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I keep seeing different posts asking about 12/4 or 10/3 lumber when referring to different projects here and other sites. Upon further reading I can see no true dimentions referring this this 12/4 or 10/3 in what appears to be jargon not true dimentions. Can anyone straighten me out on this?
Regards
Bob
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10/3 sounds like a wire specification, not wood (10 gauge, 3 insulated conductors).
Otherwise, those are quarters of an inch being called out. A piece 12/4 is three inches thick.
The obvious question is why woodworkers are crazy enough to call "one inch" lumber 4/4 (around here, pronounced "four quarter")? It is because is the lumber is rough cut, and an inch thick, when it is surfaced it will be thinner, but still called "one inch". So, four quarter lumber is rough, not surfaced, and better be at least an inch thick. Often it is slightly over.
It's late, and I feel like I could have done a better job explaining that last paragraph. Hopefully someone more fully awake will fill in... ;-)
Dave
*Dave, you done good. Bob, never heard of lumber referred to in 3rds. Basically, all lumber is referred to in it's "pre-surfaced" dimensions. 4/4, surfaced (2S), will be somewhere between 13/16 and 7/8, depending on the mill. Rule of thumb; when figuring for stock, surfaced, subtract 3/16 from the nominal to get actual.Technically, soft woods are ordered by nominal dimension; 1x, 2x, etc. and hard wood is ordered by thickness, 4/4, 8/4, etc. and surfacing; 2S1E, meaning the board is surfaced on two sides and one edge. FWIW.Dano
*It's not exact is it? I appreciate the answer. I think Im getting it.
*I went out and measured my 1x6 inch rough cut cypress boards. The thinnest was 7/8 and the thickest was 1.25". 90% were 1.125 inches thick. The widths were from 5 and 3/4" to 6 and an 8th inches thick. I can now refer to is as 24/4 lumber. Is that correct?Thanks and regardsBob PS sorry for the late responce. I just got back.
*No, you only call out the thickness in quarters. Width is different.To select one of those boards, a thick one, it calls out as a 5/4 thick, 6 inch wide (five quarter by six). The 7/8 one is tricky, I'm not used to rough cut less than 4/4 thick. If it is rough, and measures 7/8" thick on a rule, you don't want to call it 4/4. The number of quarters is a minimum.Dave
*BobI rekon that the sooner the timber world goes metric the better - hows that for a seditious statement :-) Seriously, we in the other hemisphere have been using metric for years and once you get used to it you wont go back.Sounds like your 7/8" board was under-cut, we tend to rely on the mills supplying 26mm or a shade over 1" as a minimum, but the occassional thinner board does slip thru. It is probably more important to be able to dress to your desired finished size which means other factors such as cupping & bowing come into the equation.Don
*I suspect the vague way wood dimensions are labelled is due to the fact that wood has such variable dimensions. If exposed to changes in relative humidity, it's dimensions will fluctuate. I teach furniture design to college students, and the single most frustrating aspect of using wood for them is the dimensioning. They get confused with how to order it. They don't understand how much "extra" thickness to insure a smooth and accurate final thickness. They don't know how to calculate board feet or cost because they can't figure out how much wood they actually used. "It was only 5/8ths thick, so why do I have to pay for 1 inch?" is typical. Many drift into using metal for their designs, and I believe the "truth" in metal dimensions and purchasing make it a less stressful material to use. They know if they need a 1/2" x 1/8" x 24" alumninum strap for their project, that that's exactly what they should buy.Me? I just measure everything the same day with the same tape. My dimensioning system is "an inch and a half and a quarter and a 32nd and halfway to the next mark" instead of 1 and 51/64ths. Works for me.dave ;-)
*Dave, 64ths? That's that long grey line, right?
*A rule that measures in 64th is ALL a gray line... ;-)Dave
*My measuring system always works, no matter how fine of detail gone to. It's true that I'm usually measuring something like 12 and 3/8ths and a little bit, but wanted to demonstrate the extreme it could be taken to. By the way, the little bit after an 8th is always larger than the little bit after a 16th. ;-)64ths (I can actually see the marks if I take my glasses off) are mostly used laying out metal parts to be cut. Unfortunately, my students use alot of metal in their furniture designs. I'll use it occasionally, but I always round metal dimensions to the nearest 1/2inch. ;-)Dave
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