Wizcrafts

To add to what Uwe said, bonded nylon thread is a combination of several monofilamint strands that are twisted and bonded together. The overall strength of the resulting bonded package is a known factor that is available in various thread size charts, including this needle and thread size chart. You can look at the tensile strength for each listed size of thread and make your own determinations about which size will work best for your various sewing jobs. For example, #69 (T70) bonded nylon thread has a tensile (breaking) strength of about 11 pounds of pull. That is about what a medium sized bass might exert when you try to reel him in and he is fighting you. If your line has too little tensile strength the fish may break it and swim away. But, it was easier to cast because of its light weight and you got more yards on the spool you bought that a heavier line that had less thread for the same price. This is false economy. So, while a compound (triple) feed walking foot machine is rated at a guaranteed maximum thickness of 3/8 inch, or 10mm, and that machine can be fitted with a #18 needle, and that needle threaded with 11 pound test #69 bonded nylon thread, three 8 ounces pieces of veg-tan leather might have more flex force than the thread can withstand. A couple of bends in the wrong direction, or a sharp fold may break the thread and let the project fall apart. My shop has several sewing machines that do different jobs, based on their best capacities, not their worst. I don't sew 24 ounces of leather, Biothane, or webbing on my upholstery grade walking foot machines. I use my Cowboy CB4500, or my buddy's Cobra Class 4. I don't even consider using #69 thread in those machines, even though it "can be done." Rather, I'll use #277 bonded thread, with a #25 needle to sew 3/8 inch of dense leather or webbing. This size of thread has 44 pounds breaking strength, per stitch. This is inline with the thickness and possible stresses that belt, case, sheath, strap or holster is likely to encounter. A leather crafter who owns sewing machines may eventually go into the repairing things business. Those things may include zippers, patches, cuffs, hems, purses, backpacks, holsters, seats, saddles and more. If you already own a patching machine and you can't say you will never get into doing repairs, do not get rid of that machine if it works. If it needs a little tweaking, pay someone to tweak it. Repairs that call for a patcher are innumerable! I use my patchers almost every day for some job that cannot be sewn on the other machines. When the thickness exceeds the patcher's ability to feed and sew it, I move the work to a walking foot machine. I sew patches onto bikers' vests all the time. I sew the backs and shoulders on a flatbed walking foot machine, then move it to a patcher to sew over pockets, or on sleeves of jackets. Of course, if you are unhappy with your Adler patcher, Uwe or I will be happy to give it a new home.

Funny thing is my partner and I, as a custom shop, do occasionally make strange items from time to time. It's not my specialty, but if it needs to be sewn, I can do it. How much weight it takes before it slips off the boys; that's another matter.

Huh?

I actually would have a use for a curved needle and awl machine. I guess I am also one of the idiots that don't know when to leave well enough alone.

Sewing machines used in our type of leathercraft tend to be run at a turtle's pace, compared to a garment making machine. These slow speed machines are usually manually oiled, whereas the high speed cousins have a sump pump like a car. There are very few self oiling machines that can efficiently pump oil to all the extremities at speeds under 2000 stitches per minute (33 per second). There are very few types of leather sewing operations that need or use than kind of speed. The exceptions would be upholstery shops and leather garment factories, where time is money. Garment and upholstery leather can usually be sewn very fast (33 sps+) without the needle smoking and melting the thread and burning the inside of the leather. Veg-tan leather, unless it is soft, will burnish inside and grab the needle at rates much faster than 12 to 15 stitches per second. I can usually get away with sewing belts at 10 per second with little or no smoke. The heat actually fuses the knots inside the leather. Chaps, like upholstery leather, can be sewn very fast.

My first attempt at sewing a garment leather belt on a 441 machine resulted in the leather getting squished down into the throat plate feeder cutout, then eaten by the huge slot in the feed dog. The flat slotted plate solved that instantly. Other peoples' mileage may vary. Just sayin'

I can't ID that machine from the photo. You would be smart to take some of the shoe upper leather with you and see if the machine can hold it down, feed it without binding, use #69 bonded thread and sew slowly. If you see a glass oil bubble, it indicates that this is a high speed self oiled machine with a pump. It is supposed to run at several thousand rpm to distribute the oil. The 243 is definitely a very high speed machine, made to run at over 4000 stitches per minute.

