General rule when to use filled frame wrt direct boards gluing

Back to: Woodworking Methods and Techniques2 Replies

Welcome! / Forums / General Woodworking Discussions / Woodworking Methods and Techniques / General rule when to use filled frame wrt direct boards gluing

  • Author
    Posts
  • dejfson
    27 January 2023 at 8:26 am #789155

    Dear all,

    my question is rather generic. I always struggle in my designs to decide when to use the panellization technique (the one where we assemble a panel, and fill it with thinner large panel) and when to use just straight large beams and glue them together.

    There are some obvious examples of the techniques:

    – table-top is clearly glued out of boards
    – door is made by framing

    But there are tons of cases, where it is not clear. For example, I’m now in process of bed frame fabrication. The one which has to be hiding drawers. So I need sides to be filled in, and the bed frame will look more like a cabinet with dovetails, than a structure with visibly connected legs. The size is 1200×400 mm. Is it better to do as panel? Or – can I glue just boards and assume that it won’t warp when dovetailed to other pieces? Not clear to me, so some general rules when to use panels and when I can afford having just large glued surface would help. What is the decisive factor?

    Any advice helps

    Thanks

    sanford
    27 January 2023 at 10:16 pm #789223

    Hi Dejfson, The main reason to use frame and panel construction (besides the fact that it looks nice) is to deal with wood expansion and contraction. A fairly wide board can expand and contract a fair amount and that can break things. So suppose you have a door that is reasonably wide. As a single piece of solid wood, it can expand and contract a lot. So you “float” the panel inside a fairly narrow frame. The frame pieces, being narrow, do not expand and contract much. And since the large panel is floating in the frame, it is free to expand and contract a fair amount without changing the overall size of the door. Bingo.

    So when do you not need frame and panel construction? When it is not needed to control expansion and contraction. Here are some cases. 1. The example of the table top you mention. Of course, that wide table top can expand and contract, but you can take that into account by how you attach it to the apron of the table. 2. In a door where it does not matter how much it expands of contracts, say because it simply overlays the cabinet opening without being embedded in it. (Note, most of Paul’s doors are frame and panel because they embed into the cabinet opening so expansion and contraction will quickly jam and then loose them.) 3. Plywood does not expand or contract much so you can generally ignore the need to take it into account. This means that you do not need frame and panel for, say, a plywood door — though you might want it just because it looks nice. Modern furniture construction uses plywood for a number of reasons, and one is that it does not require frame and panel construction for wide pieces. 4. If you are dovetailing two boards together, say for a box, it is done end grain to end grain. So the two boards will expand and contract together and the joint will not generally break. (Hm . . . different species of wood expand and contract at different rates. I wonder if they differ enough to be a problem there when the boards are wide? )

    Anyway, that is the general idea. Of course, frame and panel is sometimes used for purely decorative purposes too. My house has doors made from some sort of artificial material with fake grain and fake panels.

    I am not sure, but it sounds like the bed you are thinking of is a sort of large box with holes for drawers etc. (A sketch of what you have in mind might help.) If so, like any box, I bet it is fine with dovetailed sides and no frame and panel construction, at least as far as wood movement goes.

    Good luck with it!

    Sven-Olof Jansson
    27 January 2023 at 10:41 pm #789230

    Where drawers are to be on top of one another, a solid wood carcass will perhaps provide the better structure for the drawer supporting structures (runners and rails). If the support structures are joined to the sides by sliding dovetails, warping of the sides becomes less of problems. The runners do not necessarily have to glued to the sockets, which removes a lot of worries around seasonal changes.

    Sven-Olof Jansson
    London, UK; Boston, MA

  • Author
    Posts
  • You must be logged in to reply to this topic.