Grading

[jim king]

This has easy to understand photos.

http://www.natlhardwood.org/illustrated_guide/IllustratedGradingGuide.pdf

[dad2nine]

Jim thanks for the info - I seen that publication before but never paid it much mind till now.

Thinking about this more - I think I may have F...ed up in my previous post. Seems that for FAS there needs to be 10/12 clear (defect free), same for Select (10/12) and 8/12 for #1 Common.

Seeing that my example board is 8x8 that gives me a SM of 64. If 64 were 12 10 would be 53.3 or 53 rounded

ratio n proportion math
12=64
10=X

X= 10*64/12
X= 53.3 (53 rounded)

My 6x7 clear cutting from my sample board has a SM of 42 and is shy of the select grade  of 53 :-\

But to make #1 common the board would need to be 8/12 clear

so if:
12=64
8=X
X= 8*64/12
X= 42.67 or (43 rounded)

Still shy at 42,  #2 would need to be 6/12 (SM of 32) clear . My sample board is clear, SM of 42.  So my sample board is closer to a #1 common than a #2 so so I'll call it #1 common...

[beenthere]

I think it has to be a No. 2 C if it won't make No. 1 C..  ;) ;)

"close" only counts in horseshoes..

[inspectorwoody]

"close" only counts in horseshoes.. 

Close counts in grading lumber too.  ;) Every inspector grades differently...The rules are the rules and we do follow them but apperance plays a large role also.

You can pick up a lumber rule from http://www.conwaycleveland.com/. They are located in Grandrapids,MI. I use the #400N. 4 line rule with 12',10',14',16' on one side and 9',11',13,15, on the other.

Hopefully, you are able to read the picture clearly. It explains how to read a lumber rule. Scanner isn't working so I opted for the next best thing.  ;) I could email you the full size image if you would like.



Rule 16,page 5: "To determine the surface measure of a board, multiply the full width of the piece in inches by the standard length in feet and divide by 12, rounding to the nearest whole foot."

7 3/4 x 8: 7x8=56/12=4.6 rounded to 5bf.

In your example of 6"x8', you have a 4' SM, not 48. You have 48 cutting units, if you are using the 6x8 as a cutting.

To determine number of cuttings allowed: SM/4. With a 5' SM, you are allowed one cut to reach 50 units. (SMx10) Now if you are taking one cut that is 6" wide x 7' long than you only come up with 42 cutting units. It will not make a FAS,F1F or Select. The only difference between FAS and Select is board size.

On to 1com: 5'SMx8=40 cutting units needed to make the grade. 5'SM +1=6/3=2 cuts to come up with 40 cutting units. If you take a cutting that is 6" wide x 7' long, you end up with 42 cutting units which meets and exceeds the number of units needed to make the grade.

I am assuming the reverse side of the cuttings are sound.

You are doing very well.  When I sat down in class for the first day, I never thought I could get it and it sounded so overwhelming but six years later,I'm still going at it.  ;D Hang in there.  ;)

[dad2nine]

Woody - Thanks for the responses here - yes please send me that file - I'm gathering up all the info I can to try and learn...

Looks like I really messed up on this and got cutting units and surface measurement confused, not surprising with me :

If I understand correctly:

SM (Surface Measurement) is Width * Length / 12 and rounded to the nearest whole number. Board foot factors in thickness so I can't call it a board foot. This formula is actually the same as square foot except for the rounding part.

Anyways for my example board:
SM = width*length/12
SM = 7 3/4*8/12 = 5.16 = rounded to (5)

I'm a little confused why in your reply you took the 7 3/4" width and rounded it to 7, if anything I thought it would be rounded up to 8? But I guess even if it were rounded to 8" wide, it would still come out to 5.3 (8*8/12) and be rounded to 5 ;D. Strange how this works, isn't it... I think the light bulb came on... round before or after, it doesn't matter much, just so much as you only round once.  ;D

Woody I'm going to wait for a response from you on what I think is right on SM, before I move on to Cutting Units. One Step at a time, I don't want to get off on the wrong foot... you know

Thanks

[inspectorwoody]

SM (Surface Measurement) is Width * Length / 12 and rounded to the nearest whole number

Correct! 

