What you need
s4s (surface four side) piece or of wood (length will vary on the size of your frame)
Table saw (TechShop)
Chop Saw (TechShop)
sand paper 120
scrap block wood
Brad Nailer (with nails) (TechShop)
I’m going to show you how I make a stretcher out of hard wood. The hard wood that I used was Poplar, I use Poplar most of the time. It has a nice straight grain and it cheap. I made my stretcher 24 by 24 inches. You can make the stretcher whatever size you want but just beware that you make a lager stretcher you are going to have to add cross braces, which I do not go over in Instructable.
Step 1: Table Saw
The wood that I used was 2.5 x2.5 inches; you do not have to make your boards this size. But I would not make the thickness any less than 1 inch thick. Starting at the table saw, move the angle of the blade to about 23 degrees, run each one of the board thru the table saw. You will have a trapezoid shape. You want to cut the board on the angle so the canvas doesn’t sit right on the wood. If you have the canvas set right on the wood the paint will soak in to the wood.
Step 2: Cutting the 45
Lay out the boards with the highest point being on the outside, and mark the 45 degree angles on each one of the corners. I make the board so I don’t have to think about what angle to cut while Im at the chop saw. Cut the 45s on the chop saw. For this I cut all the 45s on one side and then move the chop saw to the 45 on the other side of the chop saw and cut. You want to make sure the boards are the same length.
Step 3: Glue Up
Since you are not going to see the nails, I glue and using a brad nailer to nail the corners of the frame. I used 1 inch nails, this could vary on the thickness of your board. Lay out the frame, apply glue to the corners and shoot two nails in to each of the corners, making sure that the corners are square. Let the wood glue set for a few hours.
If you are going to make at of frames i would buy some corner clamps.
While the glue is setting you can grab some sand paper with a block and take down the top edge, you want to this so the canvas will no rip on the sharp edge. All you have to do next is stretch your canvas and you are ready to paint. I have made a lot of stretcher for my friends and I have saved them a ton of money.