There are two different, relatively easy ways to accomplish this.
Which way to choose depends on how close to the edge of the quilt your quilting is.
If your quilting is relatively close, you may not have enough space to fold the backing under the quilt, so an alternative is to place a rotary cutting mat between the backing and the batting.
Place what you want to cut off on top of the second mat, and then cut.
You could do this with just one mat, however, it is nice to have two, just in case your rotary cutter slides off the end of the quilt.
A second way to cut the batting and quilt top, leaving the backing is to fold the backing under the quilt
.To do this, you must have plenty of space between your quilting and the edge of the quilt. I generally recommend that amount be more than 1/2 inch.
The thing is, you want to be able to lay the backing flat enough so that you can easily place your rotary cutter on the edge of the quilt and trim the batting and excess top fabric without having a big lump of backing.
Happy Quilting!
Penny Halgren
www.HowToBindAQuilt.com
