Explain this to me please

[Madman_Mark]

What are all these diferrent measurements I see for lumber - 4/4, 12/4 etc etc.... ? Thanks

[Tom]

Quarter scales are a marketing measurement for rough cut lumber that insures a full inch is available to the user/finisher.   It is a measurement in quarter inches and the roughcut lumber must be at least that thickness to be sold as such.  For example, a board is 4/4 (four quarter) from a full one inch of thickness up and until it reaches 5/4 (five quarter), at which time it can be sold as 5/4.

Just because 5/4 produces a finished product of 1" thickness doesn't mean that roughcut boards can be legitimately sold as 5/4 boards.  This is why you also hear the terms "Finished" and "Nominal" used when the sawyers are talking with people who deal in finished lumber.

Finished lumber continues to use lesser measurements.  A finished 2 x 4 can now be 1 1/2" thick by 3 1/2 inchs wide.  Those are its "Finished" dimensions.  A rough cut, or Nominal, 2 x 4 must be at least a true 2" x 4" to be sold as such. Though some buyers will accept anything that will allow them to reach the dressed sizes, it's the buyer who must accept less.

You will also find that the term "Board foot" is a volume measurement of rough dimensions and not intended to be used for finished sizes.   When figuring board footage, the nominal measurements are used.

[ARKANSAWYER]

  It is how ole timers know when they are talking to rookies.  It is like the secret hand shake at the Piggy Roast.  When you learn it there will come a day when you will know it.
  What Tom said.

[Magicman]

It is sometimes funny to listen to folks using those terms.  Novice woodworkers throw them out so that you will know that they are "wood savy".   I once asked a farmer if he wanted his lumber a full 4/4.  He said "no", he wanted it a full one inch.     Bottom line, it all depends upon who you are talking to, but Tom gave you the correct answer.   

[sdunston]

Well said Tom,
 And as I was reading i was thinking about the metric system, Is 3/4 used in all countries or do they use 19mm, is it a brd foot or a brd meter? I know I have seen pic's of mills that use metric magnetic setworks rules. Just wondering?
Thanks Sam

[paul case]

i have heard our aussie friends talk about meter cubed. it gets confusing? easy to confuse me though. pc

[tyb525]

A safe rule of thumb that I use is get your rough lumber a quarter thicker than you want your finished boards. If you want 3/4" planed boards, get rough 4/4. 1" planed, get rough 5/4, and so on.

[Ianab]

Well said Tom,
 And as I was reading i was thinking about the metric system, Is 3/4 used in all countries or do they use 19mm, is it a brd foot or a brd meter? I know I have seen pic's of mills that use metric magnetic setworks rules. Just wondering?
Thanks Sam

Here, and is Aussie, the standard measure would be Cubic Metres. Simple to visualise, it's a stack of timber 1m x 1m x 1m. Measure the stack and do some simple maths.

25mm is about 1", so a 4x2 becomes a 50x100. My planer has a stop at 19mm, approx 3/4" and that's the common finished size for boards.

No one locally would use brd/ft as a measurement.

Because NZ converted to metric in the 70s there are still us folks that grew up with inches, so most rulers and tapes still have both inches and metric on them.

Ian

[Ernie]

Because NZ converted to metric in the 70s there are still us folks that grew up with inches, so most rulers and tapes still have both inches and metric on them.

Ian

If I want to visualize a building or shed or virtually anything labelled in metrics, I always do the mental conversion into imperial so I actually know what size it is.  But that said, when cutting and machining I work in millimeters.  Must be my feeble attempt at becoming metrificated. Although I still call a 50 X 100 a 2 by 4 like I did in Canada not a 4 by 2 kiwi style.

[Tom]

I've tried to do that Ernie.  The "Smart" people in the USA have been trying to get the working people to use metrics for years.  As hard as I've tried, I just can't picture the metric in my head.  In all honesty, the first measurement I think of is a 100yd football field.   I think of my foot as a foot and my height as six feet, for comparison's sake, even though they aren't.   My hand spread is 9 inches, my hand span about four, and I've no idea what a kilometer is, but a mile is about half way between here and the crossroads.  A teaspoon of sugar goes in my tea, a tablespoon in my milkshake and I buy butter a pound at a time.   