When determining SM, you don't round the width of the board and or the  length.

Rule states, full width in inches. Not width in inches and fractions.

Standard lengths are from 4' - 16'.

Only in cutting units do you use fractions.

"Multiply the width in inches and fractions of each cutting by its length in feet and fractions..."

A board foot is 1' long x 1' wide x 1" thick.

SM is the number of board feet contained in a piece. So if you have a piece of lumber that is 12" wide x 12' long x 1" thick, you have 12 board feet or 12 pieces 1' long x 1' wide x 1" thick. 12x12=144/12=12.

Hope I didn't confuse you.  ;)

So since you don't use fractions when determining SM, than your 7 3/4" becomes 7. Than you take 7x8=56. Than 56/12=4.66666667. Now you round to the nearest foot, giving you 5' SM or 5bf.

Now when you have a piece that is 5/4 (5/4=1.25), than you take your SMx1.25. So a piece 1.25" thick x 6" wide x 8' long = 5bf. A piece the same size, only 6/4 (6/4=1.5) contains 6bf.

[beenthere]

.................................SM is the number of board feet contained in a piece. ...................

But is only the same IF the board is 1" or less in thickness.   This might be confusing to dad2nine.

I think of SM as just that...the surface measure, regardless of thickness, for grading calculations.

Hope this helps.

[dad2nine]

Gotcha Woody - Thanks man ;D - I knew how to calculate BF but never thought of it as anything but BF. I actually have all the widths for 1 and 2" thicknesses memorized for the 8' length. Only because I've had to measure so many boards while sawing out orders for folks. When your getting paid to saw by the BF, you kinda learn to keep track of every last one ;D.

If I ever get the hang of this I can imagine looking at a cant on the mill and saying the next board is going to be X grade, man would that make me a better sawyer or what? Since I usually mark the BF on the board with a lumber crayon, I could also mark the grade along with, now that would be cool... and I could be even more dangerous than I already am :

Now that I got a foot off in the right direction, on to Cutting Units...

I've got the lil green covered NHLA (Effective Jan 1 2007) rule book in front of me.

Page 12 Rule 37. (Cutting Unit Method) says a lot S..t but I think boils down to Actual length * Actual Width? since the book says "The cutting unit is one inch by one foot (or its equivalent). Multiply the width in inches and fractions of each cutting by its length in feet and fractions; the total of the products thus obtained will be the number of cutting units in the board."

Question: Can you round the width and length to the nearest inch and foot. Like my example board is 7 3/4 x 8' 3" Why not just call it 8" wide x 8' long instead of all this fraction stuff? Granted on the example board there is a little wane on one edge so I would be more than happy to also call it 7" wide.

When I look at the grading stick picture you posted it's got marks in between the numbers, those are 1/2 way marks if I'm correct? So if a board width is over the 1/2 way mark it's rounded up to the next nearest whole number it's it's below the 1/2 way mark it's rounded down to the nearest lower number - right?

Anyways Cutting unit is width (in inches) * length (in feet) just because I like stuff easy for now and if it's correct I'm going to round to the nearest width inch and length foot and do away with the fractions of an inch and foot.

Please correct me if I'm wrong on any of this and if I'm right what do you do with Cutting Units, what's the next step?

Thanks Woody

[dad2nine]

.................................SM is the number of board feet contained in a piece. ...................

But is only the same IF the board is 1" or less in thickness.   This might be confusing to dad2nine.

I think of SM as just that...the surface measure, regardless of thickness, for grading calculations.

Hope this helps.

Got that BeenThere - SM as just that...the surface measure, regardless of thickness, for grading calculations. I know thickness is calculated into BF - SM is the rounded width * length /12.

Thanks

[MikeH]

 I have heard you grade off the worst side of board when selling green and grade off the best side when Kiln dried?

