Making a bed – Joint mock-up

Before I got cracking on this bed I wanted to look into how the joints work where the rail meets the leg.

The foot board and side rail both have to connect to the leg. The foot board gets joined with a permanent mortise and tenon joint. The side rail though has to be removable so that the bed frame can be moved from workshop to bedroom.

Given these constraints, it is common for a side rail to be attached to the leg with knock-down hardware of some kind. Another approach is to use two dowels in the end of the side rail that project into the leg, with the assembly drawn tight with a bolt.

The way I wanted to do it was with a stub tenon on the end of the side rail, with a bolt to draw the joint tight. The tenon would be more resistant to shear forces caused by loading on the rails that a couple of dowels would be. Also, having a shoulder all the way round the tenon would help resist rotation at the joint: something I feel knock-down hardware is prone to.

Theories aside, it was time to start chopping some wood.

I rough cut out a 2×4 to the approximate shape. The leg would have a flat tried and true upper section with the bottom shaped to a curve.

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Then I chopped out a 1/2″ mortise.

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I cut down a short length of wood to act as a side rail. This was thicknessed to 1″. The I cut a 1/2″ wide stub tenon on it.

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And pushed in to fit:

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Next up I had to cut a tenon on the foot board. This board is about 7″ tall and would have to be glued in.

I didn’t want a 7″ tall tenon though as that amount of glued-up connection would be prone to splitting if I did not account for wood movement.

My solution was to cut some haunches on the tenon at the top and bottom. This would allow the tenon to seat fully in the mortise but with only the longest section in the middle getting the glue.

Here is the tenon marked out:

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..and cut out:

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and fitted:

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I test fit the side rail at the same time to see how everything looked. I had to clamp the side rail on as there was no bolt holding the joint tight.

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The foot board is not centered front-to-back on the leg. This is so the mattress will be held in on the end as much as it is held on the sides. Otherwise the mattress would have to be pushed out of shape in order to fit, which seemed silly to me. The legs might not look as odd if they had a square cross section, but then if they did they wouldn’t match the legs at the headboard. So, I’m calling it a “design motif” and moving on. I like the way it looks.

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Next to be done was to fit the bolt, nut and washer to draw the side rail tight to the leg.

I pushed together the joint and then drilled from the outside of the leg through until the bit went a ways into the side rail.

I took apart the joint and deepened the hole in the side rail. Then, I chose a couple of test spots for a nut and washer.

I put in a carriage bolt in the end.

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..and a nut and washer in the rail and cinched the lot up.

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I didn’t like the look of the carriage bolt on the end of the bet so I chopped out a recess and put together the joint again, with the nut and washer moved to compensate.

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With this figured out, it was time to go build the bed for real.

Note, most of this I worked out on the computer, but I think there’s no replacement for making up the part in real life. Also, it is good practice before making the real thing.

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