I am working up a design for a Captain’s Bed. The base will probably use at least 4 bed bolts (at the corners), but since it’s a king size, I have been wondering about the internal joints, and what options I have for joints that are easy to disassemble (I know I will be moving at least twice in the next 5 years), preferably do not use screws, and do not require a ton of effort to cover.
My idea was this: imagine taking an unbacked bookcase that uses dovetail slide-in shelves (unglued), and put it on its back, then slap plywood on top, and mattress on that. Obviously the real thing would be a bit more elegant, but that should convey the idea.
The basic ‘box’ of the bed frame will contain 2 full length internal vertical (head-to-toe) supports, and between these will be some shorter supports on which to hang drawers, etc. I am considering to all of the internal joints this way, since the primary stress of the weight isn’t on the dovetail itself.
In the very rough diagram below, the ‘+’s would be dovetails, and the ‘*’s (four corners) would be bed bolts. Each slot with a D will get some form of drawer or shelf.
*-------+-------+-------* | | | | | D | | D | | | | | +-------+ +-------+ | | | | | D +-------+ D | | | | | +-------+ +-------+ | | D | | | D | | D | | | | | *-------+-------+-------*
If I cut the dovetails loose enough to pull apart by hand, will this likely be strong enough? Are there other mechanism that would easily accomplish the same thing?
Thanks.
ben
Replies
Is it fair comment to suggest that your design presently is at great risk from racking, there being no integrity in dovetails used in this fashion so too much reliance is placed on bed bolts?
In order to retain that principle you could consider making each unit enclosing a drawer a separate item, then combining those units by bolting them together on internal faces. Corner blocks in each unit would add strength and the eventual disassembly should be easier and the units moved complete with drawers and contents.
All commentary is fair game. I should have disclaimered this: I'm fairly new to woodworking, and this will be the first major project. There may be simpler things to start on, but this is motivated by need (my bed has been laying on the floor for over a year).I don't understand specifically what you mean by racking. My understanding of racking is what happens if you have a bookshelf with no back, and it slowly starts to lean to one way or the other. If my understanding is correct, do you mean racking "toward the floor", ie, just like a bookcase? Or do you mean racking toward the wall -- ie, if you pulled on the upper left and lower right corners of the bed at the same time? Or do I totally miss the point? :)I do plan to have a thin plywood top, which I could screw if it added sufficiently to the strength. This would help w/ racking of the second sort, but not of the first. Would the addition of screws in the interior joints help much here?It would definitely be stronger to build it up drawer by drawer, almost like a cabinets with a flat top. But it would take a lot more time, and since this is a first project, I won't be surprised if it ends up being replaced in a few years.Thanks again.
Edited 9/30/2007 7:39 pm ET by benomatic42
Sorry for not making myself clear. I meant movement in every direction, after all beds get bounced on and take a lot of hammer.
By my thinking this is a large project so a thin ply skin on top- and nothing on the bottom face will not be enough.
I've got a king size pencil post bed, largely held together with bed bolts, and using the sliding stopped dovetail for center rails to support slats. With bed bolts securing properly fitted stub tenons on beefy rails it is been quite solid in use, even though it breaks down completely for transport.
Yes, in your circumstances I appreciate it will work to your satisfaction. I had just got the impression from the original enquiry that the structure would be lightly built and compromised by drawers in every division. For that to work I think structural stiffness has to be paramount, otherwise those drawers may just not work as hoped.
Yes, structural stiffness is important. The bed bolts are up to the task if the structure is sufficiently beefy. Mine has 2 1/2" square legs and 2 1/2" x4" rails which makes it easy for the bed bolts to work.
Thanks again (to all chipping in) for further thoughts. I've been giving a lot of thought to the notion of building 3 distinct sections and joining them together, but haven't yet given up on my original thought.
As I see it, there are 2 main forces that will act regularly on the bed: pure vertical force (the weight of the mattress, etc.), and an angled vertical force (as if I ran across the room and jumped onto the bed).
My instinct (my only hope, since I have no experience) says that the pure vertical force should be handled adequately well by having the full height "box cell" design. The angled forces individually ought to be fine, but over time I can imagine the dovetails loosening and sliding... which has led me to a next thought.
Imagine again that the outer four corners are still using bed bolts, but that the design is basically a tic-tac-toe board (ie, the middle looks like the sides). At each inner joint, instead of having a single solid piece with dovetailed angles, imagine that the 2 pieces are notched so as to mate top and bottom, like this:
---------------------------
+-+
| |
| |
------------+ +------------
------------+ +------------
| |
| |
+-+
---------------------------
(By the way, I have no idea if this kind of thing has a "known name"... if so, please fill me in :)
From here I could use blocks in these corners to provide reinforcement against rotation gluing cleats to one board and bolting/screwing the other through the cleats. I could obviously use this kind of cleat on the dovetailed connections as well, but I was beginning to wonder if using whole length pieces on the interior would be better.
Have I gone off the deep end yet? Thanks again.
ben
Number 11 seems to have done a good job in advising you Ben. And if everything you did was perfect, where is the fun? If it's not life or death, jump in and paddle.
If it's not life or death, jump in and paddle AND make the slats a Torsion Table!
I think you might have a real elegant idea here. The execution will be challenging, but it would be something worth bragging about down the road.
Dad built one years ago, and the base is two solid units that do not break down. There are six drawers in each unit, the ones that are inside are accessed by removing the front drawers and pulling the back ones towards you.
Like most things Dad built they are overly stout and could be used as jack stands for a tank, with only minor surface scratches.
If you proceed with your design there are Knock Down (KD) fasteners that would work instead of the dovetails. Check out the Lee Valley, Rocklers, Woodcraft, etc. Just do a Google search for "Knock Down Fasteners" and you will have a bunch of online sources.
If you do use dovetails, I would recommend tapered ones.
But really, if it were me I would get away from the idea of a knockdown bed. The ones Dad made are about the size of a box spring bed base, and other than being heavier, are just as easy to move. Two twin longs side by side are the size of a California King.
I am the proud owner of a hand made king size bed. Although it is huge, it is as solid as a rock -- tug on any one corner, and the bed will slide as a unit on the floor, without racking.
I wish I could take credit for making it -- but no.
As your is designed, mine has bed bolts in the corners, and wide (2-1/2 to 3") mating surfaces there.
And as you suggest, mine has a slat pattern and mounting system that helps with rigidity.
There is a center head-to-foot slat support which is cut from 10/4 hardwood. It is dovetailed into both the headboard and the footboard. It's placement is such that the side-to-side slats rest on it as well as on the sideboards.
And one of the side-to-side slats is also dovetailed into the sideboards. The others are placed like traditional slats, mostly just sitting there.
And if you think about the geometry of this design, you'll realize how much those two pieces add to the structure. It's virtually impossible for the head, foot, or sides to bow in either direction -- not true with free-floating slats.
And if the outer pieces can't bow, the remaining slats are much less likely to sag.
Now here's an even better trick -- if you can figure out how to cut the joints. For the 'captive' slats (both directions), mount them a bit on a diagonal. They will have the same effect of avoiding the sag, but will also now act as diagonal bracing for the outer frame.
Politics is the antithesis of problem solving.
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