The Bed Broke - and now I Gotta Fix It

[radhak]

First off - not because of what you were thinking, you one-track minds !



We had a party the other day and a half-dozen tweens and teens sat on the lower bunk in the kids' room at the same time, and of course it broke.



As you can see, it was pine, but it broke right at the weakest spot - with two knots.

Fixing it is easy - just replace with a similar sized (76" x 4") piece. But I'm thinking, will it be strong enough if I use pine again, as long as I avoid knotty pieces? Or should I put in an oak piece?

Oak will look out of place, and cost more, so am wondering if it'd be worth it. This one stood for 7 years, and with both girls in double digit ages, we may not need this bunk bed for too long, so the pine from HD is tempting.

Whaddya say?

[tommyt654]

Try the Tite-Bond No drip glue for a quick and long lasting fix

[LCHIEN]

it should hold up OK, obviously the piece broke at the weak point and would probably have held up to more if it had not had those knots. You can also strengthen it a bit using a wider piece as the shelf for the cross members to sit on.

[cabinetman]

How is that piece installed?

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[JimD]

Cabinetman asks an excellant question for multiple reasons. Most obviously, how it is attached affects the difficulty of the repair. How rigidly the rail is attached also affects it's deflection and ultimately how much weight it can support.

The deflection and ultimate strength of the beam are a function of the material but also the width and height of the beam. Oak would have about a 20% advantage over pine. So pine 20% thicher would have the same strength as oak the same thickness as the piece that broke. If you can increase the height, going up 20% would increase strength over 70%. (the deflection or strength is a cube function of the height and a linear function of the width and modulus of elasticity).

Jim

[RAV2]

We bought my kids those beds and at setup, I had a welding shop make some 3/4" angle iron supports that I ran along the side rails. I screwed the supports in every 6 inches and lagged them into the upright rails.

Worked for me.

[radhak]

Good question guys - it's installed with 4 5" long bolts, 2 on each side. But the posts are 4" thick, so these bolts are only 1.5" into this piece on each end.

Good info, Jim. Current piece is 5" wide. I could look to increasing it to 6" and staying with pine.

Interesting idea, Rav; might take it up if we think the bed's gonna be used long enough.

Of course, there's an inner piece attached all along this one, to support the bed slats, 2" x 2" cross-section. Currently that piece is broken up into 3 smaller ones (they must have just used some shorts). I'm thinking of converting it to a single long piece; would give additional length-wise strength.

[cabinetman]

Good question guys - it's installed with 4 5" long bolts, 2 on each side. But the posts are 4" thick, so these bolts are only 1.5" into this piece on each end.

So what you're saying is the a 5" bolt (with a screw end?) goes through a 4" leg into endgrain of a 5" high by ¾" thick pine?

If that's the case, a piece of pine without knots would be better, or clear vertical grain fir. You could also use 5" hardwood plywood. That won't deflect like pine will. Once you decide what to use, we''ll come up with the joinery.

.

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[radhak]

I'll use pine. As for joinery, I might as well replicate what exists currently, right? After all, the joinery did not fail, the wood did!

[eezlock]

the bed broke........

Why not make double rails on both sides of the bed, sandwich the rails together
with glue and countersunk screws. Then cover the screw heads with plugs.
That way you wouldn't change the outward appearance by using a different
species of lumber.

[chopnhack]

Why not make double rails on both sides of the bed, sandwich the rails together
with glue and countersunk screws. Then cover the screw heads with plugs.
That way you wouldn't change the outward appearance by using a different
species of lumber.

A very good suggestion and very easily implemented! The only other change I can think of if you decide to go this route, is shortening the slat length by twice the thickness of the new board's width. Should outlast the tweeners ;-)

[sscherin]

All the bed rails I've made so far have been maple or poplar.

The one I'm working on right now is 5.5" x 3/4" poplar with a 3/4 x 1" rail glued/screwed on to hold the slats.

Same 4 bolt mounting system.

I got a good deal on a set of bunk bead headboards missing the rails.

[cabinetman]

A permanent fix would be to just use 2x6 pine (pick out a good one). Add the 2x2 cleat for the slats. Just screw it on from the inside. At the ends, use a type of bed rail fastener. There are several on this page. There are friction catches, tapered connecters, and surface screw on connectors. Many of them will work and require no involved machining.

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[JimD]

If the "bolts" attaching the rails are lag bolts - wood screw type attachment - you may want to think about putting a captured nut into the replacement. It is cheap and pretty easy. All you do is drill a hole with a forstener bit for the nut and then make a half round piece to support it. Or you could get a special nut made of round stock (or tap a piece yourself). It allows for taking it apart and will hold better. The lag bolts will work too as long as you don't take it apart and attempt to put it back together. You could probably do that once, maybe twice, but at some point the wood will be chewed up and the lag won't hold.

Jim

[radhak]

I should be able to disassemble that part fully today so I'd see how exactly it's put together; but I am expecting to re-use whatever they used - like I said, the failure was not at the join at the end, but in the wood in the middle. Since their joinery lasted 7 years, might as well not try to fix it.

Unless of course I find the bolts/screws are bent or whatever... will keep you posted.