If I was to take two 9-1/2 fabrics and sewed them together right sides together, corner to corner (diagonally) and then sew down the middle of the 2 fabrics and cut them apart right beside each sewn seam.

When it cut apart I would have 4 half triangles.

Do you think that would work?

yep, that would work. there is also a tut about half square triangles that has you sew all around the square and cut an X in the square and it gives you 4 half square triangle as well.

http://www.quiltingboard.com/t-36008-1.htm

this is another way to make a lot of 1/2 sq traingles, haven't tried it.

this is why i love thangles and there is another brand out there that makes 4 at once also with just sewing two lines i cant remember the name of them wishing something. makes my life easy in my little quilt world

I use this same type of method but sew across both diagonals, cut it into 4 sqs and then cut the diagonal line. Makes 8 HSTs. This is an Eleanor Burns method. Using 6" squares I get 2-1/2" HSTs after they are trimmed.

mltquilt

The way you described will work just fine.
This other method, puts the bias edges on the outside of the block, making handling them a little more tricky :wink: :D:D:D