Wood dimensioning...

[Externet]

In need to make a jig for manufacturing something, went to a (U.S.) Lowe's store.

In the land ruled by medieval inches, cannot buy a ONE INCH wide/thick piece of wood. Told to buy something else and 'rip'/cut to needs.  Tried also to buy a HALF inch plywood sheet... No such thing.  There is one they CALL half inch, being actual 15/32" or something like that...
The 'two by four' studs aren't even 1 1/2" x 3 1/2" x 96" if measured carefully.
What is going/gone wrong here ?  Why this habit of misleading ? Or is that the system went metric and kept in hiding from the public ?  How is wood dimensions sold in Europe ?

 I know a few years ago, Lowe's lost some millions on a suit from mislabeling dimensions. Now they label as 'nominal' and 'real'...

[Strange]

I'm guessing that manufacturing is done to proper, worldwide, modern metric standards and then marked up for sale in the local primitive units.

Perhaps to simplify international trade. (Or perhaps because metric is just the right way to do it. )

In the UK, you can go to a builders merchant and ask for a piece of "two by four" and you will be sold a piece of wood that is 50mm x 100mm. But everybody knows that.

[StringJunky]

23 minutes ago, Externet said:

In need to make a jig for manufacturing something, went to a (U.S.) Lowe's store.

In the land ruled by medieval inches, cannot buy a ONE INCH wide/thick piece of wood. Told to buy something else and 'rip'/cut to needs.  Tried also to buy a HALF inch plywood sheet... No such thing.  There is one they CALL half inch, being actual 15/32" or something like that...
The 'two by four' studs aren't even 1 1/2" x 3 1/2" x 96" if measured carefully.
What is going/gone wrong here ?  Why this habit of misleading ? Or is that the system went metric and kept in hiding from the public ?  How is wood dimensions sold in Europe ?

 I know a few years ago, Lowe's lost some millions on a suit from mislabeling dimensions. Now they label as 'nominal' and 'real'...

I'm guessing you are asking for planed or finished wood. The initial rough-sawn stock wood will be exactly an inch or whatever but then you'll lose a 1/16thish on each side for the planing. If you want the right dimensions try getting the rough--sawn.  Any jobbing joiner or woodworker knows this. The people suing were obviously woodworking neophytes.

 

Edited January 27, 2020 by StringJunky

[Strange]

9 minutes ago, StringJunky said:

I'm guessing you are asking for planed or finished wood. The initial rough-sawn stock wood will be exactly an inch or whatever but then you'll lose a 1/16thish on each side for the planing. If you want the right dimensions try getting the rough--sawn.  Any jobbing joiner or woodworker knows this. The people suing were obviously woodworking neophytes.

 

Sub-neophyte (barely capable) wood-worker here. That's a good point. I have always wondered why wood is sold in odd dimensions like 44x18mm instead of 45x20 or something.

[StringJunky]

8 minutes ago, Strange said:

Sub-neophyte (barely capable) wood-worker here. That's a good point. I have always wondered why wood is sold in odd dimensions like 44x18mm instead of 45x20 or something.

Yeah, in metric, I would expect maybe 2mm-3mm off each face on planed, so 50 mm roughsawn wood will be 45mm-46mm planed. If you wanted 1inch finished you would have to pay for the next size stock up and have all that waste to pay for

Edited January 27, 2020 by StringJunky

[Strange]

2 minutes ago, StringJunky said:

Yeah, in metric, I would expect maybe 2mm-3mm off each face on planed, so 50 mm roughsawn wood will be 45mm-46mm planed.

But they could have started with 56mm sawn wood (which must be approximate, pretty much by definition) and then planed to an exact round number. But I suppose it doesn't matter what the actual size is, as long as it is specified and consistent. 

[StringJunky]

Just now, Strange said:

But they could have started with 56mm sawn wood (which must be approximate, pretty much by definition) and then planed to an exact round number. But I suppose it doesn't matter what the actual size is, as long as it is specified and consistent. 

I added a bit more to my post. You just get used to it.

[iNow]

It's called dimensional lumber. They sell them as "2x4" and "1x6," but actual dimension is always lower. You need to look at the actual dimensions, which is usually on the tag at the store. 

In general, buy larger wood and dimension it yourself at home. Frustrating. Stupid, but sort of par for the course here in the US.

[Externet]

😖 No way to find 1 inch lumber at Lowe's.  Looked and asked the personnel there...🙄  Suspect will be the same at Home Depot, etc.  The 'actual' labeling may not be at other stores.

[Strange]

Where I used to live, there was a timber merchant who would cut and plane (and profile) wood to any size & shape you wanted.

[iNow]

15 minutes ago, Externet said:

The 'actual' labeling may not be at other stores.

They all tend to get their products from similar sources. It's consistent at the major box stores

[Enthalpy]

Wood profiles have wide standard tolerances, and I've never seen a part using the upper range of the tolerance. This is for metric units.

So: manufacturers achieve a far better accuracy than what standards require, and use this capability to produce more parts from the timber.

[zapatos]

Building standards of old called for 2x4 lumber, which was 2" x 4". Some years later when engineering caught up with construction, it was determined that all functional requirements were met by using "2x4s" that were actually 1 1/2" x 3 1/2". No one wanted to go back and change all existing documentation, so they continued to call them 2x4s, even though that was no longer the actual dimension. The same changes apply to other lumber too. (Additionally, no one wanted to say "Hey, someone grab me a three and a half by one and a half". Much easier to say "two by four".)

You can also purchase five quarter (5/4) lumber that is typically 1 1/16 inch in thickness.

Also, Lowes is for the most part construction lumber. If you want different dimensions, especially in hardwoods, buy from a store that sells hardwoods to cabinet makers.

[studiot]

On 1/27/2020 at 2:32 PM, StringJunky said:

I'm guessing you are asking for planed or finished wood. The initial rough-sawn stock wood will be exactly an inch or whatever but then you'll lose a 1/16thish on each side for the planing. If you want the right dimensions try getting the rough--sawn.  Any jobbing joiner or woodworker knows this. The people suing were obviously woodworking neophytes.

 

There are various forms of planed or finished specifications.

Here is a good guide

https://diy.stackexchange.com/questions/29617/what-is-the-difference-between-planed-square-edge-timber-and-planed-all-round

All finishing will result in some dimensional reduction.

So the term "ex 4 x 2" is used to indicate the starting point and the purchaser specifies the final dimensions.

There has been a trend since the 1960s to use more finished timber in building.

So for instance my 1930s rafters are sawn and 4 x 2 or 6 x 3.

The timber is also a resinous fir which resists attack by many borers and fungi, if kept dry.

More modern timbers are finished. Partly because the crampon connectors now used bite better into finished timber and truss design has also changed towards more smaller pieces.

Moisture content makes a difference to dimensions, most evidently where the modern timbers have been 'treated' after finishing (it cna't be done effectively before) because they alck the natural protection I mentioned earlier.