 #1 common cutting units required

7-6) Calculate amount of clear Cutting Units, In this example there are two, one is 3” wide by 8’ long which is 24 cutting units and the other is 5” wide by 4’ long to equal 20 cutting units. The sum of both cuttings equal 44 which exceeds the allowable #1 common grade by 4 cutting units.

Also we fall into our maximum of 2 cuts allowed one is a rip cut and the other is a cross cut. Our narrowest board is 3” and our shortest board is 4’ - Yep this example makes the #1 common grade.

I think the easiest way to determine if a board meets the #1 common grade, is look at its poorest face and say to yourself (is two thirds of this board clear)? If the answer is yes, chances are pretty high it’s #1. I also think a lot of grading in the industry is done by sight, graders have seen so many boards they just know what grade it’ll be, But you could always do the math and find out for sure…

When I get some time, I’ll try and tackle F1F, then Select – stay tuned… If I made any errors please feel free to correct me I'm trying to learn and it might be very possible I'm all wet here. Any comments welcome...

Thanks

[jeff...]

Wondering if I bored everyone or if folks are just uninterested in this topic?

Should I continue with the other grades (F1F / Select and #2)? Then maybe finish it off with a species and drill down into the specifics of that particular species.

I don't see a need to continue if there is not any interest.

Thanks

[McRabbet]

Jeff...

Bring it on! I'd like to see you pull all of this into a write-up we could put into the Download Library -- I'd be willing to help if needed.

[Makinsawdust]

Originally Posted by Grgramps

Jeff, I think we all benefit by understanding how board feet are calculated. (It's not like buying 5 lbs of potatoes.)

Is there a difference when calculating board feet of green wood and wood that has been dried? The reason for asking is because when I bought from Gennetts in Asheville they made the calculation to account for the shrinkage of the kiln dried lumber.

I haven't experienced this elsewhere so I wonder if this is just their policy? It has probably been a couple of years since buying from them after finding other lumber sellers did not follow that method. I can't say how they presently calculate.

Roy

Roy,
The practice of calulating on what's called "gross tally" is practiced by most wholesale distibutors on domestic woods. They usually add 8% for shrinkage. It is pretty widely done and not just this dealer. It is important when getting a quote to understand if they are calulating on gross or net tally. Net tally is the actual board feet that you get. Most retailers use the later and that's why you have not seen the practive before.
My domestic wood wholesale supplier uses gross tally and my exotic wood importer/wholesaler uses net tally. So I have to take this account.
Like I said in another post lately, you need to make sure you are comparing the same grade of wood when shopping price.
Hope this helps you understand why they did what they did.
Rob

[Monty]

This looks like it will be an awesome reference - keep it up, Jeff!

[jeff...]

8 ) Understanding of F1F basic grade requirements. F1F is the abbreviation for FAS ONE FACE. Meaning the poor side of the board must grade to #1 common and the good side of the board must grade to FAS. It may be hard to understand that lumber cut from the out side of the tree usually yields a higher grade than lumber that’s closer to the pith. As a sapling grows it side shoots lots of branches as it also continues to gain height, as it grows taller it sheds it’s lower branches. New girth growth grows over the shed branch sockets and continues to produce new wood. It’s this new growth that produces higher quality and grade than when the tree was young. In todays hurry up world, not many forest trees are allowed to remain standing long enough to produce high amounts of FAS lumber. At some point I would like to write up something about log grades and lumber that can be expected but that’s another subject for another time.

As you would expect the grade rules are the same for FAS, here’s a summary:

* Minimum board size of 6” wide x 8’ long
* Minimum cutting size of 4” wide x 5’ long or 3” wide x 7’ long
* F1F yield is SM x 10 or 83 1/3%
* Formula to calculate number of allowable cuts is SM / 4 with a maximum of 4

9) Let’s take a look at an F1F example; the poor side is identical in respect to the number and size of clear cuttings to our #1 common example, so we already know the poor side grades to #1 common. However, note the 9’ long end grain split on the right hand side of the example, it’s not a surface check, it’s actually a split that is present on both sides of the board. For the purpose of understanding the basics and simplicity we’ll round the spit defect up to a length of one foot long. Also note the arched lines on the right hand side as characteristic of a board sawn from a log that had trapper on the small end of the log and can either be wane (bark) or missing wood. Since we already know the poor side grades to #1 common, does the good side grade to FAS?



