I make them larger and use the Quilt In A Day triangle square up ruler that you only have to make one cut to square up.
It is the best investment for a ruler I have made.

All the reading I've done for HST, say to add 7/8 of an inch to whatever size of HST you want, I just make it an inch bigger and then square it off, so I've never had a problem. I don't know if you're cutting the triangles first or not, but I don't. If I want a 2.5" HST, I cut 2, 3.5" squares, layered, draw 2 lines diagonally, 1/4" from the direct diagonal line, sew on the 2 lines, cut on the direct diagonal line. This way, you're not sewing a cut bias edge. I hope I explained this so you can understand it.

@ Jan in VA. That is a great tutorial on Triangles. I love the things you show with borders. Thanks so much for sharing!

Try this:

https://picasaweb.google.com/samanka...rqtbep97a9pwE#

Use the tut here or one of the many others available on the web. Just do a search for half square triangles. If one explanation does not work for you, another will. I use my June Taylor Shape cut, but any ruler with a clear 45 degree line marked will do. Master this skill and you will be very glad you did. I taught a class at my LQS about a year and a half ago. Everyone got it without tearing out their hair. It is really just a matter of going step by step. I am grateful to the lady who taught me.

I use Thangles papers to make my 1/2 square triangles and they are great! You can make several at a time. So easy!

Great tut! Thanks for sharing.

this is my method for making half squares makes 8 at a time and does work for me if I want a 3 inch square 3 x3 =
6 add one inch so cut two 7 inch squares draw an X sew on both sides of all lines cut ceoss wise twice then between the lines you will have 8 half square triangles press and trim to 3 inches always perfect size

Thanks Jan for providing the instructions for Making Blocks with Triangles. I have added your instructions to my go to place when I need clear, concise instructions for a quiting technique.

Thank you Jan for the tutorial.