How to sew concave & convex curves together

If you’re new to sewing or simply need a refresher on the basics, you’ll want to check out this tutorial for sewing curves! With these simple tips & tricks you’ll learn how to sew a curved seam so you can rock at sewing smooth curves every time!

Sewing curves

When I first started using a sewing  machine, the idea of sewing curves used to scare the soul out of me! It took me a while to get the courage to tart sewing curves and a lot more to sew different types of curves together!

In sewing there’s a lot of squares and rectangles, especially in home decor sewing and quilting. But curves add beauty and interest to any project! So at one point in your life, you will want to learn sewing curved seams if you want to step up your sewing skills and make project that are not only prettier but look professional too!

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If you’re fairly new to sewing or simply never had the interest to learn about sewing curves, there are two kind of curves you need know about: convex and concave. A convex curve shapes outward, much like a football while a concave curve shapes inwards.

In your sewing journey you will encounter opportunities where you’ll need to attach two curves of the same type together (two concave curves to each other or two convex curves to each other. This situation might not be as easy as sewing a straight seam but with a little patience you will manage to tackle the task in a pinch.

But there will also be some opportunities where you’ll have to join concave curves to convex curves and this is where you might find yourself a little puzzled! No need to panic though as I’ve got you covered for this kind of situations right here in this tutorial for sewing curves. Before getting into the nitty gritty of sewing concave and convex curves together, let’s get through some tips that will make sewing curves together a breeze! It all boils down to using correct seam allowance, adjusting stitch length, pinning and pressing.

Tips for sewing curves

1. Use a small seam allowance. Anything above 1/4″ will make it difficult for you to get a smooth curved seam line.

2. Mark your seam allowances before sewing. Take the time to mark the entire seam and clearly mark your seam line.

3. Adjust the stitch length to a shorter one. I normally decrease the length to a 2.0. Shorter stitches help you shape the curves easier than longer ones as you are more in control.

4. Use lots and lots of pins! I like to pin about every 1/4″. This offers me more control and helps with handling creasing a lot better.

5. Sew slow! If you have a digital machine set it to the slowest speed so you can take your time when sewing those curves. This is particularly useful for small curves that are very tight. The smaller the curve, the tighter it gets and harder to sew.

6. Lift the foot and smooth out the fabric whenever you encounter creasing. Make sure no crease is caught in the needle. But if this happen, don’t panic! Grab your seam ripper, unpick the seam and start over.

8. On tight curves it helps to stop and pivot every once in a while, whenever shifting the fabric won’t work. Stop the machine, keep the needle down, lift the presser foot up and shift the fabric as needed. The lower the foot and continue sewing.

8. Clip and notch seam allowances when needed. On tight curves this is a really necessary step while wider curves might not need this step as the seam has plenty of room to fit. This is particularly true if you’re using a very narrow seam allowance.

9. Press well but use the right motion. The curves will stretch because of the cut on the bias so pushing the iron in an back and forth motion will stretch the fabric around the seam. To avoid that, use an up and down motion and work in small sections.

How to sew curves

Materials:

• two fabric pieces, one with a concave curve and the other with a convex curve.
• fabric marker
• seam gauge
• pins
• sewing machine
• matching thread
• pressing iron

Directions:

Prepare the fabrics

1. Start by washing, drying and pressing your fabrics well.

2. Using your seam gauge and the fabric marker, trace 1/4″ seam allowance. Take your time to measure and mark as accurately as possible. If you’re experienced and have a sewing machine with guides on the plate, you can skip this step.

3. Fold each fabric piece in half, finger press the middle and mark with fabric marker.

Attach fabrics together

4. Place the convex curve fabric right side up and top with the concave curve fabric wrong side up, matching at the traced you made in the previous step. Pin at the mark.

5. From this center pin start moving to your left and pin the fabrics together every 1/4″. I like to use thin long pins. You will notice creasing is forming in the convex fabric as you pin towards the edge. This is normal so don’t panic!

6. Repeat for the right side of the center pin.

Sew the curves

7. Take the fabrics to the sewing machine and start sewing right on the seam allowance mark, sewing slow and taking care not to catch the creases in the seam. If that happens, don’t worry! Just rip out the seam in that spot, smooth out the seam and start over.

Press the curve

8. Fold the concave fabric up, finger press the seam and then press with your iron on steam. Take note of the tip I shared above when pressing.

If you’re sewing a narrow curve, or your project requires a wider seam allowance you will need to do some clipping and cut notches in your seam allowance. On a wider curve you might not need to do this. Not sure if you need to skip this step or not? Simply push the fabric up and see if the seam is accommodated comfortably. If you get a bunched up seam or the seam doesn’t align properly because it can’t stretch enough, you will need to clip and cut notches in the seam allowance.

And that’s it! I hope I managed to convince you that sewing curves, even opposite ones, is simple and easy to manage! Please let me know your thoughts in the comment section below and don’t forget to rate this tutorial! Thanks!

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