Mass Producing 1/2 Square Triangles

Mass producing half square triangles


Learn how to set up a grid system to make many half square triangles.

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download transcripts Video Transcript: CUTTING AND SEWING HALF SQUARE TRIANGLES – Mass Producing ½ Square Triangles (#7 of 8 videos)

Some quilt patterns require lots of triangles like this Tree of Life block. Instead of cutting one or two at a time, I like to “mass produce” these using a grid system. The grid can be any size depending on how many triangles you need. In this video, I will show you how to make a grid system that will speed up your production of these pairs of half square triangles.

Let me show you how this works on a small grid. A single square will give me two triangles when cut on the diagonal. If I use two pieces of fabric then I get twice the amount of triangles.

If I add another square to this grid, I will double my amount of triangles. Now I have four triangles. If I use two pieces of fabric, I end up with eight triangles. I can add more squares to my grid. If I need to make sixteen triangles then I would use this grid and two pieces of fabric. Thirty-two triangles? Then I would use a grid like this also with two pieces of fabric.

To figure out the size of the squares in your grid you need to find the finished size or the shorter leg of the triangle. So let’s look at this triangle here. And here’s a short side and there’s another short side, so that measures 2”. Add 1” to that finished size so 2” plus 1” equals 3”. Since each square will be 3” then my grid will measure 3” plus 3” or 6” across by 3” plus 3” or 6” down.

I cut a 6” square out of two pieces of fabric. I made sure that their right sides were together before I cut. And I’ve cut these on the straight of grain and cross grain.

I used a marking pen to make these grid lines. First I marked the 3” squares. So I came over 3”, marked that line and came down three inches and marked that line. Then I mark the diagonals as you can see on this piece. I’ve put the diagonals in. I will be sewing around these diagonals so no pins along the diagonal.

I am ready to begin sewing. I like to start on a scrap piece of fabric so let’s get that. I am using red thread so you’ll be able to see but you will want to use a matching or neutral color. I don’t think it makes any difference if I start on the inside or the outside. So I’ll start on the outside edge here. I am a ¼” away from that line. If you don’t have a ¼” foot (see my foot is exactly ¼”), if you don’t have a foot like this for your machine then you’ll need to draw that line in.

So I am at the end. I pick up my pressure foot, pivot, and begin sewing ¼” from the line. Now I am coming to the end here. Let me clip this little piece off. Notice how I’ve avoided all the pins because ahead of time I knew where my… where I was going to stitch. So I am at the end now. I want to lift up my presser foot and my needle, pull out a little bit of thread and now I going to be sewing ¼” on this side of the line.

So this is a little bit different. I need to make sure that I am starting on this straight line here that I marked for my squares. So there we go and I want to make sure that I end on that line. So when I get to the end, I want to slow down. I’ve got my needle down, I pivot, ¼” from the edge and I work my way all the way around. Here I am again. When I get to the end just lift up my needle; I don’t have to backstitch or anything and clip my threads.

After sewing, I’m ready to cut. At this point, I want to make sure that all these pins have been removed before I begin to cut. First I want to cut the squares apart on these lines. Then I’ll cut the squares on the diagonal. So let me line this up. Cut.

I can take these individually. I could leave it the way it was and cut across but it is easier for me to cut like this. And let’s take this one and cut on that line. And now I am ready to cut these diagonals. I don’t have to be exact on the diagonals because the seam allowance is already in there but I like to try to keep it as close as I can. It just makes it a little bit neater on the other side but let me show you what it looks like if I don’t cut. See – it’s still Ok (when I open this up) Lets finger press this a little. I’ll open that one up. It’s going to look the same as when I open this one up. That’s why that seam allowance is not so important on the diagonals but it is important to get those first couple of lines cut.

So after I cut this now, I want to take it over to the pressing board and press it. And then I am going to l “square up” each of those triangles.
Now I have 16 squares made from 32 half square triangles.

You can find more information about cutting and sewing half square triangles at under “Beginner Basics” – “Cutting” and “Sewing”.

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