What allowances for when timber will be dressed?

[KiwiCharlie]

G'day Guys,
When milling timber, what size would you cut when your wood will be dressed?  Ie, if cutting a 4x2 how much larger do you cut it, so that when dressed it beomes the correct size?
Cheers
Charlie.

[Back40x2]

 
   Kiwi,

      It depends if it is for a customer, or me.  If its for the customer and he wants a fully dressed 2x4, then I cut it 2.25 x 4.25.  It's just easier for me to cut it that way.  I will also charge them more to specifically cut that way too!  ;)
         Up here, a 2x4 is anything from 2 1/8x4 1/8 to 1 3/4 x 3 3/4.  Usually thou, I just cut 'er 2x4.  That is for softwood dimensional.  Hardwood I usually run about an 3/16 over each.

[Ianab]

Remember when you buy a surfaced 4x2 from the timber yard it's not actually a 4x2. It probably came off the saw as that, then was dried and planed down to around 1.5" x 3.5". If you make your 4x2s true size they wont fit in with existing timber. If you do want a true 2" thick surfaced then yeah, just saw it 1/4 - 1/2" oversize

Cheers

Ian

[sigidi]

Charlie if it's for a customer, like the others have said you will have find out exactly what they are doing with the timber (once you know what they are doing with it you can give them the best timber you possibly can for what they want) also would pay to give them a little education on timber terminology and what a 4x2 means - ie it gets cut as 4" x 2" then as Ian said gets processed from that size. THis is why when you go buying timber you get such odd sizes like 42x38mm as this is the finished size and it came form a different sized blank.

If it's for you well you know what you want and ifn you are mathching up existing then cut em fat to allow to machine down, if it's all new then cut em at 4X2 and then they will all be the same when ya finished

I guess that was a long way of saying what they said :D

[Jim_Rogers]

I can't speak about the lumber sizes down under, in either country, but in the US there are standards that all lumber is cut to. These sizes are controlled by the industry, not the government. The lumber industry in the US is self policed and self regulated, by the member organizations, such as NELMA (New England Lumber Man's Association), SPB (Southern Pine Bureau), and WWP (Western Wood Producers)(this may have an "A" on the end for Association). These private member run organizations have inspectors who travel around making sure each member follows the rules. This is how these organizations are "self-policed".
Some time ago, these organizations got together and decided to make all the lumber rules and sizes standard nation wide. So that a 2x4 on the west coast would match, in size, a 2x4 on the east coast.

If you were to set a new milling operation, then milling lumber to these standard sizes and dressing them down to these approved sizes would be a good way to begin, if you are intending to sell to the "average" person.

If you are going to create some lumber for yourself then you can make them any size you wish and dress them down to any size you need.

A small piece of lumber was called a 2x4 because years ago before lumber was "dressed" that was the rough lumber size.

At one time the 2x4 was dressed down to 1 5/8" x 3 5/8" before the nation wide standard of 1 1/2"x 3 1/2" was adopted.

A 2x6 is dressed down to 1 1/2" x 5 1/2", but a 2x8 is dressed down to 1 1/2" x 7 1/4".  Any lumber size bigger then 6" is dressed down to the 1/4" under the larger size. So 10" to 9 1/4" and 12" to 11 1/4", and so on.

There are also standards for sizes of other pieces of dressed lumber such as boards and moldings.

Jim Rogers

[KiwiCharlie]

Hi Guys,
Thanks for your replies, thats great info.  Also, thanks Jim for the indepth reply.  Very interesting stuff.
Cheers
Charlie.

[Timo]

Here in Canada I believe that lumber sizes are mainly regulated by the building code or 'end user regulation'. This probably stemmed from original dimensions that fell out of standardization proceedures similar to our friends down south. In the end, a 2x4 in Quebec is the same as one in British Columbia (1.5x 3.5).

The only thing I can add here beyond what everyone else has said is sometimes a building inspector will alow the use of rough lumber (ungraded - no stamp) in a house but usually it has to be full size i.e. a true 2x4. Here this seems to be a case by case situation up to the descretion of the inspector. My local guy insists on inspected wood, but will alow the house to go up, and be inspected (by a grader) prior to closing it in. Go figure! I guess the risk goes to the builder to choose wood that is above the minimum requirement.

At any rate, I just wanted to point out that the local building code might be the place to look for such standards, rather then any governing body dedicated to lumber production.