How Do I Sew Smooth Curves in a Bag?

Curved seams can feel intimidating, especially when you're working with foam stabiliser, vinyl or several thick layers, but a few simple tricks can make them much easier to sew smoothly.

The most important part actually happens before you reach the sewing machine. If the pieces are positioned evenly and securely, sewing the curve itself becomes much easier.

Mark and match your centre points

Start by marking the centre point on both pieces you're joining. Match and clip those centre marks first, along with any other notches or markings included in the pattern.

Then work outwards from these points, distributing the fabric evenly around the curve.

This is much easier than starting at one end and working your way around, only to discover that the other ends suddenly don't want to meet. 😄

And if the curve really doesn't want to stay put, I have another favourite trick...

Try staples for stubborn curves

Yes. Staples. 😄

For thick, slippery or particularly awkward curved seams, ordinary staples can hold the layers much more securely than clips while you sew, without getting in the way of your presser foot.

First position the entire seam with sewing clips so you're happy with how everything fits. Then replace the clips with staples placed near the outer edge of the seam allowance, well away from your stitching line.

The layers stay exactly where you put them, which greatly reduces the chance of folds or unevenness developing while you sew. This is a trick I've used for years for troublesome bag seams. 

Once the seam is sewn, trim the seam allowance as instructed in your pattern. If you've positioned the staples close to the outer edge, they'll be removed along with the trimmed-off seam allowance - no sitting there pulling out a hundred tiny staples afterwards! 😂

Important: This works best when you have enough seam allowance to keep the staples safely outside the stitching line. In my original example I used a 1/2" seam allowance.

Notch the seam allowance

Clip small notches into the seam allowance where needed to help the curved edge spread and follow the shape of the piece it's being attached to.

Be careful to only clip within the seam allowance - never clip into or beyond the stitching line.

This is especially helpful on tighter curves where the seam allowance would otherwise fight against the shape you're trying to create.

Keep the smaller curved piece on top

When joining two differently shaped pieces, I generally sew with the smaller curved piece on top, where I can see and control it.

For example, when sewing a side panel into the larger body of a bag, I would normally have the side panel up, facing me.

This makes it much easier to spot any little folds or puckers forming before you accidentally sew over them.

Use a slim presser foot

A bulky presser foot can make curved bag seams unnecessarily difficult, particularly when you're sewing beside thick foam or another stabiliser.

I prefer a slimmer presser foot that lets me sew right up against the edge of the interfacing or stabiliser while still keeping proper presser-foot pressure on the seam.

That gives you much more control than trying to force a wide foot over uneven layers.

I also often use sewing tweezers to help me hold on to my seam allowance while I work, when it's tight as my fingers are usually too bulky.  I even have a set of locking forceps next to my sewing machine for especially cumbersome curves. 

Slow down around tight curves

There's no prize for sewing a curved seam at full speed. 😄

Take it slowly and let the machine feed the fabric rather than pulling or stretching the pieces.

If you need to reposition the fabric around a particularly tight section, stop with the needle down in the fabric, raise the presser foot and gently reposition the layers. Lower the presser foot again before continuing.

Small adjustments as you go are much easier to control than trying to force the entire curve through at once.

Before turning the seam

Once you've sewn the curve, check it from both sides before trimming anything. It's much easier to fix a little fold or pucker now than after you've cut down the seam allowance.

Once you're happy with the seam, trim and notch the seam allowance as instructed in your pattern so the finished curve can turn and lie smoothly.

The most important thing?

Don't fight the curve at the sewing machine.

Match your centres, notch where needed, distribute the fabric evenly and secure everything properly before you sew. If the layers are already sitting where they need to be, your sewing machine has a much easier job.

And when clips aren't enough...

Well, apparently that's why office supplies belong in the sewing room. 😂📎❤️