Wizcrafts

@thobgood In case you didn't know, Juki machines are top shelf for many applications. Yours is a top notch garment material sewing machine with a fixed foot and bottom/drop feed. Once you get the timing right, it will be a money maker. Many leather crafters on this forum sew heavy and thick leather projects on specialized machines we often refer to as harness or holster stitchers. Way back around 1986, or so, Juki came out with a heavy duty harness stitcher that they assigned the model name/number: TSC-441. I saw one that was still in a wooden carton in a sewing machine warehouse. At that time, the dealer told me that I could take it home form only just under $6.000. I didn't have that kind of money and they didn't do financing to individual buyers. Fast forward to around 2011 and a Chinese sewing machine company obtained a Juki 441 and disassembled it. Then they made molds and began casing new versions of that Juki. They gave them new model names and sold them to dealers who assigned their own brand names. I bought one in 2012 that I still use every time I need to sew a thick project. It is a Cowboy cb4500. My best friend has an equivalent brand, called a Cobra Class 4. Both have the same capabilities. Techsew offers their own model as a Techsew 5100. You can now buy one of these machines for between $3500 and $4400, with all manner of accessories! In contrast, I just found a new Juki TSC-441 for sale from a dealer for $9400 plus shipping. Enjoy your Juki!

Some hooks have a deflector shield that will prevent the needle from touching the needle. They are thin steel and bendable. Yours may or may not have one. If not, just move the hook away from the needle slightly. This may alter the timing, so recheck it afterward and advance or retard the hook as necessary.

No, that isn't the opener. On some machines there is a lever with a bent arm that pulls back on the bobbin case to let the thread slip through without getting hung up. If your machine has a latch opener, it is quite abrupt in comparison to those found on our typical walking foot machines. Without the opener lever, the only thing making room for the thread to the hook is the thread itself. That works if the top thread is taut, but can fail if it has too much slack.

The bottom travel stopper is set by the bottom screw inside the open channel in the bracket. The slack adjustment is the little screw in the curved slot that's above the main shaft and nut.

@thobgood When a machine that normally sews well suddenly starts missing stitches, there are three usual suspects. The first is when the needle and hook are out of time. The second is when the check spring motion is incorrect. The third is when the foot pressure is too light to hold the material flat during the needle take-up cycle. Since you have removed the cover plate, you can easily see if the hook is intersecting the needle above the eye, but still within the cutout "scarf." Where the point of the hook is can matter a lot, depending on the quality of the loop that's formed by the ascending needle. You could have perfect timing, but a too small thread loop that might not persist when the hook arrives to pick it off. I normally time my machines so that the hook intersects the needle 1/8 inch above the eye after it ascends about 1/8th inch. This isn't set in stone, but is a good starting point. If your timing isn't close to that, either move the needle bar or the hook. The quality of the loop is determined by two main parts. The first is the motion of the needle. The needle needs to go all the way down with the thread basically taut, then begin to ascend after the thread loosens up. That's where the upward motion comes into play. The hook must wait until the needle comes up as mentioned before. But, if the needle rises as specified and the hook arrives at the designated position and the loop doesn't get picked off reliably, the usual suspect is the check spring assembly! The check spring assembly usually has these three adjustable components. The stop motion bracket. This is a movable bracket that stops the downward motion of the spring where the thread comes out of it. It must keep tension on the top thread until the needle pierces the top of the material. Then it can stop moving. You might let the spring move down after the needle penetrates the bottom layer if it leads to better results. But, never stop before the needle meets the top or it might separate the thread and shred it! The slack adjustment. This is usually a curved slot with a tiny screw that is set to give a decent amount of slack thread. Normally, setting it to the far left gives the least slack thread and vice-versa. The normal position is dead center in the slot. A tighter setting leads to tighter laying stitches and the opposite direction leads to looser stitches. The spring tension adjustment. The tension is adjusted by finding and loosening a screw that is close to the body. It locks the shaft holding the spring in its position. That shaft is slotted on the outside for a flat blade screwdriver. Loosen it and use a screw driver to rotate it one way or the other until it just has enough pressure to hold the thread taut until it stops moving down. If it is too light, the spring may not move all the way down, which can lead to skipped stitches. However, it is it too tight, it may override the main thread tension disks setting. Balance the overall thread knot position by adjusting the top disks after any adjustments to the check spring assembly, and/or the bobbin spring. This may be a lot to absorb, but, it's important to understand. By playing with these adjustments you will better understand why your machine sews as it does, or misses stitches. The last thing I mentioned was the foot pressure. This is actually a two pronged issue. The foot, or feet in a walking foot system, must hold the materiel flat as the needle ascends and the hook arrives at pick-off time. If the material lifts with the needle, you will probably get skipped stitches! So, tighten the foot pressure screw on top of the head! But, what if you have tightened the foot action and the material still lifts between the legs? Yep, skipped stitches! When this happens, buy another foot with less space between the inside of the legs! Recap. Either confirm or adjust the nook to needle timing. Adjust the quality of the thread loop via the check spring. Make sure your presser foot is able to hold down the material between the legs. Once you fine-tune these settings, your stitches will be more reliable. Afterward, you might want to tweak the hook position for the quietest pick-off. If it is too close to or too far from the needle's eye, the thread will snap as it goes around the hook. It is usually louder if the timing is a little late. Try advancing the hook a little. Just make sure it arrives about 1/8th above the eye after the needle rises about 1/8th inch. Your manual may give the exact factory specification for timing the needle. If so, use them. The check spring slack setting can fine tune the quality of the loop. I hope this helps!