I suppose that I'm a lost soul.  They'll have to wait on yet another generation too.  My sons and my friends children are all talking in feet and inches too. 

[tyb525]

I was taught metric in elementary, but that's about it. We used it in science too, but those were all measurements.

I can't estimate anything in metric, it's just so much easier with imperial. They way it works out, and is easily divided, and is in fractions, instead of decimals, makes it handy.

[bandmiller2]

Every trade has its jargon so you can tell the pilgrims from the players.I'an too old to go metric and won't RIP unless 6 feet under. Frank C.

[paul case]

i have just sorta got down pat counting backwards in  fractions( a key to being a good sawyer) in my head and there is no room for anything else new.
i have a computer memory. i have to forget something old to remember something new.
pc

[Ianab]

Every trade has its jargon so you can tell the pilgrims from the players.I'an too old to go metric and won't RIP unless 6 feet under. Frank C.

Make sure they don't make the hole 2 metres deep 
(6' 6&3/4")
 
Ian

[DanG]

Well I ain't got a clue what a "metre" is, but I'm fairly conversant in meters and the derivatives thereof.  It is just like speaking a second language.  You will always think in your native tongue(or tongeu if you're Kiwi  ) even if you can speak in another.  In military aviation we had to think in kilometers a lot, and being too cheap to pay a mechanic, I have to think in M&Ms a lot.  If 1/2 is too little and 9/16 is too big, go with a 13.  It ain't that hard.

[Magicman]

Just wait until we convert to a metric clock/calendar.    Let's see: 100 seconds to the minute, 100 minutes to the hour, 10 hours to the day, 10 days in a week, 10 weeks to the month, 10 months to the year.....

[Cedarman]

I think the bad taste of going metric was that they tried to teach it by making kids convert from english to metric and metric to english with all the messy arithmetic involved.  It made kids heads hurt.  If they had just made kids measure in metric, estimate in metric,  calculate in metric, they might have gotten the job done.  How is metric taught these days?
Doesn't 4/4 hardwood go by a different thickness rule than 4/4 softwood?

[sawguy21]

Mag, you are just trying to make a bad situation worse. In Canada, the kids don't know what a foot or a pound or a mile is. We were metrified in the mid 70's, the imperial system disappeared from the school system. It's funny, I still think in terms of pounds and inches yet when I go south of the border I find myself converting miles to kilometers because that is what I am used to.
Back to the original topic, I like bandmiller's line about players and pilgrims.

[Ernie]

I think the worst is gas mileage.  I know well what 20 mpg is (in imperial gallons )  because it is so many units of distance for each unit of fuel -- common sense.  But I neither understand nor see any merit in "litres/100 km". 

[SwampDonkey]

They way it works out, and is easily divided, and is in fractions, instead of decimals, makes it handy.

A decimal is a fraction. 0.1 = 1/10. Metric is in tenths, where all you have to do is move the decimal left or right depending on whether you divide or multiply. With imperial and it's 1/8, 1/16, 1/32 it takes a little more juggling in the noggin to do the math with complex numbers.

Ex: imperial: 1645 and 11/32" divide by 1/16 of an inch  (which is not 0.16) Whenever the math involves something outside the familiar 1/8, 1/16, 1/32 etc it involved more time. Sometimes stuff might be 1/65536 of an inch.

Metric 1645.3862 divide by 20 cm  ...all you do is move the decimal point left one move and divide by 2. I'm done the math in metric in way less than 1 minute and your still cogitating.

Some people think base 2 is much easier. Your typing on a base 2 machine.

Ok, enough tormenting you guys. But did you know it's on the books in the US as using metric as the official measure? It is usually metric published in scientific literature, often with imperial equivalents. Although, no body can make up their mind how big a gallon is.

metre is the unit of measure, meter is what you measure it with.