Please Help Me
 

I need to make squares that are half square triangles that end up 3-1/2" unfinished.

When I add 7/8" to the squares before I sew them, they end up too big. I've tried cutting various sizes to get the 3-1/2" squares but just can't seem to come up with the right measurement. :rolleyes:

What am I doing wrong? What size should I be cutting my squares?

Thanks in advance for all your help!

Sue

Personally, I prefer the square to be a little big so I can trim it to size, square it up, etc.

do you cut them 3 7/8 or are you adding the 7/8 to the 3 1/2? I usually add one inch to the 3 inch size and then trim for exact. some people have great luck doing the 7/8 inch bit though. but always add that to the "finished" size, not the unfinished size. and if you do trim always place the 45 degree line on the seam corner to corner, line up to size you want, like 3 1/2 and trim two sides. then turn the block, place ruler and trim the other two sides. try again, you seem to be doing fine.

Here is my tutorial on many different triangles, including the Half Square Triangles you need. It's in pdf. format so you will need adobe reader to open it. That is available free on the internet for download.

As a quick reference, make your base squares ONE INCH larger than the desired half square triangles, then trim them down for better accuracy after sewing them.

Jan in VA

I agree with the others. 7/8 is a pain. Add 1 inch to the finished size you want the squares to be. If you want 3 inch finished HST, start with two 4 inch squares. You will have a bit to square up, but that seems to work better for me.

Math and i are not friends so when I run into that problem I cut larger and trim down to the size I need. It is so much easier that way and saves me from a lot of frustration.

I also recommend starting out with 4 inches, then trim down. The fastest and most accurate way I have found to "square up" is to use the Quilt in A Day Triangle Square up Ruler. LOVE that tool.

Another one in the camp of cut big and trim down...particularly with HST's. Those bloody things never come out straight/true no matter how careful I am. But you do add the increase (regardless if you chose 7/8 or 1") to the FINISHED size (in your case - 3" + 7/8") and you will end up with 3.5" hst's.

I say just cut it down that way you dont have to stress about wonky blocks.