LumberJocks

Need help understanding

  • Advertise with us

« back to Woodworking Skill Share forum

Forum topic by yakerjax posted 09-03-2007 02:37 AM 1036 views 0 times favorited 14 replies Add to Favorites Watch
View yakerjax's profile

yakerjax

60 posts in 2625 days


09-03-2007 02:37 AM

Sorry to sound so ignorant but I am so confused on Board Foot and Linear Foot…. I do not understand the difference..
I also do not understand 4/4 etc.. That I see both on here and in some of the plans and in magazine articles..

I am new at all this and never was good with measurements and math..

Thank you all for understanding and helping me to understand..

Cheryl


14 replies so far

View Douglas Bordner's profile

Douglas Bordner

3966 posts in 2729 days


#1 posted 09-03-2007 02:48 AM

Stole this here:

A lineal foot measures one dimensional distance and is expressed as a single number to represent that distance. The length of a 2×4 expressed as 96” illustrates lineal feet.

Square foot measures area and is a two dimensional calculation expressed as width x length. The amount of tile needed to cover a 10’ x 12’ floor will be 120 square feet.

Board feet measures volume and is a 3 dimensional calculation. A board foot is a volume of lumber measuring 1” thick x 12” long x 12” wide. A board foot is 144 cubic inches. A piece of wood 12” wide x 24” long x 1/2” thick is the equivalent of 1 board-foot of lumber.

4/4 is a ratio used to express the thickness of hardwood
4/4 = 1 inch, 6/4 = 1.5 inches, 8/4 = 2 inches

In the board foot example shown above the piece of wood is 12˝ wide x 24˝ long and is a piece of 2/4 lumber.

-- "Bordnerizing" perfectly good lumber for over a decade.

View WayneC's profile

WayneC

12290 posts in 2763 days


#2 posted 09-03-2007 02:51 AM

Also probably good to point out is that the dimensions above are when the lumber is cut. It is typically not as thick as identified above as there is some shinkage as it dries.

Wikipedia has a pretty good entry on this subject under lumber

http://en.wikipedia.org/wiki/Lumber

-- We must guard our enthusiasm as we would our life - James Krenov

View yakerjax's profile

yakerjax

60 posts in 2625 days


#3 posted 09-03-2007 03:34 AM

Argh.. I am going to have to study on this one.. I just can’t get it to stick.. I appreciate all the links because I am going to need them… I will study them I know its gotta be simple to understand I am probably over thinking it… I will lay it down for tonight and come back tomorrow and reread and I feel certain I can get it… Again thank you all for the quick tips and links… You all like always are awesome..

Thank you
Cheryl

View Karson's profile (online now)

Karson

34878 posts in 3066 days


#4 posted 09-03-2007 05:40 AM

Cheryl:

let me confuse you more.

Most sawmills cut their wood in even foot lengths like 8’ or 10’ etc.

the boards are random width. Whatever they are able to get out of the log. so when they are calculating BdFt of lumber they group the boards by length
1-8” x 8’, 3-6” X 8’, 1- 10” x 8’ so what they have is 1 X 8 = 8 + 3 X 6 = 18 + 1 X 10 = 10 or 8 + 18 + 10 = 36” in width. So they multiply the 8’ in length X the 36” in width = 288. Since one figure was by ” and the other is by ’ they divide by 12 (instead of 144) and they get288 / 12 = 24BdFt.

The sawmills tend to use the length in ft and not inches because the math is easier to figure out.

So it’s take all of the widths and add them together so the widths one the previous example is 36 ” or 3 ft. then it multiple 3 X 8’ for the length and you get 24.

If you have a stack of lumber 4 ’ wide by 8’ long you have approx 32 bd ft per layer and if there is 20 layers you have approx 640bd ft. and you start your negotiation from there.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View brunob's profile

brunob

2275 posts in 2835 days


#5 posted 09-03-2007 05:59 AM

So let me weigh in here with more confusion:
A board foot in simple measurement could be 12” by 12” by 1” = 144 square inches, it could also be 6” by 24” by 1” = 144 square inches, it could also be 6” by 12” by 2” = 144 square inches – all = one board foot.
Linear measure is the simple length of a board. It could be 1’ by 6” by 2” but the linear measure is 1’. It could be 6’ by 4” by 2” but the linear measure would be 6’.
4/4 referes to thickness in quarters of an inch. a 4/4 board is 1” thick (4 quarters). A 6/4 board is 1 1/2” thick (6 quarters).

