Today, we are talking about how to get accurate square in a square blocks (aka diamond in a square blocks). With many of my quilt patterns, you will notice that you will be directed many times in the pattern instructions to sew a triangle to a square, “being sure that your triangle is accurately centered.” That “accurately” part is what we are going to go over today!
Believe it or not, when I first started quilting, no one told me that it was important to measure my square before adding the triangle- I would just “eyeball” it and hope it turned out right! Even if you’ve got a good eye, you will get optimum results if you use one of the methods shown below to assemble your blocks. Yes, I know it takes a little extra time to do it this way, but you will be much happier with the results than if you just “wing it”…
The first way to do it, and the quickest, is the finger pressing method:
You will start with your square for the center (this could simply be a square of fabric, or it may be pieced, appliqued, or embroidered) and 4 triangles:
Fold the square in half and finger press to make a light crease. Unfold the square, and then fold in the other direction.
Now, use that light crease on the square to position your triangle with the top edge of the triangle lined up with the edge of the square, and the center point of the triangle lined up with the center crease of the square:
That’s the important part- make sure the your triangle point is lined up with the exact center of square! Don’t “eyeball” or guess at that part…
Your triangle will be centered between the left and right sides– it probably won’t be centered between the top and bottom edges. The left-to-right center is the only thing you need to worry about.
Now, if I could give you just one bit of advise for improving your piecing, it would be Pin it! Pin it! Pin it! I pin everything- even if I’m just sewing squares together into pairs or sewing strips together. It takes a little longer, but I feel that the accuracy you gain is well worth it.
You will also need to pin on the triangle on the opposite side of the square. You will need to get that first triangle out of the way so you can see your crease and get your second triangle lined up properly:
Sew your triangles to the square along the edge of the squre. Press out the triangles, being careful not to flatten the center fold- you’re going to need that crease for the next pair of triangles. Repeat the process for the next pair of triangles:
Sew on 2 more triangles. Press out the triangles:
and trim off “dog ears”:
While this method works well for a simple fabric square like shown above, the finger pressing method may not work as well for block center squares which are pieced or have been appliqued. For these types of blocks, I measure the center point with a ruler, and mark with a pin or with chalk, and then I position my triangles and pin them in place.
If you are following a pattern, the sizes for your squares and triangles will be given. But if you’d like to make some blocks on your own, and for those of you who have asked what size to cut your triangles, here is the formula that I use:
- Add .75 to your center square size (so, if your square is cut 6 1/2″ square, adding .75 gives you 7.25)
- Multiply by 0.7071 (so 7.25 x 0.7071=5.126, or 5 1/8″)
- This is the size to cut your square, which you will cut in half to make 2 triangles (so you would need 2 squares, 5 1/8″, to make 4 triangles for one block)
- If you would like, you can also round up 1/4-1/2″, and then trim the block when you are finished. So in this case, cut your squares about 5 3/8-5 5/8″ before cutting into triangles. This will give you a large seam allowance and plenty of “wiggle” room for trimming.
This technique is perfect if you are making my FREE pattern called Grammy’s Rose Garden – you will get LOTS of practice with your square in a square blocks!