Wizcrafts

To change to #138 thread, change to a #23 needle, increase the top thread tension a turn or two and crank down the presser foot pressure adjuster. Also, make sure that both feet go all the way down, alternately.

Keyair; It may be time to take or ship the head to a qualified industrial sewing machine shop. Have them correct the tensioner disks and plates, time the feed dog and needle to the hook - at all stitch lengths, tighten loose screws and adjust the walking feet for equal lift, then oil and lube it as needed. Ask them to set it up so that the machine can sew with any thread from #69 through #138, on top and bottom, or explain why it can't handle #138 thread. BTW: I recommend using a #23 needle with #138 thread, top and bottom. A good mechanic will be able to do all that in an hour or two. It will be money well spent.

My 1921 31-15 will not pass #138 thread around the shuttle and bobbin case, no matter what adjustments I make. I consider them garment machines, best limited to #69 thread. Newer models, so to speak, may handle #138, if you are lucky. The springs and take-up parts are not meant for heavy work.

Merry Christmas back atcha Steve.

From what I've read, a number 5 needle is about the right size for use with 5 cord waxed linen thread. You may also try some bonded nylon or polyester, say #207. Anything thicker and the knots will be hard to center.

Very nice redesign Steve. Kudos to the Webmaster.

I think that you may have better luck if you posted your question on the Crispin Colloquy Shoe Machines forum They are the foremost shoe and boot making forum I know of. Other than that, if you do use the Frobana, try to get a small enough needle to sew with 4 or 5 cord thread. The knots should be centerable with that thickness of thread into thin soles.

Order some series 136x16 leather point needles in the appropriate sizes for the thread you intend to use. Here is a thread and needle size chart to explain the combinations. You can order needles from the company (Toledo Industrial Sewing Machines).

In system 135, x16 is leather point (any geometric shape from chisel to diamond) and x17 is standard round point.

It appears that you have a mixture of system 134-35 and 135x17 needles. You must find the type that works the best for your current timing and stick with that type. Or, move the needle bar up or down to place the pick up point of the hook a little (~2 or 3 mm) above the eye of the needle, as it comes around and begins its upstroke. The easiest way to set the height of the needle bar is by removing the throat cover plate so that you can actually see the needle's position and its eye, as the hook approaches it. System 135x16 and 135x17 are the most commonly deployed needles for upholstery grade walking foot machines. They are 1.75" long and available wherever industrial sewing machines are sold and serviced. Why use system 135x16 rather than 190 LR? The Pfaff system 190 needles are longer and tend to bend or break more easily. They are deflected by lumps in layers, like skived folds on the edges of leather jackets and vests. After a couple of years of fighting with them, I converted my two flatbed walking foot machines back to system 135 and rarely bend or break a needle. This means I can't sew as much thickness on those machines as before, but they still make it to 3/8 inch. I sew anything over 3/8 on my big Cowboy CB4500.

This is just a guess, but it looks to me like the thread is too thick for the wallets. That's why the knots are hard to control. Your machine is designed to sew with up to #138 bonded nylon or bonded polyester. Your designation 10/3 looks like #277 thickness to me. No matter what thread you choose to sew with, if knots vary in position as you sew, tighten the bobbin spring for a stronger pull, then add more top tension to bring the knots to the middle of the material. Move down one needle size for the current thread. Further, clean any thread link from the thread path, including the upper disks and around the bobbin case, shuttle, and shuttle race. Oil the machine liberally, then place a paper towel under the feet to absorb to run-off from the presser and needle bars.

The machine's needle bar must have been lowered to use system 135x16 (&x17), or possibly system 134-35 LR needles. Both are approximately 1 3/4" long. The 134-35 have a narrower top shaft diameter than the 135x16 needles, which are the same top diameter as system 190.

A previous owner had the needle bar raised to use series 16x257 needles. It's that simple.

The thread is glazed linen, left twist, 4 cord, which is about the same thickness as #138 or #207, but nowhere near the strength of bonded nylon thread. This thread is used for strongly visible top stitching on couches and chairs, where the thread's visibility is part of the overall design. Despite its diameter, it is softer than bonded nylon and easier to get a proper tension than say #207 bonded. The knots will be tighter and will hide inside thinner material than its bonded cousins.

The Juki TSC-441 is built for sewing heavy webbing tow ropes, car wash cloths, buffing wheels, tactical gear, parachutes and other very thick material goods. While they can sew leather, they are not optimized, or normally setup to do so. There has been an increasing demand for heavy duty sewing machines built to sew thick leather, with thick thread, out of the box, with an easy learning curve. This buyer demand led to the modification of the Juki TSC-441 design, sold as the Cowboy, Cobra and Techsew leather sewing machine brands advertised at the top of every page on this website. These brands are maintained by a very few dealers who have a huge vested interest in servicing and helping to improve their machines. Here are some model numbers for your research: Cowboy cb3500, cb4500 and cb5500 and very recently, the cb3200 Cobra Class 3, Class 4 and Class 4-25 Techsew 4100 and 5100 All of those machines have triple (compound) feed, with special harness feet, smooth feed dogs, custom shaped throat plates for holsters and stirrups, powerful servo motors, speed reducers, large, heavy balance wheels and in several cases, built in bobbin winders. All feature a single up/down stitch length lever that raises for reverse sewing and stays where you put it, in either direction. They have been modified from the Juki spec to sew a solid 7/8 inches of real leather, with thread as thick as #415 (with a #27 needle). The harness feet come in three forms: double toe, left toe and right toe. These machines are priced competitively, at about 1/2 the price of a Juki TSC-441 and are fully supported by our dealers who are members of this forum..

