4 Basic Sewing Machine Seams and Seam Allowance Tips

seams and seam allowances

In this tutorial I am going to go over the basic sewing machine seams and give you some seam allowance tips.

What are seams?

Seams are the building blocks of a clothing item and are the points of connection between fabric pieces. As a beginner seamstress, the first thing you will learn how to do is sew a basic seam. (Sew two pieces of fabric together).

There are several different types of sewing stitches that you can use to make up seams. Be sure to check out my SEW SIMPLE SERIES, A BEGINNERS GUIDE TO SEWING, where I show you all the basic stitches, seams and guide you through several easy sewing projects. (PATTERNS INCLUDED).

seam allowance

What is a seam allowance?

Whenever you sew seams, you’ll have some kind of seam allowance. This is the distance from the seamline to the raw edge of the fabric, which allows the fabric pieces to be durably connected without fraying or coming unsewn.

 

Here are some basic seam allowance “facts” and “rules”

  • The width of the seam allowance depends on the type of fabric and the seam finishing technique used. A thicker, bulkier fabric requires a larger seam allowance while thinner, lightweight fabrics work well with a narrower seam allowance.
  • The most commonly used seam allowance measures 3/8” to ½”.
  • Some seam allowances are finished to ensure seam durability and prevent the raw fabric edges from fraying. Fabrics like knit or polyester do not need to be finished. Here are some simple techniques to finish seams (NO SERGER NEEDED).
  • After the seam is stitched, the seam allowance should always be ironed down in a specified direction in order for the seam to lay flat (you’ll see a demonstration of this in the sewing tutorial video below).
    All conventional sewing machines have a seam allowance guide to the right of the sewing machine needle. In order to sew each seam at the proper seam allowance, the raw edge of the fabric is aligned with the appropriate seam allowance guideline according to the required seam allowance length. In my tutorials, I usually give some great tips on things you can do and use to make following these guides easier.
  • Most patterns will give you the SEAM ALLOWANCE requirements and measurement for that specific project. If it doesn’t, use the standard 3/8 inch seam allowance. (This by the way is just the edge of your normal presser foot).

BASIC 3/8 INCH SEAMS INSTRUCTIONS

  1. Place the two pieces of fabric you are working with together, matching edges and pin in place. Use the 3/8 inch guide on the top plate of your machine to line up the edges of the fabric, or if your presser foot edge is at that measurement, you can just use the edge of the presser foot as your guide.pressing seams
  2. Sew the seam. Open up the seam allowance and press flat using an iron.

FLAT FELLED SEAMS INSTRUCTIONS

A flat felled seam is basically an overlapping seam that’s sewn flat. When the seam is complete, there are no raw edges showing. It’s used frequently in menswear because it’s extremely durable and sturdy and provides a neat finish. If you’re wearing jeans, take a look at the seams. They are almost certainly flat-felled. Use a flat felled seam on shirts or trousers, which see a lot of stress, and you’ll get a durable finish.

Here’s how to go about sewing a flat felled seam.

  1. Pin fabric with right sides together. You will be using a 5/8 inch seam allowance. tape seam allowance guideI like to place a piece of masking or painter’s tape onto the sewing plate at the 5/8 inch mark. This will help you see more clearly and help you guide the fabric along as you sew.pressing seam allowance
  2. Instead of pressing the seam open, you’re going to fold the seam allowance to one side and press.flat felled seam stitching
  3. Flip the fabric over to the right side. Now sew a straight line on the side that the seam allowance is pressed to.1/8 inch seam allowance
  4. Sew 1/8 inch from the seam line fold. TIP: Most presser feet will have little notches indicating 1/8 inch marks. This is nice to use this feature when sewing this seam. Simple line the fabric up with that right 1/8 inch guide and sew away.

FINISHED FLAT FELLED SEAMS INSTRUCTIONS

trimming seam allowance

  1. Sew the seam with a ½ seam allowance. Before pressing the seam, take your scissors and trim away ¼ inch from the right seam allowance.pressing seam allowance
  2. Fold the uncut seam allowance over the cut seam allowance and press in place.
  3. Now fold the top seam allowance under ¼ inch encasing the cut allowance. Press in place.
  4. Topstitch in place along the folded edge to secure in place.

FRENCH SEAMS INSTRUCTIONS

French seams are perfect to use on lightweight, sheer fabrics, or lace. I like using this seam when I make pillowcases. The seam encasing all of the fraying fabric edges inside a tiny seam allowance of 1/4″ (5mm). French seams can be great to use if you haven’t got an overlocker (serger) and want to create a perfect finish to your project.

  1. When sewing a French seam, you start by placing WRONG SIDES OF THE FABRIC TOGETHER, instead of right sides together.French seam 1/4 inch seam
  2. Sew the first seam using a ¼ inch seam allowance. Then, fold the fabric along the seam line, so the right sides of the fabric are together and the stitching is at the edge of the fold. Press well, so you are working with a sharp crease at the fold on the seam. You may want to pin the fabric edge, especially if you are using a slippery fabric.3/8 inch seam allowance
  3. Now sew another seam using a 3/8 inch seam allowance.

     

  4. Press the finished seam to one side or the other.

Play Video

There you have it, 4 basic seams for you to use.

HINT: my SEW SIMPLE COURSE COMES WITH INSTRUCTIONS AND MEASUREMENTS FOR ALL SIZES OF PILLOWCASES.

OTHER BLOG POSTS YOU MAY BE INTERESTED IN:

7 Sewing Machine Presser Feet and How To Use Them

Unpicking Serger Stitches the EASY WAY

SEWING BY HAND | Most Important Stitches to Know

Have fun sewing my friends!

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