1

I am very new to woodworking, and I'm planning on building a table for my living room, from boards that are roughly 4x7 cm (1,6 x 2,6") and with metal legs.

The table should look like this:

Table type

but with more timbers since they are smaller.

I would like to assemble it so it can be fully dismantled (including the tabletop) because it will probably go through multiple house moves in the next few years, and it would be very heavy and cumbersome to move as a single piece.

I thought I would assemble the boards together by using a flat perforated metal bar underneath the tabletop and M8 screws and inserts, but I worry that it won't allow the wood to properly dilate under heat and humidity.

Is there an other way I could assemble the timbers together?

Graphus
  • 65,691
  • 3
  • 50
  • 139
Raphael
  • 11
  • 1
  • Hi, welcome to Woodworking. In principle what you plan to do is fine, but there are some important details that we need to know. The first is the type of perforated metal bar — both how long they are and how big the holes are in relation to the screws are vital to success. Also important is how the wood attaches to the legs.... metal 'legs' like those pictured are notorious for not allowing wood to move as much as needed (although they can be modified so that they do). BTW you don't need to use M8 here, much smaller screws can work fine. But if you have the M8s already then use them. – Graphus May 17 '21 at 18:48
  • The metal bar would, in my idea, be the width of the table: 90cm / 35" example, but I don't have the size of the holes on the shop's website :/ Regarding leg fixation, I assume I would have to widen the holes ?x If M8 is overkill, what would you recommend ? – Raphael May 17 '21 at 19:46
  • If you're planning on using inserts for the screws to go into then M4s are likely to be perfectly adequate here (they're already quite a bit thicker than the core of many screws used in furniture construction). Smaller screws have the advantage too that they leave more room in the drilled holes in the metal bar, allowing for more movement without the need for any modification. But as I say, if you have M8s already then by all means use them, there's no harm in erring on the side of strength. And enlarging of some of the holes (the outermost ones) can be done easily enough using a file. – Graphus May 17 '21 at 21:35
  • And regardless of the screw size or type typically you'd want to use washers. This will bridge any holes that are too large for the screws by themselves. – Graphus May 17 '21 at 21:39
  • Re. what you ask about below, using a wooden batten instead, yes you can do this. See Stabilizer for softwood tabletop that bows for details. You may also want to look at my Answer to this Question. – Graphus May 18 '21 at 12:41
  • so either way the wooden battent doesn't fix the sliding issue, since it's not oriented the same way ? I will allow some slack : I guess if I don't tighten too much, I can have a point where the wood don't wiggle and leaves spaces between the pieces but still allow enough movement so the dilatation "force" is enough to let it move – Raphael May 18 '21 at 15:44
  • You don't give overall dimensions, but it's a table, it's not going to be that heavy to move. You may want to reconsider the "complete disassembly" concept. Maybe make the legs removable for simplicity, but the top, while heavy won't be immovable. – FreeMan May 18 '21 at 17:48
  • Sorry I don't understand, what sliding issue? "leaves spaces between the pieces" I wouldn't leave spaces between the boards, because crumbs or other food debris will either fall through to the floor or get lodged in the gaps. In a batten the whole point of the slots at each end, instead of simple drilled holes, is to allow for the movement of the wood, you don't need to leave gaps to allow for more. If using the metal bar the enlarged holes towards the ends will similarly allow for all the expected movement (the ones closer to the centre look like they will be large enough as they are). – Graphus May 18 '21 at 19:48
  • I mean, In order to allow the wood movement, I have to keep the screws not to tight. But if it is not correctly tighten, I fear that the wood pieces wont stay close to each others, and eventuelly leave a gap between them (which I do not want) – Raphael May 20 '21 at 06:50

1 Answers1

1

As long as the holes in the metal bars are larger than the width of the screws, it will be fine. 5mm play or more should be enough. Over time, you can re-tighten the screws if the wood movement is an issue.

ewm
  • 2,226
  • 10
  • 19
  • If I let bigger holes than screws, wont the wood piece have too much slack and leave spaces between them ? Is it enough to only rely on screw tightening ? To avoid the dilatation issue, is it ok to use a wooden batten instead of the metal bar ? It would be the same wood (pine) but not the same fiber orientation – Raphael May 17 '21 at 20:10
  • @Raphael you either leave room for movement, or you risk warping or splitting. This table is more or less a "deck", and your best bet is to leave gaps between them and live with it. Because either you put in gaps now, or you will have gaps later as the boards expand and then contract. –  May 18 '21 at 14:01
  • @jdv, I'm visualising this as expanding and contracting as a single unit, much as if it were glued up as a single panel (which obviously would be ideal here). A deck is different since the fasteners rigidly fix each board to a cross-grain piece; the metal bar, or a batten drilled the right way, while also cross-grain are completely different. – Graphus May 18 '21 at 19:53
  • @Graphus I understand, but I don't they are going to act as one piece. Each of those "decking" pieces is going to move somewhat independently if they are not attached to each other. If you allow for movement at the edges, you will have to allow for movement in the middle. Barring a clever way to keep them gathered but still allow movement in both directions. –  May 18 '21 at 21:37
  • So, maybe a batten that allows for expansion, but some sort of clever band or tensioner that allows for movement, but will close inevitable gaps. –  May 18 '21 at 21:38
  • @jdv, yes it's an imperfect system if they're not jointed and glued, which would be the ideal here. I'll try a test on this sometime when I build a solid-wood top on something utilitarian (I have a fold-up work table on the to-do list and that would be perfect cos I wouldn't care about gaps), see if the boards squeezed together do afterwards tend to act as a unit. If they don't then obviously leaving definite gaps (1/16"?) at the outset would be preferable. I'm uncomfortable with this idea in a dining or kitchen table tho, since crumbs etc. and cleaning liquid can go directly to the floor. – Graphus May 19 '21 at 06:25
  • Yeah. I have a dining table that has slightly ill-fitting leaves in the middle. It's astonishing what collects under that. –  May 19 '21 at 12:51
  • @jdv I like your idea of having some sort of tensioner ! I will consider further my real needs and wether or not I really need to be able to take it apart – Raphael May 20 '21 at 06:56