a brief tutorial on isosceles triangles- how to sew them, not how to spell them!

a new RSC19 project for me this year is to make a monthly donation quilt, using the color of the month, and a complimentary fabric for the alternate triangle. 

after a couple bumpy months of trial and error, the math behind the isosceles triangles finally hit home, and my quilts are turning out the correct size now, rather than bafflingly too large. (you can read about my geometry revelation here.) 

i did have a few questions about the triangle quilts, so thought it would be "fun" to do a tutorial. i'm just going to try and hit the high points, and make things a bit less fuzzy, should you decide to do one of your own. (i say "less fuzzy" because i'm sure it won't be crystal clear at the end...) 

first, i cut my strips (light and dark) in preparation for cutting the triangles. i usually put a new blade in my rotary cutter at the beginning of the month. here, I've cut strips 6½" wide- conveniently the width of my main ruler. (if i had a wider ruler, i'd probably cut my strips wider, too..) 

then, i'll use my isosceles ruler, and line up the strips with the 6½" line, and cut the triangles across the WOF, flipping the ruler up and down as i go. if i remember correctly, i get 4 sets across, giving me 8 triangles from each strip.

here is a ruler similar to what i'm using, just a bit bigger. (not an affiliate link) nextly, i use the leftover bits on the end to cut my side triangles. the only difference here is to line up the straight edges of the triangle, allowing for the seam allowance. 

hopefully you've figured out your math correctly, and cut out the right amount of triangles and side pieces the first time. 

the ruler gives a nice cut off point, making it easy to line up and sew, without getting all those annoying and bulky dog ears on the back of the quilt. 

now it's time to sew! (and i do find it super helpful to have the schematic of the quilt to refer to...) i like to sew all the rows together so the straight of grain (SOG= WHITE ARROW) is running parallel with the rows. this will make it easier to tie/quilt it, without the quilt getting all stretched out and wonky. also, i always keep the color of the month pointing up. (in this case, the green, which is actually upside down in this picture. oops!) 

now it's time to flip the triangles right side together in preparation for sewing. the SOG = WHITE ARROWS, the BIAS/SEWING LINE = YELLOW ARROWS. use an accurate ¼" seam allowance throughout. although- if you use any consistent seam allowance, it will be fine... 

here the 2 triangles are sewn together, and the arrows show the orientation of the bias and straight grain. continue sewing your triangles together until you have enough for the width of your quilt, then add the half-triangles on the ends of each row.

my isosceles quilt has 13 rows as designed, but it would probably be better with 14 rows. (you can see A's embroidery project keeping my 1st row company on my design wall. she's making 12 of these animal blocks, and now has 8 of them done. each is "sashed" with Kona cotton solids, and i'm really excited to see it done! it's going to be a fantastic quilt!) 

and here we have the classic "receding rectangle" picture of the completed quilt top. it will be tied at one of our next Scraps2Wraps meetings, and then passed along for a local need, or donation overseas. 

so: i hope my little tutorial helps make the waters a bit less muddy! questions? ask away in the comments, and i'll answer as best i can!