9-1) First calculate Board Foot (BF)

Thickness 2 * Width 8 * Length 8
---------------------------------- = 10.67 BF
12

9-2) Calculate the surface measure (SM)

Width 8 * Length 8
--------------------- = 5.33 SM (5 rounded)
12

9-3) Calculate the number of cutting units (CU) contained in the example

Width 8 * Length 8 = 64 CU


9-4) Calculate number of allowable FAS cuttings to make grade

SM (5)
----- = 1.25 FAS allowable cuts (1 fraction dropped)
4

9-5) Calculate FAS CU Yield required

SM (5) * 10 = 50 FAS cutting units required

9-6) Calculate Clear Cutting Units of clear piece on the good side of the board, Width 8 * Length 7 = 56 Clear Cutting Units

As you would expect the board in this example does qualify for the F1F grade by making one cross cut at approx 1 foot from the end leaving a 8” wide 7’ long piece of lumber. FAS clear cutting yield equals 50 and the actual clear piece of lumber after our one allowable cut represents 56 clear cutting units.

[Grgramps]

Originally Posted by Makinsawdust

Roy,
The practice of calculating on what's called "gross tally" is practiced by most wholesale distributors on domestic woods. They usually add 8% for shrinkage. It is pretty widely done and not just this dealer. It is important when getting a quote to understand if they are calculating on gross or net tally. Net tally is the actual board feet that you get. Most retailers use the later and that's why you have not seen the practice before.
My domestic wood wholesale supplier uses gross tally and my exotic wood importer/wholesaler uses net tally. So I have to take this account.
Like I said in another post lately, you need to make sure you are comparing the same grade of wood when shopping price.
Hope this helps you understand why they did what they did.
Rob

Rob, I appreciate your taking the time to explain this. Gennett's never gave me an explanation, but I'll admit that I didn't question management. I only dealt with the people in the warehouse and what I got from them was a distant stare as though I was speaking a foreign language. It would have helped if they had explained that the were using "gross tally" and that I was paying for 8% more than it measured.

I suppose I'm lucky that they didn't take into consideration how the
U.S. dollar that I paid with has depreciated.

Roy

[jeff...]

10) Basic understanding of the Select grade. Although hardwood lumber is graded from the poorest side of the board, there are a few exceptions; F1F and Select are the exceptions. Many boards have a good side and can be used in many applications by taking advantage of the better side of the board. Thus the select grade rules were written to account for these valuable boards.

* Minimum board size is 4” wide by 6’ long, note the difference of a full 2’ in length and 2” in width from FAS and F1F Minimum board size.
* Minimum size of cuttings are 4” wide by 5’ long or 3” wide by 7’ long (same as FAS and F1F)
* Select yield can be qualified two different ways:

1. The good side will grade FAS with the poor side sound (note the poor side does not have to meet any special grade requirement, just be sound+)
2. The good side will grade FAS with the poor side grading to #1 common or better. (The poor does not have to be sound+)
3. +Sound is defined as free from rot, pith, shake, and wane, texture is not considered. Admits sound knots, bird peck, stain, streaks, or equivalent, season checks, and worm holes)

* Number of allowed cuts is SM / 4 drop any fraction (same as FAS and F1F)

I'll add more when I get some time

Thanks

[jeff...]

Guess the Grade

The board is 4/4 thick, 9" wide and 8' long there is pith on the far right side that starts about 7" from the lower edge and extended at an angle till it disappears about 2' from the end where it started. The pith is considered defect because the board is split in the pith and will be required to be cut out be use. The rest of the board is clear on both sides and free of defect.

[IMG][/IMG]

Heres a little table to help you determine the grade.

Board foot = thickness x length x width / 12
Surface Measure = length x width /12
Cutting Units = length x width
Number of allowed cuts is (FAS F1F and Select = Surface Measure / 4) (#1 Common is Surface Measure +1 / 3)
Required FAS F1F and Select clear cutting units is Surface Measure * 10
Required #1 Common clear cutting units is Surface Measure * 8

How many clear cutting units are in this board? Hint 7" wide by 8' long

How many clear cutting units are required per grade?

What's grade is this board?

[jeff...]

No body wants to take a guess? Not even Bas - man you guys are a tough crowd

[FredP]

ok here is a guess. 1 common. if you was to rip the pith off it would be FAS select.????????????

fred p the guess master!!!

[jeff...]

Originally Posted by FredP

ok here is a guess. 1 common. if you was to rip the pith off it would be FAS select.????????????

fred p the guess master!!!

Wow Fred you da man there, does your wife know you are da man?

Your right it's #1 common and if I were to rip the pith out, it would become FAS at 7" wide x 8' long. This is a good example why an edger and end trimmer are vital pieces of machinery in a FAS ~ Select yard. And the very reason why us other guys who don't have edgers and trimmer produce a lot of #1 common