Half rectangles to the modern quilter are what half square triangles are to the traditional quilter.
Here goes... the last word on Half Rectangles!
I tried random sized half rectangles, cut on the diagonal, offset the pieces and sewed. Sometimes with success, sometimes not.
I tried the method where you put dots in the corner, draw a diagonal line and sew on either side of the line like we do for HST. Couldn't get that one to work for the life of me.
It just can't be that hard- can it?? All I am trying to do is to sew a half rectangle unit with perfect points. I am not the kind of quilter that rips out her seams until they are perfect far be it- don't look too close at my piecing.....see? Sometimes we just need to sew even though it isn't perfect!
I just want half a shot at being able to BE perfect!!!!!!
So here I was attempting (yet again) to sew the perfect half rectangle, using the Half Rectangle Triangle Calculator in QuiltSandwich as my guide to what the finished size of my pieced unit should be. I wasn't having much success with keeping my points so I finally called Allen, the resident Quilt Math expert for QuiltSandwich.
(Warning- this is a long post. But I wanted to put everything in one blog post. )
The truth about half rectangles
Half rectangles are tricky because we can make them tall, or short. Fat or skinny. The size of the half rectangles we want to use in our quilting these days is limited by only our imagination.
There are a couple of half rectangle rulers on the market. They do the job. But if you want to do something that is not supported by the ruler, what to do? And what if you don't want to go buy yet another specialty ruler?
Half rectangles can be paper pieced too. But what it you want your triangles to be really long and skinny and thus won't fit on a piece of paper?
THE ANSWER!! WHOO HOO!!!!
The answer lies in creating a template. Now don't get scared. This is a really slick trick to learn. What you are going to learn how to create for any size half rectangle you want to make is a corner trimmer!
What? You say. Well dear Quilter, read on and be prepared to be amazed. This is an awesome piece of knowledge to have in your quilting repretoire.
Step 1: Determine the cut size of the rectangle needed to create the HRT
Using graph paper or a blank sheet of paper accurately draw the CUT SIZE of just the rectangle for right now. It will eventually be cut in half, but we need to start with a simple rectangle. I used a piece of stabilizer.
If you don't know the cut size, but know the finished size, use the Half Rectangle Triangle Calculator to determine the cut size of the rectangle. Use the Cut Size Width and Length numbers to draw the rectangle.
The cut size of my HRT is 9 3/8" x 4 3/4". The finished size of my HRT will be 8" x 4".
This seems like a lot of work, why in the world do I need to do this? Well- it has to do with the 1/4" seam allowance we need for piecing. Or, so Allen tells me!
if you are aiming for a specific size, the reason you need to use the Half Rectangle Triangle Calculator to determine the cut size is because the math is not as simple as adding a 7/8" seam allowance.
Allen, our QuiltMath expert, explained that this was because the angle of the half rectangle at the tippy top is different than the angle at the bottom. You can see the top and bottom angles when you use the Half Rectangle Calculator.
The top angle of my triangle is 26.6 degrees and the bottom angle is 63.4 degrees. Yikes! But not to worry!
The Half Rectangle Calculator accounts for the 1/4" seam and the difference in the top and bottom angles when determining the cut and finished sizes. We don't have to think about it- Allen did all of the work for us- we just get to play! Yea!!
I drew my cutting lines in GREEN marker.
Step 2: Draw a diagonal to create the HRT
The diagonal line is drawn in PINK.
Step 3: Draw the seam lines
I would strongly suggest using a different color pen to draw the seam lines than the one used to draw the diagonal and the cutting lines. Its just a little bit easier to see what is going on. If you don't have a different color pen then make dashed lines for the seam lines.
Mark the 1/4" seam line on all 4 edges of the rectangle and on either side of the diagonal. My seam lines are marked in BLUE.
Step 4: Draw a circle where the seam lines meet
Using another color of pen, where the lines intersect, draw a 1/2" circle. Eyeballing where to place the circle is good enough.
It may be easier to see where the lines intersect and to find the center of the 1/2" circle by placing a dot at the intersection.
Draw the circle.
There is a PDF at the bottom of this post with a half in circle that you can cut out. Paper is fine, cardstock is good too, or a good stiff piece of junk mail to create the circle template. i used a Post It note.
There are 4 places where the seams intersect. Can you see that I marked where the seams intersected with a purple dot?
Here are my 4 circles:
This is my circle template.. I just used a square post it note and cut out the circle.
Here is a PDF with a template for 1/2" circle that you can cut out:
Step 4: Cut out the rectangle
Using a ruler and your rotary cutter cut out the rectangle. Don't cut on the seam lines you drew, you want to cut out the shape using the cut lines. My cut lines are GREEN. Cut out the rectangle:
Now, again using a ruler and rotary cutter, cut the rectangle in half on the diagonal line you drew. The line that goes from corner to corner. My diagonal line was PINK. Don't cut on the Blue seam lines!
Step 5: Align the circles and the magic begins...
Align the 2 HRT as if you were going to sew them together. The tips are offset. But how do you know they are aligned exactly right? Move the two pieces until the circles align with each other!
I used cardstock to make the templates for this blog post. If you use cardstock too, then use a pin to line up the circles. There is a picture below. I also have pictures below of the template made from stabilizer- you can see through it enough to see how the circles line up.
Here is where we are headed: we are trying to identify that portion of the top of the triangle that is the dog year, so we can cut it off and align our HRT halves for perfect piecing. Where the circles intersect is where the dog ear is created. Isn't Allen a genius?
Step 6: Cut off the dog ear...
The amount of the tip that is showing, is the dog ear that needs to be trimmed. So take a pencil and mark a line where the dog ear is. Mark both halves of the triangle. With a pair of scissors, cut off the dog ear. My cutting line for the dog ear is in BLACK. I hope you can see it OK. Do this for both pieces too.
And voila! This is the template to use to cut off the dog ear for the HRT you wan to make. Use this template like a half square or quarter square corner trimmer. When the dog ear, is trimmed off the pieces align perfectly and they are a cinch to sew!
Below is a series of pictures so you can see how I worked with the template. Because there is a right and a left, when cutting two fabrics at the same time, put Right Sides Up for both pieces when layering. If you are working with batiks and there is no right or wrong side, then you are very lucky indeed!
Easy right? So how do you know that you are going to get that half a shot at perfect points? You know when you see that little 1/8" square part at the top and bottom of the diagonal seam. A bigger picture is below. Don't cut this off, don't square up your block. If you were accurate in your cutting and sewing then you will have perfect points!
Here's to joyful quilting!