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How To Piece Biased Edges



One of the most tedious piecing issues emerges when piecing triangles; this is almost always because they involve biased edges. When you cut fabric at any angle across the grain it will have a tendency to stretch during piecing… and that can make anyone tear their hair out! Flying geese blocks are notorious for accuracy issues because of stretching. I will show you my technique for those in the second half of this post.


I’m whipping up a simple kids quilt for a friend made out of 6.5” triangles. Here I am using my triangle ruler to cut out all my triangles and two of the edges will be biased. The bottom of the triangle is on the grain and will not stretch.

I lined up all my triangles with their biased edges facing each other and their on-grain edges at either the top or bottom of the rows. This way, I will be sewing bias to bias and when the rows go together, the on-grain edges will be sewn to each other.

Lay one triangle onto the next one making sure the two biased edges will be sewn together. If one fabric tries to stretch more than the other, you can just tug a little on the one that needs to stretch more to match.

I use a handy tool called a stiletto as almost a third hand or an extra long pointy finger :) try not to think about how creepy that would be. It works wonders holding pieces in place as I feed them into the machine (especially those pointy angles).

Sew the triangles into sets of two and then those sets into rows. Press all the seams in Row: One to the right and all the seams in Row: Two to the left (continue alternating each rows pressing direction). This will ensure that the intersections “nest” together when you sew the rows together.

Now, the rows go together and these edges are not biased and will not stretch. Match up each intersection and “nest” the seams as you go. I then pressed my cross seams, open. Perfect match!

What to do when mixing biased edges with non-biased edges, as sometimes happens in flying geese blocks.


In this block, the gray edges are on-grain and the purple edges are biased.


When this is the case, always piece with the biased edges on the bottom against your sewing machine's feed dogs. The feed dogs will do all the work of pulling the fabric along and not letting it stretch out of place.

I press these seams open so everything lays super flat for the next piece.

I’m going to sew two of these flying geese together and this time the top purple edge is the on-grain edge and the bottom edge of the gray goose is biased. I will sew from the purple side with the gray biased side towards the feed dogs and use my stiletto to hold it in place as I sew.

Press these seams to open flat and ta-da… Done! I hope this was helpful and will give you confidence piecing triangles!


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Seattle, WA USA

© 2020 Krista Moser.