[dad2nine]

I have heard you grade off the worst side of board when selling green and grade off the best side when Kiln dried?

Mike as you already know - I don't really know what I'm talking about, however rule 4 ~ 6 of the NHLA book says:

4. Lumber shall be inspected and measured as the inspector finds it,
of full length, width and thickness. No allowance shall be made
for the purpose of raising the grade, except that in rough stock,
wane, and other defects which can be removed by surfacing to
standard rough thickness shall not be considered. Nothing herein
shall be construed as prohibiting the shipper from improving the
grade or appearance of the lumber at time of or prior to shipment.
The surface grade as determined by the cutting yield shall first be
established by the inspector, after which the thickness shall be
determined. Thickness does not determine grade.
After grade and thickness have been determined, special features,
such as the amount of forty-five degree radial grain for
classification as quarter sawn lumber and the amount of figure as
specified for figured woods and some quartered woods, shall be
considered.
5. The grade shall be determined from the poor side of the piece,
except when otherwise specified. In the cutting grades the poor
side of the board is determined by the side with the lower grade,
or if both sides have the same grade, it is the side with the least
number of cutting units.
When determining the poor side of a board, grade each face
independently without regard to the reverse side of the cuttings.
After the poor side has been determined, then look to the reverse
side for soundness.
6. These rules define the poorest piece in any given Standard or
Special grade, but the respective grades shall contain all pieces up
to the next higher Standard or Special grade as defined in these
rules.

http://www.natlhardwood.org/pdf/2007_Rules.pdf

I know what your saying... When I build furniture, it's the good side that shows and the poor side gets hidden if possible. But for the purpose of establishing "grade" per the rules, the lumber is graded as the inspector find it, per the poor side unless otherwise specified.

I'm glad some are reading this post, I see folks are real quiet  :

Thanks

[Ron Wenrich]

For those that are playing along, a copy of the NHLA hardwood lumber rules can be had at:
http://www.natlhardwood.org/pdf/2007_Rules.pdf  Download it to your computer.

Seems like you're coming along on the grading thing.  You will find that after you start sawing hardwoods, you will know when the defects are about to appear.  Its called reading a log, and you can get a really good read by looking at a cant face and know that defect is on the back side.  Wherever there is a diversion of grain means there is something behind it.  I find that boards usually drop about 1 grade from the face after you get past the good stuff.   ;)

I think you got the idea on surface measure.  After that, you need to go through a couple of steps to get to your grade.

Your first step should be the number of allowable cuts.  For FAS, its SM/4.   We drop all fractions, and there's no rounding up.  Second step is to figure out how many cutting units are needed.  That is 10/12 for FAS.  So, its 10*SM.  SM is always a whole number, with no fractions. 

I would go with the fractions and not try to round your width off.  If you round up, you will over estimate how much clear cuttings you have.  That can hurt you if your buyer gets too much that's over estimated.  Round down and you under estimate, which hurts you. 

The industry revolves around what I call sight grading.  Inspectors have seen so many boards that they pretty much know what boards make which grade without getting down on their hands and knees to figure a board out.  But, they had to go through the process of knowing what makes which grade before they got good enough to do it. 

As for where to get a grading stick, our friends at Bailey's have them. 
http://www.baileysonline.com/itemdetail.asp?item=200N&catID=155

[dad2nine]

Hey Ron Thanks for the info - I'm going to order me a Grade Stick, next week.

To recap:
(SM) Surface Measurement  = Width to the nearest inch * length to the nearest foot /12
(BF) Board Foot = Thickness * Width * length / 12
(CU) Cutting Units = Width to the nearest inch * length to the nearest foot
Where the rubber meets the road FAS Grade Rules
Clear cutting units for FAS Grade = SM*10 or 12/10
Number of cuts allowed to reach yield = SM/4 with (4 max)
Minimum FAS board size 6" x 8' 
Minimum size cutting 4"x5' or 3"x 7'

What next?

[inspectorwoody]

Cutting Units: "Multiply the width in inches and fractions of each cutting by its length in feet and fractions..."

