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I am building a console as shown below (not to scale). The boards are 5 cm (2 inches) thick pine. The sides are joined to the top using dovetails.

I have not assembled this yet but I am concerned about racking. What would be a traditional / time-tested way to reinforce something like this?

I have thought of three options:

  1. A shelf attached with dadoes & tenons. This seems right, but I am not sure it will be useful as a shelf, and if not, it will take up more space than other options.
  2. A reinforcement bar with a vertical cross-section. Is a mortise & tenon joint appropriate here provided the bar is small?
  3. A dovetailed reinforcement bar on the back. Would this work w.r.t. wood movement? One advantage is that I can add it after the initial glue-up.

console plan

stanch
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  • per bowlturners answer, option 1 is not so good for racking, especially if the load is large. You need more vertical distribution to prevent legs from racking. Option 3 will work for wood movement. Wood expands and contracts in width and height, but not in length so if the top and the brace grains are in the same direction, then no differential movement will affect the assembly. – Ashlar Feb 20 '24 at 14:22
  • Thanks @Ashlar! My concern with option 3 was the cross-grain situation between the brace and the side (where the grain runs from top to bottom). I suppose it’s not an issue if things are narrow enough, but still was wondering if that can weaken the joint. – stanch Feb 20 '24 at 17:04
  • I think the two things to focus on here are 1, this is just a console and 2, the stock you're using is thick. Once you build this and the glue fully cured I think you'll be seriously impressed by how little racking you see. Even without glue something like this can be surprisingly rack-resistant! Now if you have ANY concerns about racking in service by all means add some reinforcement — as has been said here many many times one rarely regrets making something stronger! Even if it's not strictly needed you could add something just for peace of mind. Or simply because you like the looks! – Graphus Feb 21 '24 at 09:28
  • Re. no.3 and the cross-grain situation, yes the stretcher is narrow enough that it is a non-issue — think about the apron pieces in every conventional table and their join with the legs. Also many workbenches have stretchers that attach to the legs either with the stretcher fully enclosed or in a halving joint (lap joint). Even if just overlaid, if they're glued on and pegged, nailed or screwed it's basically the same. If you do add something I'd go with 1 or 3 simply because each represents an opportunity for useful practice; I wouldn't consider either inherently superior (for this). – Graphus Feb 21 '24 at 09:37
  • Thanks @Graphus! You are right about practice… I admit one of the reasons for these options was that I wanted to practice using my new router plane :) – stanch Feb 21 '24 at 13:47
  • And you are right about stability. I put together one of the dovetails yesterday (no glue) and it’s not going anywhere – stanch Feb 21 '24 at 13:48
  • Quite separately, can anyone explain what 'racking' is? Google seems to have no better idea than I haven't… – Robbie Goodwin Feb 21 '24 at 22:24
  • @RobbieGoodwin imagine the leg joints (or legs themselves) flexing so that the whole thing rocks side to side – stanch Feb 22 '24 at 09:19
  • Jesus, I see the problem you faced! I know what I'm searching for and I still can't find it o_O Racking is the tendency of something to go out of shape (generally in use due to forces exerted on it, especially sideways forces, not just when sitting static). In furniture it tends to refer to rectilinear shapes parallelogramming, which with a simple box can mean it leans over to one side, flattening downwards, and potentially collapsing entirely. – Graphus Feb 22 '24 at 09:49
  • OK re. the router plane then you have to go with option no. 3, since there's little or no use for it in 1 or 2. If you'd like to take on a project that requires a lot more use of the router plane & doesn't require a lot of wood, a box for a loose sharpening stone is a good project — the shallow mortises needed are frequently flattened off using a router, although you can do it with a chisel alone if absolutely necessary (eventually sliding it along bevel-down, which resists the tendency of a chisel to dive into the workpiece). Google oilstone box + Graham Haydon / Toolerable for two references – Graphus Feb 22 '24 at 10:01
  • @Graphus Thanks again! Option 1 would be housed, as shown in The Essential Woodworker. Hence the use of a router plane. It’s fine though if I don’t use it on this project, I have some tenons coming up elsewhere that I can flush with it. I’m afraid my diamond stones (plus strop) just sit permanently on my auxiliary bench at all times, ready to go :) – stanch Feb 22 '24 at 13:39
  • I thought of the housed option for the board ends in 1 only after I'd posted *doh* Incidentally if you ever do this and the aesthetics of the tenon ends aren't important you could skip them and just use through-dowels. Obviously a massive saving in time since you just need to drill some holes to form both parts of the joint, but despite being so much faster this option can easily result in a joint stronger than the M&Ts! You can stack them in multiples, do a whole row and/or angle some/all for a dovetail-like hold that resists separation mechanically. – Graphus Feb 23 '24 at 07:47
  • It was a bit of a long shot that you'd have a loose oilstone lying around needing a home ^_^ Kudos on going with diamond plates BTW! The sanest option these days since they're so versatile (will sharpen anything, even up to carbides) and require almost zero maintenance. A tip if you haven't heard this yet or thought of it yourself: try going from your coarsest plate directly to your finest when honing; no intermediate steps are needed, because honing isn't sanding (so the principles of sanding don't apply) plus diamonds are many times more abrasive than anything else commonly in use. – Graphus Feb 23 '24 at 07:50
  • @Graphus For honing, I find I only need a few strokes on the 1200 grit plate, followed by polishing on the strop with the Veritas green compound. (For chisels, 90% of the time just the strop, unless it does nothing and then I hone.) My only other plate is 600 grit and I only used it once. To be fair, I am yet to need to regrind anything since I switched to this setup! – stanch Feb 23 '24 at 08:41
  • Excellent! That's a very good approach to honing, sidestepping so much wasted energy of the 400-1000-3000-5000-10k variety! If you do ever need to do a major reprofiling or edge repair you're going to want either a grinder or a really coarse diamond plate; using a 600 you'd just lose the will to live ^_^ Unless you have an objection to shopping there the best place for a single very coarse (150 or below) diamond plate is probably AliExpress, I've seen them sub-$5 regularly over the years and now with new-user deals being very common you might find one for under a dollar and free shipping! – Graphus Feb 24 '24 at 08:05

