Bed Build

[Brian]

Taking a break from my cabinet to build a piece with slightly more urgent demand. However, even with more of a rush for this project it will be built without metal fasteners and will use all joinery in solid wood.

I sincerely despise the middle support legs under beds and so I'm doing my best to avoid using one. The center beam is quite heavy and will serve as a major support for the legs in addition to being a support for slats.



Chris' carpentry writing has been incredibly insight and so I've decided to put my new knowledge to use;

[Brian]

The gap looking area is a pencil line.

[Chris Hall]

Good on ya for tackling a rod joint with shachi.

I would say however that you have made the rod itself a tad fat, which means the receiving member with a fork has fork blades a bit on the skinny side. When the shachi are inserted they will likely open up the interface between the fork side faces and the rod's side faces as the fork blades will not quite be stiff enough. You could change the shachi to the parallelogram shape type to compensate a little.

Ideally the rod width is 1/3 the receiving member. It can be slimmer, depending upon timber sizes, but fatter is not advised. The rod you have made there looks to be about 1/2-section thickness.

[Brian]

Thanks Chris! Ahh, makes sense, exactly like Mortise and tenon.

I could also laminate 3/16" cheeks that would extend into the center beam, what are you thoughts on this coarse of action?

I saw that you rec'd the parallelogram in the writing as well as it directs the forces in more of a straight line, I will do this as it makes the layout more intuitive. I have a 10 degree dovetail plane which will help make the parallelogram pretty easy to cut.

[Chris Hall]

Well, if you can swing it in terms of your material pile, and it would work design-wise, I'd cut new rails, sized in width to be 3x the rod section thickness. I would do that in preference to gluing cheeks on to fatten it up, which I would consider a 'last recourse' sort of thing.

[Brian]

3" wide should work, these are hidden by the outside frame which has an elevation equal to the rails.

I kick myself designing on the fly, I had originally planned half laps supported by center legs, but I decided to ditch the center leg because they're always catching on things.

[Brian]

Chris,

I decided first to cut parallelogram shachi before making a decision. I installed these and drove them in pretty well, the deflection is under .003" per side.



The pins are surprisingly easy to make with a 10 degree dovetail plane clamped in a vise.

[Chris Hall]

That came out well - nice to be able to keep the pieces you already had and worth the gamble for sure.

[Brian]

Thanks Chris! And I will certainly be doing 1/3 proportions on the next project.

[Chris Hall]

In most cases, 1/3 is about right, though you can go as small as 1/4. When the pieces get on the wide side, then look to go to twin rod tenons, or passing rod tenons.