Why the 1/4-inch Seam is Important…Except When it isn’t

One of the very few quilting “rules” is the ¼-inch seam.  It’s one of the standards drilled into our quilting consciousness from the time we pick up our first quilt pattern. 

Sew a ¼-inch seam.

Keep a consistent ¼-inch seam.

You’ll always use a ¼-inch seam.

There’s no denying ¼-inch seam is pretty important. However, what’s more important is to know what tools there are available to help us keep that consistent ¼-inch seam, and the difference between a ¼-inch seam and a scant ¼-inch seam.  Let’s talk about the two different types of seams first.

Two Types of Quilt Seams

The standard ¼-inch seam is just that – a full ¼ of an inch.  It should measure consistently ¼-inch throughout the seam.  In most quilt patterns, if the directions state ¼-inch seams or don’t indicate the seam width at all, it’s understood the full ¼-inch seam allowance is implied.  A scant ¼-inch seam means the seam allowance is a thread or two under a full ¼-inch.  Usually quilt directions will indicate if a scant seam allowance should be used.  The pictures below show the difference between the regular ¼-inch and the scant ¼-inch seams.  The white chalk line is ¼-inch away from the edge of the fabric.  When I use a full ¼-inch seam, the stitches fall directly on top of the chalk line.

When I use a scant ¼-inch seam, the stitches fall slightly to the right of the chalk line.

The dilemma a lot of us quilters fall into is Multiple Machine Management.  One of the standard pieces of advice I received throughout my quilting years was, “Always use the same machine throughout your piecing and assembly process.”  I determined a few years ago the reason this tidbit of guidance was continually flung my way is this – different sewing machines mark their ¼-inches differently and it can be easy to get confused if you switch out machines, resulting in your seams not remaining consistently ¼-inch.  And while this really is excellent advice, most quilters know this may not be possible, because most of us have more than one sewing machine.

I currently have five domestic sewing machines.  And let me remind you this is a Nonjudgement Zone.  I have a Featherweight, a small Juki I use for classes, a Juki 2010Q, a Janome 7700, and my M7 Continental.  Most of the time, I start and finish my quilts on my M7.  However, if I decide to attend a day quilt retreat, bring a machine to a sit and sew, or take a class, I’m not hauling around my M7.  She’s a beast.  I’ll take the Janome 7700 or my small Juki.  In all actuality, I may trade off machines several times during my quilting process.  I need a way to make sure all my machines are sewing an accurate ¼-inch seam allowance. 

There are several techniques and tools available for this process.  We’ll take a look at each and weigh the pros and cons.

The Quilting Foot

Before the advent of sewing machines designed especially for quilters, these were considered “specialty feet” and were an added cost.  Now if you purchase a sewing machine designed for quilters, these are normally thrown in at no additional charge.  These feet vary in appearance from machine to machine, but the standard feature among all of them is they have some way of letting you know you’re sewing a full ¼-inch seam.  The foot for my M7 looks like this:

The phalange on the right lines up with the edges of my fabric.  As long as the fabric stays snuggled up to the phalange, I’m sewing a full ¼-inch seam. 

Quilting feet may also look like this:

As long as the edges of your fabric are lined up with the right side of this foot, you’re sewing a full ¼-inch seam. 

There are even walking feet which have a ¼-inch seam designation.  This is the one for my machine.

Quarter Inch Walking Foot

Regular Walking Foot

I use my regular walking foot for sewing on binding, paper piecing, or quilting.  However, I have found the ¼-inch walking foot to be remarkably handy if I am piecing a quilt with lots of seams joining together at one spot. 

There are also scant ¼-inch quilting feet.  Some quilter’s sewing machines have this foot thrown in as part of the package.  With others, this foot is a separate purchase.  I use the Little Foot brand scant ¼-inch foot. 

When you line the edges of your fabric up with the right side the foot, you sew the scant ¼-inch.  If you’re able to move your machine needle’s position a little further to the right, you may be able to sew a scant seam without purchasing an additional foot.  Read your sewing machine manual or Google your brand to find out. 

Faith in the Feet

If each of your sewing machines has a quilting foot (which in my opinion really should be called a “piecing foot”), the assumption is you can sew a consistent ¼-inch seam no matter what machine you’re using.  The idea is valid, but that’s putting a lot of faith in your presser feet without solid proof.  It’s super-important to know for sure the ¼-inch seam is consistent throughout your machines.  Fortunately, there are a few ways to handle this.

The first way is to set up your machines to sew a ¼-inch seam.  Gather some scrappage and sew a ¼-inch seam 6-inches long on each of the machines.  Then, one at a time, take each seam and press it open (I think it’s good to do one at a time, so you won’t forget what fabric was sewn by what machine).  Measure the pressed-open seam allowance.  If it measures a full ½-inch, then you know that sewing machine does sew a consistent ¼-inch seam allowance. 

