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Piecing a Quilt or Block on Point
How to piece a quilt or block on-point
A quilt that is set on point is almost always more interesting than one done with a straight-set. But it can be tricky to piece. Although you are working in rows, each row has a triangle at both ends so you can piece the rows diagonally as shown below. But first, you need to know – how big do you cut the Side Setting Triangles (SST) and the Corner Setting Triangles (CST)?
The Side Setting Triangles on the quilt above are in yellow. To cut them so that the bias is on the inside and the straight-of-grain along the edge, you must start with an oversize square and cut it on an X. The diagram to the left illustrates this. The formula for this is: Size of the finished on-point block times 1.414, then add 1 1/4 inches.
The corner setting triangles (the purple ones in the illustration above) are also cut so the bias is on the inside and the straight of grain is along the edges, but since they include a corner of the quilt, they are cut differently. These start with a square which is cut on the diagonal. The formula for this is: size of the finished block divided by 1.414 plus 7/8 inch (.875 if you are using a calculator.)
Here is a quick reference chart for piecing a quilt or block on point
(the numbers have been rounded up slightly)
| Finished size of block | Size to cut square for setting triangle | Size to cut square for corner triangle |
| 4 | 7 | 3 3/4 |
| 5 | 8 1/2 | 4 1/2 |
| 6 | 9 3/4 | 5 1/4 |
| 7 | 11 1/4 | 6 |
| 8 | 12 3/4 | 6 3/4 |
| 9 | 14 | 7 1/2 |
| 10 | 15 1/2 | 8 |
| 11 | 17 | 8 3/4 |
| 12 | 18 1/4 | 9 1/2 |
| 13 | 19 3/4 | 10 1/4 |
| 14 | 21 | 11 |
| 15 | 22 1/2 | 11 3/4 |
| 16 | 24 | 12 1/4 |
| 17 | 25 1/4 | 13 |
| 18 | 26 3/4 | 13 3/4 |
| 19 | 28 1/4 | 14 1/2 |
| 20 | 29 1/2 | 15 1/4 |
Could you use this formula to set a block on point? Yes, you could use the corner setting formula, or try this one: Size of the block multiplied by itself divided in two. The square root of this number would be the size of the square you would need to cut on the diagonal.
Conversions from inches for the calculator:
| 1/8 | .12 | 5/8 | .62 |
| 1/4 | .25 | 3/4 | .75 |
| 3/8 | .37 | 7/8 | .875 |
| 1/2 | .5 | 1 | 1 |
Now, how do you actually piece this quilt? You sew it sideways in rows, like this:
Still having trouble? Sometimes you just need to draw things out on graph paper. Fortunately, you can download what you need for free at this link: https://incompetech.com/graphpaper/
Here are some quilts set on point
This free pattern is set on point – a full explanation is in the pattern. Enjoy!
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Thank you for this great article on how to cut the side setting triangles and corner setting triangles! The size chart you included will be so helpful when planning future projects!