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Post by sdb777 on Dec 27, 2009 5:08:11 GMT -6
Been wondering why wood is always expressed in the 4ths?
For instance, 2x2x36 maple blank for tuning is actual called 8/4 x 36 at the lumber yard. Why? I mean 2x2x36 tells so much more, and it's not any harder to say......
Does anyone know the history behind the 4ths?
Scott (curious about the weird) B
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Post by sachbvn on Dec 27, 2009 7:41:21 GMT -6
I know what you mean Scott - but I believe it is generally expressed in "quarters" - not "fourths" - but - to you and me, their the same thing.
The reason why is because dimensional lumber "2x4x96" for example - is primarily used in general construction. Hardwoods are sold as "board feet." Now - you have probably noticed you do not go to your local hardwood dealer and tell him you want a "1x6x48" Cherry board.... - what YOU need to do is find a board with those dimensions and buy the whole board - may be close to size, may be quite a bit bigger. Also - the only measurement you really HAVE to have - is the length. You can always glue two boards together to make a real wide board.... but - you can't really add to the length of a board, and adding to the thickness would require laminating two boards and often that would not be appropriate for the situation.
Starting to visualize that woodworkers needs in lumber and a construction crews needs in lumber are different?
Another example - you build a wall - you order x amount of 2x4's - you can even get them cut to stud length so you have to cut VERY little..... a woodworker is probably going to joint one side of the board, joint one face of the board, plane the other face of the board - and finally rip the remaining edge of the board - leaving a perfectly squared board to work with.....
Hope that helps - as far as the "history" not sure when this all started happening.
Zac
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sawduster
Moderator 
The Motley Crew
Posts: 1,831
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Post by sawduster on Dec 27, 2009 9:05:27 GMT -6
If you put a ruler to that 8/4 piece you will likely find that it is just a little shy of full 2", especially if it has been surface planed. What it goes back to is that the ?/4 was the original thickness cut at the mill. Some shrinkage from drying occurs and when the board is surface planed it becomes a bit thinner yet. A 4/4 board, for instance, will be somewhere around 7/8" thick, maybe a little more or less depending on the species.
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Post by TDHofstetter on Dec 27, 2009 10:26:00 GMT -6
The sawmill saws lumber to quarter-inch increments. They don't do it to smaller increments because it'd be meaningless in roughsawn wood, but folks don't want to buy it in half-inch increments 'cause that represents a LOT of planing to dimension it down to quarter-inches again if ya want - like - 5/4 lumber. Folks DEFINITELY won't accept 2" lumber if they need 5/4, since they'd be planing away (after paying for) roughly half the stock.
Another benefit to sawing it to quarters is economy; when you get to the far side of the log & all you have left to make a reasonable board is 1-3/8", you can saw a 5/4 board from it instead of a 1" board & sell it for more buckolas.
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Post by Leo Voisine on Dec 27, 2009 13:02:48 GMT -6
Good question.
My guess is that the measuring system goes back in time, and to the sawmill.
If you watch you tube videos on antique sawmills, they had mechanisms to guide the tree through the saw mill. Those mechanisms might have ratcheted in quarters of an inch. They most likely needed to count the notches. So if they were going to cut a tree into 2" thick boards - they would ratchet eight times - or 8 quarters. That would result is something like 2" thick wood.
That is me guessing - based on some limited knowledge and watching you tube vids on antique saw mills.
So the terminology is old - but that is the terminology wood dealers and sawmills talk in. I have heard it said that a forestry guy can look at a tree and guesstimate how many board feet the tree will yield.
Board feet - is how wood is sold. Even softwoods. It is easier to calculate a forest full of wood that way - or even a tree full of wood.
The finished product - is called "dimensioned" lumber and is basically sold in linear feet. This is what most people see at hardware stores, or Lowe's, or Home Depot and even some lumber yards.
Most hardwood dealers sell rough sawn wood. It is called "rough sawn" because it is not finish milled to become "dimensioned" lumber. Because it is still in the rough state - as though it just came from a saw mill - it is still considered in mill terms -- hence, rough sawn, and in quarters of an inch.
Some hardwood dealers will - "dimension" the wood for you, along with a charge. Some will not.
Anyway - that's my take on it.
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