Wizcrafts

What we have here is a failure to communicate. What I was trying to suggest to you was that after you loosen the set screws on the small worm gear that secures the hook shaft, you should be able to rotate the hook freely by hand. Nothing else should move underneath; not the worm gear, ring gear or any other shafts. Perhaps I mistook the location of those gears. I believed that they were under the hook.

Set the needle bar for the 135x16 needles, then retime the hook to intersect above the eye, inside the scarf.

Probably just stuck after decades of being there. Try loosening the screws #5 and see if the hook moves freely.

If that machine is just a bottom feed straight stitch machine, with an oil pump on the bottom, forget it. It is for light duty, very high speed sewing, using thin, soft cotton thread sewn into shirts, pants and aprons (aka, flat work). The needles they use are short and too thin for the thread you will need to hold your horse hide project together. You will at least need a well-maintained walking foot machine to sew 14 ounces of horse hide together. Expect to run it at its thread limit, with light colored #207 on top and #138 in the bobbin, with a #23 or #24 leather point needle. You may have to replace the original clutch motor with a more easily controlled servo motor, equipped with a small 2" pulley. This will call for a shorter v-belt if the original motor has a 3" to 4" pulley (if the motor mounts in the same position, you lose one inch per inch less pulley diameter on the belt.). If it was me, I would use my big Cowboy CB4500, with #277 thread. But you don't have one of those (yet).

I have sewn hundreds of guitar straps and rifle slings, both with padded suede linings and plain. A typical tooled strap is about 8-9 ounces thick. There is no sense using thread under #138 bonded nylon, especially if there is any lining on the back. A 4 ounce lining makes the package about 12 ounces thick (3/16"). The best needle size for this job is a #23 (160) leather point. There is only one type of machine I can honestly recommend for these jobs: a compound feed, walking foot machine, with a large M style bobbin (Consew, Chandler, Adler, Pfaff, Seiko), or a Juki DNU-1541 or LU-1508N, which have a double capacity Juki LU bobbin. Any of these machines can sew up to 3/8 inches of real leather strapping, using #138 thread on top and in the bobbin, with spacing over 4 to the inch possible. They are manually oiled, with large bearings, and can be sewn very slowly, at one stitch per inch if you are so-inclined. If you speed up to about 10 stitches per second, smoke will come off the needle. The machine you mentioned is a very high speed tailoring and garment factory machine, meant to be run at about 50 to 60 stitches per second. Also, those stitches will be close together. The maximum regular thread handling capacity is #69 bonded. It will be a stretch to get it to sew with a #23 needle and #138 thread, if at all. Finally, it is a bottom feed machine and has lighter tensioning parts that are suited to garment sewing.

The sewing machines that are meant to handle waxed thread are needle and awl harness stitchers, or shoe sole stitchers, or Puritan chainstitch machines. Regular lockstitch machines fair badly when waxed thread is run through them. I tried it on my CB4500 and only got about one or two inches of stitches before the thread broke. It tends to stick inside the eye of the needle and this stops the loop from forming on the upstroke. No loop = skipped stitches. One might possibly have better luck by using a #26 or #27 needle and spraying silicon lube on the needle.

You have misinterpreted the numbers 30/3. Here is what thread they represent: "Regular Jean Thread 30/3 T-60"

A machine rated to use #80 or #100 needles is not going to work for you. It is certainly a light duty post machine for use on shoe uppers, moccasins, or soft leather hats, using very light weight thread, not exceeding #69 bonded. A #100 needle will just barely feed #69 thread. It is better limited to #46 bonded, or T50 cloth thread.

TeddyCrafts; You still don't understand how these machines sew. Walking foot and straight stitch machines used in our trade are lockstitch machines. Google this term. Lockstitch machines have bobbins on the bottom, which form the bottom half of the stitches. Bobbin thread can be any color you choose, since the operator of the machine usually loads his or her own bobbins from large spools of thread. As for the feed dog leaving marks, this is not going to be noticeable on textured leather. Further, you can reduce the pressure on the presser foot/feet to minimize and marks on the bottom. As I suggested, go buy a home sewing machine and learn how they work. Experiment with different thread and presser feet. Move up to an industrial machine once you really know what you want. This will save you a lot of aggravation and pestering of your suppliers.

What I should have said earlier is that on a straight stitch roller foot machine, you need the bottom teeth on the feed dog to pull the leather to form the stitches. The top roller on a roller foot machine spins with the top grain to avoid drag, while still holding the leather down between stitches. If you get a walking foot machine, the needle and inside foot feed the material, with the assistance of the feed dog. Some folks fill in the teeth on the feed dog with rubber or silicon, or such, to reduce the effect of the teeth on the bottom. I don't think tooth marks on the bottom will be a problem for watch bands..

