21
You can use screws, but in a slightly different manner. Instead of simply pre-drilling a hole and screwing the screw, you can use a router to create a slot with a countersink or counterbore bit.
Source: LeeValley
This slot will allow wood movement of your solid top while staying securely attached on your cross rails.
18
In such a wildly changing environment, how is it actually possible to let wood reach its EMC, or is the advice misguided, and does it not actually matter?
It does matter, and the moisture content bit is a bit easier than you're making it out to be. Let me explain.
Humidity fluctuates throughout the day, as we all know. However, on average, an area's ...
15
That page you link to is correct, wood movement is almost completely across the grain. Longitudinal or long-grain movement is so slight it can nearly always be ignored.
Just to note, we must remember movement is both expansion and contraction, which typically happens seasonally:
Obviously there are specific instances where movement cannot be accurately ...
15
Tabletops are often attached to the frame and aprons using tabletop fasteners such as these, which allow for some wood movement:
(Source)
This is what they look like installed:
(Source)
13
The wood in your top will expand and contract in one direction, while the cross braces will expand and contract perpendicular to that.
There are a couple of different products and techniques that would help.
For a set of rails like the ones in your picture, consider 'figure 8' fasteners.
https://www.leevalley.com/US/Garden/page.aspx?p=50311&cat=3,41306,...
12
I can think of a couple options for mounting a breadboard, which you will have to adapt to suit your tools and skill set:
Use biscuits to join the breadboard to the rest of the top (not necessarily the best option since you have a continuous glue line across the width of the top) (source: Popular Woodworking)
Mortise & tenon joints (note the elongated ...
12
Wood is made of fibers. Think of wood as a bunch of soda straws or flexible rubber tubes bundled together. When you add water, the fibers expand to hold the extra water. When it dries, they contract. So you will see expansion across the width of the grain, and very little along its length.
There are two types of wood, heartwood and sap wood. Sap wood ...
8
It might be a regional issue, but I hadn't heard the term "regularized" in the context of buying lumber. Perhaps that threw off the people at the store, although even if you had asked for S4S (surfaced 4 sides) hardwood lumber, the employees at a home improvement store may or may not have been able to help you.
If wood is "regularized" and not dried, ...
8
There are many techniques for designing a piece of furniture that will not tear itself apart with environmental fluctuations, but the key point you're missing is that you ideally want to work the wood while it is at the EMC of the environment in which it will ultimately reside.
All the climate data you have crunched is presumably for a piece that sits ...
7
This is not really an answer but a large comment that could point out several pitfalls that could have brought you to this point. I am not sure of the best advice for your situation as the warping looks significant. Like discussed in comments I think you might be better off starting over and paying attention to points below.
Knots and Pith
Depending on ...
7
To warp or to twist, that is the question
It is extremely important to let wood sit for a while in the environment it is intended to be used in before using it for a project so that it reaches equilibrium moisture content (EMC) with the environment. Evidence: This advice comes up time and time again here, in forums, in articles, everywhere.
This is very ...
7
Do pocket hole screws allow for proper expansion and contraction in planked table tops?
It completely depends on where they're sited. They're perfectly acceptable in some places and utterly wrong in others.
Refer to this previous Question, What general considerations do I need to take into account for wood movement? for more info on that regard with some ...
7
There's a lot written about the ideal conditions for the workshop but you have to be careful about the source since the figures quoted aren't as universal as sometimes implied or stated, some sources not taking into account very different conditions to theirs (much drier or much damper).
For example it's much damper in the British Isles generally than in ...
7
In which direction do wood boards expand?
Short answer: across the grain.
Wood does move along its length but the amount is negligible and can almost always be ignored.
This has been posted before but it's worth reposting as it shows the differences so clearly:
As you can see radial movement is only half that of tangential (approximately, much greater ...
7
The top is attached (at least in part) using buttons, although it's hard to tell what's going on with the cross-bracing framework. Buttons are one of the established ways of allowing for seasonal changes in the width of a tabletop. These ones are crude though, and as a result may not allow sufficient movement. The ones on the sides in particular must allow ...
