So this is where I've reached ---please advise
 

My first attempt to make a Star pattern . have made 4 so far ..now i do not want to go with the block lay-out shown in my pattern . What I would like to do is to add 4 Triangles to this star block such that it becomes a bigger square block.
Thought & calculated & recalculated ..then realised I was not as smart as i have believed so far !!!! and am sending out this "help" message . Rt now this block is at 8" finished / 8 1/2 unfinished ..And thank you in advance for any advice given.

What do you need help with? Adding the triangles? First, I'd square up the block, being careful to leave 1/4" between the points of the star and the edge of the fabric. If you cut a 6" square in half diagonally, the long sides will be 8.5". You can then sew the long edge onto the block. I'd starch the square before cutting diagonally, since you will be working with bias.

Google it but im doing the same block size now and i cut mine 6 7/8 squares then cut on the diagnal and it matched up. Think thats what your asking.

While technically correct (a 6" square's diagonal is about 8.5"), you need a larger square because of the shapes and seam allowances. Make your square at least 6 5/8" before slicing it. If you want to make it a little larger (6 7/8"-7") you can cut it down after you stitch it. Starch is a great idea, and don't be surprised that adding triangles to a block - and winding up with a square block - is harder than it looks.

I agree with Dunster - I did it in my head, didn't test it with paper or muslin first, so it's entirely possible she's right. I don't think my calculations included seam allowances. You'll want to square up afterwards, also, so you'd be better off cutting a larger piece.

All of the above, including cutting the square larger than necessary. It doesn't hurt if the triangle is too big. Just sew it on, press the seam, then trim to correct size.

I would definitely recommend heavily starching the fabric before cutting the triangles, to keep the pieces stable while you handle the bias edges. Spray starching and blocking the block to size first is good too.

found this
http://www.generations-quilt-pattern...triangles.html
and this
http://quilting.about.com/od/quiltse...ngtriangls.htm
i have a large ruler that has all the triangle cut info on it.

Thank you for all the prompt help

1. Cut 2 squares at 9.5" square.
2. Cut each of these on ONE diagonal, corner to corner, to create 4 triangles.
3. Fold each triangle in half along the long side of the triangle, pinch the fold on that long side to mark the middle.
4. Apply triangles to opposite sides of the block; trim off the overhanging points even with the block edges. (Note that the triangle will be "too big"....you want that!)
5. Apply the remaining triangles to the other two sides of the block. Trim.
6. Now you will notice that your block can be placed into a quilt without losing the points of the block because you used triangles that were larger than absolutely necessary.

Jan in VA