1 Answers1

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Always need triangles to prevent racking. Your options 2 and 3 are the most viable to do that. Though the 3rd option I might try 2 of them across, though the wider it is the better it would be at preventing racking. This is why so many pieces of furniture have the entire back covered with thin sheet material.

If the back side is going to be against a wall, the easiest would be to literally screw triangles into the back top corners, they will prevent all racking. You can also hide them a little more and make them smaller by putting in 4 just a few inches back from the edge on each corner, making it a nice 'feature', that is partially hidden.

FreeMan
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bowlturner
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  • Absolutely, 100% what I would have suggested! – FreeMan Feb 20 '24 at 14:13
  • Oh, haven’t thought of that! So a couple of plywood triangles (or just cross members, like on chair frame corners) screwed/nailed and potentially sunk into stopped rabbets to not protrude? Not sure I follow “make them smaller by putting in 4”, but that’s what I understood. – stanch Feb 20 '24 at 17:08
  • I think I get it, you mean 4 triangles, 2 on the corners facing the wall and 2 on the front, but away from the edge to not be seen? – stanch Feb 20 '24 at 17:11
  • @stanch yes, that is what I mean. If you are ok with plywood you can just put the triangles on the back so they overlap the entire corner as well – bowlturner Feb 20 '24 at 17:18
  • I could also use some chunky triangles from offcuts of the same 2" pine. Will need to see how visible that is from the front. Although with a plywood “back” I could have quite a wide rabbet and just glue them in and not worry about screws getting loose. Thanks for the suggestions! – stanch Feb 20 '24 at 17:29
  • "Always need triangles to prevent racking" Erm, not always. One of the thing about dovetailed corners in particular is how stiff they are, by themselves through dovetails (or finger joints, which can basically be considered equivalent) resist racking, especially in thick stock. You seen the many modern seating benches with the interlocking top and side legs? Zero additional reinforcement is present (or needed) even with a potential load in excess of 500lb. – Graphus Feb 21 '24 at 09:22
  • @Graphus well technically, dovetails are a bunch of small triangles.... ;) – bowlturner Feb 21 '24 at 13:22
  • @bowlturner, tee hee, I guess they are! – Graphus Feb 22 '24 at 09:32