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I am trying to make a king-size bed frame. I have 2"x6"x80" pine boards that were free (always best). I planed them down to 1" thick to use for the head/foot/side rails. If I rip these down to 1"x4" with the 4" vertical, if only supported at the ends on 3" legs will they be strong enough to support the box springs, 14" mattress, and us (2 adults & a dog - 390lbs). The link provided is the bed I am using as a base design (per the wife). Thanks in advance.

bed frame

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    I deleted previous comment because I looked at your link. That bed is not made from pine, and rails are not only 1x4 . And still it is not strong enough, it bends in this photo!!!
    – Volfram K
    Oct 14 '21 at 1:24
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    Hi, welcome to StackExchange. We get strength queries like this regularly and just be aware that it's usually impossible to answer because wood varies so much. And just "pine" doesn't tell us nearly enough — which type? Are you sure it's even pine and not fir? Additionally every single board could be a different strength over a fixed distance because of grain changes and/or knots. And anyway this even assumes you can rip 80" lengths without excessive loss of material, which is tricky at best, i.e. you won't get two 1x6s from each 2x6. Best you could hope for would be two 3/4" x 6" from each.
    – Graphus
    Oct 14 '21 at 7:13
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    Good eye, @VolframK. I didn't see your pic (on their site), but I took a screen shot of the main photo and drew a line. It's visible here, too.
    – FreeMan
    Oct 14 '21 at 12:29
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    There are many species of pine that have different strengths. Keep in mind that the frame you see in the link has more that just the sides - there are other members. Gluing or screwing the strips that will support the box spring has a lot to do with the rigidity and overall strength. A single 1 X 4 is not the only part supporting the weight.
    – Gmck
    Oct 14 '21 at 19:41
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    @Caleb even if 4 inch wide rails are not only 1 inch thick. And not pine. Are you professional sceptic? :) The rail is 100% bending in the image I posted, does it matter if not in another image? And it is bending in Freeman's image - look at carpet!
    – Volfram K
    Oct 15 '21 at 5:47
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Board strength of true 1"x4"

Further to what I say above in my Comment, because wood varies so much it's impossible to give real-world figures for this type of query. You can find tables for wood strength in various places online1 but they aren't really of much help when it comes down to the material at hand and the strength of individual boards is important, as it is here.

It's particularly hard to rely on published data with typical softwood material these days, one reason being the frequent presence of knots. Knots can be relatively inconsequential if within a board2 but locate one near the middle of a span along the bottom edge and just one can fatally undermine the strength of a board.

Or to put it another way, forget the data, what's this board like?

If I rip these down to 1"x4" with the 4" vertical... will they be strong enough to support the box springs, 14" mattress, and us (2 adults & a dog - 390lbs).

Without seeing photos of your material to better judge its qualities I think it's still possible to make a judgement call here, and mine is: a definite NO.

My back-of-envelope calculations put the total load here, conservatively, at 600lb (!) or >270kg for my metric brethren. For that kind of weight I'd very much want to err on the side of strength if working with an unknown softwood, no matter how straight-grained and clear it was.

Also you're converting from a hardwood prototype to softwood, and the rule of thumb is you beef up material when you do this (often by going both thicker and wider).


And I hadn't spotted this myself, thanks to @VolframK and @FreeMan, but the commercial item itself appears not to be built strongly enough3..... so yeah, definitely beef up the design if you're going ahead:

Bed sagging under load


1 Much of it apparently sourced from the FPL since you usually see their numbers reproduced verbatim.

2 And live, not dead (loose).

3 Despite costing more than a grand O_O

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