I thought I would show my steps on how I sew a zippered fly. This is for Girl's pants; For boys you simply flip it the opposite way.
1. Constructing the fly shield. It should look like this:
Fold it in half, right sides together. Sew only bottom edge. Trim seam and flip so right sides are out. Press.
Serge unfinished side.
Apply WonderTape to the right edge
Remove WonderTape backing and place Zipper on that edge (You may need to shorten zipper first as I have below).
Using zipper foot, sew close to zipper teeth dow the right side. Keep Zipper pull in teh middle and stop when you reach it. Keep needle in fabric, lift presser foot and pull zipper past foot to the top. Then put presser foot back down and continue sewing down the right side to the bottom.
Serge raw edges of both sides of pants.
2. Fold seam allowance on narrow edge of zipper placket to wrong side (shown on right, below). Place WonderTape on fly shield over the zipper tape on the right side where you just sewed one side of the zipper in above steps.
Put fly shield under folded over zipper placket as seen below. Align, remove WonderTape backing and stick them together as shown below. Sew on the right side zipper placket from the top down to the bottom of the zipper.
Here is where I sew crotch seam from back waistline to bottom of zipper placket. I double stitch the seams on the crotch to reinforce.
3. Now we will WonderTape the left side of the zipper tape on the placket and attach it to the other zipper placket. We have already serged the raw end of this larger placket and folded it under. Align it so the crotch lays smooth and use the WonderTape to stick the loose side zipper tape to the other placket.
Below I have WonderTape on left side of zipper tape and the curved placket is at the way bottom waiting to be laid on top
Unzip zipper so that the loose tape is stuck to the large placket as seen below.
Now fold open the placket and sew on the loose zipper tape.
4. Top stitching. I always look to the inside (wrong side) of the zipper shield and plackets and stick a pin in the bottom of the shield.
Then I go to the right side and pin my placket down so it stays smooth. I make a mark where the underneath pin pokes through. This is where you want to catch the fly shield in your stitching on the top. You only want to catch the bottom of the fly shield in your stitching.
Now I mark out my top-stitching with a quilter's pencil. Make sure you know where the fly shield will be brought in to the bottom.
Unzip zipper (See my sloppy lines on the bottom slope? I had to reconfigure to make sure I caught all of the placket bottoms into my top-stitching so there would be no holes in the crotch. The top two straighter lines wouldn't cover it so I slopped them down more).
Pin fly shield out of the way for now. You don't want to stitch it yet.
Top-stitch the lines you drew. Stop at the bottom where you had the pin come through and are now sewing the fly shield to the bottom. Unpin the fly shield and lay it nicely into place. Sew over the bottom of the fly shield when you continue your top-stitching. (See second pic for more detail)
This is a view at the wrong side. See the green arrows? This is where I caught just the bottom of the fly shield in my top-stitching.
You now bar-tack the two lines at the bottom. (I was experimenting with this here, they should not be curved but straight My bar-tack stitch I haven't quite got right yet. Next time I will use a short zig-zag stitch back and forth on the two spots).
Here is a view of the completed Zipper Fly!
~ Happy Sewing! ~ Kristin ~