Sewing help: skipping stitches

This is an issue with a lot of possible causes. Two pretty common mechanical causes and possible fixes:

1: the needle might bend a little due to a slight timing error in the machine or the layers of fabric stacks too high for the machine. Even the needle bar can be briefly (during a stitch) bent or offset by too much to pierce through or timing errors each.
Try with a thicker needle that bends less. If that solves it, either the height of the stacked fabrics are too high for the machine to handle or there is a slight error in feed timing.
Another workaround is a straight stitch needle plate and straight stitch foot or some other single hole extra for your machine. This keeps more of the fabric in place, and will prevent the needle moving away from the hook.

2: the thread is too thick for your machine’s tension setting mechanism, or other thread feeding parts.
A thinner and/or more slippery thread sometimes does the trick. Try a random thread to find if it works better. If this works out, you have to use another thread for your pack. Almost any machine I’ve set up works great with Gutermann Tera 80, tex 35 – it’s a continuous filament polyester thread which is super smooth and will feed easily in most tension mechanisms.

I have no clue about if coating is related to this, but more slippery fabrics due to coating and a needle being forced to move a few micrometers by the weaved fabric surely is a factor if the needles are blunt. A sharp point or microtex 100/16 needle should do 4 layers of 70D without bending out of shape, given all other correctly timed and set up.

yeah, new needle?

but putting a new needle in has it’s own risks, easy to put in the wrong needle or install it backwards.

or let the fabric feed through the machine without you pushing or pulling the fabric

I would generally agree with Lasse and will speculate a bit..

Sounds to me that the small loop that should form as the needle starts up is not forming so the hook can’t catch it.  Why no loop?  Mechanical timing could be off – possible but not likely if machine generally sews ok.  The loop formation also depends on friction from the fabric holding the thread in the groove of the needle as it comes up. Possibly the coating on the fabric acts like a lubricant?   That’s where the needle size (and the groove width) and the thread diameter come into play.

I would go with a microtex (sharp) or the jeans (denim) needle which is also sharp and also stiffer.  And as noted above you might want to try a smaller TEX  35 to 50 (thinner) thread.  I have two different Gutermann upholstery threads on hand… tex 75 and tex 70 both polyester.  My two home machines can use them (with tension adjustments) but not reliably.

You might also try to increase the presser foot tension tighter just in case it is not holding the fabric down on the upstroke.

Needle or tension. Try a shorter stitch. Had the machine long? I’ve got one machine that hates the hd thread. Stick with it.

There MIGHT be a mis-alignment between the needle and the hook, but if it normally sews OK that is not all that likely.

A thinner thread might partly solve the problem – but is not a desired solution with a pack. It would be masking the problem anyhow.

My best guess would be inadequate pressure on the foot. With the drag from 4 layers of fabric as the needle is lifted the foot is being pulled upwards, and this is upsetting the loop formation. Yes, the coating will contribute to the drag, but that means fixing the machine settings. Increase the foot pressure and try again. There should be some instructions in the book on how to do this.

Cheers

Thanks for the suggestions, everyone.

I tried 2 different needle sizes, and 3 different of the larger size just to see.  I pulled the bobbin holder and visually confirmed the timing of the hook vs needle.  Again, it works fine on less fabric, so not likely off.  I can spin the wheel by hand and still get mixed results – fabric isn’t moving vertically, so I can’t imagine foot pressure is a factor.

This is attaching the waist belt, so I’d really prefer to stick w/ the heavier thread.

My solution is to work around the problem (love it when I can solve things by not solving them) and use a different fabric for the belt.  Certainly doesn’t need to be water proof, and it’ll be lighter with out the coating.

Cheers!

Interesting. If you are sure the foot pressure is holding the fabric down, then try an even bigger needle. They are available.  If the thread you are using is too big for the groove in the needle and/or the eye and the needle gets at all sticky from the coating, then the needle could drag the thread back up.

Alternately, and especially if the needle shows any sign at all of being sticky (magnifying glass), try lubricating the thread a whisker. Yes indeed, commercial high-speed machines do have lubricators on the thread. Machine oil, olive oil, whatever. Just a very small amount.

Cheers

I find that when I am having problems with stitching that is not related to tension, rethreading the needle through all of the guides solves the problem.  Usually.

You can try a walking foot/even-feed presser foot.

Or, what I’d try first is to just hand baste near the raw edge to keep the fabric from sliding around.  It doesn’t have to look pretty and if it does then you are spending to much time on it; you can baste the entire hip belt with a hand-sewn stitch in five minutes or less.

Follow up: pack is done!

30L+, carbon frame, plenty stable with 25 lbs, tips the scale at 8.4oz.

I wanted to see just how light I can get a frame pack.  It’s mostly 30D, so it may have a short life span – no trips planned at the moment.  If I like it, it may be re-incarnated in cuben.