Full Quarter Inch Seams

Scant Quarter Inch Seams

If you have a machine (or two) which fail this ¼-inch seam allowance assessment, try this second test to make sure something didn’t go wonky on the first one:

1.  Cut three strips of fabric, 2-inches wide by 7-inches long.  Two of the strips should be the same color and one needs to be a contrasting color (this just makes the test easier).
2. Sew the three strips together, using the same ¼-inch foot used on the first test. 
3. Press the seams towards the center strip.  Measure the joined strips crosswise.  It should measure exactly 5-inches in width.
4. Measure the center strip.  It should measure exactly 1 ½-inches wide.  If it’s narrower than this, your foot is grabbing more than ¼-inch.  If it’s wider, then it’s grabbing less. 

If this test meets the 5-inch and 1 ½-inch measurements listed above, run the first test again just to be sure.  On the first try, the machine could have wobbled, the foot could have bobbled, or something happened to alter the ¼-inch seam.  If you have two consistent tests producing two consistent ¼-inch seams, you’re good to go. 

If your machine and its foot failed you, don’t despair.  There is still something you can do.  This little tool right here:

Is an amazing apparatus to have in your quilting notions.  It’s the Perfect Piecing Seam Guide.  It’s available through Keepsake Quilting, Perkins Dry Goods (perkinsdrygoods.com), and Amazon.  It’s not a major purchase, cashing in at a mere $8.15 (on average).  However, it’s one of the handiest gadgets to have on hand, especially if you’re test driving a new sewing machine and want to make sure its quilting foot is truly ¼-inch. 

On the right side of the guide is a raised edge.  In the middle of the raised edge is a tiny hole, just big enough to insert a sewing machine needle.  Raise the presser foot on your machine and adjust the seam guide so your needle will go through the hole on the guide completely.  Do this manually or you may break a needle and scare yourself silly and ruin the guide.  Once the needle is through the hole, leave it in the down position and then mark your needle plate on the right side of the edge of the seam guide.  That mark shows you where you need to have the edge of your fabric as you sew.  Some folks use moleskin, fingernail polish, a fine-tipped permanent marker, or a magnetic seam guild to mark this ¼-inch spot.

At this point, usually the question pops up about moving your sewing machine needle – instead of marking your machine on the ¼-inch spot, can’t you just move your needle over to the left or right to adjust for the difference?  Of course!  Just two pieces of advice here – make a note somewhere about how much to move the needle over (the note section on your cell phone is a handy-dandy place to put it) and make sure you move the needle back to the original position when you’re through. 

Now, after all of this, I’m getting ready to completely disavow the ¼-inch seam quilting rule: It’s not always valid all of the time.

Nope.  The ¼-inch seam rule is not the do-all, be-all, and end-all of quilting.  It’s far more important your blocks consistently come out the same unfinished size called for in the pattern.   Sometimes this may mean using a scantier-than-scant seam allowance.  Sometimes this may mean using a larger seam allowance than the ¼-inch.  Most of the time, however, the true ¼-inch will work best.  But you really need to know this information before you start slicing and dicing your beautiful quilt fabric.  For this reason, I strongly recommend making a test block out of some scrap fabric and then measuring it after it’s finished and pressed.  If this block comes out slightly larger or smaller than the desired unfinished size, check a couple of things:

1.  If you’ve moved your needle recently, did you move it back to its normal position before you began sewing?
2. Did you grab the right presser foot?  One of my machine applique feet looks nearly identical to my Little Foot.  I have put the wrong foot on my machine more than once. 
3. Did your foot “bobble” any?  Sometimes in our rush to sew, we don’t attach the presser foot correctly, and it wiggles a bit.  Make sure your foot is on securely. 

Also make sure you’re feeding the fabric through your machine at a steady rate.  Frequent stopping and starting can cause seam allowance issues, as well as sewing too fast.  It’s difficult to control your fabric when you’re sewing too quickly.  Steady fabric feeding and a moderate speed are helpful to maintaining the ¼-inch seam allowance. 

4.  Check your thread.  The weight as well as the number of plies can make a difference.  If your block is just a tad too big, try switching to a heavier weight thread with more plies.  If it’s just a bit too small, switch to a lighter weight thread with 2-plies.

Standard disclaimer here:  I do not work for Janome, Juki, Singer, The Little Foot Company, Amazon, or Keepsake Quilting.  When I mention products, it’s because I use them, like them, and get stellar customer service.  I am not paid by these companies nor do I receive any free goods for mentioning them in my blog. 

Most of the time quilt patterns use a full ¼-inch seam.  Knowing how to consistently sew one is a little detail which makes a huge impact on your quilt and your quilting experience.  However…it’s just as important to know when to break that ¼-inch rule and how to do it.

Until Next Week, Remember the Details Make the Difference!

Love and Stitches,

Sherri