I am partway through my second backpack project and I have a few questions and I am looking for sage advice from the sewing masters out there.

First, I am having a bit of trouble sewing though the shoulder straps on my pack. I made tubes out of pieces of nylon and then stuffed them with 1/4" CCF, but when I went to put a few bar tacks through the foam to keep the shoulder straps from spinning around the padding my machine gets all gummed up on the bobbin side of the shoulder strap. I tried a new needle to no avail. Is there a special needle or a change in tension, or some other trick to sew through the foam? I picked 1/4" specifically so it would be less thick and I am trying to design with the least sewing through the thick fabric.

How spread out should pack stays be? I'm going to attach a hip belt to the center 6" of the pack body, but I'm worried if I put the pack stays that close together that they will be uncomfortable against my back. If I put them further apart, will they fail to transfer the weight to a hip belt that is only attached to the pack at the center of the pack body? Should I use a wing style hip belt instead of a more belt style?

Thanks for your help

> I am having a bit of trouble sewing though the shoulder straps on my pack.
Some light sewing machines just cannot handle that thickness combined with the thread drag from the foam.

Cheers

Sounds a bit obvious, but sometimes when I have been sewing thick materials I have occasionally forgotten to drop the presser foot. It's easily done when the foot is held up by foam anyway. Not dropping it will still affect the way they machine sews.
Matt

Rotate the machine manually?

Sometimes that helps

Sometimes there's a "bird's nest" of thread on the bottom

If all you want to do is keep the foam from rotating in a sleeve, a few hand stitches may help

Just a thought of something to try, as I'm a novice myself. There are needles meant to be burlier (size 16, size 18, ones meant for denim). This should only be a problem if the needle breaks or maybe has trouble piercing the fabric, not with thread bunching. It sounds to me however that yeah, maybe your presser foot is down if it's stopping up and having thread bunching issues on the bobbin side.

Also I'm not sure how long you've had your sewing machine. I recently bought one from Walmart (brother brand) that had no bobbin tension, at all, it'd just slide around. I could tighten the bobbin tension but only by taking apart the dang machine. In the end I messed it up worse trying, then just exchanged the machine. It stopped doing the bunching on bottom (bobbin side for me) thing.

Again though, my bet is that you didn't drop the presser foot.

If your machine has a adjustable tension for the presser foot. Set it as tight as possible then sew a straight a 4 or 5 mm straight stitch through the webbing/ foam/shoulder pad with out locking the stitch. It will compress the foam down. Then set your machine on the number 1 part of your 4 step button hole and the set the stitching really close together for the zigzag bar tacking of the webbing on to foam. I also use a heavy duty needle Schmetz jeans/denim 10/16 needle for sewing backpacks and heavy duty T 69 polyester bonded thread.

If it does not work and the machine binds look at the model number tag and the amperage of the motor if it .6 or .60 amp or below the motor is not power full enough to sew through foam.Also If the machines is a recently manufactured machine the clutch and gearing can not take the stress of sewing through the foam.

I have found you really don't need to sew through the foam as long as your bar tack is good on the top fabric of the shoulder pad and the foam fits in really snug the foam will not roll. The other option is to purchase
pre made shoulder pad from Zimmerbuilt packs or the cloud 9 shoulder pads from Jandd Mountaineering . Chris shoulder pads are sewn on the Jandd pads are removable held on to the pack with 1" plastic loops.
Terry

Edited by socal-nomad on 04/26/2012 09:56:36 MDT.

Good suggestions so far. IE hand rotate the wheel, heavier needle, hand sew,

Also try a little oil on the thread. Don't use the reverse, rotate the fabric instead.

or

Find another sewist with a heavier machine for that part.

+1 on setting presser foot tension to max. +1 on moving to straight stitch rather than bar tack, if item 1 doesn't fix the problem.

I just finished a pack and had a similar issue at first. My main pack material required a lower bottom thread tension in general. The different material and padding in the straps required a higher bottom tension.

My pack has straight, carbon fiber, external stays. I moved them as far to the sides as possible and used a standard padded belt. I included an external pad sleave to protect my back from the stays. When finished, I found this unnecessary since my kit rounds the back panel of the pack enough to keep the stays off my body. This was a pleasant discovery and allows me to put the pad inside the pack, which I prefer.

The stay attachments are 1-2 inches outside the belt attachment and the load transfer is excellent.

I had similar issues on my last project, and that was sewing only thin layers of nylon, on what is usually a very reliable machine. Just checked the manual and (embarrassed to admit it) it looks like I had the bobbin in backwards, (ie, it was unwinding in the opposite direction, which affects tension).

I am a TOTAL newb at sewing (trying to learn, tho) and I found that a problem I was having was threading the machine with the presser foot down. I have a Singer and I finally read the manual about how to thread and step one was "Raise Presser Foot". Threading with presser foot down does not tension the thread properly and you'll get the bird's nest on the bottom (bobbin side).

Since I have been threading properly, no issues...

HTH

Edited by shhQuiet on 04/26/2012 18:20:48 MDT.

Thank you all for the advice. I just finished my backpack and I am quite pleased, though not every stitch looks professional at this stage in my sewing career. I ended up putting the carbon pack stays (also my tent pole sections) 8 inches apart and the weight transfer seems to be good while loaded up with some water bottles and a half a dozen sweaters from my closet.

Sewing the foam was impossible until I tried sewing with the presser foot up, which seemed to work really well for straight stitching (still can't sew foam with zigzag on my machine.

Thank again for the help, I think I might be catching the sewing bug. Travis

Steve Horne mentions the reason you shouldn't sew with the presser foot up. On the vast majority of machines, lifting the presser foot disengages the top thread tension. (Among other reasons, it makes it easier to remove the work, if you don't have to fight the tension to do so.) With out the tension on the needle threads, it's likely that the two sets of threads aren't properly locked together. If they're not, they may fail.

Some machines, like my Necchi have a two stage lift on the presser foot. Position one allows free motion sewing. Position two, all the way up, disengages the top tension.

Know your machine.