Last month I looked at the variety of designs that could come from just using squares in blocks. This month I aim to show how the introduction of right-angled triangles as a half-square triangle unit, gives hundreds more design possibilities. 

A ‘half square triangle’ unit is one where a square in a block is sub-divided into two triangles through the diagonal. The two short sides of the triangle are on the straight of grain and the longer, diagonal side is on the bias, dia. 1a..

The most economic way to cut such right angle triangles is from a square, but to accommodate a ¼" seam allowance, the square has to be ‘finished size’ PLUS 7/8". If you are ever not sure of the size square required, draw the finished size triangle onto squared or graph paper, add ¼" all round and measure side (a), dia. 1b.

When quilters began piecing by machine, techniques were developed to speed up the cutting and stitching process. Initially the cutting was done with scissors, but it was rotary cutting that revolutionised even these ideas, making the initial stages of quilt-making much less tedious.

Individual triangles
In many blocks where the square units within the block are made up of two triangles, the triangles can be cut individually using a template and sewn together in pairs along the diagonal. However there are many ways of speed piecing them depending upon the amount of fabric you have and whether you want repeats of colour combinations or a scrap look. If you are making a charm quilt (no two fabrics the same) then triangles will need to be cut individually.

Triangles from individual squares
If making a scrap quilt where you do not mind the same combination of fabrics appearing more than once and you are using up small pieces, then the following method can be employed, dia. 2:

1. Cut appropriate size squares from variety of fabrics.
2. Place 2 different squares right sides together, with lighter coloured one uppermost
3. Draw in one diagonal line..
4. Stitch ¼" both sides of that line.
5. Cut along the drawn line.
6. Press seams towards the lighter fabric.
7. At this stage the squares should measure ‘finished size’ plus 1/2"

1. Lay and press two fabrics right sides together.
2. Cut a strip the same width as the required square e.g. for 3" finished size – cut 3 7/8" width strip.
3. Pin strips together.
4. Draw a diagonal line in each square as shown.
5. Stitch with ¼" seam allowance along one side of the diagonals to end of strip..
6. Turn and stitch with ¼" seam allowance along other side.
7. Cut out squares,
8. Cut along diagonals.
9. Press as above.

1. Straighten one edge of two fabrics.
2. Lay and press two fabrics right sides together, with lighter fabric o top, straightened edges even.
3. Draw a line parallel and a short way away from straightened edge.
4. Draw further lines parallel to this line at intervals required, e.g. for 3" finished size – cut 3 7/8" width strip.
5. Draw parallel lines in a similar manner, at 90º to these lines to produce squares.
6. Draw diagonal lines in one direction only, through all the squares.
7. Stitch ¼" either side of the diagonal lines.
8. Cut out squares.
9. Cut along diagonal lines.
10. Press as above.