I'm sure others have come up with a similar concept for different sizes, but this is where I learned it and the size I use. These blocks finish at 4 inches and are constructed with 1/4" seams.
Updated 6/14/14 to include additional sizes. Cutting for 5" and 6" blocks, respectively, in parentheses.
To make two blocks you will need to cut:
- two accent squares 2-1/2" (3", 3-1/2"),
- two light rectangles 2-1/2" x 3-1/2" (3" x 4", 3-1/2" x 4-1/2"), and
- one dark rectangle 4-1/2" x 5-1/2" (5-1/2" x 6-1/2", 6-1/2" x 7-1/2").
|Enough for 2 finished squares|
Begin by sewing the accent squares to the short side of the light rectangles. Press toward the accent square (I finger press). These units should measure 2-1/2" x 5-1/2". Position the two units, right sides together (RST), with the accent squares on opposite ends.
|Accent square sewn to light rectangle|
Stitch along one of the long sides, feeding the accent square end under the presser foot first or your units won't look like mine (ask me how I know ;-} ). Clip the seam about halfway between the two accent squares. Don't be afraid of clipping too close to the seam because it will be cut away. Press away from the squares (I use the iron at this point). This unit should measure 4-1/2" x 5-1/2" .
|Seam clipped and pressed away from the squares|
Note: Sally suggests creating a plastic template triangle to mark the stitching line, but I have found either a right triangle ruler or a ruler with a 45-degree angle line will work. (My illustrations are right-handed; hopefully lefties will know how to adapt.)
Position the right triangle ruler so that the base of the triangle is aligned with the bottom of the pieced unit and the point all the way to the corner. The angled edge of the ruler should fall on the seam intersection. If it doesn't, adjust the position so that it does and draw a line.
|Line drawn -- should have been a little more to the left!|
Or use any ruler with a 45-degree line positioned along the bottom edge of the unit. The ruler needs to be long enough to extend to the corner and the edge should fall on the seam intersection; if it doesn't adjust accordingly.
Turn the unit around and repeat on the other side.
Place this unit on top of the 4-1/2" x 5-1/2" dark rectangle, RST.
Stitch just to the left of the drawn lines, trying to be about a thread's width outside the seam intersection. Cut apart between the stitching lines. This seam will be slightly larger than 1/4".
Press toward the dark triangle. Trim if necessary; however, if you have stitched accurately all you should need to do is snip the one dog-ear. These blocks should measure 4-1/2" unfinished.
Mary's Triangles can replace half-square triangles in any setting -- furrows, sunlight and shadow, diamond, etc. Also, the accent square can be replaced with a 2-1/2" half-square triangle for a more complex look.
I hope you will give this a try. And be sure to let me know how you do!