A “Y Seam” Tutorial


Why Not Make a Y Seam?

Have you ever looked at a block, and you are intrigued by it, but ultimately you give up the idea of trying it out? Why? because you can’t quite figure out how it will be constructed, and you realized that you would have to do a Y Seam. You could go out of your way to make the block happen by perhaps cutting the corner square (that you would have to use a Y Seam on) into half square triangles. OR…you have an isosceles triangle you want to put together using 3  – 120 degree triangles. Instead of using a Y Seam, I suppose you could seam the final third triangle. Don’t let your never having done a Y Seam stop you, the amazingly and creative quilter, from doing the block you want!

I am currently working on a quilt that is made using the Creative Grids 120 Degree Ruler.


I am making Isosceles Triangles to make these stars for a quilt. This involves many Y Seams, and at the end of the quilt, I have only had to fix one unit! That my friend is success!

I will give my example using the triangles, but will add a paragraph at the end for making Y Seams when joining a square. If your machine has a needle down option, use it! If not, when you stop at the corner before pivoting, put your needle in the down position.20160606_200625-1.jpg

  1. Lay out the triangle as shown. 20160606_200247-1.jpgBegin by sewing the center straight seam RST, from the outside edge toward the edge where you will make the Y Seam join. STOP 1/4″ before you get to the edge, backstitch a couple of stitches. Press this seam open.
  2. Lay the piece you just stitched Right Side Up, with the point toward you and the V edge where you will join the 3rd piece away from you.
  3. Take the 3rd piece Wrong Side Up and insert a pin through it 1/4″ in from the corner point where the 2 short sides of the triangle meet.20160606_200514.jpg

20160606_202101-1.jpg4. Take the 3rd piece and place it over the pieces you previously joined with the RST , and insert the pin through this 1/4″ in from the V. Note: this is where you did the backstitch. Very often I place the pin after the first visible stitch.20160606_200514-1.jpg20160606_201521-1-1.jpg

5. With the pin in place through both layers RST, line up the raw edges to the left of the pin. Then pin all layers in place with the point of the pin facing to the left.20160606_201620-1-1.jpg20160606_201735-1-1.jpg

6. Stitch from the left hand point toward the center, removing pin as you get close. Stop at the center (where you can most likely see the pin hole).


7. Raise your presser foot. Take the remaining right hand side of the top triangle and swivel it to match up the raw edges with the bottom piece. 20160606_202149-1-1.jpg

8. Lower presser foot making sure everything is even. Continue stitching to the outer edge. 20160606_202226-1-1.jpg

9. Press seam toward the triangle you just joined.    20160606_202510-1.jpgThere you have it! Not so hard really! I have to confess though that by the time I was done with all my units, I was kind of tired of Y Seams!

Sewing a square block into a corner using a Y Seam:

Take the corner block piece Wrong Side Up and insert a pin through it 1/4″ in from the corner point.

Place this over the top of the piece you are joining it to, RST and place the pin 1/4″ in from V.

Continue from Step 5 above. Press seams out toward corner block.


Hope the tutorial helps!






One response »

  1. Pingback: Thinking about This one! | Quilting Shenanigans

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