this is a page for

Tag: Uses half square triangles

Blocks that use HST’s in their design

Cotton Reels Quilt Block

Technically a cotton reel is a spool of cotton thread, but the Cotton Reels Quilt Block is not to be confused with the Spool Quilt Block. The Cotton Reels Quilt Block is an entirely different motif.

The Cotton Reels Quilt Block is made up entirely of alternating squares and half square triangles. As the blocks alternate, the color motifs are kept consistent along the diagonal, so that the top HST is always the same color, but the bottom HST in each diagonal line is a different color. As you can see in the grouping image below, this creates a beautiful ribbon/pennant effect when the blocks are assembled straight set.

I am not sure why this design is named Cotton Reels, but I have a theory. Before there were transformers and Star Wars action figures, a common toy in the home was the Cotton Reel tank.  This contraption was made with a spool of cotton thread, a matchstick, a rubber band and a pencil. You can find out how to make it yourself at this link. Or watch the video below to see them in action.


Notice how when the tanks are "racing" they are staggered. I think that's what someone had in mind when they named this block. I think the consistent upper HST's represents the pencils on the tanks (which many moons ago would have most certainly all have been yellow) and the lower HST's represents the different colors of thread on three different cotton reel tanks that are racing. Or perhaps different colored spools. Again, it's just a theory, but I think it makes sense.

Illustration of a Grouping of Cotton Reels Quilt Block
Grouping of Cotton Reels Quilt Block

Block Construction

Illustration of the Exploded version of Cotton Reels Quilt Block
Exploded version of Cotton Reels Quilt Block

Coloring Sheets

Click image to download coloring sheets

Tent of Armageddon Quilt Block

If you like making HST's you're going to have a lot of fun making the Tent of Armageddon Quilt Block, as it's basically a 5x5 grid of half square triangles.  I suppose that ladies before our time must have thought these resembled tents of soldiers preparing for combat.  A similar block that is a 6x6 grid of HST's rotated 90 degrees goes by the name "Battleground."

Block Construction

Follow the instructions on the Half Square Triangles page to make the units used in this block.

Image of the Exploded version of the Tent of Armageddon Quilt Block
Exploded version of the Tent of Armageddon Quilt Block

Coloring Sheets

Click to download coloring sheets for the Tent of Armageddon Quilt Block

Half Square Triangle Units

Knowing how to make Half Square Triangles (HSTs) is a useful quilting skill.  These foundational units are used in many blocks, and learning how to make a perfect HST unit will open many design possibilities to your quilting.

There are several methods that quilters have developed to make these classic units. Below are two of the most popular, along with cutting charts for making each type.


If you want to give yourself some wiggle room, cut your pieces slightly larger than the size given in the chart.  After the unit is completed, trim down to the unfinished* size, making sure the diagonal line of your unit follows a diagonal line on your ruler.

*Don't accidentally trim off your seam allowance!

Image of Half Square Triangle Unit
Image of Half Square Triangle Unit (Exploded)
Half Square Triangle Unit (Exploded)

Quick Sew Method

This method creates two HST units at a time, a real time saver!

  1. Choose two contrasting fabrics, typically one light and one dark.
  2. Cut squares that are 7/8" larger than your finished size unit. (For example, if your finished HST unit will be 2", then your squares should be 2 7/8" square.)
  3. On the wrong side of your light square, draw a diagonal line from corner to corner.  Pin the light square to a dark square.
  4. Take to your machine and sew 1/4" to the left of the diagonal line. Turn unit around the other way and sew 1/4" to the left on the other side of the diagonal line.
  5. Cut the unit in half along the drawn diagonal line. 
  6. Gently press the seam towards the darker fabric.

Cutting Instructions for Quick Sew Method

Finished Size of HST UnitCut 2 Squares from contrasting fabric that are size indicated below
1"1 7/8"
1.5"2 3/8"
2"2 7/8"
2.5"3 3/8"
3"3 7/8"
3.5"4 3/8"
4"4 7/8"
4.5"5 3/8"
5"5 7/8"
5.5"6 3/8"
6"6 7/8"

Using a Half Square Triangle Ruler

HST Ruler Method

To use this method, you will need a HST ruler, such as the one made by Creative Grids. The advantage of this method, is the quick precise cutting method, and how easily these units can be chain pieced, allowing you to cut and sew the units rather quickly. This is the way to go if you are making LOTS of HSTs.

  1. Determine the finished size you need your unit to be.
  2. Cut strips from two contrasting fabrics the width of your finished size unit.  For example, for 2" HST units, you should cut your strips 2" wide.
  3. Place two contrasting strips right sides together (RST), making sure the raw edges along the long sides of the strips are perfectly aligned. It is helpful to place a pin in one end of the set to minimize shifting.
  4. If you are right handed, square off the left end of the strip set. Align your ruler so that the bottom of the strip set lines up with the marked line for the width of your strip, and so that the left edge of the ruler lines up with the squared off edge of the set. In our example of 2" HST finished units, you would align the bottom of the strip with the 2" line. (If you are left handed, you should reverse these instructions.)
  5. Cut your strip along the diagonal of the ruler. Place a pin in the two fabrics you just cut.
  6. Turn the ruler 180 degrees and this time align the TOP of the strip with the measuring line (Again, in our example this would be the 2" line.) Pin the cut pieces
  7. Continue along the strip until you have cut as many triangular sets as possible.
  8. Take the cut sets to your machine and sew along the diagonal using a 1/4" seam.
  9. Gently press to the dark side.

Video: Make Half Square Triangle Units using a Multi-size Ruler