Someone recently posted a question about the difference between the two seam allowances. I came across this post that illustrates it clearly. Hope it helps!

http://www.diaryofaquilter.com/2011/...t-14-inch.html

Well, that's the first explanation I've ever seen that actually made sense - at least to me. I've been fighting with a block that is supposed to be 8 1/2" but it keeps coming out to just over 8 1/4" to just under 8 1/2". I'd probably just finesse it if it were for me but I'm sending it to someone so I want it really exact. Here's the block at Quilter's Cache and this makes total, total sense.
http://www.quilterscache.com/N/NorthernLightsBlock.html

THANK YOU!!!!!

thanks for the link, great information

:thumbup:

Thank you for this link! I think I finally understand the difference!

thanks for the link

Good explanation and something I now think I can do with moving the needle. I couldn't figure out how to be consistent and not use something to line it up against.

thanks!!! a picture is worth a thousand words.

Thanks for the link. I've always had the same problem with the "scant" Now I'm going to move my needle to the right one move and see if that helps me. I've also got to find a foot that will work with moving my needle, the 1/4" foot I have now won't work there's no extra room on the sides.

I love that site but I don't like her method for making HST's. I always do the square, mark the diagonal and sew a scant 1/4" on both sides of the line. When I try to use her method, the fabric gets distorted or I get confused or both. It also helps if you make the squares a smidgeon bigger than you need and trim them back down after pressing open. The "rule" for HST's is 7/8" more than the finished size so I just do a full inch. That extra 1/8" isn't going to waste too much fabric and will really pay off in the accuracy of the blocks.