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How To Piece Biased Edges

Updated: Apr 16, 2022

One of the most tedious piecing issues emerges when piecing triangles; this is almost always because triangles involve biased edges.... and those stretch. I have gotten a few request recently asking for help when piecing with bias, so thought I would repost this blog from awhile back!

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 also notorious for accuracy issues because of stretching. So, I thought I would show you my technique for piecing those in the second half of this post.

I was whipping up a simple kids quilt for a friend made out of 6.5” triangles. These are mostly scraps and odd strips that I could get a few triangles out of.

Here you see my triangles cut from strips have two bias edges, one on each side, those will stretch and the straight of grain edge along the bottom will not stretch.

To lay out the quilt, I lined up all my triangles with their biased edges facing each other on the sides and their on-grain edges at either the top or bottom of the rows. This way, I will be sewing bias to bias when piecing the blocks into rows and the on-grain edges will be sewn to each other when the rows are sewn together.

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 give a gentle tug on the one that needs to stretch more to match. If you need a quick way to tell what is bias and what is straight, pick at the edge with your finger nail and you'll get the straight of grain edge to fray and the bias edge will stretch if you tug on it.

I use a handy tool called a stiletto as almost a third hand or an extra long pointy finger :) It works wonders holding pieces in place as I feed them into the machine (especially those pointy angles). I would be lost without this tool!

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. You could also press all your seams open if it's easier to stay organized that way.

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 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 using 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 bias edges!

Happy Easter everyone


Follow all my quilty adventures on Instagram, Facebook, and Pinterest. Visit my Youtube channel for free tutorials and tips. If you like my patterns, you can buy them on Etsy, and here on the website.


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