I’m getting ready to start building a shelf that will act as the mantle over my fireplace. I have a 2X4 screwed to the wall that the shelf will slide over so I can attach it.
The finished piece will be 60″ long, about 14″ deep and 5 inches tall(thick). It is essentially a rectangular box with the back left open. Sounds simple enough, but I’m concerned about wood movement. I’ll be using QS white oak for the two ends and the front side. On the top and bottom I was planning to use flat sawn white oak. My original idea was to miter all the corener and match the grain carefully to make it looke like I just screwed a big oak beam to the wall. If joined properly (and grain matches well enough) it would look like a beam except for the lack of end grain at each end.
I’m concerned about the top and bottom moving more than the qs front and sides and causing problems. Is this going to be a problem at this scale? Should I just use plywood for the top and bottom?
Replies
Why not use flat sawn, with the grain running vertically, for the two ends, then you won't have the problem.
I see two bigger problems:
1. Trying to get seamless miter joints on pieces that large, it will present challenging accuracy and glue up problems. You are talking about creating 15 feet of mitered edges, and some tricky three way mitered corners. Its not a job I'd take for any amount of pay.
2. The leverage on the 2 by 4 will be huge, I doubt if the resulting shelf would be stable unless you are also using brackets to support the mantle.
John W.
Like John said, you have some cross grain issues. I'll post a pic I made out of oak quite a while back. It's a fireplace mantle for my mother-in-law. The box is made of oak plywood, which you can miter, attach mouldings to, etc... without incident. About 8 years and running, the joints are all tight. The top shelf is 8/4 flatsawn oak, one wide piece. It moves a little, but I allowed for that with fasteners. If you're careful, and follow the simple rules of wood movement, you build exactly what you want, and have it last forever.
Jeff
Jeff: That's a nice piece. I'll have to work something out similar to it that is more arts & crafts style.
John: The 2X4 is solidly anchored into the studs behind the stone work that is there. I would post a picture but the cable for my camera has gone missing (typical of the way my luck runs). The cultured stone we used for the fireplace is anywhere from 1-1/2" to 3" thick. 14" for the mantle shelf would give me 11" - 12-1/2" of surface area on top of the mantle from pretty much whatever my wife wants to put up there. I have not made provisions for brackets as I just wanted a floating shelf much like the one in Jeff's picture. I suppose I could tone down the amount of projection from the wall, but that wall is 11' tall and the proportions were going to be pretty good at that depth. Especially given the size of the raised hearth.
Looks like I'm off to research some arts & crafts style pieces to see if I can come up with something that will work that will not be so heavy or rip my 2X4 off the wall.
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