June 29, 2004
INDEX
Cutting the Edges!
This lesson teaches the "math" behind cutting the edges and Lesson 7 tackles the corners for an on-point quilt setting.
At this point, the quilt top should look similar to the one shown below. Note that the three blocks in the middle (scissors, ice cream cone, and wrench) are sewn together as one row. The block at the top/left (screwdriver) and the block at the lower/right (hammer) are not attached to the middle row at this point.
In every On-Point Setting quilt, there are two types of triangles that are needed: Edges and Corners. In the diagram below, the pink triangles represent the EDGES and the purple triangles represent the CORNERS.
To cut both the edges and the corners, we begin by cutting simple squares! However, the instructions for a sashed quilt are a little different than an unsashed quilt. Below, you can find instructions for both types.
Cutting The Edge Triangles For An Unsashed Quilt (such as the blue/white/pink/purple example above)
The edge triangles are made from a square that is cut diagonally, both directions, in an "x" fashion. Each square that you "x" cut yields four triangles. These four triangles have bias edges, but we will account for that when we sew them so that they do not stretch. Although the edges are the hardest to calculate, with the math simplified, it's a piece of cake!
Note: Ignore the fact that the photo illustrations in this section do have sashings! The idea of what it should look similar to is the same, so forgive me this one time!
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Count the number of edge triangles needed for your quilt. In the quilt that we are making, we simply need four, so one square is all that is needed. In the blue/white/pink/purple diagram above, there are eight edges, so two squares would be needed. If, for some reason, you have a quilt that has a number of edge triangles that doesn't divide by four equally, then round it up so that it comes out even. For example, if the quilt has 6 edges, the closest number divisible by four that is larger is 8, so use 8 instead.
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Let's do the math. How many edges do you have? _____ How many squares do you need? _____
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Next, you must find the diagonal measurement of your blocks. The blocks in our lessons are 10" unfinished, but we need to know the finished size for this measurement. A 10" unfinished block is a 9.5" finished block. So, the size of our block is 9.5". To find the diagonal measurement of the block, multiply the finished size (9.5") by 1.414. In our case, 9.5 x 1.414 = 13.433. Always round it up, so 13.433 rounds up to 13.5. So, our 9.5" finished block has a diagonal measurement of 13.5".
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Using the measurement derived in step 3, add a minimum of 1.5". So, we calculated a diagonal measurement of 13.5", so with the addition of 1.5", we now have 15". Personally, I usually add 2" to my diagonal measurement because it is best to have too much rather than too little, so I would cut my squares 15.5".
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Let's do the math. My finished block is? _____ My diagonal measurement is (multiply finished block by 1.414)? _____ The size of square(s) needed is (add at least 1.5")? _____
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Cut the number of squares you need (step 2) the size you came up with in step 5. In the sample above, I will be cutting 1 square for my edge triangles that is 15.5" (because I like a little room for err!). How many and what size are you cutting?
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Cut each square in the "x" fashion to yield 4 smaller triangles, such as the examples shown below:
Cut the square Cutting the first diagonal of the "x"
Cutting the second diagonal of the "x" 4 smaller triangles
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Place your edge triangles in their positions in your quilt layout, always making sure that the non-bias edge (the longest edge of the triangle, when cut in an "x" fashion) of the triangle is on the outside edge, as shown below:
Layout with the edges Closeup of an edge
Note: In the photos above, notice two things: 1) The outside edges of the triangles (the long sides of the triangles) are also the outside edges of the square(s) when you cut... this keeps the bias edges on the inside and it results in non-bias edges on the outside of the quilt top, which is a good thing, and 2) The triangles are a little larger than the area that they are going to be sewn in, which is a good thing in that it gives you room to sew more accurately! -
Let's review! To find the dimensions of the squares needed for the edge triangles, you simply: 1) Determine how many squares you need by counting the number of edges and dividing by 4 (round up, when uneven), 2) Find the diagonal of your finished square by multiplying the finished size by 1.414, then round it up, 3) Add at least 1.5" to the diagonal size and that is the minimum size to cut your squares, and 4) Cut each square in an "x" fashion, that yields 4 smaller triangles.
Cutting The Edge Triangles For A Sashed Quilt (such as the one being made in this class)
The edge triangles are cut using the same calculations above, only we now take into consideration any sashing that you may have. The sashing is considered to be part of the block when calculating the edges.
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Count the number of edge triangles needed for your quilt. In the quilt that we are making, we simply need four, so one square is all that is needed. In the blue/white/pink/purple diagram above, there are eight edges, so two squares would be needed. If, for some reason, you have a quilt that has a number of edge triangles that doesn't divide by four equally, then round it up so that it comes out even. For example, if the quilt has 6 edges, the closest number divisible by four that is larger is 8, so use 8 instead.
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Let's do the math. How many edges do you have? _____ How many squares do you need? _____
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Next, you must find the diagonal measurement of your blocks. First, figure out what the finished size of the block would be, and be sure to include the sashings! For example, a 10" unfinished block is 9.5" finished. If your finished sashing strips are 2", add 2" to this to get 11.5" for the finished block size (always double the finished sashing strip size to add to the finished block size). To find the diagonal measurement of the block, multiply the finished size (11.5") by 1.414. In our case, 11.5 x 1.414 = 16.26. Always round it up, so 16.26 rounds up to 16.5. So, our 11.5" finished block has a diagonal measurement of 16.5".
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Using the measurement derived in step 3, add a minimum of 1.5". So, we calculated a diagonal measurement of 16.5", so with the addition of 1.5", we now have 18". Personally, I usually add 2" to my diagonal measurement because it is best to have too much rather than too little, so I would cut my squares 18.5" for this sashed block.
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Let's do the math. My finished block is? _____ If there is a sashing, the finished width of it is _____, making my finished block/sashing total _____. My diagonal measurement is (multiply finished block/sashing by 1.414)? _____ The size of square(s) needed is (add at least 1.5")? _____
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Cut the number of squares you need (step 2) the size you came up with in step 5. I will be cutting 1 square for my edge triangles that is 18.5" (because I like a little room for err!). How many and what size are you cutting?
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Cut each square in the "x" fashion to yield 4 smaller triangles, such as the examples shown below:
Cut the square Cutting the first diagonal of the "x"
Cutting the second diagonal of the "x" 4 smaller triangles
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Place your edge triangles in their positions in your quilt layout, always making sure that the non-bias edge (the longest edge of the triangle, when cut in an "x" fashion) of the triangle is on the outside edge, as shown below:
Layout with the edges Closeup of an edge
Note: In the photos above, notice two things: 1) The outside edges of the triangles (the long sides of the triangles) are also the outside edges of the square(s) when you cut... this keeps the bias edges on the inside and it results in non-bias edges on the outside of the quilt top, which is a good thing, and 2) The triangles are a little larger than the area that they are going to be sewn in, which is a good thing in that it gives you room to sew more accurately! -
Let's review! To find the dimensions of the squares needed for the edge triangles, you simply: 1) Determine how many squares you need by counting the number of edges and dividing by 4 (round up, when uneven), 2) Find the diagonal of your finished square with finished sashing by multiplying the finished size by 1.414, then round it up, 3) Add at least 1.5" to the diagonal size and that is the minimum size to cut your squares, and 4) Cut each square in an "x" fashion, that yields 4 smaller triangles.
Lesson 7 will cut the corner triangles, Lesson 8 will attach the edge and corner triangles to the quilt top and wrap up the quilt. We're getting close to the finish line!
