Thursday, July 9, 2015

Block 101- The Half Square Triangle (HST)

Simple.  Versatile.  Ubiquitous. 

The half square triangle - HST - is a basic foundation block which is used a part of countless other blocks.


To assemble, you need two squares of equal size.   Draw a line down from corner to corner of the light block. 





Place right sides together with the lighter square with the drawn line facing up.  To each side of the diagonal line, stitch at ¼” distance. The photo below uses black thread to make it more visible on the screen.

First sew on one side



Then the other




Cut apart on the pencil line between the stitches.



You've now created 2 HST.



Press the seams to the darker side and trim to desired size. Congratulations - you now have two HST!!

The table below can help you figure out how big you need to cut the initial square in order to get the HST size you want.

For example, for a HST that will finish at 2½” in your finished quilt, you need to cut the initial two squares at 3½” and then trim after pressing to 3". (Since you'll sew with a  ¼” seam on all sides, your trimmed 3" square will become a 2½” HST in your quilt.




Finished HST
Unfinished HST - TRIM
Cut Square
1”
1½”
2”
1½”
2”
2½”
2”
2½”
3”
2½”
3”
3½”
3”
3½”
4”
3½”
4”
4½”
4”
4½”
5”
4½”
5”
5½”
5”
5½”
6”
X”
X + ½”
X + 1”



The formula is easy -  take any finish size you need for the HST and add 1 inch to get the initial cut square.   (Technically, you only need to add 7/8" but I have found it difficult to cut 7/8" so round up to the nearest ¼”.)


Have a wonderful day! Patty

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