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How big is a 2 x 4?

Posted: Fri Nov 12, 2010 1:38 pm
by keakap
I have searched (alas I am terrible inadequate at it) and did not find the answer.
Basic question: what are the dimensions of 2 x 4s that you would buy to build a woodshop workbench (that required 2x4s in the plan)? (Over-sized?)

Follow up: to what final size will you dimension the 2x4s when the plans say ^1-1/2" x 3-1/2"^?

Did I buy the wrong stuff? Not wanting to post "finished product" pictures in Fine Woodworking. Among 5 plans on Woodsmith & Shop Notes, chose the one in Issue 66, the one with the fancy title "Workbench".
"Construction lumber and a weekend's work..." sounded like what I wanted.

Fairly basic (cheap), nothing fancy (cheap), necessary but not frivolous features (cheap), and no "finished 4 sides" on the shopping list (cheap), uses (cheap) studs doubled-up to get beefy legs and rails.
Functional yet frugal.

So I went to Lowes and combed the stacks until I had the requisite number (+2) of reasonably straight and flat 2x4x8 "studs" and some other stuff.

And here's where my (basic) question comes in. The studs are roughly 1-1/2" by 3-1/2" (+/-) with all long corners rounded, to various amounts. "Rounded" seemed fishy to me, so for the halibut I ran a 2' piece thru the jointer until it was minimally "F4S" with square corners in a least a few spots, all 'round.

Measurements now are ~1-15/32 x ~3-5/16, with some little edge-rounding in spots (these are, after all, studs), which I think will be fine for a workbench (perhaps even overkill?).

Does that sound 'right'?

Reference the plan, which indicates 1-1/2" x 3-1/2". Given "construction lumber", do those figures typically indicate precision sizing, or is it meant to be a more realistic measurement for construction stock, like, say "give or take a foot"?

As far as I can tell (without a microscope or running it thru CAD) if all the lengths of the various structural pieces are faithfully followed, minor discrapencies in width of the legs & rails pieces should not be a factor.

Any thoughts?
I've seen a number of articles, etc., concerning procedures for "squaring up" rough stock (joint, joint, rip, joint, plane, for instance), but nary a mention of how you start with 1-1/2 x 3-1/2, take a bunch off, and wind up with 1-1/2 x 3-1/2.

[The big mystery, as I re-read this thing, is why this never occurred to me before. Maybe because I usually either make my own plans or edit others'.]

Posted: Fri Nov 12, 2010 2:05 pm
by dusty
The text book answer to your question is that a finished 2x4 will actually measure 1 5/8" x 3 5/8". In reality, these days, I don't believe there is a correct answer. They are whatever they are.

If you need specific measurements, find a lumber yard that sells rough cut lumber and buy real 2x4s (rough cut 2x4) and mill them down yourself or use them rough.

Posted: Fri Nov 12, 2010 2:09 pm
by terrydowning
Your logic is correct on all counts

2 x 4 = 1 1/2 X 3 1/2
As for final dimensioning. It all depends on the desired effect on the finished product. For a workbench I don't even bother re-dimensioning. I just buy the straightest ones I can pick through at the store.

Fine furniture: start with over sized stock and dimension properly with a planer and a jointer.

How did the work bench come out?

And hey, you were making sawdust and something useful.:D

Posted: Fri Nov 12, 2010 2:15 pm
by dusty
I guess that even the dimensions on finished lumber has changed since I was in school.

When Terry answered your question differently than I did, I had to check. Here is what I found.

Learn something new every day.

Posted: Fri Nov 12, 2010 3:44 pm
by mickyd
dusty wrote:The text book answer to your question is that a finished 2x4 will actually measure 1 5/8" x 3 5/8". In reality, these days, I don't believe there is a correct answer. They are whatever they are.

If you need specific measurements, find a lumber yard that sells rough cut lumber and buy real 2x4s (rough cut 2x4) and mill them down yourself or use them rough.
Green 2x4's at Home Depot are specified as 1-5/8" x 3-5/8". Dried calls out 1-1/2" x 3-1/2". I noticed that when I bought the Douglas Fir for the pegboard storage rack.

My assumption has always been to buy dried lumber for woodworking projects. Correct assumption?

