Wizcrafts

You need to list your location if you want a local sewer or artisan to help you. Add it to your profile. Welcome to the forum.

There are a couple things that can cause this. One is loosely bonded thread. Another if overly taut thread and another is retarded timing. The fixes are listed below. If the top thread is loosely bonded it will tend to unravel at the slightest provocation. Further, single needle lockstitch machines are meant to use reverse (Z) twist thread. If perchance your thread has a right twist, it will loosen and unravel as you sew. Try using a different or newer spool of thread on top! If the top thread is held taut all the way down as the needle bar approaches BDC, the loop will be small and tight. This can be corrected via the check spring travel limiter bracket that stops the downward motion of the spring. Set this for the best results by loosening the bracket set screw and handwheeling until the needle moves down to the top of the feed dog. Stop there and adjust the bracket so it stops the spring from going any lower. You might also change the position of the small screw in the curved slot on the check spring disks. The top thread needs some slack thread to function properly. This is controlled by the aforementioned position of the check disks. Moving the disks clockwise reduces the amount of slack. Moving counterclockwise adds more slack thread. I find that if the top thread is snapping as it goes around the hook and bobbin case, adding more slack quiets it down and makes for more controllable sewing. The hook to needle timing affects how the top thread loop is picked off the needle and wrapped around the bobbin case. Sometimes, retarded timing lets bad things happen as the thread goes around the case. It also causes the top thread to snap as it goes around (when it doesn't jam) Try advancing the hook slightly and see if that solves your problem.A combination of tweaking the hook timing and check spring may correct the shredding problem if everything else has been ruled out.

Some servo motors are affected by the side angle of the chain that connects to the "go" pedal. My CB4500 had that problem so I placed a large C clamp on the pedestal post to feed the chain more inline with the motor's control arm. I also moved the chain mounting bracket as far to the right as it would go on the pedal. That solved the problem of slowing down unexpectedly when I want it to speed up.

Read this post for suggestions to reduce an image's filesize.

If a #22 needle gets stuck in the hole in the throat plate, that suggests to me that the machine is meant to use thinner needles and thread, like a maximum of a #18/110 needle and #69 bonded thread. I recommend using a #19/120 needle with #92 thread, if that machine can handle it. It sounds like you bought a tailoring/dressmakers' machine, or maybe just a domestic/household machine falsely advertised as industrial. Does the machine come on a 20x48 inch table with a large clutch or servo motor underneath it, shipped on a pallet? Or, is the machine sitting in a small fitted box with a removable carrying case lid with a tiny motor attached to the back of the head? If the latter, it's a domestic machine for sewing thin cloth with small spools of cotton or polycore home sewing machine thread with thin needles (e.g., #10, 12, 14, etc). If so, you can probably forget about sewing 8 ounces of leather.

Either use an anti-backlash spring under the bobbin, or insert the bobbin against the direction of rotation of the shuttle. This means the bobbin thread will make a sharp turn off the bobbin to the slot and stay under the spring better. It does add a tish more bobbin tension which may need to be counteracted by backing off 1/2 turn on the bobbin tension screw. Negatory. Mine is manually oiled. Everybody calls me Wiz. That's who and what I am!

When this happens to me I chalk it up to the convergence of forces beyond my comprehension!

I dunno the standards for needle/thread combos in the sail sewing field, but in the leather end we usually use a #19 or possibly #20 needle maximum with #92 bonded thread. It seems to me that a #22 needle is poking too big of a hole and the tip can't slide past the thread knots as easily. I occasionally sew non-leather items in my shop. Of course that calls for round point needles. Lately, I have been buying Groz-Beckert Gebedur needles and they are fantastic. Gebedur needles are titanium coated, but last longer under stress than the Orange brand. You might try dinking with the check spring slider position. Normal operation has the screw in the middle of a curved slot. Turning the disks clockwise tightens the top thread by reducing the slack on the downstroke. Try doing that. Loosen the little screw in the curved slot, back off the round nut and turn the disks clockwise, then lock them back down. If it gets better, problem solved. If not, return the screw to the middle, or try turning it ccw for more slack. Note: tightening the check spring slack setting all the way may cause the top thread to snap as it goes around the shuttle. If this happens, back off a tad.

Suz, may I call you Suz? There is a trick to avoiding jamming your machine with top thread wrapping around the shuttle. Hold back the starting threads for a few stitches. If the bobbin thread is inaccessible, hold back the top thread. You will probably have to pull up or down to hide the first knot or two later on. Failure to do this usually results in the machine coming to a halt and you having to cut the thread under the material to remove it, then open the shuttle cover (and maybe the throat plate too) and as you found, the gib holding the bobbin case, then pull out all the double or triple wrapped thread. You may have to retime the hook if the machine lacks a safety clutch that disengages the hook when there's a thread jam. It is an unfortunate fact that a large number of perfectly good industrial sewing machines suffer from firsttitchitis; the grabbing of the top thread and double-wrapping it around the shuttle and bobbin case. Sometimes you may get lucky and be able to start sewing without jamming the hook, but only if the take-up lever is already on the downstroke and the top thread is firmly captured under the presser foot, and the foot has enough pressure to not let the thread slip out. Too many ifs in play.