Welcome back, Andrew! We missed you!

Is this motor optically controlled? If so, there were people printing variable density optical filters that users could install inside their digital motors. These filters smoothed out to speed variations so the motor started at zero rpm and steadily increased as the operator pushed down on the speed pedal. Stopping the foot motion left the motor at that speed until one backed it off or pushed down further. I had this modification on a motor that came with my Cowboy cb4500, in 2011 or 2012. I would compare the action to the analog motors that replaced it.

My first Juki was an LU-563. The reverse stitches were always smaller then the forward stitches Eventually, I discovered the adjustment to get the distances closer. However, as you found out, the faster I sewed, the greater the difference became. This was in the mid 1980s. Since then, I've had various machines with reverse levers, some of which matched at any speed and some of which were flakey, like my old Juki. A Consew 206RB-5 was pretty reliable in both directions. Many of my current crop of sewing machines don't even have a reverse lever. I either sew all around to sew over the starting threads, or spin the work around 180 degrees and perform what I call, "poor man's reverse." In both cases, the stitch length is constant. I sometimes do it on a machine that has reverse simply out of habit.

One problem I have had with digital servo motors vs analog servo motors is the jerky start up. I can understand that lowering the startup speed to 50 rpm will be less jerky than a 100 or 200 rpm startup, it will still engage with a hit. Analog servo motors I have start at zero and smoothly increase in speed as the pedal is pressed. There is no jerk at startup on those motors. I have helped convert several Cowboy and Cobra 441 clones and one Union Lockstitch machine from digital to analog servos for this very reason. Once the change was made, the owners never complained about being able to control the machine or position the needle as needed. I would be happy to have a digital servo motor that started at zero and increased in speed only as I pressed down more on the speed pedal. I don't like motors that start fairly slow, then speed up on their own ("ramp up"). The motor speed should be pegged to your foot position on the speed pedal. If one needs an external speed knob, the same should apply. As the knob is rotated, the speed should increase. Because many servos lack high torque at lower speeds. I can see that the ones having more coils will have more low end torque. I would gladly pay more for an analog servo motor that eliminated to need for a speed reducer. However, when sewing thick veg-tan leather, the faster one sews, the greater the heat that is generated on the needle. I found that when I sewed at 15 stitches per second, smoke came from the needle! This also began melting the bonding agent on the nylon thread. The result was a weakened stitch line. I doubt that I am the only person who prefers to sew slowly to maintain control of the stitch line and needle placement, as well as to keep down the heat on the needle. I typically sew within a range of 1 (for detailed designs) to 6 or 7 (on straight edges) stitches per second. When I sew at higher speeds, I use an edge guide. When the leather is thinner, I can sew faster than when it is very thick. It can be dangerous to sew 3/4 inch at 5 or more stitches per second. If a fast moving needle is deflected by thick layers and breaks, it could embed itself in one's skin! Ask how I know this!

I got my first ULS in 1986 or 87. I bought it off Tandy Leather. It was sitting in the middle of their parts warehouse, unused for years. There was nothing with it except the needle and awl in the head. No accessories or thread. Once I got a manual and learned how to thread it correctly, I used the large sizes of thread I already had from a Singer 132k6, which was my previous heavy duty machine. All my thread was bonded nylon. So, I used nylon thread in various sizes. I adjusted the pull up positioner, the looper, etc, until I got perfect stitches. I did this for most of the time I owned that machine. I tried running Barbour's Irish Linen thread, but it kept hanging in the barbed needle, or on the looper. I just couldn't figure out how to run linen thread through liquid wax without it sticking to the needle or looper. Arrg! So, I kept going back to bonded nylon. If I get another ULS, I will buy bonded polyester thread just to keep it happy! ;-)

