Ah, the humble and yet ever-so-essential Half Square Triangle (or HST as you'll commonly see it referred). Alone it is a wonderful unit, and together with other shapes, amazing wonderful blocks can emerge. The lovely thing about the HST is there are SOOOO many ways to make it! Let's look at a few!
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Use (2) HSTs
A tried and true method, this method begins with two different HST units cut from a square.
How to do: With RST (right sides together), match up the long diagonal cut side. Sew with a 1/4" seam allowance. Open and either press to the dark side of the HST unit, or (my preferred), press the seam open.
Positive: This gives you completely flexibility regarding what fabrics the two sides are made from.
Negative: The two inside sides of the HST are exposed bias, which means they can stretch and cause your HST unit to curve along the seam
Math: While the general rule is 7/8" larger than you want to end (ie 2 7/8" square, cut in half corner to corner for each HST segment, to yield a 2" finished, 2 1/2" unfinished HST unit), I tend to round up to go up 1". What this means is if I want a 2" finished HST unit (2 1/2" unfinished), I will begin with 3" squares. It ALSO means I will need to trim down. I'll address trimming toward the end of this post.
Use (2) Squares
How to do: With RST (right sides together), match up the two squares. Draw a line corner to corner. Sew with a 1/4" seam allowance on EACH side of the drawn line. Cut along the drawn line. Open and either press to the dark side of the HST unit, or (my preferred), press the seam open.
Positive: This stabilizes the long bias seam, making your HST unit much straighter.
Negative: You will have two HST units of the same fabric combination. I know - doesn't sound like a negative unless you don't NEED two HSTs that are identical.
Math: While the general rule is 7/8" larger than you want to end (ie 2 7/8" square to yield a 2" finished, 2 1/2" unfinished HST unit), I tend to round up to go up 1". What this means is if I want a 2" finished HST unit (2 1/2" unfinished), I will begin with 3" squares. It ALSO means I will need to trim down. I'll address trimming toward the end of this post.
4 at a Time
How to do: With RST (right sides together), match up the two squares. Sew with a 1/4" seam allowance around the entire perimeter of the paired squares. Cut the sewn pair corner to corner TWICE. Open and either press to the dark side of the HST unit, or (my preferred), press the seam open.
Positive: A quick, non-template method for creating multiple HST units of the same fabrics
Negative: You will have four HST units of the same fabric combination. I know - doesn't sound like a negative unless you don't NEED two HSTs that are identical. And then there's the math.....
Math: Begin with your desired UNFINISHED (raw edge) size. Divide the desired unfinished size by .64 to determine what size squares to begin with. Hey, I didn't say you'd like the math - just sharing! For example, to get a 5" unfinished (that would 4 1/2" finished), divide 5" by .64. Result is 7.8125. Round up to 8". Yup - you will need to trim (not a bad thing!).
8 at a Time
How to do: With RST (right sides together), match up the two squares. Draw a line from corner to corner. Draw a second line corner to corner on the opposite corners (you should have an "X" on your paired squares). Sew with a 1/4" seam allowance on EACH side of ALL drawn lines. Cut along all drawn lines.
Cut the resulting triangles in half at the center. Open and either press to the dark side of the HST unit, or (my preferred), press the seam open.
Positive: A quick, non-template method for creating multiple HST units of the same fabrics
Negative: You will have eight HST units of the same fabric combination. I know - doesn't sound like a negative unless you don't NEED two HSTs that are identical. And then there's the math.....
Math: Begin with your desired FINISHED size. Add 1" to the desired finished size. Multiply the result by 2. The result with be the size squares you need to use. For example, to get a 3" finished, add 1" to 3". 3 + 1 = 4. Now mutlply by 2. 3 + 1 = 4. 4 x 2 = 8. Begin with 8" squares. You may need to trim (not a bad thing!).
Feeling discouraged because of all the math? I know - me too! But all is not lost! There are some awesome templates to give you great HSTs with NO MATH! Woot woot!
Triangles on a Roll
How to do: Triangles on a Roll, just like it sounds, is a roll of paper that has preprinted templates to make a specific size HST. Triangles on a Roll are available for many different standard finished sizes.Determine the desired finished HST size.
Determine the number of HSTs needed. Note - the number of HSTs produced per row of paper will vary depending upon the size. In my example pictured above, I can get (4) 2 1/2" finished HST units per row of paper. Cut the fabric to the size specified on the template paper. Cut the paper to size (ie how long/how many rows do you need). With RST, pin the paper template to the cut fabric.