The frame is a tent pole down each side of the back panel (inspired by KS Ultralight Gear) – weighs about an ounce.  That’s a full wrap waist belt – didn’t want to rely on stitches in thin fabric any more than necessary.  There’s a bit of CCF at the tips of the belt to keep them from collapsing under tension.  I passed on side release buckles in favor of hooks because they’re more durable (and a hair lighter).  Most of the black webbing is grosgrain ribbon.  Closure is half inch velcro.  No pockets; only non-essential feature is a hydro port and loops to hang a bladder.

It’s a little sloppy, but for an experiment in ultralight minimalism, I’m pretty happy with it.

Can I make one wee suggestion? Add a tiny top flap to go over the roll-top.
Yes, in theory a roll top shoulld be waterproof. Yeah, well …

OK, trip photos!

Cheers

Nice looking pack

How did you fix the skipping stitches?

@Rene

Your work deserves a thread other than this one asking for sewing help. You made something worth checking out and many people will miss it here.

Looks great! At 8.4oz the weight is great! Nice job.

Shoulder harness: Too long. It only needs to cover the upper parts of your shoulder, not down under your armpits. A bit narrow, too. I like a wider strap with minimal padding (1/8″)
Frame: With the pads tied in, I don’t think you gain anything with a frame, too.

Overall: reducing to a more cubic shape will increase internal volume over the eliptical shape. Wider and shorter would save close to an ounce in fabric weight for the same volume.

I would drop the belt adjusters and cut down the top a bit, using the adjusters to pull a flap down over the top. The roll top makes a heavy bunch of fabric for water resistance. I see Roger already recommended this.

Katharina – thanks :)  Maybe I’ll post once I’ve had it on a trail.  Or if this thread keeps going.

Jerry – I didn’t solve it, I worked around it and used uncoated fabric for the hip belt.

Roger – My heavy pack is an Exped Lightning which has a roll top.  I live in California and have only seen a few light showers in the past decade, and the roll top has worked fine for me so far.  If it ever breaks, I’ll try some fixing :)

James – that said, I’ve thought plenty about other ways to close a pack.  Compared to a skirt, draw cord and top lid/flap, a roll top is still a competitive use of material.

Can you post a pic of your shoulder straps?  This is the first area I intend to iterate on.  I didn’t sew the skins shut, so it’s easy to replace the padding, and I put a ladder lock at the top to fine tune the position so they’re completely removable.  I thought of 1/8″ but am concerned they may bunch up sideways in some areas.

I get what you’re saying about pack proportions.  Deeper brings the pack’s center of gravity further from your spine, and I want load lifters, which dictates the height – I have a long torso.

Let’s explore this one.  The closed dimensions are 12 x 6 x 26 = 1872 cu.in. with a surface area of 1080 sq.in.  If I change the cross section to 10 x 8, the height would be 23.4 for the same volume giving an area of 1002.4 sq.in., saving 77.6 sq.in., or .06 sq.yd.  Pending fabric, that’s .1oz to .3oz.  And out of curiosity, a 26″ tall cylinder of the same volume saves twice as much area, .12 sq. yd.  Not much of a win at the lower denier end of the spectrum, but the figures are good to be familiar with.

I’ll see how it handles a real load w/o the frame rods.  I was just going for weight in my testing – it was all pillows and water bottles.

Rene, I believe you will find that many or most packs will approximate an ellipse once fully loaded.

One of the reasons a simple multiplication never seems to jive with published specifications. Internal volume will expand to the constraints of the fabric and frame. I accept that a frame is relatively flat. So a half ellipse will approximate the volume.

So, for your pack:
12x6x26 is approximatly 2200ci
(The 12 x 6 x 26 will push out to a half-ellipse at 12x9x26. 9 is half way between the maximum of 12 and the starting point of 6, roughly the pressure of expansion of pack assuming constant density. I understand it varies a bit.)

Follow?

I have just a roll top, and get lots of rain to test it.  I do get a little leakage, but I don’t think it’s coming through the roll top, I think it’s the fabric.  Still, good to get lots of ideas

Good that you’re able to make do with stitches.  For the heaviest places like shoulder straps, I sometimes have problems but just make do.  It seems if I try to push or pull it through it makes it worse, better to just let it feed by itself.

James,

Yes, I’m familiar w/ the way the cross section of a pack deforms depending on how you fill it.  I was using the box dimensions as a reference for comparison.

I’d still love to see any pics of your pack you might be able to share – both shoulder straps and top closure.

Rene, I thought I mentioned I use one or the other GG Murmurs, sorry. I posted my use on a LOT of other threads and assumed you knew.

3″ wide base shoulder harness (allows a LOT of strength/stitching at the top,)
1/8″ padding in the shoulder harness,
with 5 layer pad in the pad keepers a relatively shorter shoulder strap,
external pad, like yours, also acts as a frame and saves about 350 or more ci of volume,
over the top closure (great for easy on/off of a sweater or rain jacket,)
Xpack or dyneema, I forget what they called it, fairly rugged,
About 10oz, without the pad and stripped of extraneous plastic.

