Illsa

How do you keep triangles square when sewing onto a square? Noses are always in the middle and I trim them prior to attaching the next triangle but they don't come out square...... What am I doing wrong? Always use 1/4" seam. Illsa

Tartan

If you are doing triangles that have bias along the long edge, I pin them and sew carefully trying not to stretch them. Try starching your fabric before cutting your pieces as it makes them more stable. You can also cut them a little big and trim them after sewing them together to the correct size.

Jingle

Tartan has a great idea. You can't go wrong with that method. I haven't had a problem.

nycquilter

I sew my HST by using the grid method. I mark my grid squares about 1/2 to 1 inch larger than I want my finished squares. I sew on all the lines, then press the large piece to set the stitches. Then, I cut on all the cutting lines and iron the squares open, usually pressing toward the darker side of the triangle. Then, back to the cutting board and I cut the squares to size. This way, there is no bias stretch as you sew. My squares all come out the right size and I have no problems sewing into larger blocks. Yesterday, I sewed and cut 72 HST this way.

Digitizingqueen

I always make mine using two squares bigger than what I want the finished size to be, then I use my square ruler to get them the right size there is a mark accros the ruler that I line up with the seam, works really well all the time getting them all the right size

bearisgray

It also may be that your seam allowance is uneven - do you veer off on either end?
Or your seam is bowed.

That could also make the units not lay flat.