Sew along the lines, as directed. NOTE: I shorten my stitch length, just as you would with paper piecing, so that the stitches won't pull out when I remover the paper. Cut along the cutting lines. CAREFULLY remove the paper. Open and either press to the dark side of the HST unit, or (my preferred), press the seam open.
Positive: A quick method for creating accurate multiple HST units of the same fabrics
Negative: Triangles on a Roll is size specific, so you will need to purchase a roll for EACH size HST youneed. Each roll will produce a LOT of HSTs, however (exact number varies based on size). You will have multiple HST units of the same fabric combination. I know - doesn't sound like a negative unless you don't NEED multiple HSTs that are identical. And you will have to remove the paper on EACH HST.
Math: There isn't any!
Want Triangles on a Roll? Get them here!
Thangles
How to do: Thangles are paper strips that provide size specific templates for piecing HSTs. Like Triangles on a Roll, they are size specific. However, Thangles are short paper strips, which some find easier to work with. Determine the desired finished HST size.
Determine the number of HSTs needed. Note - the number of HSTs produced per strip of paper will vary depending upon the size. In my example pictured above, I can get (4) 3" finished HST units per strip of paper. Cut the fabric to the size as specified on the template paper. With RST, pin the paper template to the cut fabric.
Sew along the lines, as directed. NOTE: I shorten my stitch length, just as you would with paper piecing, so that the stitches won't pull out when I remover the paper. Cut along the cutting lines. CAREFULLY remove the paper. Open and either press to the dark side of the HST unit, or (my preferred), press the seam open.
Positive: A quick method for creating accurate multiple HST units of the same fabrics
Negative: Thangles is size specific, so you will need to purchase a packet for EACH size HST you need. Each packet will produce a LOT of HSTs, however (exact number varies based on size). You will have multiple HST units of the same fabric combination. I know - doesn't sound like a negative unless you don't NEED multiple HSTs that are identical. And you will have to remove the paper on EACH HST.
Math: There isn't any!
Sunday Best Quiltworks Template
How to do: Sunday Best Quiltworks' templates are plastic template sheets that, like other templates, are size specific templates for piecing HSTs. However, because they are templates, you only need to purchase your desired size (or sizes) once!
Determine the desired finished HST size. Determine the number of HSTs needed. Note - the number of HSTs produced per template will vary depending upon the size. In my example pictured above, I only wanted a few HSTs, so I cut my fabrics to a bit larger than needed to produce the desired number of HSTs. Cut the fabric to the size needed for the number of HSTs, plus a bit extra for pinning room. With RST, pin the template to the cut fabric.
Using a chalk marker, water erasable marker, or sewing/quilting pen, draw along the marked template lines. Remove the pinned template. Sew along the lines, as directed. Cut along the cutting lines. Open and either press to the dark side of the HST unit, or (my preferred), press the seam open.
Positive: A quick method for creating accurate multiple HST units of the same fabrics
Negative: The templates are size specific, so you will need to purchase a template for EACH size HST you need. Each template will produce unlimited numbers of HSTs. You will have multiple HST units of the same fabric combination. I know - doesn't sound like a negative unless you don't NEED multiple HSTs that are identical.
Math: There isn't any!
Want Sunday Best Quiltworks Templates? Visit their website (non-affiliate link).
Trimming
Regardless of method, I strongly recommend trimming up the half square triangles (HST). While in some instances you may only be trimming away a few threads, accurate units yield accurate blocks, which in turn yield accurate quilts. And don't we all want the best looking project possible? Yup!
Using your favorite square ruler or trimming tool (mine is the Tucker Trimmer by Studio 180), place the half square triangle (HST) under the ruler, matching up the diagonal seam with the 45 degree line on the ruler. I'm trimming this unit down to 5" unfinished. Note that the raw edge UNDER the ruler goes beyond the 5" line. This is important - I want to trim ALL sides.
With your favorite rotary cutter, cut along the right and top side of the ruler (leftys, your blocks and rulers will be oriented opposite this, and you will trim along left and top). Make sure you have good cut, and remove the trimmed edges BEFORE moving your ruler!
Rotate the trimmed block 90 degrees, so that the trimmed sides align with the desired cut size (in my case, 5"), and the seam lines up with the diagonal line on the ruler. Trim away the excess to the right and top.
Want the Tucker Trimmer? Get it here!
The result? A practically perfect in every way half square triangle! Ta da! Totally worth the time!
Head over to Kate's blog. She will have some wonderful tips and suggestions to improve your HST game as well.
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