From the first comment I suspect that you have absolutely no understanding of how sewing machines work. You would do well to purchase a used home style sewing machine and watch how it moves material along. You need a better understanding of the mechanics before you start telling dealers what you want them to order or build for you.

Yes, if your dealer is able to get a manually oiled straight stitch machine, setup with a servo motor for slow speed operation, and convert it to a roller feed. Many of the newer straight stitch machines are made for very high speed sewing (e.g. 5,000+ SPM) and contain oil pumps that sit inside an oil pan that has a gasket between it and the machine head. Unless those machines are routinely spun at over 2,000 RPM, the oil may not be properly distributed to the end points. That's when __it happens and the machine seizes. FYI: 5,000 SPM = 5,000 Stitches Per Minute \60 = 83 stitches per second!

3.2 mm = 8 ounces = 8/64 inches = 1/8 inches Most domestic sewing machines max out with #B69 (T70) bonded nylon thread and a #18 (110) leather point needle. Leather that is 8 ounces thick is usually very tough; too tough for most home type sewing machines to handle. So, even though the presser foot may let you clear 1/4 inch of "material," it probably shouldn't be anything harder than Denim jeans or maybe vest leather. Dense belt and strap leather tends to grab the needle and lift up with the ascending needle and thread. This causes skipped stitches and possibly broken needles and other parts. You will probably knock the timing out after the leather lifts with the needle a few times. In my own experience, using several different ancient Singer cast iron body home machines, an 8 ounce belt, sewn with #69 bonded thread, using a #18 leather point needle, was the practical limit. To even do that I have to crank down the presser foot pressure spring screw on top. This kept the leather from lifting with the needle, but reduced the length of the stitches to an almost useless distance of about 8 or 9 per inch. Changing the presser foot to a Teflon foot helped reduce drag and allowed slightly longer stitches. Forgetting to keep the Teflon foot raised when the material is out of the machine ruins it by pressing the feed dog teeth into it. If your New Home is a Janome plastic body, multi-stitch machine, I have one of those also. It is only made to sew light cloth; maybe denim. You will break the machine if you sew leather on it.

The sewing machine in the Hadley Roma video is a plain old straight stitch Singer 31-15 or equivalent, with a roller foot conversion and an inline edge guide screwed onto the body. These are slow speed, manually oiled tailors' machines. My Dad used one and I have one at home. They have a sewing capacity of 1/4 inch, or 6 mm. The thread handling maxes out at #69 (T70) or maybe #92 (T90) bonded nylon or polyester. The largest practical needle size is #140 (Singer #22). My guess is that those straps were being sewn with high quality B46/T50 thread, using a #75 or 80 needle. You should be able to find a complete Singer tailors' machine, with motor and table, for about $500. Another $150 to $200 gets you the servo motor conversion. The roller foot conversion will cost you about $40 USD and consists of three parts: the roller foot attachment, single row feed dog and a matching single slot throat plate. You will need to adjust the presser bar up to install the roller foot attachment, then move it sideways to line up the roller with the slot and feed dog. Some dealers will convert a straight stitch slow speed machine into a roller foot machine. This saves you a lot of dinking around and possibly bad mistakes. These machines normally come with a 20" x 48" x 1.75" table, mounted onto a "k-legs" steel stand. There is a big floor pedal that connects to an industrial motor and a knee lever under the oil pan that lifts the presser foot and releases the top thread tension. There should be a thread stand that holds two or more large cones and a bobbin winder attachment screwed onto the right side of the long slot for the v-belt that powers the machine. The bobbin winder has a big wheel that you push into the belt to load a bobbin. There is an adjustable metal tang that moves out as the bobbin loads. When the bobbin is as full as you can safely load it, the tang pops up, disengaging the bobbin winder wheel from the v-belt. Don't make the mistake of buying a new high speed self oiling machine. You will never spin it fast enough to distribute the oil to the extremities, sewing watch bands

The only upholstery grade machine in your list appears to be the Rex. As long as you stick to chrome tan leather it will do a good job. However, if you use it to sew veg-tan or bridle leather it will mark the top pretty badly with the teeth on the feet.