G style bobbins are too small for Big Barb! Don't even think about it! They are like half the size. Just load your own U bobbins with the bobbin winder.

Spammers post links on forums hoping for search engines to pick them up and help promote those websites. It is the oldest trick in the books since the Internet moved from just bulletin boards (BBS) to websites with graphics and shopping carts. I was about to defang the link but you beat me to the punch and deleted it.

The spam link goes to a Russian industrial sewing machine dealer with their own name branded machines. I deleted the post as I do for all spam links I learn about.

Sometimes prewound bobbins are wider than metal bobbins, especially in larger sizes, like U. You might have to waste a few yards of thread to get them to drop in if that's the case. I haven't had that problem yet with the G size prewounds I buy from them and other places. But, somebody who uses them did and told be to be aware.

Red nail polish using the little brush in the bottle.

You must have bribed them with GlenLivet single malt scotch!

The Cowboy inline foot set would also work good on narrow gussets.

That looks like a 18th Century glockenoodleshitzer from the Outlander series. The British used them to torture the Highland Scots they captured during the battle at Glenlevit.

Do you need the flatbed to sew 1/2 inch with #207 or #277 thread? There are a limited number of qualified machines that will do that. I went down this rabbit hole during my first couple of years sewing leather goods. Rather than enumerate all the numerous machines that didn't work out, the one that did was an Adler 204-374. These are as rare as hen's teeth. However, there is a clone of this machine made by Cowboy. It is model CB-243. It is expensive and only sews flat work. Do you know that you can buy a heavy duty cylinder arm machine and get a table attachment with it? This gives the best of both Worlds. Here is the machine I have for sewing holsters and gun belts. It came with an accessory pack that included a large flat table that bolts onto the pedestal stand. It is expensive too, but will save you having to buy a second machine.

Are you using a curved throat plate (recommended for this), or a flat plate? Gussets do worse on a flat plate that squishes the leather. A rounded/curved throat plate more closely follows the corner curves. This assumes that you sew on the top/outside of the gussets so they can fold around the throat plate. If you sew from the inside, the curves fight the feed and will hit the head and interfere with the stitches. For tight curves on gussets, consider using the stirrup throat plate. It is perfectly rounded on top. But, you lose the feed dog and only have needle and inside foot feed. Reverse won't line up as before. That won't be a problem if you either double tap the ends or stitch over the beginning stitches for 4 or 5 stitches. I would add more foot pressure going around the gusset and use a double toe foot for maximum even pressure. Another thing you might could try is to reduce the top and bottom thread tensions. This will make it easier for the machine to pull the leather through, especially when operating in needle feed mode.

What you described is the method used on lockstitch sewing machines when one wants a bold top thread appearance, but there is insufficient thickness to hide the knots if the same size thread is used in the bobbin. A thinner bobbin thread bends tighter and won't cause noticeable bumps along the folded down and topstitched seams. I sometimes use this technique when a customer asks to have a belt edge stitched for appearance, but the leather is too thin to hide the knots formed by #138 or #207 thread. Using a thinner bobbin thread lets the knots stay low down, but not sticking out the bottom. Know that anytime you use a thinner bobbin thread, the strength of each stitch is that of the weaker thread.

Unless somebody has custom fitted a Juki hook and milled out the chamber it resides in, your bobbins are M style, not U.

My hope is that as a result of the things discussed in this topic about matching forward and reverse stitch lengths, that the attacks against some of our dealers will stop. No sewing machine is perfect all the time unless it has expensive electronic controls that make it sell for $10k (think Adler 969 ECO). I am happy to be able to buy a heavy leather stitcher for about $3k that does the same sewing, but needs a little adjustment with a shim, or a tweak of a moving part. One of our dealers is a two man shop, another may have three people and another is a division of a larger company that has more employees who don't necessarily specialize in heavy leather stitchers. Resellers of brand name machines, like Cobra, may not have the training or hands-on experience that the official company technician/set-up man has. With the effects of Covid restrictions during 2020 and 2021, some techs and adjusters have been laid off. Some may have moved on to other occupations. There are machines on ocean freighters waiting to be allowed to dock and be unloaded. And, on top of all this, we are now back in a revived Cold War, possibly the blink of an eye, or miscalculation away from World War III. And ya'll are bitchin about reverse not perfectly aligning with forward! Most of my sewing machines don't even have reverse levers.

My hope is that as a result of the things discussed in this topic about matching forward and reverse stitch lengths, that the assault against our dealers will stop. No machine is perfect all the time unless it has expensive electronic controls that make it sell for $10k (think Adler 969 ECO). I am happy to be able to buy a heavy leather stitcher for about $3k that does the same sewing, but needs a little adjustment with a round washer.

I used a small washer on my machine. It really does work to correct the reverse, as long as the timing of the inside foot and needle is matched. Until I put a washer under the top of my stitch nacelle, reverse never matched forward 100%. Now it does. It beats laying the machine down and dinking with the internal cams.

The entire problem with that link was that it pointed to http instead of https. I corrected the link so it opens or saves the file without a security warning. I downloaded it and it is safe.