The size to make the quilt depends on how large is the mattress and how much "drop" you want. Drop is defined as the amount of quilt that you wish to have hanging down to cover the side of the mattress and beyond. Some mattresses are very thick so up to a 15 inch drop would be required. Obviously if your mattress is less, you would need to have less for your drop.
For instance, the top of a queen size mattress is 60 inches wide by 80 inches long. If the mattress is 10 inches thick, you would need to add 20 inches to the width of the top of the mattress for a 10 inch drop on each side and 10 inches for the drop at the foot of the bed. Be sure to add an inch or two in each direction to compensate for the "take-up" in quilting.
For our example above -- not counting extra for the pillow -- only counting for the drop of 10 inches on each side you would need to make your quilt 80" wide x 90" long just to accommodate the top of the bed and a 10 inch drop on each side. Adding two inches for quilting "take-up" you would need to make your quilt 82" x 92".
Piece your quilt top as usual. Layer the top, batting, and backing. Machine quilt it yourself or send it to a professional long arm quilter. Do not bind the quilt yet.
Make your mitered bottom corners or "boxed corners" as follows. Fold the bottom corner of the quilt on the diagonal -- measure 10 inches (or whatever your "drop" measurement is) from the point. Mark a small dot at the edge of the quilt. Place a crosswise line of your rotary ruler on the edge of the quilt and aligning the edge of the ruler with the dot, draw a line using a marking pencil or chalk. Your drawn line will be 10 inches from the corner of the quilt and 10 inches long. Repeat for other corner.
Place pins in the drawn line through all layers. Check the quilt on the bed -- you might want to change it slightly depending on the thickness of blankets and other bedding. Draw a new line if necessary. Keep the corner diagonal fold and the pins in place for stitching. Now you may machine stitch through all layers following the drawn line. Try the spread on the bed again to make sure everything fits. Re-stitch if necessary. Trim excess quilt from the inside of the boxed area, leaving a half inch seam allowance. Bind raw edges of seam allowance with double fold binding. Bind quilt as usual.
Are Serger Overlock Machines For Quilters?
A serger is entirely different than the standard sewing machine and works in a different way.
A serger is a sewing machine that uses three, four, or five threads. It stitches, trims, and overcasts the seam allowance all at the same time. They are also called overlock sewing machines. A standard sewing machine uses a top thread and a bobbin to form the stitch.
What a Serger Will Do
A serger will stitch a seam and overcast the edge at the same time. It will trim the seam allowance as you are stitching so there is a clean cut just before the overcast stitch encases the quarter inch seam allowance. While most modern sewing machines can make an overcast stitch, most do not have a fabric trimming device available.
A serger -- with appropriate attachments - will make a tiny rolled hem for the edge of a table cloth or napkins. A serger -- with differential feed -- can stitch sweater knits or swimsuit knits without puckering or gathering. A serger can also gather large amounts of fabric for ruffles although most regular machines have some sort of gathering foot. Some models of sergers will require additional features or attachments to do the procedures listed above. Be sure to check with your dealer about specific features on their models.
There are many good reasons to own a serger for a seamstress who makes clothing or home decorative accessories but it is not very useful for a quilter. Most of machine work a quilter needs to do are best accomplished on a standard sewing machine.
When sergers first were available to home sewers, they would stitch approximately twice as fast as a standard home sewing machine. A serger stitched at 1500 stitches per minute in comparison to a lockstitch machine that would stitch 800 stitches per minute. Many strip piecers liked the faster speed of sergers.
The past several years many of our standard lockstitch machines designed for "short-arm" quilting with the larger 10" throat will stitch 1500 - 1600 stitches per minute. The larger throat machines can also be used on a standard table and used for piecing making for faster stitching.
Don't let the faster stitching of the sergers or larger machines fool you into thinking you will be able to sew twice as fast -- remember that when piecing or chain piecing small pieces there is almost not enough time to get to top speed before having to slow down to add another pair of patches. The faster machine speed is simply too fast to be advantageous to use for basic piecing.
Sergers or overlocks usually come with an option of making stitches with either three, four or five threads. The three thread stitch is designed to use on knits or stretchy fabrics so quilts would need to be stitched with either the four or five thread seams. Obviously the more threads involved in making the seam the bulkier the seam allowance.
What a Serger Will Not Do
A serger is not recommended for standard piecing. I pieced my first quilt top on a serger or overlock sewing machine. It was a Trip Around the World that was pieced in strips and cut and those strips stitched together. My second quilt top, a Log Cabin, was also pieced on a serger. After finishing those two quilt tops, I prefer the standard lockstitch to the excess thread needed to make the stitch on the overlock. When I pressed the quilt top the bulky seams were noticeable from the right side.
A serger is not recommended for machine quilting. The serger is set up to trim a seam so it is not feasible to quilt a quilt using a serger. Even if you dis-engage the cutting blade the throat of the machine would not accommodate even the smallest quilt.
Occasionally at a large quilt show there is a charity quilt project making reversible baby quilts where the backing, batting and top fabric are stitched entirely on a serger. While these quilts are fast and supposedly easy they lack a lot in good design. Also the logistics of placing the three layers and stitching them to the previous three layers is not as easy as they said -- even for person experienced in using a serger. After stitching the required 30 minutes I got up from the sergers and vowed never to volunteer at a similar charity booth again.
If You Want To Purchase a Serger
There are different features available on sergers. Many sergers come with a differential feed. What is differential feed ratio - it is the ratio of differential feeding power that is adjustable with the main feeding. To translate -- with differential feed you can set the machine to prevent thin materials from puckering, and you can set the machine to prevent elastic or very stretchy knits from stretching or puckering.
Do not confuse the differential feed on a serger with a walking or even feed foot on a standard sewing machine. The walking foot or even feed foot on a standard sewing machine helps stitch the three layers of the quilt sandwich without a shifting of layers. The differential feed on a serger has an entirely different function. Differential feed is only needed for knit and stretchy fabrics to keep them from puckering.
If you are going to piece quilts with tightly woven 100% cotton fabric you would not use the differential feed on the serger. A serger that didn't have differential feed would be adequate for all quilt piecing.
If your piecing style is making large strip sets you might save some time using a serger or a faster machine. But remember there will be more bulk in the seam area because of the extra thread.