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Author Topic: Grading  (Read 9107 times)

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Offline dad2nine

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Grading
« on: January 17, 2008, 10:37:57 PM »
Read through the NHLA grade rule book a few times and managed to stay awake the last time I read it.

for the life of me I can't figure out what the heck they are talking about as far as "cutting units" what the... can someone please explain it to me in a way I can understand...

two examples:

1x8-8 clear (no defect)
1x8-8 5" knot 1 foot from the end of the board

how many cutting units in each? assuming oak - what's the grade for each?

Thanks

Offline Dave Shepard

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Re: Grading
« Reply #1 on: January 17, 2008, 10:44:20 PM »
This is why I like to saw pine, square it up and saw straight to the deck, and the boards don't move around on you. :)

I bet Inspectorwoody could tell you a thing or two about grading. :D I look forward to this discussion, as I, too, have been severely confuzzled by hardwood grading rules. Pine is easy, you've got your boards with knotholes, and them that don't. ;)


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Offline dad2nine

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Re: Grading
« Reply #2 on: January 17, 2008, 10:58:55 PM »
Here's a link to da grade book - http://www.natlhardwood.org/pdf/2007_Rules.pdf

starting on page 12 is where I get lost, or 37 (see below).

-----------------------------------------------------------
37. CUTTING UNIT METHOD: The percentage of cutting in a
board or plank is determined under the Cutting Unit Method.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.To determine the number
of cutting units required,multiply the surface feet of the board or
plank as tallied as follows:
For 97%multiply surface feet by 11.64.
For 91-2/3% (11/12) cutting as in FAS, multiply surface feet by
11. For 83-1/3% (10/12) cutting as in FAS, multiply surface feet
by 10. For 75% (9/12) cutting as in No. 1 Common, multiply
surface feet by 9.
For 66-2/3% (8/12) cutting as in No. 1 Common, multiply
surface feet by 8.
For 50% (6/12) cutting as in No. 2A and No. 2B Common,
multiply surface feet by 6.
For 33-1/3% (4/12) cutting as in No. 3A Common, multiply
surface feet by 4.
For 25% (3/12) cutting as in No. 3B Common, multiply surface
feet by 3.
Example:Aboard 9-3/8"wide by 16' long contains the following
Clear-Face Cuttings:
8-1/2" x 6' 51 cutting units
3" x 9-1/2' 28 1/2 cutting units
4" x 2-3/4' 11 cutting units
3" x 3-1/3' 10 cutting units
Total 100 1/2 cutting units
The surface feet of the board is counted 12, and the number of
cutting units required for 66-2/3% cutting is 8 x 12 = 96 cutting
units.This board contains more than 66-2/3%cutting, therefore it
grades Standard No. 1 Common provided it does not contain pith
in excess of one-half its length in the aggregate.
-----------------------------------------------------------

Thanks

Online beenthere

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Re: Grading
« Reply #3 on: January 17, 2008, 11:03:14 PM »
dad2nine
(That paragraph you quoted contains a lot of info...you are right, it does   :) :) )
Hardwood NHLA grades are a bit confusing. Try reading some in Chpt 5 of the Wood Handbook
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch05.pdf
and look at table 5.1

Cuttings are just the area of clear wood needed in a grade to meet that grade. The additional end-foot rule, like minimum widths and lengths, further limit what quality is acceptable to a particular grade. The NHLA grades are called "cutting" or "factory" grades, with the intent that the lumber will be further manufactured into something like furniture parts. These grades are just for sorting hardwood lumber into different groups (or grades) to identify thier potential, so a buyer and seller can come to an agreement on price. That is simplifying it quite a bit, but sometimes there is confusion with softwood grades where the piece is graded for its end use (albeit, there are softwood grades that grade for remanufacture too...). Some of that is spelled out in Chapter 5 as well.