It is unfortunate that the state of leather sewing machines is such that there is no machine means of resetting tensions to a default setting. All adjustments are done manually, testing as we go. Quilters and embroiderers have it one up on us. There are hand held pressure scales available for quilting and embroidery machines to adjust the top and bobbin thread tensions to a known value, for any given thread. Using these scales they are able to dial in the thread tensions to the optimum setting before they start sewing a project. It would be interesting to find out if these scales can be modified to work on leather sewing machines, which typically require much higher tensions on top and in the bobbin cases. One might try using a good quality fish weight scale to measure the tensions once a good setting has been found. It might get one into the ballpark, if not on the money. But, the thicker the thread and denser the leather, the stronger the top tension needs to be to pull the knots up halfway. I guess each sewer would have to establish his or her own default setting for their average work, whether it be 4-6 ounce wallets, 8-10 ounce belts, 16 ounce pancake holsters, or more serious 1/2 to 3/4 inch holsters and sheathes with welts. Each doubling in thickness may require increases in the top tension. There is one sewing machine I have used in the past that can place the knots in a predictable vertical position (up from the bottom layer) almost every time. It is the Union Lockstitch Machine. The take-up arm is designed to pull the thread knots up a distance that can be varied by turning a four sided screw. This setting is separate from the top thread tension disks.

You may need to apply penetrating oil to loosen the grip of the screws. They are normally tight, but not so much that they can't be unscrewed when necessary.

In fact, the only time I actually have to thread one of my industrial sewing machines is after I have removed the faceplate to oil the Tin Man that lives inside the head.

That's what I do on ALL of my sewing machines. Does that mean I am a Seamster?

In item #5, where I mentioned the tension on the spring on the second adjuster, I meant the beehive spring on the lower rolling disk on the faceplate. The check spring is a separate, but connected item that can be adjusted separately. What size thread are you using, on top and on the bottom? What size and point is the needle?

Some beginners are known to mark the adjuster nuts on the two upper tensions with white paint. One can even put a white dot on one side of the bobbin tensioner screw. Then, count half turns as you make delicate adjustments. This assumes that you are starting from a good reference point. Apparently, you have lost that happy place. Let's try to regain the upper hand... If you have not changed the bobbin tension, nor the bobbin thread, nor inverted the bobbin itself, adjust the top tension as follows: Examine the bobbin thread to see if it has slipped out from under the bobbin tension spring, causing a total loss of bottom tension. Check top thread path for twist-overs or knots. These cause unexpected increases in top tension. If there is no thread binding problem, if the knots are near the top, loosen the top tension adjuster counterclockwise, a turn at a time, until they drop into the leather. If the knots are at the bottom, turn top adjuster clockwise to increase top tension until they are balanced in the leather. If the top adjuster nut doesn't bring the knots to the best position, check the tension of the lower adjuster spring and its connected check spring. The check spring is factory set for heavy action, as needed to control thick thread. It may totally override the tension disk settings unless you loosen its lock nut and turn the split threaded post counter-clockwise, to relieve some spring tension. Leave enough spring tension to allow it to move all the way up and back down to the stop motion block under it. If you have changed needles, size matters. A larger than required needle allows the knots to rise to the top, where they may have been previously centered vertically.

Eric works in a magic place; a sewing Wonderland that most mortals can never see.

LU-563, as long as it is tight (but not binding) and sews a proper stitch. Also, make sure that the stitch length lever doesn't raise up when you speed up, shortening the stitches. That is caused by weak springs in the reverse mechanism.

I used one of those until I got a walking foot machine. The OP also uses a walking foot machine and won't need the jig.

Technically speaking, your Class 4 will sew under 6 ounces, but only with very light thread, a small needle and tensions rolled almost all the way off. I actually sewed a burlap bag closed on a Cobra Class 4. I also used it to sew zippers onto vinyl jackets, some of which were 4 or 5 ounces thickness. The machine needed a lot of adjustment to do this and this takes time. Here is a checklist to use for sewing under 6 ounces of material. #69 bonded nylon or polyester thread, on top and bobbin. #18 needles (not usually available with a leather point in this size). Back off the top tension entirely. Reduce the tension on the check spring for the lightest pull that still moves it all the way up and down during the take-up cycle. You may or may not need to unscrew the bottom tension spring to reduce top tension. Adjust the bobbin tension spring down for a modicum of pull; smooth, but not tight. Don't let the screw head extend so far that the top thread gets caught on it as it feeds around the bobbin case Back off the pressure on the feet using the big threaded adjuster on top. You won't need as much force to hold the leather down. Some people do the opposite and crank up the pressure. This just pushes soft leather deeper into the feed dog hole and slot. Make sure that the presser foot go all the way down, to secure the leather between stitches If you got the blanket foot set with your machine, it may work better than the harness feet. The blanket feet are large and have teeth. The outer blanket foot also has steel all the way across the back, giving more holding power behind the needle and inner foot. This gets around the issue of soft leather lifting with the needle when using harness feet, which are wide open on the back. The blanket foot set includes a different feed dog, which has teeth. It may or may not prove more efficient than the smooth dog. Also, the blanket feed dogs tend to have a smaller needle hole than the smooth dogs have. Hold the threads back and test on some scraps of the same thickness, adjusting the top or bobbin tension springs to balance the knots. If the blanket foot is too wide, take it to a grinder and cut down the right (and/or left) toe