Wizcrafts

I had a similar problem with my 1920 Singer 31-15. The top thread would occasionally get picked up too late in the oscillation cycle, preventing it from going around the bobbin. My solution was to advance the timing of the hook, which was done at the far right side of the machine, with the head tilted back on the table. There is an eccentric screw and finger driving the shuttle driver shaft. You have to loosen the nut, adjust the hook forward a bit, lock it down and test for results. These adjustments may also require the needle bar to be repositioned to get the hook above the eye at the right moment and position.

I operated one in 1989 - 1990 that used #69 bonded nylon. That's what we stocked, and I suspect, that's the probable limit.

That machine is known as a bartacker. It does just one thing: it sews a tight zig zag, approximately 5/8 inches long. The resulting stitch resembles a bar, thus the name. These machines are used to sew (tack) Velcro or webbing onto other things. It is not a shoe machine, per say. You cannot modify the stitch it sews. It is a one use machine.

Sometimes you get a spool of black thread that has been double-dipped and it is almost like a coil spring. This thread tends to twist a lot on its way off the spool and on down the line. I have even watched springy black thread lift right out of the upper tension disks! Thread like this needs to be stabilized, even if that means feeding it through an inverted funnel sitting on top of the spool. Then, go through a hole in the top post (if exists) and around the post, then through a second hole, if one exists. Do whatever it takes to keep your thread from coiling on the way to the needle. When knots move around a lot, up and down, something intermittent is changing the tension. Knots on top are caused by either too much top tension, too little bobbin tension, too large of a needle, or too large thread for the thickness being sewn. Knots on the bottom are caused by too little top tension, too much bobbin tension, or too small of a needle. Try to balance your top tension for a smooth pull with the foot lifted and top disks partially separated. Take the thread out of the eye of the needle. Pull out a few feet and if you feel the tension changing, look to see where it is happening. Maybe the thread is dropping under the spool or spool support. Maybe it is looping around the top guide in the thread stand? Springy thread can even twist inline and form a knot! Next, pull out a few feet of bobbin thread and test for a consistent, even pull. If you feel a hesitation once per revolution of the bobbin, pull it out and clip the little starting thread stub off at the hole in the bobbin. A starting thread stub on the inside will tend to get caught in the anti-backlash/bobbin ejector beehive shaped spring inside the bobbin case of 441 type machines. This increases the bobbin tension at that point in rotation and lowers the knot a bit. An out-of-round bobbin can cause the same problem. Improperly wound bobbins, with loose windings, can cause the thread to unwind against the inside of the bobbin case and even pop out of the tension spring on the case. Poof, no bobbin tension! As for needle sizes, you say you are using #277 in the bobbin, with #4 braided thread on top. I am not familiar with that thread at all. If it has the same diameter as #277, a #25 (200 metric) needle should suffice. If it has the diameter of #346 bonded nylon thread, a #26 needle should be big enough. If your needle is much larger than the diameter of the knots being formed by the top and bottom thread, vertical placement will be hard to control. It would require unchanging top and bottom tensions. If the work is thinner than 8 ounces, move down to #207 thread, with a #24 needle. The knots will be easier to control. One more thought: I sew a lot of different projects, some of which have areas that don't make full contact with each other all the way through, or on the bottom. The knots tend to move when one encounters these open areas. Sometimes they form under the work, other times, nearer the top. More pressure on the foot may help to compress the layers and force the bottom all the way down.

That means it is a "domestic" sewing machine, meant for making shirts, aprons, pants, doilies and household cloth items. It probably has a little black, 1 pound, .4 or .5 amp motor bolted onto its back side, that draws about 40 to 50 watts of power and produces about 0.05 (1/20th) horsepower. Most industrial walking foot machines are powered by a 400 to 500 watt 1/2 horsepower motor that weights anywhere from 15 to 40 pounds and is bolted under the table. Domestic sewing machines do not have walking foot drive. They are all feed dog driven machines (drop feed), with a flat presser foot. Some zig and zag, others just sew straight. Some have push buttons or computers to change the stitches. None of those machines are leather sewing machines. You need to consult an industrial sewing machine dealer who specializes in leather sewing equipment, to buy a real leather sewing machine. My first industrial sewing machine was an old Singer 96-40 straight stitch machine. The dealer lied through his teeth when he told me it was what I needed to sew a leather vest. It was NOT. I needed a compound feed walking foot machine, which I bought elsewhere.

