How to Make Combination Units Using Quarter Inch Patchwork Rulers (QIPS)

You can easily make combination units from a half-square triangle quilt block and an un-pieced square by using the MadamSew Quarter Inch Patchwork Ruler…no measuring necessary!

If you have tried sewing these patchwork quilt block units by drawing a line from corner to corner and then trying to accurately sew ¼” from each line you’ll find this method will take the guesswork out. It’s fast and easy, allowing you to dive into your quilt project!

Though the instructions for sewing half-square triangles is in the Quarter Inch Patchwork Ruler Set (QIPS) online manual we are presenting them here as well so you don’t have to link to the manual at this point. But check out the manual for additional information when you have time so you can get the most out of this versatile tool. I will be using the 9” QIP in this tutorial.

For this project, we’ll be using three different fabrics, two to make the Half-Square Triangles and an additional one to complete/make the Combination Units.

Instructions for Making Half-Square Triangle Quilt Block Units

You will need two different fabrics for this unit.

Normally, you will decide on what size half-square triangle units you want to make and cut your fabric squares ⅜” - ½” larger.

Special NOTE: Because we will be using these half-square triangles in our combination units, cut your squares ¾” larger than you want your finished combination units to be.

You will need one square in each color fabric. I’m making mine with 6” squares.

Next, Follow the steps below to make your Half-Square Triangle Units.

Step 1

Place the lighter of the two squares on your work surface, with the wrong side facing up.

Step 2

Place the QIP ruler on the square with the middle line running through opposite corners on the diagonal. Using a sharp marking pen or pencil, draw a line on both sides of the ruler. These will be your sewing lines.

Positioning QIP Ruler with middle line running through opposite corners of fabric square

Marking Sewing Lines Using a QIP Ruler on the Wrong Side of Fabric

Step 3

Place your lighter square on your darker square with the right sides together. Pin/clip if needed.

Step 4

Using a straight stitch, sew on the edge of both marked lines closest to the middle. Trim your thread tails.

Step 5

Using a cutting ruler and rotary cutter (I like using the 45mm rotary cutter), not the QIP, cut down the middle between the two sewn lines to make your half-square triangles. For ease of the remainder of the steps, I’m also using the MadamSew Self-Healing Rotating Cutting Mat so that I don’t have to walk around my work space or contort when I need to turn my unit around for a step.

Cutting between the lines using a rotary cutter and cutting ruler

Step 6

Carefully press each unit toward the darker side if you can. Or press open. For this step, I love using the Wool Pressing Mat to get a nice, crisp press.

Step 7

Cut off the little tails from each unit and square up your half-square triangles.

Cutting tails off of the half-square triangle

You will end up with two half-square triangle units. Remember, I started with two 6” square pieces of fabric and my units are now each 5 ⅝” square. This size difference is because adding the seams makes the squares smaller.

Two Half-Square Triangle quilt block units side by side

You are halfway there! Follow the next set of instructions and before long, you will have two completed Combination Square Units!

Instructions for Making Combination Units

To make combination quilt block units, you will need one half-square triangle and one fabric square of equal size. (Because my Half-Square Triangle Units from the first part of this “How To” tutorial are 5 ⅝” square, my new fabric square will also need to be 5 ⅝” square.)

Half-square triangle next to a fabric square