sewing two materials w/ differing stretch characteristics

same here

after playing with it several times:

go from top to bottom the same direction on both sides so it will stretch the same

I did mesh on top. Really push the mesh down against the non-stretchy fabric to keep it from slipping. And have a finger half on the mesh, half on the non stretchy fabric as it feeds under the pressure foot. You can prevent most slippage.

Try it several times and you'll get the hang of it.

A "walking foot" machine would probably be better. I think these are expensive. I've only seen video of them. Cool : )

I dislike using pins and try to avoid them whenever possible . . but this is a case where they can come in handy. You could try pinning every 2-3 inches.

Another thing to do is to pay attention to which way the material stretches. Usually one direction is stretchier than the other. Align the stretchier direction with the shorter side of your piece (like, across rather than along the shoulder strap) and you'll have fewer issues.

This is one case where thinking a bit about the design of the seam will pay dividends.

If you pin the mesh to the silnylon from the sil side, then you can fold the silnylon over once and pin it down, with the mesh on the inside of the fold. This means your machine is now sewing with sil top and bottom (and the mesh is 'inside').

You can of course then sew the seam out flat with some care. Adhesive tape on top of the mesh works, but can be slightly slow to remove.

Cheers

I use bias tape, 5mm wide, double sided sticky, crafting tape also works, use it to hold a bond the seam and sew through it, i use 3 layers in a flat felled seam, joins anything even polycro to mesh. End up with a strong no stretch seam easy to sew and no pins.

I have had some success using a lightweight tissue paper over the top fabric.

Rogers' suggestion seams to be more simple. ;)

Have you tried loosening the presser foot pressure on your lsz-1?

Mark your two fabrics along the length using either little cut notches or a marker at intervals and then make sure those marks line up as you sew.

back zillions of years ago, I remember thats what my mom did – patterns have these little triangle notches – actualy they stick out rather than in. You line up the inversere notches on the two pieces.

This is sewing 101 for real sewers.

I haven't wrestled with this issue for a long time, but have a suggestion. Try stabilizing the stretchy material by machine basting it to some sort of tear-able paper (tissue, wax, packing). Then sew your materials together before ripping away the paper. Tape could work but you will be "stuck" with residue. For clothing, one could iron on an interfacing before stitching , but that probably is the wrong approach for this instance. I think there is some sewing notion that stabilizes and can wash out, but who wants to wash shoulder straps and try to get them to dry?

Thanks for all the suggestions, obviously this is something that most of us have struggled with. I've done pinning but also find it time consuming and annoying, i've adjusted the presser foot pressure on both the juki and sailrite, but i haven't tried some sort of tissue or tape or the sewing in the same direction technique. I wonder how this issue is dealt with in industrial settings. I'm not sure if anyone has industrial experience here but there surely has to be some way this is dealt with that doesn't involve pinning thousands of pins for a run of backpacks.

Thanks,
Michael

I would imagine that if I were making shoulder straps in an industrial setting I would either cut my 3d mesh pieces to just the right length so that they stretch to the correct length, or I would sew with the 3d mesh on top and gently bunch it up as I went to correct for the stretch.

I already use the latter method sometimes and it works ok in the right situations. I think either method would be easy to perfect if you were doing it all day. Doing it once or twice is another matter…

Here's a method I've used, similar to what Nick mentioned. Rather than preventing the mesh from stretching, let it lengthen intentionally. When the mesh stretches and upper material does not, the straps have a slight natural curve around the shoulders. It looks acceptable on the finished product, and it may even prevent the mesh from otherwise becoming bunched up when in use on the finished pack.

I cut both strap pieces to the same dimension, but start stitching from the top down and offset the mesh up about 1/2 inch. By the time you get to the bottom of the shoulder strap, the two pieces are aligned pretty well.

Hey there, ok, non stretchy stuff Laid flat on a table, tape it down with masking tape round the edges so it doesn't shift around – esp if it's slippy fabric. Lay stretchy stuff on top and ensure it's flat not stretched (unless you want it to be) tape it down at one end and tack it using large stitches a few cMs from where your stitch line on your machine is going to be.

Then take the tape off and you will have the two pieces loosely joined but joined. Now sew with machine, and yes a walking foot will help. It also helps for there to be good support under the fabric 'tail' if it's all hanging over the edge of the table it's going to stretch and there's going to be cursing.

If you're talking fiddly pieces hold them together in one hand as you tack with the other – I use double thread In a completely contrasting colour knotted at the end long enough to tack a decent length or it'll be fiddle some but not so long the thread will self knot.

I have also used small clothes pegs! Two pieces of fabric pinned together with pegs at the ends then at intervals all the way along, then I have sewn inside the line of the pegs. These are mini Christmas card pegs – you can get them in stationers and card shops, or. If it's big fabric I guess ordinary pegs would do…

after keeping this issue in the back of my mind for a few months it occurred to me that if i lower to presser foot tension as much as possible this might allow both materials to move together and make it so the 3d mesh (or other stretchy material) doesn't stretch more than the top material. I tried this out last night and found that it worked just as i had imagined. I lowered the tension on my Juki DDL-8700 until the presser spring bolt came out then screwed it in just a couple of more times. Just for references i was using 3d Mesh and 200d uncoated oxford. Hope this helps someone.

michael