MB, when the ULS was main primary stitcher, I bought every size needle and awl available. First, I got them from New York. Later, from CR. If memory serves half right, I had needles from .5 through 6 or 7 and awls from 1 through 7 or 8. My most used combos were a #2.5 needle and a #3 or 4 awl. Some of the awls had slanted leather points. These made tighter holes for edge stitching. I was able to sew with thread sizes 69 through 554. You're right about the reason for the tool tray. I kept the round wrenches in it, as well as packs of needles and awls. Did you ever do business with Freedman (or Freidman) Harness in Toronto? That's where I learned about Campbell and Randall machines and how to operate them. They helped my with setting up my first ULS machine (from 1968). I brought that machine with me when I moved back to Michigan. I wish I had kept it. The then wife said why don't you sell that big ugly thing that's taking up space in "my" dining room. She's long gone, but so is that machine!

Having owned and sewn on ULS machines, I can confirm that they are unlike modern single needle machines. I've owned several heavy duty lockstitch machines, but none can come close to the tightness of a properly adjusted Union Lockstitch machine. Admittedly, they take some time to learn how to operate and adjust them. But, it is worth the effort. I even taught myself how to sew thinner leather projects on mine. I was able to sew single leather 10-12 ounce bridle leather belts on my ULS machines. In some cases, that included sewing fishtail stitching patterns; aka: gunfighter stitching. I still use the knowledge gained on old ULS machines when sewing fishtail patterns on belts using my current big Cowboy cb4500. For anybody reading this topic and having a ULS or Randall lockstitch machine, I will share a tip I learned from experimentation to avoid ratting a previous stitch when sewing over it in a design, or to end a row by sewing over the starting stitches. As you approach a previous stitch, if you carefully rotate the work, or reposition the angle of the barbed needle, you can sew right next to an existing stitch without ratting it with a forward facing barb in the needle. I taught myself to just angle the stitch line to one side as the needle came up and the looper threaded it. As the barb comes down, I made sure the previous stitch was at an angle to the barb. If one masters this, you can sew inline over the starting threads without ratting them on the way down. Feel free to test this free tip! It was also important to choose the smallest needle that still held the top thread in place without dividing the thread strands. A filled needle is less likely to catch a previous stitch! Last time I checked, Campbell-Randall stocked needles and awls in a wide range of sizes. I always used an awl that was one number larger than the needle. If the finished project holes look too big, tap the surface with a steel harness makers' hammer.

That machine sounds like the bobbin drops in vertically and a securing latch snaps down on top of the bobbin. If that bobbin thread slides out of the edge of the bobbin, it wil either wind around under over over the bobbin and wrap around the post or the snap down retainer. Maybe this bobbin thread is wound too loosle and is unwinding outside the edges of that particular bobbin. Try winding another bobbin and see if it has closer toerances inside the basket. Also, feed the bobbin thread against the rotation of the shuttle.

During the mid-1980s, I was trained to sew harness straps and reins on a Randall Lockstitch machine from the early 20th Century. The straps and reins tapered from about 1/4 or 3/8 inch at the folded ends to a solid 3/4 inch along the length. That machine laid down the most perfect stitches using yellow 4 cord Barbour's Irish linen thread. It chugged along at 300 rpm, which translated to a about 3 stitches per second. The thread ran through a waxpot filled with Super Ceroxylon clear thread lube/wax, which is still available from Campbell-Randall Co. When straps were much longer, or time was of essence, I switched to running a Union Lockstitch Machine, built around 1940. It ran at 15 stitches per second when I floored it! Campbell-Randall is still the rebuilder and seller of the ULS machines. They stock parts, needles and awls for it, as well as the Campbell and Randall Lockstitch macines. I've owned two Union Lockstitch machines, so far. I have a friend in Roseville Michigan who owns and uses one Union Lockstitch and three Campbell-Randall Lockstitch machines. I can honestly say that unless one never oils or maintains them, these machines will keep working as designed for over a century. This information was totally unsolicited. I am simply sharing my personal experience running their machinery. It was and continues to be targeted at the harness making and repairing industries.

I sometimes sew denim with walking foot machines. I only tweak the check spring position and balance the tensions so the knots don't show on the outside. I find that as long as there is sufficient pressure on both feet to hold the material all the way down against the feed dog, I don't get odd knots or skipped sititches. So, try adding more foot pressure. Adjust the inside foot to press down just before the needle hits the material. Match the check spring throw to stop just as the needle penetrates the material, and not before.