Posted: Fri Nov 12, 2010 4:04 pm
by dusty
Micky, I may be wrong but in the days when I was learning what I think I know about wood and wood working - the yards did not sell green lumber. It was possible then to buy straight lumber that was properly dimensional and it stayed that way.

They also did not sell treated lumber. If you needed something to be treated, you bought creosote and did it yourself. I have applied more creosote that I want to remember. We creosoted anything that was put in the ground and everything that was used on the bridges.

Posted: Fri Nov 12, 2010 6:32 pm
by robinson46176
dusty wrote:Micky, I may be wrong but in the days when I was learning what I think I know about wood and wood working - the yards did not sell green lumber. It was possible then to buy straight lumber that was properly dimensional and it stayed that way.

They also did not sell treated lumber. If you needed something to be treated, you bought creosote and did it yourself. I have applied more creosote that I want to remember. We creosoted anything that was put in the ground and everything that was used on the bridges.


I built a livestock loading chute as a 4-H project when I was about 16. It used Ford model T frame rails for the side rails and full 2" oak across for the floor with wood cleats a across to keep them from slipping. The sides were painted but the white oak floor was all heavily creosoted along with the cleats. It was really hot and I kept using my sleeve to wipe my face. It seems that I was sensitive to creosote... :eek: My face was still peeling 3 weeks later.
I shudder to think how many thousands of hogs (and a good number of cattle) I jockeyed up that ramp. Later we made a steel pipe handrail for the ramp and the truck was used as a flat-bed as a stage at a good number of events, mostly county fair related.
Today if I were to use any creosote it would be using a brush with an 8' handle. :)

Posted: Fri Nov 12, 2010 6:39 pm
by dusty
robinson46176 wrote:I built a livestock loading chute as a 4-H project when I was about 16. It used Ford model T frame rails for the side rails and full 2" oak across for the floor with wood cleats a across to keep them from slipping. The sides were painted but the white oak floor was all heavily creosoted along with the cleats. It was really hot and I kept using my sleeve to wipe my face. It seems that I was sensitive to creosote... :eek: My face was still peeling 3 weeks later.
I shudder to think how many thousands of hogs (and a good number of cattle) I jockeyed up that ramp. Later we made a steel pipe handrail for the ramp and the truck was used as a flat-bed as a stage at a good number of events, mostly county fair related.
Today if I were to use any creosote it would be using a brush with an 8' handle. :)
I do understand. I too have had creosote burns from handling it with a short sleeve shirt on. I was probably warned but too young to pay attention.

Posted: Fri Nov 12, 2010 7:30 pm
by 8iowa
Anymore, I can't find any 2 x 4s that are suitable for "furniture" type projects. I search and search thru stacks and it's almost a "give it up" exercise. If you can find straight & non-twisted boards, you still need to give them a lot of time to dry in your shop, maybe even months.

My next project is a workbench for my Gainesville shop. I have some kiln dryed 8/4 yellow pine boards and I am going to make my own 2 x4s.

Posted: Fri Nov 12, 2010 8:40 pm
by keakap
dusty wrote:I guess that even the dimensions on finished lumber has changed since I was in school.

When Terry answered your question differently than I did, I had to check. Here is what I found.

Learn something new every day.
Wholly cow! I read a couply pages of that Wickedpedia thing and saved the rest to read more closely later. Fun info.

Between what you and Terry said, I suspect Woodsmith bought oversized (rough) and dimensioned to a clean 1-1/2 x 3-1/2. Next time I may do the same, as it is SO much easier, cleaner, and cheaper (*altho I dunno if it's cheaper than studs). So I'm in a compromise, which I think is, or will be, okay. I got rid of the splinters, cups, warps and dings, mostly, but there'll be nobody mistaking my legs for 4-bys. What da hey. "Workbench".

Ya know what's weird? I'd kinda forgot that I'd kinda put real "rough" lumber out of my mind. I don't even know if we have an actual lumber yard on this island, and Lowes, Home Despot and Ace the helpless hardware man have 'finished' (really finished, as in ready to sit on, costing one arm, one leg and the TWO first-born per board foot), 'stud', and "white wood", which appears to be pine of some sort that everybody else rejected.

Yep, next time, if as I think "rough" is unavailable, I'll re-draw the plans so that all pieces are 1/4" smaller. Easier and cleaner to prepare.

Got more than half the wood prepped. I plan on waiting a few days to see if any of it goes contorsionist on me, then here come de glue.