Wizcrafts

@Chapelworx The weight of the leather at the edge must be the problem. To control any misalignment from the weight over the edge, try increasing the foot pressure via the large threaded pressure adjuster on the top of the head (over the presser foot). If there is also an inner foot adjuster screw, turn it down too. Are you using the stock feet? Does the outer foot have left and right toes, or just a left toe? You might need to use a double toe foot to keep pressure on the right edge to keep the leather from lifting at the inside edge. Are you using the needle and thread that shipped with the machine? What are their sizes? Check the edge of the throat plate to see if it is tapered at the left edge. Finally, using your left hand, slightly raise the left side of the belt a little higher than the right as you sew. Push the belt towards the right as you sew. Can you take a picture of the left nose end of the machine from the front view and post it here? Keep the resolution to the smallest allowed by your phone or camera. If you have the option, use .jpg format as it is usually a smaller file size.

I have the same machine. It could be that you are trying to run a thread size that is bigger than the machine is rated for. That would be #138 (T135) bonded thread.

You have correctly summarized the check spring. As for when the spring lets go (the stroke), it should always be after the needle fully penetrates the material. This will be longer on thicker stacks than thinner ones. When this spring first appeared, most people were sewing cloth garments. The problem of running without any check spring is that the top thread loosens as the take-up lever moves down from TDC. All of that loose thread flopping around tends to get caught by the needle and is likely to split if the needle hits it square on. The purpose of a thread controller, as it is officially called, is to keep the thread taut until the needle is inside or under the top of the material so that it doesn't split the loose thread by accident. Since thicknesses do vary, I usually adjust the stroke stopper bracket lower to keep the thread taut a little longer. I set the spring tension to manage the size of the thread, using less force on thin thread and more on thick thread. If you set too much spring tension, it can override the main top tension disks. I use just enough spring action to both fully seat it in the lowered position and to control the amount of slack, but not to add appreciably to the top disks adjustment. The adjustment for the "throw" varies with the design of the check spring assembly. No matter its geometry, there should always be some method of adding or subtracting how much loose thread is fed to the descending needle. The lesser the looseness, the tighter the lay of the stitches, and vice-versa. If you sew something that is thin and soft, like garment leather, denim, broadcloth, linings, etc, and the stitch line is puckering, stop sewing and cut the thread, then pull the work to remove the puckers. Move the slack adjustment to add more top thread, run a test, then resume sewing the job. You will find a happy position where the work lies flat and the stitches aren't too loose on top. The actual spring tension is controlled by rotating the entire check assembly one way or the other. On most of my SInger style machines, there is a locking screw underneather the metal housing that the assemble fits into. That screw stops the assembly from turning on its own. To change the spring's force, loosen that screw on the housing, then put a narrow flat blade screwdriver into the end of the split shaft and turn it to get the amount of spring tension you want. Tighten it down after you're satisfied. Most thread controllers I encounter have the slack adjusment in a curved slot with a small screw that sits inside the slot. You loosen the screw and the nut that tightens the assembly, then rotate to the right for more slack, then tighten it all down. Factory standard is dead center in the slot. However, the distance that the spring travels up and down comes into play if it's much longer or shorter than the default factory position (typically about 8 to 9 o'clock in the resting position). machines setup to sew leather usually have a lower resting position of the stop bracket or adjustment. I recommend experimenting with any new sewing machine until you are familiar with all of its adjustments and how thay interact.

Nice work!

@OscarRush Sewing those thicknesses of veg-tan leather are beyond the scope of upholstery class walking foot machines. You'll need to buy a machine that's built to sew holsters, saddles and horse harnesses. Most of these machines can sew at least a half inch of hard leather. Some, like the cb3500 and 4500 that AlZilla mentioned, can sew 7/8 inch of saddle skirting. I have the 4500 and a bunch of walking foot machines, so I know what I'm talking about. My walking foot machines can sew up to 3/8 inch of chap or garment leather, using #138 bonded thread. My Cowboy cb4500 can sew from just under 8 ounces, up to 52 ounces thickness with very heavy thread, like #441. I personally never go beyond #346, but I could if I needed to.

Neither of these machines was built to handle or tension #207/T210 bonded thread. Do so at your own risk. Sewing with #207 thread on the top and bottom calls for a #24 needle. You might need to find a heavy duty beehive tension spring to get enough top tension to pull the knots up into the leather. The bobbin tension would have to be very light, which can lead to other problems. Also, the hook will probably need to be moved farther away from the larger needle and the deflector tab may need to be bent out a little more (or not). Moving the hook sideways changes the timing. If you do manage to get one of these machines to sew properly with #207 thread, which has a 33 pound breaking strength, be prepared to replace the take-up lever and the connecting rods and crank shafts inside the head. These parts will wear out much faster than if the thread maxed out at 22 pound test #138. You might be able to soften the forces acting on the moving parts by reducing the bobbin tension to almost zero, while installing an anti-backlash spring under the bobbin, then balance the knots with the top tensioner. Last, set the check spring position for the maximum amount of slack in the top thread. On disk shaped check assemblies there is a screw inside a curved slot to control the slack. Loosen the little screw, rotate the assembly fully counterclockwise so the screw is at the right end of the slot, then tighten down the screw. Next, you may need to change both the check spring tension and bottom stopper position to hold onto the top thread as the take-up lever descends until the needle completely penetrates the bottom layer, and possibly longer. You'll need to get a substantial loop in the needle's scarf for the hook to pick it off at the distance it will have to be away from that thick needle. The hook timing may also need to be advanced to reduce the snapping as the top thread tries to go around the shuttle.

