Wizcrafts

The Cobra Class 4 can sew with up to #415 thread. #207 is towards its lower end. The Juki that sews with up to #207 is the LU-1508NH

The check spring's job is to keep the thread taut until the needle enters the work. Is it stops moving down too soon the thread will be loose at the tip of the needle, where it can get pierced. the only caveat is that it must stop moving down before the needle starts ascending to form a loop for the hook to pick off. Otherwise, no loop for you!

The little stud is the tension release stud. It goes inside the hollow threaded post upon which the tension parts reside.

That is the tension release rod. Feed it inside the hollow threaded post that holds the tension disks and release plate, spring and thumbscrew. If that little stud is perfectly straight, it can go in from the back before you reinstall the tension release bracket. If it has a bigger end on one side, or if the release bracket is already screwed down, feed it in from the front through the hollowed post. Then install the two disks, the metal plate that the little sud pushes against, the beehive spring and the nut. Some things are better left alone, if you know what I mean.

I think you could use more travel in the check spring. Loosen and lower the bracket that stops the spring at the bottom. Try to get about 1/8 inch more drop. Did you change the feed dog to the one with teeth and the smaller hole? It is part of the blanket foot set. You can probably stand to back off the foot pressure hollow screw on top for webbing. Less pressure on the inside foot should mean less puckering into the feed dog on the bottom.

I acquired a post machine in October that had to fit where a long arm patcher on a cast iron base had been. Bob Kovar (Toledo Industrial Sewing Machines) made me a custom fit table on steel legs that was just the right length to fit between the other two machines along that wall. The table top was professionally rounded with fresh protective banding. The servo motor, reducer, thread stand and bobbin winder were stock. He installed a floor pedal for the presser foot lifter. In all, it's a compact setup that is fully industrial, but in a very limited space. He could probably modify a standard 31-15 table to fit your room and fit it with a Family Sew servo motor.

Webbing has very little resistance to a big needle being driven at 9:1 pulley ratio. It's like sewing air after making a hole with an M16 round. You may need to start playing with the check spring throw. Try dropping the bottom stop bracket so the spring goes farther down. Also, try using a #23 needle instead (7x3 round point only). Can you post a close-up photo of your thread path around the bottom tensioner and check spring, with the spring at read against the stopper? Another thing that may affect the outcome is the thread tensions and pressure of the feet. If all else fails, try substituting the standard throat pate and feed dog for just the narrow slotted throat plate. Its narrow slot doesn't let softer materials get pushed into the slot as much as the humongous hole in the standard feed dog. In fact, you might just try changing the feed dog to the blanket feed dog that has a smaller hole and teeth. The teeth will help move the slippery webbing better than the smooth dog and the smaller hole may hold the material up better.

It is usually unnecessary to feed the thread over the positioning pin on the tension disks. I would only do this if the thread kept popping out of the disks and nothing else worked. That pint is really only there to keep the disks from rotating as the thread feeds around them. The check spring looks properly threaded. But, make sure you hear a click when you load the thread around it and up. You might try lowering the stop bracket under the check spring so it travels further. Its job is to keep the threat taut until the needle has gone through, or at least into the material.

Is there a reason why you posted this topic 5 times in a row?

Check your check spring threading.

The 31 class are for tailors, seamstresses and decorative shoe uppers. Some later models can be tweaked to use #92 and possibly even #138 thread (mine cannot). But, they are very light duty machines with bottom feed and soft tension and pressure springs. You need to move up to a different class of machine to sew rugs and tack. Check out the CB2500.

I found this: " Same as 31-15 except fitted with reversible drop feed. For cloth. (10/1952) "

As long as those feet are advertised as fitting compound feed, Singer 111 type walking foot machines, yes. That class of machines uses the same diameter bars for the inside and back feet and have the same mounting system (slotted rear and narrow round front bars). Note, most, if not all Pfaff and Adler walking foot machines use different foot mounting systems and will not be compatible with Singer style machines.

If I was in the market for a portable walking foot machine, I would not hesitate to buy a Sailrite. The price may be higher than the Asian clones, but the quality offsets the difference. Sailrite has optional knurled feet and feed dogs for sewing veg-tan leather. The feed is not as efficient as a triple feed machine, but is better than just bottom feed. Best of all, if you overstress one of their machines, Sailrite will sell you replacement parts, many of which will be beefier than the originals from a decade ago and more. The Ultrafeed machines were discussed at great length about a decade ago on this forum. Use our site search for Sailrite and read through the results. Or, use Google search with the phrase: site: leatherworker.net sailrite ultrafeed - where you will find fascinating discussions like this topic about modding a Sailrite.