Example: You have a board that is 6.5" x 8'. You have a SM of 4. To make FAS/F1F, you need 4x10=40 units. Say you have a knot that is two foot in from one end of the board. So, now you have a cutting that is 6.5" x 6'. This gives you 39 units. No, your not at 40 but if you have a good clear face cutting etc., no one is going to scream at being shy one unit.

If you only used 6"x6' as your cutting than you only have 36 units. Now 4 units shy is a different story. Say that board is worth 2.00/bf for FAS. Say it is worth 1.75/1com. By not using the fraction, you have created a loss of a 1.00. Doesn't seem like much but it all adds up.  ;)

FAS also allows you to take an extra cutting if you have a SM between 6-15' but with the extra cutting, the yield increases also. SMx11.

FAS also has a special yield: 97% Rule, 2 cuts full width, any length. Pieces 6" and wider with a 6-12' SM. SMx11.64 now becomes the yield. Yield is simply the number of cutting units needed.

Than you get into the pith limitation,wane limitation,splits, knot size etc.  ;)

When I look at the grading stick picture you posted it's got marks in between the numbers, those are 1/2 way marks if I'm correct? So if a board width is over the 1/2 way mark it's rounded up to the next nearest whole number it's it's below the 1/2 way mark it's rounded down to the nearest lower number - right?

You are correct for full lengths. For half lengths, you divide the even number between the two odd numbers by two.

Ron is correct about sight grading. Obviously, we can't cut out 30MBF+ of lumber in a day but if someone questions your call, you have to be able to back it up.  ;)

Bailey's is a great place to due business and I apologize to them and the FF for not recommending them. I personally have always done business with the other for grading equipment. Have to change that. 

[Ron Wenrich]

I think you'll find that a grading stick is a tremendous help.  You won't have to figure out your surface measure, you can see it right there.  If you were doing 12' lengths, any ruler would give you surface measure.  Put it across the board, and you'll be able to see how it works. 

What's next?  Well, you can either move on to other grades or start grading on your own.  When we did the short course, they would lay out a bunch of boards and we would give the boards a grade by going through the mechanics.  Its a really good exercise and you'll be able to see how you can quickly eliminate certain grades as you go down your checklist.

For example, if the width is less than 6", forget FAS.  If you have a Select market, then you may have that grade.  If no Select market, then you're looking at a 1 Common at best.

Sometimes it makes sense to draw out the cuts you are going to use on the board.  It helps you visualize a lot better.  You'll find that there aren't a whole lot of boards that are borderline.  It either makes grade or it doesn't.  Borderline boards can often be upgraded through edging or trimming.

[dad2nine]

Everyone Thanks for all the information - I'm putting together a write up on the very basics of grading. Just so I can capture the information I learned here on FF  :P. You guys are pretty DanG cool to help a guy like me understand the basics of grading.

Thanks again and I'll post this write up a little later when I get it completed.

[dad2nine]

Understanding Hardwood Lumber Grading - the very basics

1) Calculate Board Feet (BF). Measure lumber width, thickness and length. One BF is a piece of lumber that is 1" thick 12" wide and 1 foot long or its equivalent. The formula to figure board feet is as follows:

Thickness * Width * Length
------------------------------------ = BF
           12   
It's best to round your measurements for simplicity sake. For example you find a piece of Oak lumber that measures 2 1/8" thick, 7 3/4" wide and 8' 3" long. Round down the thickness to the nearest 1/4", width to nearest whole inch and length to the nearest whole foot. In our example we'll make this piece of oak lumber a thickness of 2 inches, a width of 7 inches and a length of 8 foot, by rounding all three measurements down as specified above.

Thickness (2) * Width (7) * Length (8 )
------------------------------------------------- = 9.3 BF
    12

2) Calculate Surface Measure (SM). SM is nothing more than the surface measurement of one of the two faces of a piece of lumber. It's calculated by measuring the width and length of the lumber and dividing the resultant by 12. If the SM calculated winds up to be a fraction, round the fraction to the nearest whole number, (.5 and above up, .49 and below down). Take note that thickness is not taken into account when determining SM.

