Please help
 

I can't get this to square at 12 1/2". What am I doing wrong?

What size does it square up to now?

Just looking at the picture I can see that where the red and white make outside points they are not all the same. They should meet at 1/4" from the side seams. Yours are uneven.

Also you might want to check your seam allowances ... or use a finer thread, like Aurifil.

You have several square in squares within the block. Are each of them the size they should be? That will help you pinpoint where the problem lies. Good luck - we've all been there.

The squares are 4 5/8, 6 1/2, 9 1/4 and not quite 12 1/2. I have searched the Internet for a tutorial and what size the squares should be with no luck. Guess I will take the outside ring off and try again. Thanks for the input. :)

Snail's trail is not an easy block to sew. I paper piece them after starting with the inside 4-patch. Sooooo much easier!

Your outside triangles are too small. I usually sew them oversized and trim them down. It's an extra step but it has great results.

I always centre the triangles on the centre of the other side. If you look carefully the centre of one triangle is further one way than the other. Remember the triangle should have a very small 1/4" triangle at the top where you begin to sew. Also a press without seam should also help. If after that still not right sizes either down size or make the last 4 triangles larger and centre.then cut down. At present I think the triangle is a 61/4" squAre cut in half. Try for one only a 7" square cut in half then centre in place. You may be able to make smaller after the first try. When I do this play section I use my scrap fabric.