According to this needle and thread chart, 0.6mm falls somewhere between #277 and #346 bonded thread. The minimum needle size would be a #25/200 and the maximum would be a #26/220. To use these combinations requires a harness stitcher class of machine, like the Cowboy CB4500 and the Cobra Class 4. If you don't need to sew 3/4 inch, a Cowboy CB3200 is a less expensive alternative. If these machines are beyond your budget, the CB2500 and similar GA5-1 type machines, like the Techsew 3650HD can handle #277 thread and sew up to 7/16 inch of leather. These are clones of the ancient Singer 45k series and are bottom feed machines only with a fixed presser foot. The teeth on the feed dog are substantial. You can forget about any of the upholstery class machines if you want to use #277 or #346 thread. Furthermore, the lockstitch knots formed by such heavy thread are very prominent and require at least 12 to 16 ounces of leather to completely bury them. Note: most modern lockstitch machines cannot use waxed linen thread. They must be operated with bonded nylon or bonded polyester, or another synthetic, or dry, glazed, left twist linen thread (5 or 6 cord).

Please define "thicker thread."

If the bobbin anti-backlash spring is missing, AND if the bobbin is inserted so it feeds in the same direction as the shuttle is rotating, AND the bobbin tension is a little on the loose side, extra thread can be pulled out when the OP makes a right angle turn. Personally, I would tighten the bobbin tension, then balance the knots with more top tension, then pull the bobbin out and turn it over so it feeds against the rotation of the shuttle. I've been know to do weird shit like that.

I think the previous responders were thinking that the loops were on the top side. The OP stated that the loops are the bobbin side, not the top. Let's assume this is a fact. If the bobbin thread forms a loop under the material, the bobbin might be inserted so that it's feeding the wrong way, or the anti-backlash spring is missing, or the bobbin tension spring may be too loose. All of these, but especially a missing anti-backlash spring can allow the bobbin thread to continue feeding when you stop suddenly.

I made the mistake of buying an off brand portable walking foot machine couple years ago from an eBay seller. The box was dropped on the handwheel end during shipping. When I unpacked it, the machine was seized. I tried to free it up for one day, then mailed it back and got a refund. The crank shafts were made of soft metal that had bent from the rear impact. The casing was crude and had jagged edges when I opened the top cover to check the damage.

It is my understanding that only the Sailrite brand machines have been regularly upgraded as flaws or weaknesses are discovered. They say as much on their website and in videos they produce. This is important if one intends to continue using the machine for an extended period of time. They have beefed up cranks and bearings. While not on par with a full blown industrial dual feeder, they are more than a step above the majority of Chinese clones.

Double needle machines are used in upholstery for topstitching across previously sewn seams (that were sewn together inside out). They are also used in the construction of jeans and work clothing to secure and reinforce folded down seams. These are normally flatbed machines with large bobbins with fast clutch motors (time is money in upholstery) driving them at 2000 rpm and above. Turning sharp corners is tricky with twin needles. You won't usually find these machines in hobbyists' leather shops. They are factory machines used by auto seat cover makers and professional upholsterers. Any flatbed machine gives better support to flat work than a cylinder arm machine. Sitting down at a full size table is much better than trying to fit flat work onto an add-on table attachment on a stand up cylinder arm. Cylinder arm machines are a must have if you sew things that cannot be held flat on the bottom. This includes shaped holsters, pouches and cases with belt loops and clips sewn or riveted on the back, hats, cue stick bags and round objects and preformed curved straps. Cylinder arm machines are usually built to sew at the very left edge of the arm, allowing shaped work to move below the throat plate level. You cannot do this on a flatbed machine. Clothing often takes multiple types of sewing machines to assemble. Some jeans require at least 5 different sewing machines. Backpacks and some bags can take two or three machines (flatbed, post bed and cylinder arm). You will no doubt find that you need more than one machine to do professional work. Some will be light duty and some may be heavy duty. Different builds of machines accept different ranges of thread. You have much to learn and a lot of money to set aside to experiment with. The simplest way to begin is with a common flatbed walking foot machine and build your inventory as the need reveals itself. Some members here start with a cylinder arm machine and construct or buy a slide or bolt on table attachment. But, if you really need a cylinder arm to sew a part, nothing else will do the same job.

The welt size on the foot equals the diameter of the covered cord. If your cord is 3/16" and the covering material is 1/16", the combined diameter is 1/4". That's the size of welt foot you need for that combo. Most double welt feet are 1/4", but others are available. Singer 111 feet refers to a style compatible with a Singer 111w155. Since Singer has been out of the industrial sewing machine business for a long long time, the only actual Singer feet for sale will be used, or new old stock. Good luck finding authentic Singer feet. If you hunt long enough, some will show up. otherwise, buy what's available in the market. Ask local upholstery shops if they have an extra set of "Singer" double welt feet. I scored mine with a machine I bought from an upholstery shop. It was in the drawer.

Anybody who may be interested in these machines should know that they are located in the Asian country Sri Lanka (an island nation south of India in the Indian Ocean) and the seller does not know if he is willing or able to ship them. If you live in, or near Sri Lanka, these machines could be a good deal. He has not stated what voltage and phase the motors are either.

I bought some brown and black calfskin that I use for wallets. It is about 2 ounces thick. I also have some dark brown and black haircell pigskin that is about 1 ounce thick, which I sometimes use for interiors. PM me if you want to discuss your wallet project with me.

It might be best to find an industrial sewing machine mechanic or dealer who has done this before. Otherwise, you are on your own.