Width * Length
--------------------- = SM (rounded)
      12   

Again it's best to round down width to nearest whole inch and length to the nearest whole foot. For our example piece of oak lumber, it measures an actual of 7 3/4" wide and 8' 3" long. Again for calculation simplicity, we'll round the width down to 7" and length to 8'

Width (7) * Length (8 )
---------------------------- = 4.67 SM (round up) = 5 SM
            12   

3) Calculate Cutting Units (CU). A Cutting Unit is one inch by one foot or its equivalent. Again note, lumber thickness does not play a role in calculating CU. The formula for CU is merely the multiplication of the width and the length of a piece of lumber. The result is the number of cutting units contained within that piece of lumber. As we'll see later SM and CU are vital in determining the grade of the piece of lumber.

Width * Length = CU

Similar to SM and for simplicity sake, it's best to round down the lumber width to it's nearest whole inch and it's length to the nearest whole foot. So we'll multiply 7 x 8 and arrive at 56 cutting units.

Width (7) * Length (8 ) = 56 CU

First a word about defect, for the purpose of understanding the very basics of hardwood lumber grading, we'll consider any knot, check, split, dote, hole, wane, worm holes, etc... a defect. What we are after is clear cuttings out of a piece of lumber. The grade rules cover defect and what's allowed and what's not per grade and species. Remember when reading this, that it's my intent to cover grading rules details. Details regarding hardwood grading rules can be found in the latest release of the National Hardwood Lumber Association Hardwood Grade Book.

4) Understand the basics of FAS grade requirements.

• FAS minimum board size is 6" wide by 8' long. Any board irregardless of how clear it's faces may be can not meet a FAS grade unless it meets or exceeds the minimum board size.
•    A FAS clear cutting can be no smaller than 4 inches wide by 5 foot long or 3" wide and 7' long. A cutting can be larger, but must be at least be these sizes.
• FAS number of allowable cuts is SM divided by four with a maximum of 4 cuts. The result is rounded down to the nearest whole number (drop any fractions)
  
  SM
  ----- = FAS allowable cuts (Max 4)
    4   
  
• FAS CU Yield is SM times ten. This is the minimum allowable clear wood form the lumber, for a board to make FAS ten twelve's of it's wood must be clear and be contained within the minimum FAS Clear cutting size and be cut in the FAS number of allowable cuts

5) Lets put what we've learned into perspective, with an example. The example below represents a piece of lumber that is 1 1/8" thick at it's thinnest section. The black areas represent it's poorest defective face and the dashed line is where the board would be cut to yield it's greatest clear cutting unit. Does it qualify for a FAS grade?



5-1) flip board to it's poorest side, All hardwood is graded according to it's most defect ridden face.

5-2) First calculate Board Foot (BF)

Thickness 1 * Width 10 * Length 8
-----------------------------------------------  = 6.67 BF
           12   

5-3) Calculated the surface measure (SM)

Width 10 * Length 8
--------------------- =  6.67 SM (7 rounded)
      12   

5-4) Calculate the number of cutting units contained in the example

            Width 10 * Length 8 = 80 CU


5-5) Calculate number of allowable FAS cutting to make grade

SM (7)
----- = 1.75 FAS allowable cuts (1 fraction dropped)
  4   

5-6) Calculate FAS CU Yield required
         
         SM (7) * 10 = 70 FAS cutting unit Yield required
   
   
5-7) CU of clear cutting Width 9 * Length 8 = 72 Clear Cutting

In this example with one allowable cut the board has made the FAS Grade – this is assuming both sides of the board are clear and contained in the clear cutting units made by the single allowable cut. Also note if both edges were clear and there was defect within one foot of the end of the example board, it would also make FAS grade with a width of 10 and a length of 7 resulting in clear SM of 70 matching the minimum FAS CU required.

I tried to format best I can - please correct me if I have misunderstood anything.

Thanks again everyone...