I also have a Robic one(10oz) that has more features, but smaller and just as light. I don’t bother with the heavier packs. I never needed more than one of the the Murmurs(2012-~2200ci,2015-~2000ci) or 2006 Miniposa(15oz-3200ci) for trips up to three weeks (around 27pounds) unsupported. They work well enough not to cause pain though no pack ever is exactly as comfortable to wear like a T shirt. I am looking/contemplating a 5oz pack at 35L, hence my interest here about reducing weight where possible and keeping the double duty aspect of the pad keeper, side pouches for drinks, front pouch for wet gear.

I finally got this pack out for a proper test this past September.  For various reasons, I opted for something beefier or less experimental on other trips since making it.

My girlfriend and I did a night on the PCT just south of Lake Arrowhead.  We were delighted to find a stretch that wasn’t scorching hot (mostly mid 80’s), had water in the middle of our section, and wasn’t actually, literally on fire.  Turned out we only got 2 out of three: no water.  The creek was dry, and our plans to drop a cache got swallowed by traffic on the drive out eating away the day.

We used a 12oz, WPB double bivy I made as an emergency shelter for another adventure, got our first taste of no-stove cold cooking, and were set for our lightest base weights yet!  Then we realized we had to carry 17 pounds of water.

Turns out, this thing handles 30+ pounds just fine.  The fit wasn’t quite dead on for my body, but pretty good for a first pack.  The waist belt is a touch long, and the shoulder straps didn’t sit quite right on me (they attach w/ a buckle at both ends, so I can iterate).  Using cord instead of thin webbing was mildly inconvenient in most places – no real surprise there.  The minimal padding in the waist belt worked out just fine – I only padded the ends that sit over the front of the pelvic crests.  The hydration port was frustratingly small.  The frame (2 carbon rods) worked well.  I wouldn’t have minded a pocket and possibly some bungee on the outside for a jacket.

The only real issue was that the foam pad kept shuffling up my back.  Has anyone else had this issue?  I think the fix will be a flap that covers the bottom end of it, so the down force of the pack against my lower back is transferred to the bottom of the pack, rather than the pad (which sticks to me better than the pack) which caused it to slide up.

The next iteration will be updated per the above, and use a more durable fabric.  Possibly some of the lighter X-pac.  I’m hoping to keep it close to the 8oz mark.

The only real issue was that the foam pad kept shuffling up my back. Has anyone else had this issue?

This happens to me as well with some pads and with packs that use elastic chord to hold the pad to the back panel. However, the problem does not happen if you have a backpack that uses large “flaps” or pockets to hold the pad to the back panel, such as the GG Gorilla. You can also keep the pad in place by using a stiffer pad. A two-section piece of a TAR Z Lite page (10×20″) is stiff enough to stay put, even when using elastic chords to hold the pad onto the backpack.

Rene,

Thanks for the KS Ultralight website.  Full of good info……and your link was in English.  English doesn’t seem to be one of the language options from the main website.

My frame pack goals are similar to yours and the KS ones.  You did a great job with the pack you made and the weight is impressively low…..lower than KS.   Can’t believe you are showing us such a functional first draft!

I’m currently using a MYOG frame pack that is comparable to the 50 liter KS pack.  My and the KS pack weigh about the same.

With the KS info, your recent success, the James Marco info and my own experience I’d say it is reasonable to expect a fully functional MYOG frame pack to run between 1/2 and 1 lb.  Weight would vary, depending on features included, but every important feature should be includable within this range.  I can’t even think of a feature that I would want that I couldn’t include in a 1 lb frame pack.

For what its worth :

(1) I prefer 1/2″ nylon webbing over cord.  I run it through 5/8″ ladder-lock or side release ladder-lock buckles.  It adjust easily, holds tightly, and the buckles are the smallest that are easy to use when my hands are cold.

(2) I’ve had good luck keeping a foam pad in place by putting it inside the pack bag.  A glue-on piece of Velcro at the pad top matching up with sewn-on Velcro at the bag top keeps it in place.

(3) I prefer a cord-lock closure at the top of the bag.  I find it handier than a fold-top.  I’m not concerned about keeping water out, however, because I use uncoated nylon for the pack bag.  The uncoated bag can be easily removed and run through the washer/dryer.

(4) I prefer one size of large pack for day use and overnight.  A large pack with only a few items tends to sway but a simple cinch strap can solve that problem.  I use my backpack every day.  I carry stuff to the gym.  On the way home I usually pick up groceries.  A case of beer or 20 lbs of cat litter are no problem.  The largest bear cannister will fit in sideways.  The largest pack bag weighs less than an ounce more than a smaller one.  KS says the KS50 is the most versatile: highly compressible for about the same weight and price.

(5) I don’t like to sew and problems like skipped stiches frustrate me.  Packs are easier than tents, however.  Tents have miles of stitches. Bobbins run out of thread too quickly.  I gain weight temporarily every time I work on a project.  Too much sedentary time.

(6) People sometimes ask me to make them a pack or show them how to do so.   Very time consuming.  I now have an option: if you want one similar to mine buy one from KS.

Thanks for posting.