Hope it helps.
Inspectorwoody is one of several here that can help with the actual NHLA grades.
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Offline dad2nine

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Re: Grading
« Reply #4 on: January 17, 2008, 11:18:00 PM »
Thanks beenthere - I'm printing out the hardwood section and will read it tonight (if I can stay awake) make it might turn on the light bulb.

Is there a dummy series like, NHLA hardwood grading for dummies?

Offline Ron Wenrich

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Re: Grading
« Reply #5 on: January 18, 2008, 06:03:25 AM »
Cutting units are pretty easy to figure out.  For your example of a 1x8x8, you don't have to worry about the thickness.  That figures into footage, not grading.  The number of cutting units you have are 64, (length * width).

To really be able to grade, you should have a lumber grading stick.  It makes the process a whole lot easier.  All the grade stick does is tell you how much your surface measure is in a board of a particular length.  You put it on the edge of the board, and the number is on the other edge.  SM = surface measure for the rest of the discussion.

Your first step is to measure the surface measure in the board.  In this case, that comes up to 5. 

In order to make an FAS board, you'll need 10/12 of the board to make grade.  In cutting units, it will come out to SM*10 or 50.  You'll have to do that in 1 cut.  That comes from the rule that says SM/4 for the number of cuts in and FAS board.  Remember that you're grading the worst side of the board. 

The rules also state that the minimum size of cut for FAS is either a 3"x7' or a 4"x5'.  In this example, its a clear board, so you'll easily get the 50 cutting units.  But, if there were a defect at 3", then maybe you'll have to use another rule to see if it comes up to grade.

You can have an additional cut, if you can come up with 11/12.  So, you need 55 cutting units (SM*11).  If one cutting is 4"x8', you'll have 32 cutting units (lenght*width).  If the other cutting is 3"x8', you'll have 24 cutting units.  Total is 56 cutting units.  Total needed is 55.  You got an FAS board.

If that were the best side, then your back side would have to grade out at 1 Common to get a F1F.  Wane comes into play since the backs have to have solid wood and there are certain maximums in the amount allowed for any grade.

Each grade has a minimum size of cutting, and a minimum amount of % needed to make grade.  The rules seem confusing, but after you get the hang of it, you can get pretty good.

Its important to learn about grades because its the backbone of the hardwood industry.  You should also learn how to position the knots to get the longest clear face cuttings.  It really effects the grade.
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Offline zopi

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Re: Grading
« Reply #6 on: January 18, 2008, 08:01:43 AM »
Gah...wha?  ;D

If one of the grading gods would put up some pictures of the process...That'd be great!

we like pictures... :D
Hmmm..one of you guys oughta put together an online basic grading course...you could get rich uhhh...well liked. ;D
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Offline Trees_rock

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Re: Grading
« Reply #7 on: January 18, 2008, 09:54:53 AM »
I have been thinking about grading lately myself.  Dose anyone know where I could find a grading courses near southern WI. How much do basic grading courses cost?  I would not need a formal class if someone knows granding and needs some help around the mill and could teach me a thing or two about grading i would  be up for that to.  I learn a lot more when i can see things.


Thanks  ;D

Justin   

Offline dad2nine

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Re: Grading
« Reply #8 on: January 18, 2008, 10:45:09 AM »
Ron thanks for your reply - I really do appreciate you sharing your time and knowledge, you explained  SM and cutting units in a way I can actually understand, hopefully others can too.

For simplistic sake I was wondering if you could zero in on quartered oak and explore the rules for just that species and cut... I have a few example pics I could post and maybe we could do a virtual grading of a few boards and discuss the rules?

Oak is pretty common species, so it may benefit a lot of people and spark some interesting dialog. Let me know what you think, if your game I'll go ahead and post some pics and SM measurements. If we have to get closeups of defects I can do that too. Basically whatever info is needed I'll try and supply so we all can learn for those of you who are in the know.

