I like to use oversized concave templates when piecing quarter circle / drunkard’s path blocks. In the short video below, I demonstrate how I trim curves to size so the curves will match nicely when they are sewn together.
NOTE: If you receive my blog posts via email, the YouTube video will not be embedded in the email. Visit my Trimming Quarter Circles YouTube video.
Much like oversized HSTs and flying geese, I like to use oversized concave templates to allow me the ability to trim the block square after piecing. The ability to trim my blocks square after piecing has greatly increased my piecing precision.

Right-Handed Trimming
The bottom line is that it’s all about where the ruler is placed for trimming. The video and graphic above show how I position and trim as a right-handed quilter. The two edges of the convex template should be lined up with the size you want to trim to on your ruler, and the concave fabric should be trimmed away, leaving ¼” of concave fabric remaining at the edges of the curve.

Left-Handed Trimming
And for all my left-handed friends, the bottom row of the illustration above will be what it looks like for you to trim up the left hand side and then across the top of a ruler.
There are certainly times when more concave fabric is desirable, but when a pattern calls for trimming to leave ¼” of concave fabric, I hope this quick post helps!
Linking up with Tips and Tutorials on the 22nd.
I like oversized piecing too, as you mention it helps with accuracy.
Thank you for including us lefties!!
That is a great explanation of how to trim those curvy blocks. I can never wrap my head around the left handed approach…it is so nice for lefties when we can do this!
Very helpful tutorial. Thank you so much. Now I need to redo a block the correct way. It has been bothering me that my block is wrong.
And thanks again, for always having a great tutorial to link up to Tips and Tutorials on the 22nd!
You have gotten curves down to a science! Thanks for sharing your expertise!