Question about wood thickness for projects

[Paul Button]

I'm a little embarrassed to ask such a simple question, but if you don't know, you don't know and I figured everyone on here probably would. If I'm going to work on a project that specifies using 3/4" boards, what would be the best way to progress? I know if I buy some 1x hardwood from HD or Menards or my local lumber yard, most are going to be close to 3/4", some slightly less, but probably not all exactly the same. If I need to joint them to flatten any boards, I loose a little material and some boards are going to be different thicknesses and the only way to ensure that they're all the same is to run them through a planer, which then they'll all be less than 3/4". Should I buy 4/4 which I doubt my local lumber yard stocks. It seems like I would waste a lot of material reducing everything from 1" to 3/4". Ideas?

Again, sorry for the simple question. Thank you for any help.
Paul

[Roy Harding]

What you'll buy in a big-box store (Lowes, Home Depot, and so on) is "S4S" - that means "surfaced four sides". This means that it has been "finish" planed on all four sides. This is why 2 X 4's actually measure 1.5" X 3.5" - the original 2" X 4" board has already been surfaced on all four sides.

When you buy lumber from a mill, it is usually NOT finished - so, a 1" thick board is ACTUALLY 1" (or slightly more) thick. Rough lumber is usually sold in random widths and lengths (there are exceptions - but let's leave them aside for now).

In your situation, I'm going to assume that the plans you are using are based on S4S lumber - in which case, don't thickness the boards. If you look at your plans, you'll probably find that there is a cut list, and a diagram of the boards you'll need (IE - four 1X6's, etcetera) - if so, you'll find that the 1X6's are actually 3/4" X 5.5", and that fact has already been accounted for by the designer.

[Robby Tacheny]

Sometimes you have to question whether things NEED to be exactly 3/4". Is there is a very specific reason why it has to be 3/4" or are the plans just referring to common wood thickness that you might get at your local lumber retailer. I think if you could plane all of your lumber to 11/16" or even 5/8" you'd probably be fine for many projects that call for 3/4" lumber. Uniform thickness is usually most important.

Places where you need specific thicknesses are at support areas, like legs. Or on a long table you may want 1.5" or more thickness for the top to combat flex or to look proportionate. Otherwise, thickness of lumber for a project is determined by what looks right (proportion) or may even be arbitrary due to what was on hand for making the model.

Robby

[Paul Button]

Thank you for the response Roy! But in some situations, like glue-ups, wouldn't you need to run them through a planer because those would need to be exactly the same thickness? I'm just thinking that there will be some variation between different boards even though they're supposed to be 3/4". Which would then be slightly less than 3/4". I guess then you'd pick the thickest ones and remove as little as possible, trying to stay as close to 3/4" as I can.

[Paul Button]

That's a good point too Rob. I guess if I'm making a book shelf and the shelves are in dados, and I plane the shelves a little, I just adjust the dado for the shelf thickness. I think I was looking into this way too far.

[Matt Day]

You can pretty much assume all the 1x stock at the BORG is going to be the same thickness, but it sure isn't going to the straight which is the problem.

Ideally, you'd have a jointer and planer and buy rough sawn material that you could surface to whatever thickness you want.

And as Robby said, the plans may call for 3/4, but inspect the plans as it may not need to be exact or even that close.

[Roy Harding]

Thank you for the response Roy! But in some situations, like glue-ups, wouldn't you need to run them through a planer because those would need to be exactly the same thickness? I'm just thinking that there will be some variation between different boards even though they're supposed to be 3/4". Which would then be slightly less than 3/4". I guess then you'd pick the thickest ones and remove as little as possible, trying to stay as close to 3/4" as I can.

You're right about panel glue-ups. If you're using S4S lumber, I'd suggest that the boards will be close enough to the same thickness that it would be easier to glue-up a panel first, and then surface the panel - rather than attempt to make all the boards EXACTLY the same and glue them up.

Robby makes an excellent point regarding thickness.

[Jim Dwight]

Most planned lumber here is 13/16 - a little thicker than 3/4. You don't want to worry about minor thickness variation prior to glueing up a panel because you will not have the boards lined up perfectly and they will not be perfectly flat. Even if the boards are the same thickness, there will be places where they don't line up. Ideally you use a wide sander to make them flat but I don't have one so I use a random orbit sander.

I would measure what you get and decide if you need to adjust anything and then just use them, unless you have a planner. Then you could even them up but you will still have to deal with glue-ups that don't line up and it's nice to have a little extra thickness for that. Unless your planner is really good, it's output will have a little variation too. Dealing with boards that are not perfectly flat or straight or all the same thickness is one of the things you have to learn. Wood just isn't any of those things. Fortunately it doesn't need to be.