Pack inside flat felled seam. ASAP

I assume you are wanting to sew the flat felled seam where the bottom piece joins the back and sides. It is not really possible to do a proper flat felled seam but you can come close. Most manufacturers just sew binding along the seams to provide a second row of stitching. If you want a pseudo flat felled seam then:

1. sew the back/side seams up to a few inches from the bottom. This allows you easy access to the base.
2. With the pack body inside out, sew the bottom into position with 1 row of stitching
3. Sew a second row of stitching through the base and sides to a few mm up the sides from the seam at the base. This is effectively your flat fell seam but without the roll.
4. Finish sewing the sides.

I had been wondering this same thing, since I am 80% of the way finished with my first pack.

Ayy idea how the side seams can be reinforced as well, since they are under a lot of tension? It only seems possible to really "get at" that seam with the sewing machine the upper 8-10 inches or so, without the pack being inside out.

For my latest backpack, I decided to go the route of binding using grosgrain.

I sewed the pieces together, then wrapped the ribbon around the raw edge. This gave the seams a second row of stitches (being sure they weren't right on top of the first set of stitches) and hid the raw edges from unraveling.

I did this using VX07 as the material for the pack, and it seemed to add a decent bit of desired stiffness and strength to the seams, even if it isn't as strong as a flat felled seam.

I'm confused, sewing flat felled seam to close cylinder is no big deal.

If the cylinder diameter gets small, like 12 inches or less maybe, and the length gets long it starts getting difficult. When you start the seam, it's easy, but as you sew along you have to bunch up the other side of the cylinder in front of the sewing machine foot and at some point it get's difficult.

I was trying to describe the cylinder part of the pack, i.e. back + sides & front, I'll sew the bottom as the last piece. It might be totally possible, like Jerry said. I just imagine it will be tough to feed the fabric while not accidentally sewing the other side of the pack or getting a twisted pack as it will bunch up in front of the machine.

I'll just go slow and work it out. Not now though, no more time before I head out. :)

Yeah, you have to be careful not to sew the other side, and it bunches up in front as you sew the seam.

I turn it inside out so the other side is on top and it's a little easier.

If the cylinder diameter is too small or the length too large, it gets more difficult. French seam is easier, but not as strong.

You can try to plan the sequence of joining the parts so that seams will be felled.
But I always find there are some that can't be done that way, at least not handily.
So, french seams with the edges covered by binding is what happens. You can use something heavy, like grosgrain, but I find nylon tape, like the cheap tent companies use on their french seams, is fine. The purpose is to protect the edges, not reinforce the seam, except in so far as the additional line of stitching reinforces.

Made a pack a few years back and fretted about not having it all flat felled seams.
In actual use, never even noticed. Had to go back and look at the inside of the pack to recall what was not flat felled.

Everyone else's mileage may vary but two solutions I see to be able to fell most of the seams on a pack:

1) I am using a single continuous piece of fabric for the front / bottom / back of my pack, so there are less seams to deal with. But I agree with the earlier poster about sewing the side seams up only partially, then stopping and going back to fell the bottom seams before continuing the close up the sides of the pack.

2)The other is something I did this weekend; sewing the backpanel to both of the side panels FIRST before sewing the sides the front panel. This allowed me to easily get to that area to do felled seams. I also did them in such a way that the seam faces toward my back so are essentially unseen from the front which is good cus they aren't perfect. Then I moved on to attaching the side panels to the front panel. At that point it was a cylinder so I won't be able to get at those the same way, so those will just get grosgrain to finish the raw edges and be the only non-felled seams on the pack.

Though I am also thinking it might be better than not, to do a felled seam just the last 6 inches or so of the top of the pack (since its easy get to) for the strength it should add.

It's done.
Suggest all who seek to attempt the following exercise regularly and practice sewing flat felled seams in advance.
Double sided tape. Absolutely wonderful.

Problem:
About the first 30 centimeters alright, then comes trouble. Packfabric starts bunching up in front of/above the machine.

Solutions:
One hand kung fu.

Superman.

The view.

Result:

Just finished the pack. Aah. :D Will probably make a writeup later on.