Slightly bowed pine, possible to flatten? - Woodworking Talk - Woodworkers Forum
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post #1 of 22 Old 09-29-2016, 11:47 AM Thread Starter
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Slightly bowed pine, possible to flatten?

Hi,

I posted here a few days ago about what type of wood to use for shelves, not the horizontal, but the vertical supports. I decided to use pine, got it home, cut it, and find that there is a slight bow in it. When I lay it flat we're talking about half an inch maybe.

Can this be flattened? I'm hoping to not have to get new wood and start all over. For now I've laid all the boards on top of each other with heavy objects at both ends and in the middle, hoping to flatten that way. Will that do the trick? I dont' have fancy tools to rely on so I dont' have many options.

If I can't get the bow out, will screwing and gluing the shelves in straighten everything up?

Thanks.
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post #2 of 22 Old 09-29-2016, 12:48 PM
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why do boards warp?

Straight grained boards with no knots and no elliptical grain patterns are least likely to warp. Boards with lots of grain pattern and knots will most likely warp. What do your boards look like?

Flattening warped boards is not likely. :frown2: They also warp because of uneven exposure to sunlight, dry or moist air or stacking them on unheated or moist concrete. How were your's stored?

There is "warp" in the general sense and then specifically twist, cup and curve. What do your boards look like? Cupping is easier to fix by sawing down the center than twisted, which is next to impossible. Pine sometimes has a mind of it's own and just bringing it in from the store or yard into the home will cause issues.

Shelves with dados on the sides would be a PAIN to redo. Plywood would be much less likely to warp and it does come in Pine, ask for Aruka Ply. I use it all the time for shelves and cabinets for the shop. Very flat and no voids.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 09-29-2016 at 12:53 PM.
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post #3 of 22 Old 09-29-2016, 02:03 PM
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Screwing and gluing should straighten all.

You want both verticals bowed out or both bowed in. If you use qa 1/4" plywood back board it will keep everything square.

George
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post #4 of 22 Old 09-29-2016, 05:01 PM Thread Starter
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Thanks guys. I haven't stored these that long. Picked them up from Home Depot and brought them home. They have been inside my living room that entire time. We have had some hot days, but none too humid. I'm not sure I can describe how they are bowed, like this image.

http://womeninwoodworking.com/Resource.ashx?sn=Bow

I didn't spend too much on them, maybe I'll just get some new plywood cut. I'm spending a lot of time on this project and don't want anything messing it up.

Thanks!
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post #5 of 22 Old 09-29-2016, 05:17 PM
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garek - I've had big box store lumber bow like that in virtually a couple hours.

you will encounter the phrase "furniture grade" in travels as to the "quality" of wood.
big strokes - it's wood that has been properly dried before being milled to dimensions. and I'm not talking about tens of days in a kiln. shed / air dried for years, then kiln dried, then milled.

the big box stores like HD and Lowes do not handle that quality level except by accident. clear pine _might_ be reliable. oak, popular, maple, common pine - it's the cheapest/fastest. a while back I bought some clear pine at HD - the sticker said it came from Australia....millions and millions of acres in USA pine growth, and the best clear pine supplier is in Australia? what does that tell you?

if you're going to do projects you want to look nice / professional, I recommend you check around locally for a supplier of furniture / cabinet grade woods. the big box store stuff is perfectly adequate for garage shelves. other stuff, perhaps not so much. considering the time&effort, the wood is the cheapest bit.
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post #6 of 22 Old 09-29-2016, 06:03 PM Thread Starter
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Thanks Tom. I get that, and I did visit another lumbar store and they had such great wood. The problem is I lack a lot of tools, and their wood was only guaranteed to be straight on one side. So at the moment, I'm at the mercy of wood that is already cut or square, unless I want to spend $25 to have the specialty store cut wood for me.

