Can someone explain the 7/8 rule to me?
#11
I always make my squares for half square triangles 1" larger than the finished block and then trim. I have two rulers that I use depending on which one I find first. One is a Quilt in a Day ruler that is square but you trim your half square triangle with it before you open it up so there are fewer cuts. Lay the marking on the seam line and cut the two exposed edges to square the triangle. The other method is to press the half square triangle square open and then place a square ruler with the 45 degree angle line running along the seam line. Get it as near two edges as you can with fabric under the ruler and trim the excess. Turn the square around and do the same to the two remaining sides except this time put the markings of the ruler that you want your half square triangle to be along the edges you just cut, again with the 45 degree line on the ruler along the seam line and trim the excess off the two remaining edges. With either of these methods there isn't much overage to trim, usually just slivers but you end up with true half square triangles every time. My avatar is a quilt made almost entirely of half square triangles which I did this way.
#12
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Join Date: Jun 2011
Location: Southern California
Posts: 19,127
I'm just starting to dip my toe into triangles and wanted to try drawing out a block and making it (there's only so many 8" blocks online). I'm new enough to sewing that my triangles and seams are imperfect even if the measurements are right and I don't even feel like I should know what good triangles should look like mid-piecing.
I understand that adding 7/8 to triangles pre-piecing is "correct" but I have no clue where the extra 3/8 goes and how an almost 2" triangle becomes 1", especially if my seams have an 1/8 margin of error (because they probably do).
Can anyone explain why this works and how to tell if you're on track during the piecing process?
I understand that adding 7/8 to triangles pre-piecing is "correct" but I have no clue where the extra 3/8 goes and how an almost 2" triangle becomes 1", especially if my seams have an 1/8 margin of error (because they probably do).
Can anyone explain why this works and how to tell if you're on track during the piecing process?
#15
#17
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Join Date: Jul 2010
Location: Ohio
Posts: 2,148
Sound like we are all a little confused as to what you are talking about. I suspect it is not HST but as you mentioned Square-in a Square. Do you want your center square to be on- point or do you want the block to be square? If it is to be square then I would just do sashing around the block. If you want the center block to be on point then you do need to make "setting" triangles for the corners- this is an entirely different calculation than for HST. Check the internet for " calculations for setting triangles" to see how to make these. This is not the "7/8 rule" that is used for HST. .
Here is Bonnie hunter's version: http://www.stcroixquilters.com/setting%20triangles.htm
Here is Bonnie hunter's version: http://www.stcroixquilters.com/setting%20triangles.htm
#18
Super Member
Join Date: Nov 2009
Location: Pennsylvania
Posts: 2,694
Dear Cedar,
About your HST issue. The first part is that there is not a 3/8in. left over. The measure is not 10/8ths.; It is 8/8ths. So 7/8th would leave a sliver of 1/8th . Hope this helps you,
quilter 68 who is now 72
About your HST issue. The first part is that there is not a 3/8in. left over. The measure is not 10/8ths.; It is 8/8ths. So 7/8th would leave a sliver of 1/8th . Hope this helps you,
quilter 68 who is now 72
#19
Senior Member
Join Date: May 2014
Location: North east
Posts: 360
If you draw a square (any size) then draw a line diagonally then add 1/4 seam allowance all around, then measure from corner to tip you will see why the 7/8 inch is added. It is because of the angle. I had to do this many years ago to also understand. This is only for half square triangles.
#20
Junior Member
Thread Starter
Join Date: Mar 2014
Location: Portland, OR
Posts: 190
I wanted to thank everyone who's been replying and trying to help. I have been checking measurements on right triangles and the hypotinous is 7/8 bigger, although is seems different than what I'm remembering from high school geometry.
PianoDebbie -- your square in a square link was great. It was a huge help.
Possibly silly question -- when connecting a triangle to a rectangle do you match them on he edge or do you center them? I think I just figured out centering them was important.
So I've sucessfully designed and pieced my first block. It's a little wonky in a couple places, but its improving.
PianoDebbie -- your square in a square link was great. It was a huge help.
Possibly silly question -- when connecting a triangle to a rectangle do you match them on he edge or do you center them? I think I just figured out centering them was important.
So I've sucessfully designed and pieced my first block. It's a little wonky in a couple places, but its improving.
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