shayarene

Hello Everyone, I am doing a lot of cutting this weekend and need a little help. I don't know what the quilting term is for when you take 2 squares and draw a line corner to corner and then measure out 1/4" on each side and sew on those lines and then cut them apart and you have a 2 colored block all done. But my question is: All my solid color blocks are 2.5" the half inch is seam allowance. Now, how big do I cut those blocks that I need to make 2 colored so when I open them and press them, they are also 2.5"???? I was thinking 3"? I thought I read once to make them 2 7/8" but how would that make a 2.5" square if you are taking out 1/4" on each side of the middle line you draw? This is so confusing to me. Can anyone explain this to a newbie who is confused? Thank you so very much Rachel

Sewnoma

Those are called half-square triangles.

The 7/8" measurement is needed because an angled seam ends up taking up a bit more than a quarter inch allowance when you measure it from one of the horizontal or vertical seams. Just like the angled line you draw from corner to corner is longer than one of the sides would be. So there's jut a tiny bit more added in to make up for that extra.

But I am awful at making these turn out right, so personally I'd go for the 3" squares and then trim them back down after they're made.

WandaVA

I would definitely use 3" squares and trim them after they are made. Welcome to the world of quilting! This is a great place to come with any questions--there are many knowledgeable and nice people here to help you.

nanna-up-north

Welcome to quilting, Shayarene. The puzzle about half-square triangles is exactly as sewnoma said. But you know how geometry and trigonometry can give you some crazy answers with lots of numbers to the right of the decimal point? The actual measurement isn't exactly 2 7/8"... it's just the closest measure that all of us can cut from a ruler measurement. So, I'd vote for making those 3" squares and trimming them. I know, it sounds like a lot of work but, oh my.... what a difference it makes. Trimming has been the life saver on so many quilts I've made.

winia

I also concur with the three inches. There will be waste, but it is worth it to me to know I have enough fabric to make whatever it is I'm sewing.

Silver Needle

I also vote for 3" then trimming. I credit Deb Tucker for changing my mind about this. Accuracy of matching points and seams is extremely important to me. Her rulers for trimming down accurately have changed my piecing methods. IMHO a little waste is worth it for accuracy.

willferg

I am someone who does not like extra work, at all, but I found rounding up an inch and then trimming when making half-square triangles to be totally worthwhile.

Quiltngolfer

I would go with the 3" squares and cut them down. I always like to square up my blocks anyway.

bigsister63

Do not try to figure out the math. This is really magic or a mystery like the bermuda Triangle! . Cut all blocks 3" and mark on the wrong side on the diaganal. Then sew 1/4" on either side of that line and the cut up the middle Your blocks should be slightly bigger that 2 1/2" so trim then to be 2 1/2"

joe'smom

Trimming is the one thing I hate among all quilting tasks, so I use the 2 7/8". However, I will look up these Deb Tucker rulers. If I had a way of trimming accurately, I wouldn't hate trimming so much!