-- Bruce from Central New York...now, if you'll pardon me, I have some sawdust to make.

View WayneC's profile

WayneC

12290 posts in 2763 days


#6 posted 09-03-2007 06:24 AM

: ^ O

-- We must guard our enthusiasm as we would our life - James Krenov

View dennis mitchell's profile

dennis mitchell

3994 posts in 2980 days


#7 posted 09-03-2007 06:55 AM

Board foot is surface area…like a yard of fabric. Linear foot is the length …like a foot of rope. 4/4 is a silly way of saying an inch thick.

View Thos. Angle's profile

Thos. Angle

4435 posts in 2628 days


#8 posted 09-03-2007 06:59 AM

YEAH!!!!!

-- Thos. Angle, Jordan Valley, Oregon

View Sawdust2's profile

Sawdust2

1467 posts in 2753 days


#9 posted 09-03-2007 04:29 PM

Sorry, Dennis. Board foot is NOT surface area, altho’ linear foot might be.

The major difference for the user is if the wood is quoted in quarters it is rough cut and if quoted in fractions it is generally finished. If it is finished on at least two faces the other term you often see: S2S which generally means that the edges are still rough but the wide surfaces have been planed smooth.

4/4 rough cut usually shrinks down to 15/16ths when it is dry but that depends on the mill and the drying method and the geographic area of the country.

-- No piece is cut too short. It was meant for a smaller project.

View snowdog's profile

snowdog

1132 posts in 2648 days


#10 posted 09-04-2007 01:58 PM

<just>
Whats next? Will we need mass spectrometers to calculate the weight of the wood relative to earth and then add extrac value to the BF your buying? Oh yeah moistor meters are kinda like that :)
</end>

-- "so much to learn and so little time"..

View Dadoo's profile

Dadoo

1767 posts in 2656 days


#11 posted 09-04-2007 09:23 PM

Cheryl, I find it’s good practice to be buddy-buddy with the lumberyard guys. They’re always happy to shoot the bull and help you with any questions you have. They’ll even allow you to browse about the yard and see what else they might have in stock and point you to the damage pile where you can find good stuff possibly for free. I find that a lot of my new projects come to mind just from browsing. (Which is why my wife won’t allow me to hang around the junk yards anymore!)

-- Bob Vila would be so proud of you!

View yakerjax's profile

yakerjax

60 posts in 2625 days


#12 posted 09-04-2007 10:38 PM

You all are great.. I am still green at it but I think I have the idea now.. I will be exercising my brain in the next few days as I make my first trip to the local mill (I know they just gotta love us green folk teehee).. I have been a frequent at the local lowes and home depot so much my non wood working gal friends are worried about me.. I shop more for “guy” stuff than girly girl stuff teehee.. Husband loves it tho…
The information and help you all left me is great… I can say I understand it better now and with more experience with the measurements and terminology I will be talkin like a pro soon thank to all of you all…

Thank you again for your help as always you all are great

Cheryl

View MsDebbieP's profile

MsDebbieP

18615 posts in 2826 days


#13 posted 09-04-2007 11:09 PM

you and me, both, Cheryl… we could go wood shopping and fake it so well, the guys would think we knew what we were talking about!! :)

-- ~ Debbie, Canada (https://www.facebook.com/DebbiePribeleENJOConsultant)

View Woodminer's profile

Woodminer

69 posts in 2603 days


#14 posted 09-05-2007 04:48 AM

Let me jump in here for a minute, Cheryl.

Tell the mill guys that you’re a newbie and to avoid talking technical with you for the moment, but that you’ll catch up soon! They’ll help you. Until then…

Wood that has not been milled into shapes or anything beyond simple dimensional lumber is often sold by the board foot (BF). If you have a chunk of wood that’s 2” thick and 12” square, that would be 2 BF.

Wood that HAS been milled to some specific shape (moldings, dowels, things like that) is usually sold by the linear foot. The seller knows how thick it was and how wide it was and is. They prefigure their labor and other overhead costs and know how much they have to get for each linear foot of it in order to make their prescribed amount of profit.

It makes more sense to sell moldings and such by the linear foot because we as consumers would whine severely if we were paying BF prices when most of the wood is already on the shop floor!

Hope that helps.

-- Dean, Missouri

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase