I’ve been trying to figure the best way to make a 11′ valance/cornice for our large bow window. I’d like to make it out of plywood since it is already flat on two sides. My biggest problem is deciding the best way to join two pieces of plywood together to make one long board. There also needs to be a top piece to which the two roller shades will be mounted in a staggered fashion to keep the sun out. I plan on mounting the whole unit using mating wooden cleats cut at 45°. I was going to use 1/2″ plywood in order to have some rigidity since the entire “box” will have to be open due to the shades.
Any ideas on how to “stretch” that plywood to 11′ would be greatly appreciated.
Replies
Butt two short pieces together. On the back, glue another piece of plywood which spans the joint in the butted pieces. Done.
Or is there something else you're not telling us -- like you want the grain continuous for 11', or you must see both faces of the 11' piece, or something.
No, it's nothing like that. Grain direction really won't matter because my wife is going to pad and cover the whole thing anyway. I just need it to be straight, square and strong and hopefully not too heavy.
Hi Walter ,
My advice to you and the way that I go about making those long valance and cornice faces is to cut the plywood into strips 5-6" wide cut an 8' and a 3' piece place them end to end stagger the joints and start back from the other side . We use a 1/2" wide upholstery stapler to attach each piece together , a bit of glue is good , this will stay much flatter than butting 2 pieces .
good luck dusty
Nothing is as easy as I first think it is going to be. (That always seems to happen to me). Anyway, the valance is not a symmetrical box. It is going to be 14" high in the front, about 8" in the back, 5" deep and have full sides.
I bought a plywood stretcher on ebay; will sell it to you for less than half what I paid.
: )
Your plywood must be quite ill if you have to carry it out on a stretcher. :)
Left-handed or right-handed?
Waterboy,
I recommend you scarf join two 5 1/2-foot pieces to produce the flattest, strongest, and possibly the least visible joint. But I wonder why you don't choose to use a single piece of solid stock instead of plywood.
You can read about making a simple scarf joint here: http://www.oneoceankayaks.com/stitchglue/plyshophtm/scarfjig2.htm. If strength is important, I recommend you make an 8-to-1 joint - the length of the scarf is 8 times the thickness, or 4-inches long for a 1/2-in-thick piece. This is probably the best one for plywood, but others of this joint family include a "hooked scarf," and a "keyed hooked scarf," like the ones shown here: http://home.att.net/~ShipModelFAQ/ResearchNotes/smf-RN-ScarfJoints.html. I've scarf joined a lot of pieces when building boats, including some simple scarf joints in plywood. However, as with any joining method, you may have trouble perfectly aligning the faces. If they're even a shade off, you may end up sanding through the surface veneers after the glue dries. And then you still need to edge band the raw plywood edge. All this tricky effort would be eliminated with a single piece of solid stock.
Gary W
gwwoodworking.com
Edited 9/7/2006 12:33 pm by GaryW
Thanks for your most thoughtful answer, Gary. You have given me some very valuable tips. I did, in fact consider using one long piece of wood but I'm not sure that I could find a board which was flat and true. I have an 8" jointer and 13" planer but my shop is too small to use either on a board that long. That's why I wanted to use plywood. I like the idea of the half-lap joint. The looks of the plywood don't really matter in the finished product since it is all going to be padded and covered with material by my wife. If the two pieces are a hair off I think they would be concealed by the padding and fabric. What do you think about reinforcing this type of joint with a thin (1/4" thick) strip glued to the inside face?
I was also thinking about cutting a rabbet all around the top piece to align the front, rear and side pieces, tack and glue them. Waddya think?
Forgive me if my mental image is off, but it sounds like you will be making a long, upside-down trough that will be joined at right angles along the long edges. Have those angles be rabbet joints, and just make sure the different 11' lengths of each side are made up differently on each side(front is 8+3, top is 5+6,etc.) Also, I would imagine that the valance is not very tall (just wide). Get some nice self stick veneer on a long roll for the whole face. You should be able to find something at least as good looking as plywood.
Yes, I think the idea of staggering the joints is a most excellent idea. I think I'm going to use that one! Thanks
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