One day, I'd love to skip the Big Box stores and instead buy the good stuff. But I don't think today is that day. HD plywood should be fine right?
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post #7 of 22 Old 09-29-2016, 07:46 PM
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Nope!

HD plywood is not the best. There are different grades of plywood... construction, exterior, interior, A-C, Fir, Birch, Baltic Birch, cabinet grade,etc.

I have heard better results come from Lowes...? HD plywood was been coming from China and has voids or hollows along the lengths. They do have hardwood, Birch I believe in smaller sheet 2 x 4 ft, maybe 4 x 4 ft?

an overview:
http://www.popularwoodworking.com/te..._right_plywood

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #8 of 22 Old 09-29-2016, 08:02 PM Thread Starter
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yes I have noticed voids in the wood I've already bought from them.
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post #9 of 22 Old 10-04-2016, 12:49 PM Thread Starter
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Hi,

So I put heavy objects on the four planks and went to the Keys for the weekend :P. I'm back now and it seems as though the boards have flattened out again. I have not removed the heavy objects, so I'm not sure this will hold.

What are your thoughts? Should I go ahead and get new wood anyways? Or now that these have flattened should I go ahead and build my shelves? Will the screwed and glued shelves hold everything straight?
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post #10 of 22 Old 10-04-2016, 02:49 PM
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you should post a sketch.
over short distances a bit of bow may not be seen or affect anything. as the distance between anchor points increases, the effect of "wandering wood" will be more detracting.
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post #11 of 22 Old 10-04-2016, 03:00 PM
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OK, a book shelf?

What's your construction method besides glue and screws? Any dados for the shelves to "lock" into? That would greatly decrease any potential for the shelves OR the verticals to twist. Screws really don't like end grain for strength, if that's what you are asking, but it may work.

A bookcase can get very heavy and IF there is no back to it, it will rack and collapse. The proper construction for a book case includes a back panel that is either nailed on or set in a rabbet. It also means the shelves are not the same width as the verticals because of the rabbet. A sketch would be helpful.

If you stacked all the boards together in one pile, that wouldn't allow air to get in between the boards, so they may return to the previous condition..... warped.:frown2:

In my experience, plywood shelves are not as rigid and real wood. Hardwood is much more rigid than softwood.
A shelf span of 34" is about all I recommend for books. Shelves with a back that is nailed to the shelves can prevent sagging to some degree. A trim piece on the front edge of the shelf will help even more. If the shelving is for lighter objects, then you can get away with less rigid materials.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #12 of 22 Old 10-04-2016, 08:15 PM Thread Starter
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OK guys I'm posting a picture. It's basically 100 inches with 4 24 inch wide cabinets on bottom, and the shelves will rest on top of the side cabinets, the tall ones. They will rest on those tall cabinets and also help support the center cabinets (which will also be screwed into the wall, but the right one only hit one stud).

The verticals for the shelves are about 41 inches, the shelves themselves will be 24 inches in length and plywood, should I also start over with those and get hardwood? I don't think we'll use them for books....

I can't cut dados because I don't have a router or any other method of cutting them. Is it worth buying a router for this? I don't keep a lot of tools because i live in a condo and don't have a lot of room for them.

Woodnthings, yes, I will put a solid nailer in the back of these shelves, just like a cabinet to give them side to side support, probably one at top and bottom.

oh also, I plan to have cleats under each shelf, but they'll be glued only.
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post #13 of 22 Old 10-05-2016, 10:36 AM Thread Starter
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Ok so I also took some pictures of the wood. As you can see it's pretty straight, but on one corner it looks like it's a little twisted. Is this salvageable?
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post #14 of 22 Old 10-05-2016, 11:32 AM
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Those boards are flat sawn

If you look at the ends of the boards you will see the grain is shaped like large circular segments, as it would grow in the tree...hence growth rings. As the wood dries out it tends to shrink more from the outer rings and become "cupped", a common issue when working with wide boards. That's what you have, and especially on the bottom one.