If you can't tame your digital servo motor, consider replacing it with an analog model that has brushes. The Consew CSM-550 is a perfect replacement. I use this type of servo motor, under different brand names over the years, on all of my walking foot machines, including my huge Cowboy cb4500. Servo motors with brushes like the CSM-550 start at zero rpm, but with very low torque at the minimum speed setting. They gradually increase their starting torque as you turn the speed knob a little higher. Once in motion, you can back off to maintain your preferred speed. Adding a speed reducer can double or triple the torque. Machines with this motor and a speed reducer can start turning over at less than one stitch per second and punch through whatever is under the foot/feet.

You bought the wrong needles. I used to have a Pfaff 145 and it used system 134-35 needles. I did a quick lookup and your H3 also requires System 134-35. They are much longer than the 134 you have there. The needle bar would have to be dropped down about 6 mm to accommodate the shorter needles. You'd lose sewing height as a result.

@dragharley1 There are 11 topics discussing the Singer 16-141 and 16-41. Read them here: https://leatherworker.net/forum/search/?q=singer 16-141&quick=1 The 16 series were light to medium duty upholstery machines. The models with walking feet were top and bottom dual feed where the outside presser foot pulls the work in sync with the feed dog The feet have teeth to get a solid grip on the material. The feet will leave permanent marks in veg-tan leather. I suspect that your 16-141 will max out at between 1/4 and 5/16 inch thickness. The maximum thread size is probably #92 on top and in the bobbin. The needles were originally system 16x63 and 16x64 which may be hard to find. The modern equivalents are: DBx1, 287, and 1738. These are common needles in tailoring machines, like the Singer 31-15.

That's a nice adjustment system. The shuttles on my walking foot machines have a thin steel plate that can be bent in or out to limit the position of the needle. However, in my experience, the needles seem to almost always get pulled away from the hook and deflector shield. It would probably have more protective effect on larger needles, like #22 and up than on thin needles, like #18 through 20.

@Curious Observer If making bags will be your specialty, start making plans to obtain the industrial sewing machines that are best suited to that work. Number one would be a cylinder arm walking foot machine. It should have at least 10.5 inches clearance to the right of the needle. With this type of machine you can sew completely around a bag from the outside. This is great for installing zippers as a last step. You can even use it to hem pants! Number two might be a post bed machine with a roller foot. If the post is tall enough, you can use it to sew along the bottom of a bag. This machine is also great for assembling hats, or sewing patches onto hats. Number three could be what we call a "patcher," which is a cylinder arm machine with a foot that rotates in 360 degrees that pulls the work in any direction. While the bobbins are small compared to standard industrial sewing machines, their narrow noses can sew deep into areas that other machines can't access. You're already working on getting a flat bed walking foot machine. It will handle sewing seams that lie flat.

@FDC Sweet!

I believe that the Juki LU-1508 series may be too heavy duty for the thinner leather you want to sew. This series is beefed up in order to sew into denser and thicker stacks of material. The DNU-1541(s) is probably a better match. It can sew over thick seams and has a thread range more suitable for thinner and softer leather and broad cloth, or denim. Now, if you will be sewing leather or heavy canvas jackets, with flannel, quilted, or fur linings, the LU-1508NH is the better machine. But, it may eat thin vest linings.

Bingo! This is a much overlooked issue among leathercrafters who sew on machines. Some of use have a room full of walking foot machines of varying capacities. I do! One thing they all have in common is their lust for linings and broadcloth lunches! They love to eat these thin, soft fabrics. If you are going to be sewing this kind of cloth, you need a bottom feed machine with a flat foot. The actual machine can be any ancient Singer tailoring machine, like a 31-15, or 96k40. Juki makes some superior high speed bottom feeders that have oil pumps in an oil bath and can sew at 8000 stitches per minute! My first industrial sewing machine was a Singer 96k40. I used it to sew a soft leather vest and a lining. But, when I tried to sew on a panel with fringes, that machine balked. I bought a walking foot machine that was better equipped to go over thicker seams and denser leather. You can often find tailoring machines for sale in local ads or marketplaces. A lot of them will have a clutch motor that you can either learn to feather, or replace with a servo motor.

@ohLyssa The taper on the end of the stitch length rod is what does the adjusting. You need to get somebody with a machine shop to turn the rod and recreate a nice long taper that ends in a sharp point. That system is long obsolete. I have the same machine and baby the adjuster any time I move it.