You need to choose which needle system you will be using in your machine, then adjust the height of the needle bar to meet the hook at the correct amount of lift past BDC.

None of them are really any good for anything other than thin, soft leather. If you only need to sew a vest together, or a pair of leather gloves, an old straight stitch machine should handle it. Most of them are limited to sewing no more than 1/4 inch compressed thickness. But, if you intend to sew belts, bags, holsters or large upholstery panels, an industrial sewing machine, with a very powerful motor, is a must. The old cast iron Singer sewing machines, mounted onto treadle bases, or equipped with tiny motors on the back, were made to sew fabrics. Industrial machines use 1/2 H.P., or larger clutch or servo motors. Leather goods are normally sewn on triple feed walking foot machines. These machines are mounted on 20" x 48" tables, or, in the case of cylinder arm machines, on adjustable height pedestal bases. They typically sew 3/8 inch of leather or cloth. Home machines may be able to handle up to #69 bonded nylon thread. Industrial walking foot machines easily handle #138 and sometimes, #207 on top/138 in the bobbin. Most upholstery grade machines also have almost double capacity bobbins. Home machines have small, standard bobbins. Real leather stitchers are very large and can sew over 3/4 inches, with #346 thread, or larger. They have 3/4 H.P. servo motors and speed reducers.

You can take or send your machine to an industrial sewing machine dealer and have them properly install a drop down edge guide. Most of the Chinese attachment builders have no idea what a Singer 111 looks like on the back of the head. They deal in current brands and models.

BDC is the position that is bottom-most on the travel of the needle bar. Watch the needle bar as you rotate it towards you. When it reaches its lowest point, just before it begins to raise, that is BDC.

I buy small spools of nylon thread from Wawak.com. They are available in 375 yard spools of #69 and come in a wide variety of colors.

Never eat anything bigger than your head!

I have a Singer 15-91 and am here to tell you that is is too weak to penetrate 10 ounces of veg-tan. It can sew soft temper leather, like garment leather or soft chap, but is limited to no larger than size 69 bonded thread. Worse than that, it has trouble feeding leather. The stickier the top grain, the more it drags against the steel presser foot. A Teflon foot feeds leather better, but can get gouged if it is set down on the feed dog teeth. My assessment of the 15-91 is that is is best used for sewing cloth garments, pillow covers, stuffed animals and maybe the cuffs on soft jeans.

Keep in mind that there must be some tension of the bobbin thread, or the bottom stitching will not lay straight, or inline, or tight to the leather. Also, leather point needles come in different configurations. The most common ones for type 794 are D, P and S point. Different dealers stock different types. For instance, Bob Kovar sold me some #25 diamond (D) point needles that sew in a straight line and cause the thread to lay on top of the leather. The usual type S needles cause the stitches to sink into the holes on the front and back, reducing the apparent stitch length (to the eye). Type P produce a jagged stitch line on top of the leather. But, I think you'll find that these different needle shapes also produce different results on the bottom. Experiment young Jedi!

By next size needle, I meant up. This pokes a wider hole that makes it easier for the take-up lever to pull the lockstitch knots into the leather. The photos show a combination of tension and pressure issues. Try these options: Reduce the top thread tension to bring the knots down a bit. Or, go down one needle size, for tighter holes. Or, tighten the tension spring on the bobbin case. Make sure that the thread is feeding under the bobbin tension spring! It can sometimes slip out and free-feed. Reverse the direction of the bobbin if this happens, so it feeds backwards into the diagonal slot in the case. If you got the flat, narrow-slotted plate with your machine, you can try using it without the huge feed dog and see if this improves the bottom appearance (it does on my CB4500). Here's how. Do this with the needle up and power off. Remove the shuttle cover, remove the two shuttle screws and carefully pull out the entire assembly, making sure that the shuttle and bobbin case don't fall onto the floor. With the shuttle out, rotate the hand wheel until you have a direct line of access to the flat slot in the big screw that secures the feed dog. Use a strong, wide blade screwdriver to unscrew that screw. You may need to tap on it with a mallet to loosen the screw threads, which may have blue Locktite on them. With the big screw removed, pull and wiggle the feed dog until it comes out of the movable block to which it is attached. Remove it completely. Using long and short, or right-angle flat blade screwdrivers, remove the two screws securing the throat plate. Remove the throat plate completely. Clean away any thread or leather fragments. Install the flat, slotted throat plate and apply the screws loosely to hold it onto the top of the arm, while allowing it to be moved right or left. Slowly lower the needle until it is just above the slot in the plate. Position the plate so the needle is centered right and left, than lock down the two screws.

