3d ago

Dimensional lumber tape measure

I hope it’s not against the rules here, just saw this woodworking related xkcd that I enjoyed and thought it might be appreciated here:)

https://xkcd.com/3138

63 comments

I reflexively cringed with my whole face seeing "lumber" and "measure" in the same sentence.
Look up what the fuck Board Feet is. Then imagine trying teach other people how to measure for board feet. Then imagine everyone misremembering and misinterpreting how to do it.
Fuck board feet.
Have you hard of our lord and savior, the metric system?
- ???
- Even metric is under-sized on dressed timber 4x2" ~ 100x50mm => 90x45m dressed
  
  Yeah, but then we just use the 90x45mm as a measurement...
  Also if I remember correctly it's sold as 89x44. 45mm was only used for I-joists
- We have but Canada sells so much construction supplies to the US that we don’t use metric for it.
Twin Peaks on 2x4
https://youtu.be/LEOnIpO7Xgw
Wait 2×4s are not 2×4?? What is wrong with americans??
- They were 2x4 before drying the wood (that’s what I heard)
  
  You heard wrong. They use excuses like that, but truth is they can make the final size anything they want, for many years every different sawmill decided their own final size. You start by cutting wet wood to a size, you might or might not dry it, then you plane it down to an exact size. Some sawmills started by cutting to 2x4 and then planning different amounts off. Others cut bigger so when they planed it down they finished with 2x4. Everyone did something different and so if you bought a 2x4 you better pray that sawmill remains open for when you want to remodel and need more. Eventually enough people got sick of this and decided to make a standard, the current measurements are what was decided, it was arbitrary, but at least everyone follows the same standard so you can buy from different sawmills. Exactly 2x4 is also arbitrary.
  
  Not only drying, but sanding and straightening.
  But in reality anymore they aren't even cut to 2x4 initially.
  
  It doesn't shrink by a half inch in each direction.
  The board is rough sawn to 2x4, kiln dried, and then milled. That milling takes it down to 1.5x3.5 inches. Used to be, the carpenter bought rough boards and milled them himself, now they do it for you to save the weight when shipping.
  Oh, also: 1 1/2 inches is 1/8th of a foot. 3/4" is 1/16th of a foot.
- They are until they're planed to smooth them, at which point they are approx 1.5" x3.5"
- Anything to fuck us out of our money and quality products a little bit harder.
  
  The American way.
- Just like 50x100's are usually more like 40x90's, or something even more insane - 39x86? Like I'm sorry, but the unit of measurement is NOT the problem, it's the centuries old "traditions" and "standards" to normalize dimensional lumber that are the problem.
  At any rate, one should look at the names of boards as the ratio of their dimensions and leave the inches and mm out of it and it starts to make more sense.
- 2x4 is the rough cut not the finished cut that is sold in the store. If you shopped at a proper lumber yard, you can usually get rough cut lumber if you want to finish it yourself.
  
  you know what, fuck that name. how about you dicks call it something better?
- Although I suspect this particular quirk of dimensional lumber stems from the British, the result is not too unexpected for modern-day America. After all, we (insanely) deal with sales tax the same way, where the advertised price is pre-tax, and consumers have to do math if they want to compute the final bill before reaching the checkstand.
  So having to measure the lumber to acquire its actual dimensions is entire above-board [pun intended] for anything beyond putting together a wood-frame structure.
  
  According to another commenter, 2x4 is the dimension of the rough-cut lumber. Traditionally, your carpenter would buy rough-cut, then mill it down himself and allow it to dry. Eventually we figured out that shipping already-finished lumber made more sense. So they sold "finished 2x4s", ie, 2x4s as they are after the finishing process. And because the actual dimensions of the sold lumber matter more than the name of the lumber, this just remains as an artifact. It would be very annoying if suddenly every 2x4 sold in stores was actually 2"x4", since now you have to shave off a half inch of every board if you are replacing a stud. And calling a piece of lumber a "inch and a half by three and a half" would be onerous. So the dimensions stay the same, and the name stays the same. At the end of the day, it's a thing that might trip you up once when you first get started in carpentry, and then you learn and it literally doesnt matter at all from a practical perspective.
- Honestly, the one I want to see seppukus over is that very, very few sheets of plywood are their advertised thickness.
Lee Valley used to sell a blank tape measure, for pure, real-valued metrical madness.
- Basically a storey stick.
  
  That's the idea, but significantly more expensive than a scrap piece of 1x4.
Can I get some dimensionless lumber?
- Best I can do is interdimensional lumber
  
  You get that at Bed Bath & Beyond in the Beyond section, right?
- I think this also applies to dimensionless shapes. https://preview.redd.it/5zdt1ye5ej511.jpg?auto=webp&s=66da2867d8fdf7b5bb9fdf9c2f0d499188681719
Except that all of the board length measurements will not work out.
- A nightmare if you're following written measurements or working with other people, but as long as you use the same tape to measure how much you need and how much you have/are cutting, it should work out alright.
  
  Unless you're building anything with speced sizes . Oops I framed the walls too short.
Damn creative measuring.

63 comments