I am building a chest/TV cabinet and need some advise. The sides, top and the shelf that the roll-out TV bracket attaches to are solid wood. I plan to through-tenon the shelf so the case and shelf should all move at roughly the same rate. The bracket that that the TV sits on must be secured to the solid wood shelf and must be securely affixed to the shelf. Therein lies my problem: through-bolting the bracket assembly will impede the shelf movement. Is there another way to do this short of nylon washers and expansion slots for the bracket bolts? I am leery of introducing enough play in the nut tension to permit the shelf to shift.
Thanks for any suggestions.
Doug
Replies
Doug,
My $.02...enlarge the holes where you attach the bracket to the shelf....you can even make slots so the wood can move.
Ps. don't worry about the nut tension...if the wood wants to move it moves..the nut won't stop it.
Edited 5/18/2005 4:18 pm ET by BG
BG,
Thanks. This is my first large project using nothing but solid wood throughout and I'm finding that I must carefully think through every joint and construction technique. Certainly is a different world but offers the oportunity to stretch the learning curve.
Doug
If the TV falls out I hope it wasent when a show ya loved was playing!
Gee, thanks for that contribution to the effort.
:)
It seems like I've spent more time planing and worrying about wood movment than actual woodworking. But, when something is new I guess that's part of the process.
Doug,
In order of increasing complication:
If the wood is fairly docile, ( I mean a species that doesn't move too much) you can probably get along with the above suggestion with a normal sized unit.
There is also the possibility of splitting the shelf itself into 2 parts, thereby dividing the potential problem in half. The front half and the back half can each expand and contract independently, as long as the varying gap between them is not terribly visible to a casual observer.
There is also the possibility of making the whole shelf as a frame of 4 members, floating in a dado in the cabinet sides and glued only at the front to keep the face aligned. If this is a huge unit it can be a solution despite the obvious added work.
DR
Ring,
I am using cherry which is not the most stable wood. I suppose since each bracket bolt would only be affixed to a single board, the board can move in relationship to the bolt only restrained by the adjoining board, which, one would assume, is also shifting in a similar fashion. My tentative design calls for through shelf tenons but there is no reason why I can't keep the design and have the shelf boards as floating tongue and grove since the shelf and side panels should move at roughly the same rate.
Thanks for suggestion this option.
Doug
Doug,
You actually have 2 problems: The major one is the shelf's attachment to the metal bracket, which wants to restrain the wood movement and possibly even split the shelf if it tries to contract too much. This problem would exist without the cabinet altogether - just attaching the bracket to a wooden base for example. Once you have decided how to deal with this issue, you have a secondary one which is how it relates to the adjoining cabinet sides.
My decision would depend on the size and configuration of the bracket. How far is it between the front and rear attaching screws? Up to about 10" I'd guess that you could make do with just having some slack (1/8"?) in each of the screw mounts.
If the bracket is larger than that I would use one of the solutions I proposed - either split the shelf into independent portions, or make it as a stable frame.
If you decide to split the shelf into 2 or 3 segments, you can through tenon the front one (only) as you had planned. The others need to sit in a loose tongue and groove, or dado, or sliding dovetail. The middle and rear sections are going to remain "in place" in relation to the cabinet sides that will expand and contract.
If you decide to make the shelf as a frame and panel unit, the frame needs to be designed so that the screws from the bracket go into frame members only, and not the floating panel. This also requires a sliding joint with the sides (your tongue and groove, or a dado for the shelf, or even sliding dovetail). This would be glued only on the front few inches, to allow the sides of the cabinet to move in relation to the stable shelf.
Hope this is clearer than before.
DR
DR,
Check me out here please: forgetting the bracket for a moment, through-tenoning the shelf should be no different than a box-jointed or through-dovetailed case work with the grain all running in the same direction. If this logic is correct, my shelf can be attached to the side in ways that would not constrain movement, a through-tenon for each board, glued at the front being one such technique. Further, assuming the previous assumption is correct, the shelf boards could be edged glued or T & G. With either technique, the front portion is glued and the sides and the shelf are free to laterally shift. My plan is/was to use a shallow dado - 1/8" and 4 - 2" through tenons on each side for the shelf. Originally the through-tenons were intended to be stylistic but now they take on a little more significance.
Now, adding the brackets as a consideration, the wood movement between the shelf and the sides has to accommodate the bracket bolts. If the bracket has three mounting holes on each side and the shelf is divided so that there is only one pair of mounting hole in each board (one for each side of the bracket), the boards, using tongue and grove, should be free to shift fore and aft without fear of splitting. Since the last mounting bolt does not extend into the read board, this board could be glued as the front board to provide additional stability to the case work.
What do you think?
Doug
Doug,
Absolutely right.
DR
Thanks for the help.
Doug
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