Strong Platform Bed

A friend who shops in the “big and tall” section wanted to build a platform bed that he was absolutely certain would not be broken. He wanted simple construction with heavy lumber–as he put it, “a barbarian bed”. He also wanted 12″ of clearance under the side rails for storage.
strongbed1

We used 4×4’s and 2×8’s, and put it together with 8 large carriage bolts so it could be disassembled. No special tools are needed, but it does require a few challenging cuts, careful drilling, and countersinking long screws.

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The key to this design is that the weight is transferred directly through supporting lumber under each piece. Screws and bolts primarily provide the lateral stability–most of the weight is sitting directly on top of the legs.

Dimensions

80″ x 61″ x 20″

This is the same length, and 1″ wider than standard queen mattress size. Most mattresses average a little less than standard, so if the head of the mattress is pressed against the wall, the frame will stick out 1/2″ or so on each side.

Shopping List

1 – 4×4 x 8′
4 – 2×8 x 8′
6 – 2×3 x 8′
12 – 1×4 x 8′

Cut List

4 – 4×4 x 19″ notched

2 – 2×8 x 77″
2 – 2×8 x 61″ both ends cut at 45 degree bevel

2 – 2×3 x 77″
3 – 2×3 x 58″
2 – 2×3 x 51″

12 – 1×4 x 77″

Step 1 – Notch the legs

Each of the 4 legs needs a rabbet cut at the top end. Mark a line 4″ from the top. Mark lines on opposite sides, parallel to the length, 1.5″ from one face, and across the end to join the lines. A table saw is ideal, but you can also get by with a circular saw, and finish it with a hand saw.
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Step 2 – Attach the supports to the End rails and Side rails

The 61″ 2x8s are beveled at each end, in a trapezoid, so one side is only 58″. The 2×3 support piece will attach to the inside, or the 61″ side. Align it 1″ from the top of the 2×8, and 5″ from each end. Attach with glue and 2.5″ screws.
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The 77″ 2x3s attach to the 77″ 2x8s, aligned on the ends, and 2.5″ from the top edge. If your 2x8s measure 7.5″, that will be centered, but if they only measure 7.25″, they will be 2.25″ from the bottom edge.

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The side rails also need a small block on each end, which I made with a piece of 2×3, to take up the space above the support rail.
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That piece is held only with glue. It is about 3/4″ from the end.
sbedrailblocks

Step 3 – Drill the main Bolt Holes

For consistency, and to help keep the holes at 90 degree angles, I created a drilling jig for the main bolt holes from a piece of 1×3 scrap, using my drill press with the 3/8″ drill to get them strait. I marked one edge “end” (meaning the end of the 2×8), and one end of the scrap “top”, and measured hole centers at 1 3/8″ from the “end”, and 1 7/8″ and 6 1/8″ from the “top”.

I clamped this to the side rails and drilled through the holes in the jig, giving me strait, consistent holes in the side rails.
sbedjig

Clamp a leg to the end of the side rail, with the notch firmly up against the support rail, and the end aligned with edge of the leg. Make sure the leg is square to the side rail.
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Drill through the holes in the side rails into the legs. You will need to remove the clamps and separate the parts to finish drilling through the legs, as the drill will not be long enough to go through both pieces at once.

Step 4 – Drill the screw holes in the legs

Each leg also needs 3 screw holes to attach it to the end rails. If you use 4″ screws, you should countersink the 3 holes about 1/2″.

In addition, drill one more hole through the rabbit section of the legs, perpendicular to the others, 3/4″ from one edge as shown. Note that this hole must be on the left for one leg, and the right for the other. The screw for this hole only goes through the notched part of the leg, so a 3″ screw is sufficient without countersinking.
sbedlegsholes

This is where you will need to extend your drill bit out as far as you can in the chuck while still maintaining a grip, to get the greatest depth from your small drill bit. Use care, as this increased the chance of slippage or breaking the bit. Only use this method to finish the hole after drilling most of it with a more solid grip in the chuck.
sbedlegdrill
Most narrow drill bits will not be long enough to penetrate the 4×4, but you can get deep enough that it is unlikely to cause any wood splitting when forcing a screw through it.

Step 5 – Attach the legs to the end pieces

sbedlegassem
The legs will attach to the inside, with the tall side against the end of the support piece. The rabbit on the legs should face the outside on each end. The top of the leg should align with the top of the support piece, and the bottom of the rabbit notch should be 5″ below the top of the rail.
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Make sure the legs are square to the rail, and with glue and screws.

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Step 6 – Assemble

Once the glue was dry, we assembled it using 5 1/2″ carriage bolts. They are going through 5″ of lumber, so that leaves only 1/2″ of threads when fully seated. And carriage bolts aren’t fully seated until you tighten them, so using 6″ bolts will make it easier to get everything started.
sbedframeassemble

Lay the 2x3s across the width. This photo and the Sketchup file show 3, but he ended up using 4 cross pieces.
sbedframe

One reason he used an extra cross pieces is that we used 1x3s for the slats. If you use 1x4s as specified in the cut list, you will get additional strength from that, and probably won’t feel the need for the extra cross piece.
sbeddone2

We used Minwax Special Walnut stain. And no, the legs are not finished in that photo.

Step 7 – Connect the slats together

The cross pieces and slats need to be held in place to keep them from shifting. My friend screwed the cross rails into the support pieces, which was not my first choice since it makes it more difficult to take apart. We also looked at inserting screws, slightly raised, on either side to keep them in place.
sbedslatstrap
We attached the slats together with strips of burlap, stapled to the slats. A hole through each end of the two outside slats, and an finish nail sticking up from the top of the legs keeps the slats in place.

You can also download the Sketchup file for this project.

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