Until last March, I kept a Union Lockstitch at home and my CB4500 at my shop. There wasn't enough room in the shop for both anyway. The Union Lock is an awesome holster sewing machine, as is its big brother, the Campbell Randall Lockstitch. Home work ceased, so I sold it and bought two machines with the proceeds.

Try reducing the tension on the bobbin spring. This will loosen the bottom thread making it easier for the take-up system to pull the knots up. Also, if the knots don't pull well up into the bottom layer, try using the next size of needle. Tracks from the presser feet are a part of life in the 441 world, where very heavy springs are needed to hold down thick or dense leather. I suspect that that most of our dealers have softer pressure springs laying around.

Sailrite sells a beefed up portable walking foot machine that is probably as good as you can get, in that class. Earlier models were not as strong. These are dual feed machines, with teeth of the bottom of the outer presser foot. The outside foot pulls the top layer in sync with the feed dog on the bottom. They are good for sewing 1/4 inch of material, with #92 thread (possibly #138). You would need the Monster Wheel 2 accessory to punch through leather at low speeds and to maintain those speeds. This adds another $115 to the cost, which is already around $730 for the straight stitch version. I see that Sailrite now sells a smooth bottom presser foot for $40, which they call a leather foot. The type of leather they refer to in the product description is upholstery leather, not belts. If your bags are of soft leather, this machine might be able to sew them. On the other hand, if it turns out that you need a cylinder arm machine, rather than a flat bed, the portables are out. You'll need to get an industrial machine on a pedestal table.

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More professional leather sewers use Adler 205s than TSC-441s. Dealers who specialize in leather sewing machines usually set the Adler 205 up as a sub-model 374, which has a smooth feed dog. They also offer what we call harness foot sets and special purpose throat plates, which are very useful to holster and harness makers. The Juki 441 is usually configured to sew heavy webbing tow ropes or thick buffing wheels. It will have teeth on the feed dog and both presser feet. An Adler 205 set-up by a leather machine dealer will be mounted on a pedestal table, with a powerful servo motor, feeding a speed reducer pulley, feeding the machine with combined 8 or 9 to 1 speed reduction/torque multiplication. It will usually come with harness feet and a smooth feed dog.

A 200 minimum RPM motor may or may not have a smooth transition from off to 200. Some go directly from zero to 200, with a jerk. This would not be the motor you want. The Family Sew and Toledo SewSlow (formerly known as SewPro 500GR) servo motors have very long tapers from off to on. They both can turn over at a few RPMs. What really counts is the total pulley reduction between the motor shaft and machine flywheel. If you have a 2 inch motor pulley and a 4 inch machine pulley, the top speed is cut in half and the torque is doubled. A leather sewing machine doesn't need to sew any faster than 600 RPM, or 10 stitches per second. This would be into soft leather, not belts. I usually sew belts at about 5 stitches per second, or 300 RPM, on the straight-aways. But, I slow down to one or two per second around the back and the tip. The tougher and thicker the leather, the slower the needle should move. I sew really thick holsters at one stitch per second or less.

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Go to the dealer selling the Juki and try out the machine. Then you'll know if the servo in it will sew as slowly as you want. If it doesn't, the Family Sew servo that is sold by Toledo Industrial Sewing Machines and Keystone Sewing, among others, does slow waaaaaay down. It has a multi-position rotary switch on the front, limiting the top speed from very fast, down to about 350 RPM. You will want one that has a 2.25" pulley, rather than the standard 70mm that are normally on them.

Steve, Steve: Do you know what have you done? Edit your last post while there is still time.

A Singer 31-15 can sew with #138, IF it is a later model, or has been modified to have a newer hook. The one I have is from the mid-1920s and cannot handle #138 thread at all. The shuttle and driver don't have enough clearance and the beehive spring is too light to tension #138 thread for leather.

Most industrial sewing machine shops can sell you the parts needed for different "gauges" of twin needle spacing. But, you'll have to move and time the hooks yourself, unless you have a dealer nearby.