How to Sew: HST Quilt Blocks Two at a Time

Step 1 – Prepare Fabrics (optional)

When making HSTs you will be sewing, pressing and cutting on the bias (i.e. diagonally across the straight grain) of the fabric. This means that there are several opportunities for the fabric to stretch and distort. In order to reduce this possibility, before cutting out, you can treat your fabrics with a spray of starch or starch alternative such as home-made sizing or something like Best Press or standard laundry starch spray.

Preparing your fabrics will give them a bit more body or crispness. It will also help to reduce fraying and it’s likely to help you with cutting accuracy.

Step 2 – Cut Squares

To make HSTs you will need two different fabric squares. The starting size that you need will be larger than your desired finished quilt block size. The extra takes into account the seam allowance and a little extra for trimming the HSTs to the exact correct size (once you have finished sewing and pressing).

Starting Squares = finished size of HST plus 1”

For example, if you are looking to make HSTs that are 3” square when incorporated into a final project then the starting squares need to be cut out at 4” square

Step 3 – Mark Stitching Guide

Take 2 squares the same size.

On the reverse of one square draw a line that runs diagonally from point to point.

It doesn’t matter which square you mark up, but more often than not, the drawn line will show up better on the lighter of the two fabrics.

Step 4 – Pair the Squares and Pin

Place the two squares Right Sides Together, with the wrong side of the marked square facing upmost (so that you can see it).

Pin the two squares together if desired. If using pins, keep them clear of the stitching area.

Step 5 – Sew

Sew ¼” either side of the drawn line, removing any pins as you go.

Step 6 – Cut in Half

Cut along the drawn line, between the two rows of stitching. You can use a pair of scissors or a rotary cutter.

Step 7 – Press

Set your seams by pressing over the top of the stitching lines.

Next open out so that you can see both halves of the HST. Press the seam allowance either open or to the side.

Option 1 – Press Open This gives a flatter block, and it is an easier and slightly more accurate method to use when working on smaller quilt blocks

Option 2 – Press to One Side This gives a little more strength in the finished project and it will allow you to nest the seams when joining to other HSTs or maybe other quilt blocks. Typically seams are pressed towards the darker fabric, but check pattern notes if you are working from one.

Step 8 – Trim First Two Sides

Square up the block by trimming the HST to the correct unfinished size. This example shows a 3” finished HST being trimmed to 3.5” unfinished.

If you have one, it’s easiest to use a quilting ruler that has a 45 degree line marked on it.

Place the ruler on top of the HST, lining up the 45 degree line with the diagonal seam line on the HST. Check the measurements on the ruler both horizontally and vertically to make sure that the fabric exceeds/goes further than the trimming size measurements. If not, reposition the ruler slightly, keeping the 45 degree line on top of the seam.

Trim away the excess on the right hand side and along the top edge of the HST.

Step 9 – Trim Second Two Sides

Rotate the HST 180 degrees and repeat the process to trim the remaining two sides.

The edges trimmed in the previous step should sit perfectly under the vertical and horizontal lines of the unfinished HST measurements on the ruler. The 45 degree line on the ruler should sit on top of the seam line.

REPEAT steps 7-9 with the remaining HST to give a matching pair.