Appalachian Hardwoods offered a 3 day class last year about this time. Don't know when the next one is planned http://ahc.caf.wvu.edu/index.php?option=com_content&task=view&id=368&Itemid=2

Thanks man  ;D

Offline Ron Wenrich

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Re: Grading
« Reply #9 on: January 18, 2008, 11:16:14 AM »
I'd rather have Inspectorwoody handle the particulars on quartersawn.  I don't deal in it, and I've only had a short course in grading.  I have graded lumber and it stood up against the graders.  But, I won't push a board as hard as other graders might.

Here's a good publication for you to look over.  Its a Forest Service document that you can download to your computer.  http://www.srs.fs.usda.gov/pubs/misc/hardwood_lumber_grading.pdf

Its called the simplified guidelines to hardwood grading.  It will really get you started, especially after you get the cutting units, surface measure, and how to figure up what you need.  Eventually, you'll look at a board or log face and say that you have X amount of surface measure and I need Y number of cutting units in Z cuts. 

You can post some pictures if you like.  The problem is that you can't really get all the necessary measurements from a picture to make the grade determination.  But, it may be a worthy experiment.  Give it a try.
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Online beenthere

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Re: Grading
« Reply #10 on: January 18, 2008, 11:57:29 AM »
Ron
You made some very good comments about grading, and that publication by Walt Smith is a good one too. There is a reason it has remained in existence for a good many years. Walt Smith was as fine a southern gentleman as one could ever know. He was in our "Tom" calibre, for sure (or visa-versa  :) ). Very personable man with a keen interest in transferring information into a form that regular people could understand it...

Inspectorwoody has discussed the idea of putting on an hardwood-grading short-course. At least he was contemplating it...now that may have been prior to him getting busy with some other extracurricular activities in his spare time from his full-time grading job, not the least of which is a circular mill he is resurrecting.  ;D ;D

Hardwood grading, I was told, is mathematically definable. A hunting partner of mine, back in the 70's, developed the software routines to take x,y board and defect information and determine the NHLA grade of the board. I've searched, but don't find that available..figured it was written in Fortran or Cobol language and not translated into available software for more modern computers.

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Offline dad2nine

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Re: Grading
« Reply #11 on: January 18, 2008, 12:35:30 PM »
Ron, I'm not trying to shoehorn you into anything your not comfortable with, but... You got a leg up on me and sure would like to understand what you know, if I could...

I would be more than willing to post pics and measurements of defects and do whatever is necessary to get a grade on the piece pictured.

With your's and others knowledge here on this site - you guys might be able to pound into my brain what I need to know, so I can get a handle on what I'm looking at. My goal in this whole ordeal is to become a better sawyer. I don't think I have any plain sawn (cathedral grain) oak, I'll have to check. If I don't have any could we treat a few pieces of quartered oak that I have as plain sawn?

Personally I think my understanding of grading is a bastardized mix NHLA and Hardwood flooring manufactures, only because there is no reference to rift sawn lumber in NHLA rules only quartered.

Beenthere - Thanks for your replies also, I read through the http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch05.pdf last night, need to read it again - not much stuck since I woke up with it laying on my chest.

Thanks

Offline Ron Wenrich

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Re: Grading
« Reply #12 on: January 18, 2008, 01:10:42 PM »
You're not shoehorning me into anything.  Put the pictures up and we can go over them.  Shoot, we can even give the quartersawn thing a try.  It can be a learning experience for all us, me included.   :D

What would help is if we had 2 sides of a board, and the measurements.  If you want, give what you think is the grade and how you got to that conclusion.  Then I can give an opinion, and hopefully, someone will correct me when I'm wrong. 

There are often more than one way to get your cuts, so there isn't any absolute perfect way.  Sometimes you can reach the same conclusion by going different routes.   ;)
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Offline dad2nine

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Re: Grading
« Reply #13 on: January 18, 2008, 01:16:41 PM »
Ron ok here is board #1 this is the worst side because of the worm hole at the bottom. Board has been kiln dried and measures, 4/4 thick 7 3/4" wide and is 8' 3" long - I would calculate Board Foot as 1 x 7 x 8 / 12 or 4.6 BF. I ran it through the planer so we could get a good look at the defects.

