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I saw this tutorial and I really want to build it for a workspace area at my job. Diycandy.com Bench TutorialThe measurements of this bench were 16″ high x 40″ long x 13.5″ deep, but I'd like to make a table that's 29" high x 107" long x 20" deep. The tutorial bench is built using a modified box joint with interlocking 2"x4" pieces that are glued together with liquid nails. Each of the 2"x4" pieces have a little bit removed on the 2" side to create a square look with a table saw.

Are any structural concerns with making the table this long? Would the table need to be reinforced underneath with hidden brackets? How much weight should it be able to hold?

I appreciate your help!

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  • Instead of hidden brackets you could use dowels and make the brackets part of the design. If you did this you could incorporate some of the knock-down elements described in one of the answers.
    – Dano0430
    Oct 28 '16 at 13:16
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Are any structural concerns with making the table this long?

No. Even with a top much thinner than you're going to end up with you can have a >100" span.

Would the table need to be reinforced underneath with hidden brackets?

Not at all, the interlocking box joint is very strong (lots of surface area for the glue) and the table will be naturally stiff.

How much weight should it be able to hold?

You could try using The Sagulator to calculate this, but it won't be easy since this isn't any material that it includes (because of the way the boards are oriented). Let's just say a lot.

This design orients the boards edge-up, which is using the wood at its maximum strength as regards resistance to sagging. Couple that with them being glued together what you're making here is in effect a laminated beam, so its strength is immense. I bet a heavy person could stand right in the centre and it wouldn't bow enough to notice.

There is a weight issue that you might not have thought of and that's the weight of the table itself. Obviously you like the chunky style but do be aware scaled up to table size this makes for a great mass of solid wood and it'll weight quite a bit and may be difficult to move around even just made from 2x material. Made from hardwood it would be a two-man or three-man job in a lot of cases!

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    The sheer weight and awkward size alone are enough to reconsider this design for a desk that large. At the very least I would consider making it modular, or knockdown, to where they legs can come off. Getting a desk that size into and maneuvered through a building can be nearly impossible, depending on the size and layout of the space. Also, as Graphus mentioned, this thing will be extremely heavy. Oct 28 '16 at 10:50
  • That being said, I still would be concerned with deflection, or the legs wanting to cant out over time, on a top that long without A. any type of apron or intermediate support, or B. a stretcher between the legs. Construction grade pine is a very soft wood, and once you straighten your material, you will be down to more like 3" from a 2x4. If it were maple, or even oak, I would be less concerned. I don't think it will fail, but I would definitely see it deflecting enough to be noticeable over time. Oct 28 '16 at 10:50
  • The orientation of the beams doesn't really matter. You end up with a beam 107" long, 20" wide, and 4" thick. Choosing "Pine, Spruce", allowing the ends to float, and putting a 650lb() weight as a point load in the centre, the sagulator gives about 1/8" deflection. (: I originally chose 300kg, but converted to pounds). Oct 28 '16 at 11:43
  • But beware: That was using the full 4" thickness - if the finished thickness is less, remember that the central sag is inversely related to the CUBE of the thickness - halve the thickness, and the sag rises by factor 8; change from 4" to 3" the sag would rise from 1/8" to ~ 1/3". Oct 28 '16 at 11:46
  • @MartinBonner Go into Sagulator again and put in some new numbers. Go with a top 1/4" thick (this is just to make the top essentially irrelevant, any small number will do) then assume the stiffener (edging strip) is 3.75" thick and 20" wide. The orientation of the boards most definitely matters.
    – Graphus
    Oct 28 '16 at 17:28

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