<snip> The question is, do I install the shroud lines after assembling the chute and sew them to the top of the chute? This would have the white paracord on top of the red seam on one side of each red gore. It would look better if the line was inside the seam and not showing.
<snip>
Any ideas either way?
Jeff, here's a quick summary of how I do my chutes:
My gore patterns represent the *exact* gore on the perfect surface of the canopy - no seam allowance. I mark them with (typically) a ballpoint pen. I then cut the fabric with a generous 1" overcut (or more - probably more for your chute). I then sew the apex and skirt edges - using some 3/8" ribbon weave tape in the skirt seam -- the canopy fabric just simply rolled over the tape and stitched 1/16" (or so) from the bottom edge of the gore (on that marked pattern line) and then cut the excess fabric and roll again into the inner edge of the tape and stitch a second time - which finishes off the skirt edge. Do effectively the same thing at the apex - unless I would rather add the apex reinforcing *after* canopy completion - which I did on the ringsail (I think there's a pix or two posted showing the kevlar tape reinforcing). In that case, you simply just do a folded hem at the apex - 2 to 3 layers of fabric (depending on how close you cut it.) I generally do my first fold and sew a straight stitch right off the fold, cut the excess fabric to twice the width of the hem, roll that cut edge in (butting right up to the first stitch) and then stitch again - about 1/16" from the inner edge of the hem.
Yes, this does thicken up these edges when you join the gores along the radial seams, but I've never really had that much of a problem with that -- as I 'walk' the sewing machine thru those 4 or 5 stitches at each end. Do this for all gores - then pin-baste two adjacent gores together ('right' side to 'right' side) and sew a straight stitch (from the 'wrong' side - which is what is facing out) right on the (marked pattern) seam line. Cut off the excess back to twice the width of the seam width you would want (i.e. thru both of the overcuts of the two gore panels). Open the pair of panels out and roll that into your fell seam (which will be half the width of your cutoff) and sew a second stitch about 1/16" off the inner edge of the seam. This will only be thru one of the two gores - *to the side* of the main (first) stitch - be consistent and do it either to the left or right on each radial seam. (This is just like the hem stitch noted above - but with two layers of fabric this time.) Technically, this is not the 'French fell seam' as you diagrammed, but you have 4 layers of fabric forming that 'tunnel' - and (because you got the apex and skirt hems already done) there's no real restriction for running your suspension lines INSIDE these 'tunnels' - thus hiding them from view either from the inside or the outside of the canopy.
Rolling those seams and sewing with the skirt reinforcing in place is a little tough to sew thru (you've got two layers of the skirt tape + 4 layers of your canopy fabric), but, again, it's not as bad as you may think (best is to make up a little 'trial run' mockup of the seam construction and discover for yourself). One benefit of this is that you are getting a little extra reinforcement there at the skirt *precisely where* you need it (i.e. two layers of skirt band) -- where the suspension line enters the canopy. The alternative is to wait and put your skirt band in after the canopy is complete - and, in that case, you are only having to sew thru 4 layers of canopy fabric as you join the two gore panels -- and 4 layers of F-111 is trivial for even the most minimal of sewing machines.
Join 2 - 2 panel pieces into a 4 panel 'quad' - join those into an 'octet', etc until you get the entire canopy completed. Tie off and finish all the loose threads and then you are ready to run the lines. I would measure the lines under some kind of weight (especially if you are using the 550 cord - as it stretches pretty significantly) - and I would let this be several pounds (the logic here is that you stand a better chance of getting all your lines nearer to the exact same length if marked and cut 'tensioned'. Mark them at the exact apex, the edge of the apex vent, the skirt and the confluence point tie-off (with a good foot of extra at the bottom) - something like a Sharpie is fine. Run the lines thru your seams - align your marks and 'tack' them to the canopy with, oh, a 6" zig-zag stitch at both the skirt edge and the apex vent edge - but leave the rest of the line untacked between those two points. This allows any localized stresses in either the canopy or the line to relieve itself without stressing the other component. It's not going to be necessary to anchor the line all the way from skirt to apex - as the canopy proper will easily transfer those drag forces to the suspension lines. (Remember, with the suspension lines cut under tension, this will most likely 'gather' your canopy fabric, since the dimension from skirt to apex is only 'right' under load (for the lines) - yet the canopy itself is 'right' in a relaxed state - but there's your stress relief for the canopy proper).
Once the lines are in place and tacked down, you can then sew in your skirt band (if you elected to hold off till now) and the apex vent band in place - generally on the interior of the canopy (think about the suspension line tryin to 'tear itself thru' the skirt and you can see that having the skirt band on the interior gives resistance (and reinforcement) to that possibility).
I'll try to rush up the continuation of the ringsail thread where I can illustrate with some pix - but a 'camera issue' has played some role in the delay.
[edit: 1-20-15 - 2:00pm]:
I've found a little diagram that helps quite a bit on the fell seam discussion from above:
This is pretty much how I do it - except at 'A', I trim both my pieces of fabric to the same width (after the first stitch) - equal to the width of the lower piece here (or twice the width of the finished seam). Notice that the upper piece of fabric here is the width of your finished seam +- and the lower piece is twice the width. The stitch is exactly 'on' your pattern line.
At 'B', you fold the lower, wider piece over the upper piece. Some instructions will have you iron this down (which is surely workable), but I've found that, with the lightweight ripstop material, it's really not necessary.
At 'C' is where you 'unfold' the fabric, taking the lower layer of fabric over to the right of the seam (the 'wrong' side is now facing up on both pieces of fabric). If you can visualize that your seam would now 'stand up' when you lay out your fabric as shown, then just lay that seam down to the left to get image 'C' to look like it does here.
Your final (second) stitch at 'D' is on the left of the seam and is the only stitch that goes through 4 layers of fabric.
Some of the diagrams on the French fell seam would have you interfold both pieces of fabric before running the stitch (those that show both stitches going through 4 layers of fabric) - like this:
... which is virtually impossible to sew with accuracy. Pin-basting your two panels together (aligning your pattern lines) and making that first stitch through just 2 layers of fabric (like in 'A' in the first diagram) is, truly, about the only rational way of doing this seam.
In your case, I would design for a 1/2" (or 1 1/2 cm) finished seam, min. (make it 2cm - as that will give you enough width for the 550 cord) - but sew up a little trial mockup and verify your seam widths. This would make the lower layer 'selvage' 4cm -- but *don't* try to cut your fabric initially with that width selvage. Ravelling will make things a mess before you get to finish the seam --- cut your fabric W I D E - allowing generous margins and then trim to your final widths right before sewing each individual seam.
That should explain things a little clearer.
-- john.
edits: 1:07am EST: semantic clarifications
2:00pm EST: fell seam diagrams/discussion