Yes, the 1541 is a standard walking foot machine, with triple feed. The standard presser feet are smooth on the bottom. Ones with teeth are just accessories. Make sure you get smooth presser feet. There are many accessory feet for this type of machine. You may benefit from an edge guide foot for your straps. This foot has a thin spring loaded steel plate that is hinged at the back. The guide normally sits all the way down on the right side of the work and keeps your stitch line a fixed distance inside the edge. They are available in different spacings from the guide to the center of the inside foot. You might want a set that places the stitches about 1/8 inch from the edge, or maybe a little closer. Alternately, you could purchase a left toe only outer foot and a swing-away edge guide (mounted on the right, on the body). This would let you run the stitch line any distance inside the edge you want. Make sure you order leather point needles! Regarding the servo motor; try to get one with a very small motor pulley (e.g. 50mm). This gives more slow speed range, with higher punching power. Normally, many of these motors lost torque at their slowest speeds. The smaller pulley will get some of that power back, at the expense of the top end speeds.

Aside from the pulley difference, when I opened up my motor, I looked at the switch and found that it is populated with small resistors. I'm not into electronics anymore (for 3 decades) and have no meters. But, I'm guessing that someone with the right equipment and good close-up eyesight could figure out how to replace the rotary switch with a suitable military grade, long life, log taper pot (or stacked concentric pots).

One big difference I see is that your motor has a large pulley. Mine has a 50mm (2") pulley, which gives more low speed torque and runability.

My FS-550 motor has a multi-position rotary switch. I wish it could be converted to a log taper pot. Let me know if/how any mods work out for you.

The knots should always be buried inside the layers, or at least the bottom layer. If you cannot hide the knots, the thread is too thick for the material thickness. Unlike some fancy home machines, industrial sewing machines are mostly manually adjusted 100% of the time. The amount of thread tension used in heavy leather stitchers, like your CB3500, is enormous, compared to an everyday domestic sewing machine. Those fancy plastic machines use cotton or poly-core thread in sizes 50 and under. The faster machines prefer #27 thread. You would be pushing one of those machines to its limit by running #69 bonded nylon through it. Even if the machine can tension #69 thread, it is usually limited by the mechanism to only sewing 1/4" of soft material. In contrast, real leather stitchers use thread sizes starting at #92 and going up from there. Most 441 clones, like the CB3500, are setup by the dealers to sew into 3/4 inches of veg-tan leather with #277 or #346 bonded nylon thread. I usually set the bobbin tension for a smooth, steady pull. Then I balance the knots by adjusting the top tension as needed. When adding layers, give the knob a turn or two inward. When leaving a layer, back it off, if you see the knots appearing near the top.

The hook point must intersect the scarf area above the eye of the needle on the upstroke, after about 1/8" of lift. If you can't lower or raise the needle bar to meet the hook, try re-timing the hook. This calls for loosening the screw/bolt/clamp that secures the hook to the shaft that drives it. Using the hand wheel, lower the needle to BDC, then raise it about 1/8 inch and stop. If the point of the hook is rotationally before the needle, advance it. If it has passed the needle, retard it. If your needle is still too high or low, adjust the needle bar to place the hook above the eye on the upstroke. If you have trouble balancing these two items, the hook point may be damaged. Replace the entire unit. Dinking around with old worn out parts is a losing proposition more often than not. There were a couple of system 135 designations. The more common one is 135x16 and 135x17, which is the standard walking foot machine needle. There is/used to be a 135x7, which is not the same needle. Singer no longer makes patcher needles. Patch owners now have to use system 135x16. The difference is that these needles have a cut-out scarf and the old 29x4 are straight all the way down the shaft.

Adjust the position of your needle bar to place the hook inside the scarf area, above the eye of the needle.

After you do the things that Constabulary recommended, check the top thread where it goes around the upper tension disks and make sure it is firmly seated inside the disks when you start sewing. Birdnests in the bobbin case are often caused by total loss of upper tension. Also, make sure the top thread is going through the check spring and take-up lever.

Aw shucks Maam, it twern't nuthin'!

If your 31-15 has an industrial motor, it doesn't matter what type of belt you use. The motor has an adjustable nut and bolt to raise or lower it. You can lower it for more belt tension until your leather belt stretches too much. Then, remove the belt and take out the C clamp from one of the ends. Cut that end about an inch shorter, punch a #0 hole about 5/16" in from the end and bend the C clamp into it. The leather should just touch when the clamp is in position. If you get a v-belt, make sure you get on that will fit tightly with the motor adjuster in the center of its travel. A stretched out 43 inch leather belt, already adjusted to the bottom of the motor adjusting bolt, would probably be replaced with a new 42" v-belt (type 3L only).