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attaching top cap to head/foot board

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Forum topic by trsnider posted 05-07-2016 06:03 PM 444 views 0 times favorited 5 replies Add to Favorites Watch
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trsnider

21 posts in 1469 days


05-07-2016 06:03 PM

really dumb question. I’m building a simple bed that has a board as the cap on the head and foot board. Is gluing it enough to attach it to the legs and top rail or is something more needed? I suppose biscuits could be used but that seems iffy for alignment. I should know this.


5 replies so far

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Dave G

303 posts in 1508 days


#1 posted 05-07-2016 08:54 PM

Beds take a fare amount of abuse. If you just glued it it may get knocked off a few years down the road. If you instead put a shallow tight-fitting rabbet then glue I can guarantee you that it’ll never come off. Make sure all the grain runs the same way in the two pieces glued together.

-- Dave, New England - “We are made to persist. that's how we find out who we are.” ― Tobias Wolff

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trsnider

21 posts in 1469 days


#2 posted 05-08-2016 01:06 PM

Thanks!

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BurlyBob

3646 posts in 1725 days


#3 posted 05-08-2016 03:17 PM

What David said. I did exactly that same process on a bed head and foot board. Worked like a champ.

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JBrow

813 posts in 380 days


#4 posted 05-08-2016 06:26 PM

trsnider,

Yours is not a dumb question; rather a pretty thoughtful question. There are several joinery approaches available, each with their own set of problems or challenges.

Simply gluing the cap to the connecting rail as a butt joint would work if the mating surfaces form a tight joint. However, keeping the cap positioned while applying clamping pressure can be difficult. Also the glue bond where the cap extends over the ends of the posts (if this is your design) would be weak – the remainder of the joint would be strong.

Dowels could be installed and would strengthen the butt joint and be useful in keeping the cap in alignment when gluing the cap in place. If dowels are used, drilling for the dowels with the cap clamped in position before gluing would ensure alignment of the cap and the connecting rail during glue-up. No dowels should be used at the posts since these dowels could restrict movement of the posts. The problem with this approach is that the dowels will be seen when the project is complete. Also if the cap extends over the posts, the end grain glue joint will be weak.

Biscuits or even a long continuous spline could work for alignment and to reinforce the joint, but as you mentioned, careful measurements and accurate tool set up is required.

The method outlined by Dave G would be a solid joint but leaves one edge of the cap flush with one face of the connecting rail. It also required 2-way clamping pressure. If the design calls for one edge of the cap to be flush with the face of the connecting rail, then Dave G’s approach could be followed with good results.

If the cap is to be centered on the top rail, routing a centered tongue in the connecting rail and posts and a mating centered stopped dado in the cap is an option. If the depth of the dado is a little greater than the height of the tongue, the cap can seat tight against the shoulders of the connecting rail and posts (if the tops of the posts are flush with the top of the connecting rail).

Opting for a spline, rabbet or tongue, routing could be difficult if the head board and foot board are glued-up assemblies and the posts set proud of the connecting rail. However, setup and accurate routing is doable.

Regardless of the joinery method, as Dave G stated, tight fitting joinery is important to ensure a solid connection. Also, if the cap extends over the posts, then by only gluing the first ½” or so of the post to the cap (measured from where the connecting rail meets the post) would allow for wood movement in the posts.

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Dave G

303 posts in 1508 days


#5 posted 05-08-2016 08:06 PM

“If the cap is to be centered on the top rail, routing a centered tongue in the connecting rail and posts and a mating centered stopped dado in the cap is an option. “

JBrow, The centered dado approach you suggest is what I meant. Thanks for clarifying.

-- Dave, New England - “We are made to persist. that's how we find out who we are.” ― Tobias Wolff

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