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digitalruki
07-15-2007, 12:03 PM
I'm making a huge oil painting (9'x5') and I need to make my own stretcher bars. The wood needs to be 3/4 in. think and at least a few inches wide. And I have no idea how to make corner braces. Could someone give me a quick how-to? tips? anecdotes? I'd really appreciate it.

gunzorro
07-15-2007, 03:21 PM
I would use thicker wood than 3/4" for those long spans. And cross-bracing.
How are you planning to raise (with a lip) the canvas off the wood?
You will want to secure the corners (45 degrees, with glue & clamps securing), making "strainer" frame, not stretcher frame.
If you aren't a skilled woodworker, it would seem to be an overly ambitious project.

perryjohnson
07-15-2007, 09:40 PM
It has always been difficult for me to get straight dry wood and I'm not a great woodworker so I'm listening in on this one.

Glad you have the wherewithal to paint such a large piece!

mattking
07-16-2007, 01:02 AM
theres a few things you can do to make stretcher bars. the "heavy duty" way is to take a construction 12 foot 2x4 and rip it right down the middle at and angle for the whole length of the board. now, you will have two 12 foot peices that are a weird triangli-sh shape. this method of cutting the wood is really hard to explain online. anyways, when you myter these peices, you wont need to use any quarter rounds because of the angle you cut the wood at. the second way, is to take 1/2" x 2" pieces of pine and just myter them to a square, and then put quarter round moulding over the top. for a 9'x5' i would add two cross braces each way. to make corner braces, you can go buy them for a few bucks at blick art materials. or you just take a sheet of masonite and cut the corners off and then nail or screw them to the back of your support.

HRobinson
07-16-2007, 09:56 AM
Does canvas come in that width or do you sew it together? -Harry

P.S. You might want to use some plywood on those corners.

gunzorro
07-16-2007, 10:05 AM
Ha-ha! :) Not a fan of stretching [big] canvas, huh, Harry?
Canvas and linen are commonly available in widths greater than 6 feet. 4 to 5 feet is most popular, followed by 6 to 7 foot wide.
I know Fredrix Rix linen is made at either 110 or 120 inches wide.

************
Bracing corners is the wrong approach to take.
If you have properly glued your corners, they aren't going anywhere.
Your biggest problem will be bending and warping of long strands of wood. 3/4" is wholly inadequate on any dimension for anything much over 36' wide. You need substantial size wood, and high quality straight grain with no large knot holes.
The ripped 2x4 is a great way to go if you have the proper saw and space to cut it.
Otherwise, you do like me and apply quarter round moulding to 2x2 lengths, then cut to size, and finally, glue the corners.
Even with these heavier wood bars, you still need cross bracing on spans longer than 36" or they will bow toward the center. The bracing also allows you easier handling and manuverability of the canvas.

I made one 4x8 canvas out of kiln-dried 2x3 wood, with quarter-round, and cross braces. It was over-kill and quite heavy, but it got the job done, and absolutely stable!

jimb
07-16-2007, 12:10 PM
Does it have to be 9x5?
If you can live with 4x8 then use a big sheet of construction insulation panel. Seal it with varnish or other sealer, and cover it with canvas. Light, cheap, easy...
As as far as the archival aspect. I guarantee that the panel will be around long after we're gone.

GrahamH
07-16-2007, 12:32 PM
I guess you could use large sheets of cotton drop cloth from hardware stores.
They come 12' x 9' ?

Jim Updegraff
07-16-2007, 04:25 PM
I can’t help but think that your best bet is to assemble your five foot by nine foot from four foot by eight foot pieces of hardboard using a 1“ x 3” lumber frame work to stiffen the whole thing and hold it in place.

Better yet, reduce your ambitions to four foot by eight foot and forget the assembly job.

In any event cover the whole thing with cotton or linen canvas and glue it down with rabbit skin or acrylic gesso.

I just see all sorts of problems with a do it your self wooden stretcher -- things like falling out of square, warping, sagging canvas and the like. I think that the old guys who did big stuff used professional joiners and cabinet makers to build big stretchers.