6
I would say that it is more likely that this joint failed due to the moisture from watering the dirt rather than being outside. Simply re-gluing it and keeping it inside will not be enough to fix it.
I can foresee a few options
Glue up the joint again as it was and this time line the planter with plastic so that the moist dirt does not come in direct ...
6
I know cheap construction 2x4s can warp
There are multiple possible causes for distortion in a glued-up panel like this. Often more than one of them are to blame, although there may be one major culprit. I suspect that's the case here.
Since your tabletop ended up 'in wind' (twisted) and didn't cup or bow I think the wood itself is likely to be mostly or ...
6
I believe that the main problem with your question is assuming that the wood moisture content can change in an instant. This is not the case. Wood fibers do reach a moisture equilibrium with the surrounding air's relative humidity, but this is a very slow process, especially for thicker pieces.
The calculator you used to determine EMC is well and good, but ...
6
will pocket hole screws allow the table to expand and contract as it is supposed to?
I'm assuming you built something that was fastened together along the lines of this
(source)
where you used pocket screws to attach the individual boards together.
You mentioned that you are switching to more movement-capable fasteners to attach the table top to the base,...
6
There are several issues to address in fabricating such a table top.
First, as you pointed out is wood movement. The plywood base will not have any appreciable movement in either direction while the pine planks will expand across their width. If the two are attached, the difference must be made up at each board, where it is very small. I suspect that is ...
6
I'd say go with quarter-sawn ideally.
Quarter-sawn wood can be relied upon to be much more stable, but it must be said many a breadboard end has been made from plain-sawn wood that has held up well over time.
Apart from stability there is the potential advantage in the figure on the face of the board, depending on the species you're using naturally.
If ...
6
Short answer, yes you can get your wood more straight than you will find at the box stores, and even from your hardwood dealer.
It would stand to reason, as you say that they should be able to produce a straighter product, but the reality is they are dealing in volume, and so there are many factors. First, they are going to be using the cheapest quality ...
5
To repost and add to my response to your previous question:
You will likely not be able to prevent checking and cracking of this piece as it dries. You have different rates of shrinkage depending on the direction of the grain, and with the cut being kept essentially in it's original configuration (i.e., a section cut from the whole tree), it will want to ...
5
I hate to say it, but wood is not usually predictable down to the millimeter, and your design needs to take that into consideration. For example, when making solid wood panels - these can shrink, warp, twist or cup significantly in the first year after they are manufactured, and will continue to shrink for the next 100 or so years. A design that constrains ...
5
Yes, wood moves, you want to space the boards to allow for expansion.
A common way to space boards when doing decking is to use one of your fasteners as a gauge. e.g., a 2" deck screw temporarily slid between the boards as you fasten the boards to the joists. You end up losing some screws that way, but it's the simplest method I've used.
There are fancy ...
5
The spline will expand at the same rate as the board it is in, if the grain is running parallel to the grain in the board, so there shouldn't be a problem. The reason splines are better when the grain is perpendicular to the join is for strength - wood will split along the grain much easier than it will break across it.
Normally, in a panel glue up like ...
5
Don't know where you are, but in my area, the wood from big box stores is extremely variable. Finding a specialty supplier will probably yield better results.
To answer your questions:
Wood that hasn't been dried much will probably twist and turn more than wood that has dried. That said, wood commercially dried will frequently be twisted by the time it ...
5
Easiest would be splicing in a little triangle reinforcement.
As described in this article.
You will need to clamp the corner closed when you make the cut in them and glue it up again. Here is the required cut in the box depicted with a half finished computer case:
(image source)
5
I was wondering how I could make a table similar.
You can't really, and shouldn't try. Making a table that looks similar is easy enough, but actually laminating solid wood to plywood is inherently a flawed methodology. Even when you do this with veneer it can cause bowing if it's not done correctly, and veneer is extremely thin, so it's easy to imagine the ...
5
You're right to check about wood movement with the vertical orientation of the boards on the sides, which orients the longitudinal grain horizontally (not vertically as you'd see in traditional chest construction for example).
And if the design had those boards tightly fitted together, or especially if glued-up into single panels, the expansion and ...
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