In this article, you will learn the anatomy of a plain seam; the five rules you need to know to sew pretty seams; how to sew a plain seam from start to finish; and a cool tip for verifying the accuracy of 5/8 inch seam allowances.
In cooking, there are the mother sauces; and in sewing, the plain seam is the “mother” of all machine stitches.
That is, it is the foundation on which all other sewing skills are built.
In this article, you’re going to learn everything you need to know to sew those insanely gorgeous garments you’ve been dreaming of!
You will learn…
- the anatomy of a seam; and
- how to sew a plain seam
Let’s start with the rules…
The Rules of Sewing a Seam
Rule #2: Position yourself directly in front of the sewing machine needle. This is where you need to be to sew an accurate seam allowance with as little strain on your body as possible. Click HERE to learn about the ergonomics of sewing!
Rule #3: At the start of each stitching line, make sure the takeup lever is at its highest position. Then, gently but firmly, hold both the bobbin and needle threads behind the presser foot. This will avoid gnarly, tangled up threads on the underside!
Rule #4: Please Do. Not. Watch. The. Needle! I don’t want you getting dizzy and falling off your chair. Because that would be unfortunate. Plus, it might just make you stitch an ugly, winding stitching line. And that is definitely not what we are striving for!
Instead, keep your eyes on the raw edge at the right as it grazes past the seam allowance markings on the needle plate.
Rule #5: Be safe, please! Keep your fingers at least 1” from the presser foot at all times!
Okay. Now that you know the rules, let’s learn…
The Anatomy of a Seam
A sewing machine stitch (also known as a lockstitch) is a simple thing. It is the result of the needle thread reaching down into the bobbin case looping around the bobbin thread, drawing the bobbin thread up so that they both interlock midway between two layers of fabric.
Beautiful. Simple. Process.
Once a seam is sewn, this is its anatomy…
As you can see, there are three parts to a seam:
- the stitching or seam line;
- the seam allowance; and
- the raw edges.
Alright! Now that you know the anatomy of a seam, let’s learn…
Okay. Let’s get busy learning…
How to Sew a Plain Seam
Sewing a plain seam is literally child’s play!
But first, you should keep in mind the following:
The average stitch length is…
- 2.5 to 3.0mm for medium-weight fabrics;
- 2.0mm for lightweight or delicate fabrics; and
- 3.0 to 5.0mm for topstitching, basting, and gathering.
The seam allowance (SA) for commercial garment patterns is usually 5/8 inch.
The SA guide on your sewing machine needle plate is in ⅛ inch increments. But the seam guide on your needle plate is only accurate when the needle is in the CENTER position.
Alright. Now that you’re in the know, here’s how you sew a plain seam, step by step.
But once you know-how, each step will flow effortlessly into the next, so don’t you fret the number of steps listed below…
Step 1: Sit so that your body is positioned directly in front of your sewing machine needle. Click HERE to learn the ergonomics of sewing!
Step 2: If your sewing machine has a speed control feature, set it to a moderate speed. This way even when you press the foot pedal all the way, you will still only be able to sew at a sensible speed.
Step 3: Make sure the takeup lever is at its highest position to avoid a gnarly, messy start!
Step 4: Locate the appropriate seam allowance on the needle plate. If you need more guidance as you sew than the short line provides, take a piece of masking tape or washi tape and mark your seam allowance on your needle plate (see image above).
Step 5: Align the raw edges of your fabric with the right sides together (RST). Generally, you want to place the bulk of your fabric to your LEFT.
Step 6: Now, position your fabric under your presser foot and align the raw edges at the right with the desired SA on the needle plate.
Also, align the top of the seam so it is positioned ¼ inch in from the top raw edge. This way you will avoid your fabric getting sucked into the hole on your needle plate when you begin to sew! Ugh!
Step 8: Lower your presser foot.
Step 9: Gently but firmly, hold both the bobbin and needle threads behind the presser.
Step 10: Still holding the threads, press the foot pedal to sew your first few stitches and secure the start of the stitching line; and then release the threads.
Step 11: Now continue stitching forward from the start to the end of the stitching line.
Again, as you sew, remember this: The needle isn’t moving, but your fabric is. So keep your eyes on the raw edge of the fabric to ensure an accurate SA from the start to the end of a stitching line!
Step 12: When you near the end of the stitching line, about ¼ inch away, prepare to secure it.
Step 13: Next, press your needle position button or turn the handwheel towards you to raise the needle to its highest position and complete the last stitch.
Step 14: Raise your presser foot; pull your fabric towards the BACK of your sewing machine, and use your machine’s thread cutter to cut the threads.
And if there is some resistance as you try to remove your fabric from the machine at the end of a stitching line, just turn the handwheel slightly towards you to complete the stitch and release the fabric.
Okay! How easy was that?!
Sew easy tip: The width of a standard measuring tape is exactly 5/8 inch, which is a very handy thing to know when you need to check the accuracy of your seam allowances.
You now know how super easy it is to sew a plain seam.
And you also know that looking at the raw edges of your fabric –rather than the needle– is how you maintain an accurate SA from the start to the end of a stitching line.
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