You can't prevent this, only work around it. To reduce the cup on a wide board, you simply rip it down it's length into 2 separate boards with half the amount of cup and glue them back together. Then, if you have the equipment .... you can sand them flat, plane them flat or leave them as is.

This is why plywood becomes a better choice for making cabinets. You can also use straight grained woods that have small, almost vertical lines when looking at the end grain. When these boards shrink and dry out, there is very little cupping, a better choice for making cabinet and furniture.

The best way to control any twisting or warping is to select the straightest grain boards AND to assemble them as soon as possible with whatever methods you have at your disposal... nails, screws, dados, rabbets and glue. By assembling them immediately, they will be held in place by the construction before they get a chance to warp. This also why dados are a good idea, since a board fit into a dado will not be able to cup.

If you want to make more ambitious projects, a simple entry level router with a straight edge guide or clamp would go along way to insure that your projects turn out better. Keep in mind a router is very noisy and using it in an apartment may raise the ire of nearby residents.... :frown2:

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #15 of 22 Old 10-05-2016, 12:31 PM Thread Starter
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woodnthings thank you so much for your suggestions. I already run my jigsaw in the condo, so my neighbors are used to noise :). Ok, so what's my best course of action then? Start over with new plywood for the verticals? Should I use dados if I can get a router or are glued in cleats enough? Also, is 3/4 inch plywood thick enough for dados?
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post #16 of 22 Old 10-05-2016, 03:01 PM
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your illustration .....

It show two side cases and a center cabinet. It would be best to make it in 3 separate pieces as I described. This means the center verticals will be "double" thickness" because there are 2 of them. If you want a symmetrical look you can use a face frame of the same width all around to cover the double thickness.

There real issue here is plywood and start over, OR use what you have. Pine boards with knots does not paint well and staining is more difficult to get an even, blotch free stain. They do make a blotch eliminator that will solve that.

I'm going to say this is an advanced project for someone in a condo with no power tools. That doesn't mean you can't or shouldn't do it. It would be best, to have a router, guide clamp and circular saw for a minimum. A miter saw or table saw would be even better. I really wouldn't consider this myself without those basic powertools.:frown2: Then some corner clamps and a block plane and ROS sander, brad nailer and a framing square to top it all off.....

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #17 of 22 Old 10-05-2016, 06:54 PM Thread Starter
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well I have a framing square at least :). Ok I'm not sure I follow what you mean by three pieces? so for the verticals, are you saying to screw and glue two pieces of wood together for a thickness of 1.5 inches for each? I'm fine with getting new plywood and starting over. Knowing what you know about the project and my tools, what's the best way to move forward?
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post #18 of 22 Old 10-05-2016, 09:15 PM Thread Starter
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Ok I reread your post and I think I got it. I'm going to get new plywood, but not sure I will go double thickness, unless you think it won't work otherwise.
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post #19 of 22 Old 10-05-2016, 09:24 PM
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3 separate cases/cabinets/pieces

Quote:
Originally Posted by garek007 View Post
Ok I reread your post and I think I got it. I'm going to get new plywood, but not sure I will go double thickness, unless you think it won't work otherwise.
If you make it in 2 side cases and 1 center cabinet, you will end up with a double thickness in the 2 center verticals as you sandwich them together. The outside verticals will be single thickness, but if you don't make a wide enough face frame, it won't look right.... to fat in the center and too skinny on the outsides.... :frown2:

There is a cool way to make the shelves not using dados AND you will get double thickness outside verticals. You support the shelves with a separate piece of 3/8" ply under each shelf, building/stacking up from the bottom... spacer, shelf, spacer, shelf, spacer and so on.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #20 of 22 Old 10-06-2016, 10:47 AM Thread Starter
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Do you mean to build all verticals as shown in this tutorial?
https://www.thisoldhouse.com/how-to/...build-bookcase

Like the image below? I can definitely build it this way, then all four verticals would be symmetrical, right?
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