There will be a time when you are no longer just sewing straight seams in your blocks, whether you are adding half-square triangle squares or stitch and flip corners. Angles add interest to a quilt block and quilt so it’s a good idea to learn how to stitch them accurately. I am going to concentrate on units where you use 45 degree angles because they are more common. Once you master these, you can translate what you’ve learned to other types of angles. Hopefully these tips help you whether you are a beginner or an experienced quilter.
Getting Started
It’s important to sew these seams accurately so your unit measures correctly so here are some tips that will help you when sewing these seams.
Tip#1: Don’t rely on “eyeballing” the seam you are sewing. Either draw a pencil line to follow or use guides on your machine. I will show some examples of using a pencil line in my specific examples below.
If you would rather use a guide on your machine, here’s how you set it up:



In the photo on the left, I first place a tape measure (I recommend a tape that is 1/2″ wide) under my needle and put the needle down at the “0” line. Place a piece of painter’s tape right at that point on your throat plate and sewing machine table. Then move the tape measure around (still under the needle), as in the center photo, if you are using a 1/2″ wide tape as recommended, the edge will be exactly aligned with the 1/4″ line on your throat plate and with the edge of your 1/4″ foot (last photo). Be sure it is exactly 1/4″ then draw a line on the painter’s tape. This acts to extend the 1/4″ mark from your throat plate. No more eyeballing a seam! You’ll see this in action later in this post.
Tip #2: Do not cut away any excess in the seam allowance until you press open the seam you have stitched and measure the unit to make sure it’s the size it’s supposed to be. These 45 degree seams are on the bias so you do not want to have to rip them out, which can distort your fabric. You also do not want to cut away fabric and then find out your unit doesn’t measure correctly. Then you really have to start over!
Tip #3: Because these seams are bias seams, do not pull the unit through your machine as you are stitching. This is a good rule for any seam, but especially bias seams because the fabric can be stretched severely out of shape by doing this and then your unit will not measure correctly.
Types of Units from Bias Seams
These are the types of seams and units I use the most in my creations, so these are the ones I am covering here. I think these tips will help you with other angle seams as well.
First up is the stitch and flip corners to add a design element.



As you can see above, stitch & flip usually entails placing a smaller square on a larger square or block, stitching a bias seam and then pressing it open. The above example shows this using a drawn line on the wrong side of the smaller square, placing it face down on the larger square lining up the edges and pinning in place. Then stitch along the line.



The photos in the center and on the end show how I press back the corner with my fingers and measure the unit to make sure it still measures the size of the black square. Then the excess can be cut from the seam allowance.
You can also use the tape guide I described above:

The photo above shows the point of the smaller square lined up with the left edge of the painter’s tape. Keep that lined up as you stitch the seam. Then follow the steps below, the same those above with the drawn line, to measure the unit.



This stitch & flip method is used to make some common units like flying geese and common blocks like the snowball.


Next up is the type of unit most familiar to quilters: the half-square triangle square often known as an HST square. First you can make these using the drawn line method:




As you can see in the second photo from the left, I stitched a bias seam a scant 1/4″ from the drawn line.
If you want to skip drawing the line, that’s where the line we drew on the painter’s tape above comes in. Simply sew your seam on the one side with the point of the unit lined up with the drawn line (which will be 1/4″ from the center), then flip the piece and line the point up again with the line on the tape to sew the other seam.



The last photo above shows the unit ready to be cut in half between the seams for 2 half-square triangles! If you want a scant 1/4″ just shift the point of the unit you are stitching slightly to the left of the line. Your seam lines will be closer together. Then you can trim your half-square triangle squares down to size after you press them.
So that’s it for this week. I hope you learned something or had your skills refreshed with this post!
Happy Quilting!
Deanne