10 seams X 1/16" = 5/8"

You block would measure either 10-7/8" if the seam was too big or 12-1/8" if the seam was too small. That's a lot to be off for a block.

Now if each of those blocks is sewn to a pre-cut sashing strip that is 11-1/2" long, you can see where inaccurate seam allowances makes your beginning quilting efforts more of a pain than a joy.

Stitch as accurate a seam allowance as you can.

When a Quarter Inch Isn't a Quarter Inch

When quilters refer to the quarter inch seam allowance they are really talking about a "scant" quarter inch.

In quilting, the seam is stitched, then pressed closed to set the seam, and then opened and pressed with the seam allowance generally towards the darker fabric.

A wee bit of the block is "lost" in the "turn of the cloth" or where the fabric folds back on itself when the unit is opened.

With thicker fabrics (think flannel) more fabric is lost in this "turn of the cloth". Use a thicker of heavier thread for stitching seams and even more fabric is lost.

To make up for this loss, quilters set their machines for a "scant" quarter inch seam.

Tools for Stitching a Scant Quarter Inch

There are several handy tools and gizmos available to help you sew a perfect quarter inch seam.

Quarter Inch Foot

Quarter Inch Foot

The edge of this specialty foot is a quarter inch away from the needle. This foot is a good option for machines that can't make needle position adjustments.

There are several versions on the market. The "Little Foot" is a clear version of this presser foot.

Notice how the feed dogs are exposed on the right side of the foot. Some quilters believe they don't get enough traction with this foot because of it.

Edge Stitching Foot

My personal favorite. This foot looks like your standard presser foot but with a flange on the right side as you sit facing the foot. The raw edges of your patches ride along this flange as you stitch. Starch your quilt fabric to make it even easier.

NOTE: You must be able to adjust your needle position to use this foot properly.

Make Your Own Seam Guide

Use masking tape, moleskin or Post-It-Notes to create your personal quarter inch seam guide. Here's how.

1. Grab the same ruler you use to cut your patches.
2. Place it under the presser and hand lower your needle until it is touching the right side of quarter inch line. (Remember, we're looking for a "scant" quarter inch.)
3. Making sure that your ruler is squared up with the lines of your sewing machine, lower the presser foot to hold the ruler in place.
4. Butt a piece of masking tape straight up against the ruler and position it in place.
5. Remove the ruler and complete a sewing test with the fabrics you'll use in your piecing. Adjust the masking tape as needed.

As long as your presser foot doesn't extend beyond this quarter inch line, either moleskin or a short stack of Post-It-Notes can be used instead of the tape. Either one will create a higher fence or guide.

For machines with a drop-in bobbin, this method may be more trouble than it's worth. You'll need to re-tape every time you replace your bobbin.

Check Your Accuracy with a Sewing Test

Regardless of what you use for a seam allowance guide, you'll need to do a simple "sewing test" to check for accuracy. It's easy to do.

1. Cut three strips of fabric each 4" by 1-1/2".
2. Sew two strips together along the 4" side.
3. Sew the remaining strip to a 4" side.
4. Press each seam allowance closed to set the seam.
5. Now press the patch open, with all your seam allowances pressed in the same direction.
6. Measure the finished block with your usual rotary ruler.

It should measure exactly 4" by 3-1/2". The two outside sewn strips should measure 4" x 1-1/4" each and the center strip should measure 4" by 1". If your measurements are off here make the necessary adjustments now to avoid future problems in your quilt blocks.

One final point...

Your perfect quarter inch seam allowance will change for different fabric and thread combinations. Flannel is a thicker fabric. You may need to use an even "scanter" seam.

The only way you'll know for certain is to do a quick test.

Do take the time to retest for each quilt you make. The few minutes you spend to test your seam allowance can save you hours of frustration from trying to piece a quilt that just won't go together.

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