Zipper Fly Construction- Underlayer Seam always shows

[Bifurcator]

Hello,
I always struggle with the fly construction.  Right now the biggest issue I always seem to have is the seam at the underlayer (Wearer's right side) always seems to show a little.  I've followed Paulin's book, which has you add an extension to the WR Side- 1/2" width at top of waistband tapering down to 1/4" at end of zipper, which has helped, but I still tend to have the seam show a little.

Paulin's:


My Zipper:


I think part of the problem is the front rise is curved at that area, creating a concave shape, so when it is joined to the other side, both sides are concave and struggle to overlap.  See pattern here:



Any suggestions or tricks to get a nice overlap?  Any books or reference materials that talk more about this?  I've only found Paulin's.

Thanks in advance.

[Gerry]

The following is not necessarily conventional, but it's what I do. Hopefully I've got this right - my brain is a little frazzled at the moment.

Lay the topside pattern so that the fork is on the right and the side-seam on the left, i.e. so that a left-hand-side front is cut from the top cloth (and a right-hand-side front cut from the underside).  Mark an additional  3/8" UNDER-LAP for tucking the fly. Simply draw a line parallel with the fly seam, 3/8ths away and graduate it into the top of the crotch curve (don't extend it all the way). This assumes that a seam allowance has been factored into the draft. If not, the 3/8ths is in addition to any seam you mark.

After cutting through both layers of cloth, remove the 3/8ths excess from the LHS, leaving a 3/8ths under-lap on the RHS only. You need to thread-mark the seamline for transferral to the underside, so that you can correctly align the CF seams when making the trousers.

A fly-bearer will also help prevent the zipper from being exposed.

Edit: looking at the diagram you posted, it follows the same principle? Difficult to tell because the text isn't complete. I'll have to check my book when I have a moment.

[Gerry]

OK, I checked Poulin and I've pretty much repeated what he's said, though I use a greater underlap and graduate the line into the curve rather than ending it abruptly. I also don't taper the line as it descends. That might help in your case. It tucks the bottom of the zip in a way that might feel a little unfamiliar, but it does hide it better.

I never read his section on trouser-making, so I'm glad to see that I'm not alone in doing this! 

Be sure to thread-mark the CF line on each piece, including the seam lines of the crotch curve, so that you're aligning things properly and creating the desired underlap.

[Bifurcator]

Thanks Gerry! Much appreciated.  I think we were doing it almost the same way, but instead of an 1/4" at the bottom it sounds like you have 3/8".  I tried adding that extra 1/8" at the bottom and marking the CF like you mentioned and it helped quite a bit with covering the seam.  Now I'm getting some funky drag lines from the curve and the interior needs some work, but here's the new version:



Curious what your pattern looks like compared to mine, specifically does your zipper placement go into the crotch curve?
Also when sewing the J-Stitch, how do you keep the fly shield out of the way so it doesn't get caught in the stitch?

My construction is a little unorthodox, so that may be the cause of some of my issues too.

[Gerry]

I mark the extension on the cloth, it's not part of the pattern. This is what it would look like, however:



The zipper is taken into the top part of the curve. You can see from my diagram that eventually the seams mirror one another for the main part of the sewing. If you get tension in the curve after sewing, then you might need to stretch the RHS seam a little at the curve using the iron, to allow it to sit flatter.

My fly-guard isn't sewn all the way down the seam. It's 'free' at its base so it doesn't get in the way when topstitching the fly-facing. After stitching the J-curve, a bar tack secures the base of the guard to that of the facing.

You're getting creep from the machine by the look of things, plus some lateral displacement. The LH side's front cloth and fly-facing need to be kept totally flat while sewing. Secure by basting and/or pinning to prevent the two pieces from shifting relative to one another. Press them first then baste along the edge and also just outside of the sew line.

In bespoke it's more typical to pick stitch the fly facing by hand. Not only is it more invisible, but you're less likely to create and trap fullness within the J-curve (as is happening in your photo). Even so, the area still needs basting when hand-sewing, to prevent this problem. Stab-stitch thick areas, and pick normally when/if the cloth becomes more manageable.

If you're going to machine, then it helps to tension the pieces too while you're sewing. Hold the waist from behind the foot and the base of the CF from the front (tricky, but do your best). Now gently pull in both directions with equal force. It has to be equal in order to neutralise the forces (we're not trying to pull the cloth through the machine from behind). This technique takes the give out of both pieces, which helps to prevent creep. Unpick the J stitching of your sample and try again. Press the whole area first and at the very least pin everything. Keep unpicking and practising until you get the hang of things. If it doesn't improve, consider hand-stitching.

I took a look at the last pair of trousers I made where I machined the facing. I didn't know a lot of the above at the time, so had similar issues. Not quite as bad as in your photo, but still not great. Oh well, they're still wearable.

As I mentioned earlier, the base of the fly might feel a little unfamiliar, because you need to reach into it a little more than usual. You get used to it though, and I never have a problem with the zipper showing. I also prefer this method to the usual 'Rob Peter to pay Paul' approach of creating an underlap. It's the first time I've seen it detailed in a book. Good old Poulin!

[Hendrick]

Qustion; do you use metal or other zippers?

Cheers, Hendrick

[Greger]

Practice is part of perfection. Two pieces pulled between the hands and let the machine feed it through.
Jane Rhineharts book has some explanations that has useful knowledge. (Download)
Stanley Hostek has a few books with useful knowledge.
It is interesting that some tailors can have some of the same information that tailors from other regions.