The series of pics start from the bottom and move up the board. Click on the thumbnail for a close up. The last pic is pretty bad (hard to get a full length shot) I may have to move it out from under the light.




















What Grade - I don't know, but thinking... maybe 1F1 only because this is the worst face. The other side looks much better without the worm hole.

Let me know what you need (more pics measurements of knots, defect, close ups etc...)

Thanks man

Offline Ron Wenrich

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Re: Grading
« Reply #14 on: January 18, 2008, 01:46:35 PM »
It would be a lot better if we could get the whole board in the shot.  That might be one of the drawbacks.

First off, you have 5 surface feet in the piece.  You better figure at the actual width.  The length would be to the closest foot.   Then we can assume the front is clear.

For a 1 Common back, we need to get 8/12 in 2 cuts.  We figured the number of cuts as (SM+1)/3.  So figuring at 5 SM instead of 4 has gotten you a free cut.  The number of cutting units we need is 40, which is SM*8.

I see a small defect in picture #2.  Then, you have the stain and worms in pictures 4-9.  Since we only need 40 units, then if we had a 5" wide clear piece for the whole length, that would give us the yield. 

If not, then we can have 2 cuts.  One cut can be as short as 2', as long as its 4" wide.  Let's say that you would have a 7" wide cut for the first 2 pictures that would be 2' long.  That gives 14 cutting units, and I now need 26 units in the remaining 6'.  A 4" wide cut will give you that at 6'.  Or a 5" at 5' will give it to you.  The board easily has that.

The only drawback is if the stained area has dote.  That would effect your sound back cuttings from your FAS side.  Your backs must be sound...no wane, rot or missing wood.

The only difference between quartersawn and flat sawn grades is in FAS.  A 5" piece is acceptable, but must be clear if the SM is 3 or 4, and 11/12 in 1 cut for 5 to 7' SM.  It also needs 90% in the aggregate cutting area on one face to be classified as quartersawn, if I read the rules correctly. 


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Offline dad2nine

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Re: Grading
« Reply #15 on: January 18, 2008, 02:01:00 PM »
I just realized I did a forum NO NO - can't link to other sites - I'll get a new set of pics up - I just downloaded XAT so I'll compress them and upload them to FF. Ron I was thinking I need a btter shot of the whole board. and I may mark it off into 1' sections if that would help? Give me a little time to digest what you just wrote...

Thanks

Offline dad2nine

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Re: Grading
« Reply #16 on: January 18, 2008, 02:29:42 PM »
Even after compressing with xat - I'm having some difficulty uploading pics to FF...

"File Name/URL   Error Message
1. 1.jpg   The height and or width of the uploaded picture is more than that allowed by the gallery config."

What is the allowable " height and or width"?

Offline Dan_Shade

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Re: Grading
« Reply #17 on: January 18, 2008, 02:37:14 PM »
450x450 pixels :)
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Offline dad2nine

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Re: Grading
« Reply #18 on: January 18, 2008, 03:01:33 PM »
Ok that was a little painful... got the pics back... 450 pixels max, height and width and less than 32K.

I'm going to work on getting some better pictures up maybe with some reference marks at 1' increments

Thanks


Offline dad2nine

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Re: Grading
« Reply #19 on: January 18, 2008, 05:01:28 PM »
Ron, I worked on the photos a little - what I did it divide the board into one foot sections and labeled them as such. I also drew a line best I could as if I were going to straight line rip and joint the board to a width of full 6". The way I'm seeing this now, I think I could squeeze a clear 1x6 -7' or a 1x4-8 because of the worm hole in the first 1' of the board. What grade would that be?










Thanks


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