Cuff Purgatory

[clownsyndrome]

Good eve,

I would be proudly declaring I had finished my toile for my knickerbockers today, but they have foiled me again! I drafted up the whole thing myself so it's entirely my doing whatever has gone wrong, but after cutting and sewing the same cuff and trying to troubleshoot the problem three times; I just cannot figure out what I've done incorrectly.

The inner facing of my cuff fits as it should, but as I proceed on my most recent attempt to secure both layers there is a 2cm gap left over on the outer facing. As I mentioned, I've recut and sewn the same cuff three times now, and each time the two facings end up not matching neatly. The outer facing that should just topstitch into place warps the whole cuff. Both sides of the facing have been cut to the same size and I really just need a extra set of eyes to look over what I'm doing. I'm so boggled by this and understandably a bit frustrated as I just want to move onto the actual garment. I'm wondering if maybe the overlapping SS split (which is flat felled) has anything to do with it?

Thankyou kindly for taking a gander at this!

The first picture is of someone else's work but is ideally what I'm looking to achieve. The remainder photos are what I'm working with. Very awkward trying to communicate such construction troubles via photography so please let me know if you need better pictures and whatnot.

[DrLang]

I might suggest looking at how David Coffin attaches shirt cuffs in his Shirtmaking book. To make a gross simplification of what I am doing, I attach the outer first, then work on getting the inner attached with perfect alignment through a short series of elaborate steps described by Coffin

It's actually not that complicated, but I would have a hard time explaining without Coffin's detailed description and figures. The inner facing should be cut a little bit shorter than the outer. If that is not what you did, then somehow your outter facing is getting stretched. Possibly by the presser foot?

[TTailor]

Here are some tips
Stabilize your fabric with some structure, either fusible or sewn in interfacing. You may need to stabilize both inner and outer.
I cannot tell how thick your fabric is, but if it is quite thin, 2 cm extra needed seems a lot.
You might benefit from some matching notches so when you close that cuff, you don't accidentally shift the fabric laterally as you close the cuff.
That being said, if you force some pieces  to match while flat, once it is in position, closed in a fairly small circle it can pull. The thicker the fabric the worse it gets.
You want the inner cuff to sit nice and flat against the leg.

So my advice would be to cut the inner piece as is, and make a new pattern piece for the outer layer.
Take a copy of the inner pattern and slash and spread the total 2cm evenly over four or five slashes. This will give you a pattern piece that matches the inner piece along both short edges and the lower long edge, and will accommodate what you need on the outside at the join to the leg.
This will work better than accommodating the 2cm needed all at one end.