I have posted several replies to questions like yours in reference to Cobra and Cowboy 441 clones. One lengthy reply is in the topic asking if a Cobra 4 can use #69 thread. In a nutshell, a qualified yes. But, you will have to reconfigure the machine, remove the feed dog and install a flat slotted throat plate. All springs, including the check spring, will need to be backed way off and the machine re-threaded with #69 or #92 thread. You will need to buy #19 needles, which are the smallest available and then, only in round point, not leather point. The flat plate is an optional accessory that you may or may not have received with your used machine. I have performed this changeover on my Cowboy CB4500. It takes about 1/2 hour each way (downgrade/upgrade), then more time to balance the knots. Make sure you have plenty of small needles on hand, as they are very easily deflected by inconsistencies between layers or its feeding. You will probably have a few bent and broken #19 needles. Also, the stitch length will be shorter and forward and reverse will no longer match up.

The most you can hope for is that a shoe repair shop may offer to haul it away for the price you'd get at a scrap yard. But, you never know. Somebody, somewhere may be reading this and thinking: "I wish I had that machine!"

You are asking for old parts that appear to be made of unobtanium. A drill bit should take care of that problem. Be sure you use Emory cloth afterward to remove burrs. You may have to move the shuttle to allow a much larger needle to clear it on the downstroke.

Try a few different needle points on some scrap wood first. They might be tri-point, LR, LL, round, diamond. Use the best one for the final sewing. Also, if you are going to tape or glue the leather to the wood first, use Titanium coated needles. They seem to penetrate glue and tape better than standard steel needles. My Titaniums are tri-point.

My Father was a tailor and had his own shop for a half century. He couldn't play a musical instrument, but, he sure could play his NCR cash register! Cha-ching.

Let me describe my operation and how I use different machines to sew different parts of a project. Most members in this section of the LWN are very familiar with the concept of sewing heavy and thick leather on big stitchers with large needles and thread to match. But, not every job can be sewn on those machines, or with heavy thread. You cannot hide the lockstitch knots from #277 thread inside 6 ounces of leather or denim. Also, the big 441 and 205 type machines tend to eat thin and soft material inside the hole in the feed dog and stock throat plate. This is were we must obtain lesser machines to sew thinner materials with thinner needles and thread. These machines can be both walking foot and straight stitch machines for general sewing. You are going to have serious trouble sewing together a satin lining of a leather skirt, or jacket, or a vest, on a walking foot machine. The material is extremely thin and requires common household sized thread and a tiny needle with a round point. A tailoring machine is best suited to this work. I have a Singer 31-15 tailoring machine that I use for linings and cloth garment repairs. It can use the thinnest of threads, all the way up to #69 and sometimes #92. The feed dog and throat plate can be replaced with sets for light, medium and heavy materials. It can produce stitches up to 5 to the inch, or down to almost zero. Put in a #10 or #11 needle and #33 thread and a roller foot conversion and you can sew patterns onto cowboy boot uppers. Switch to a heavy feed set, a #18 needle and #69 thread and you can sew wallets. Change some springs and you can probably get it to sew chaps with #92 thread, using a #20 needle. With all that versitality, it still has trouble sewing over seams, like on denim jeans. That is where you need to cross over to a walking foot machine. It will have higher clearance under the alternating feet and will climb over and back down seams reaching 3/8 inch in thickness. Your straight stitch machine probably cannot do that. Further, the walking foot machine has a different shuttle and bobbin system that allows it to easily sew with #138 thread. Most can be adjusted to handle up to #207 on top, usually with #138 in the bobbin. You would use this machine for everything too heavy for the straight stitcher and too light for your harness grade machine. Big harness and holster sewing machines are not designed to be nice to thin materials. They often don't have leather point needles available in sizes under #23 (160). The feed dogs have large holes to clear huge needles and thick thread. GA1-5 type machines have a giant feed dog with serious teeth. It will eat thin material and seriously mark leather on the bottom, if the grain side is down ( as in double leather pouches, cases, belts and straps). When it comes to sewing thick leather, you need a more powerfully and strongly built 441 and 205 type machine. They have beefed up parts and springs, needed to hold down thick leather and tow straps that are sewn with needles the diameter of porch nails. While you might be able to dumb down these machines to sew with thin thread and needles, into thin material, the time spent readjusting them back and forth may not be worht it if you have a busy shop. Besides, it's fun to watch your customers' expressions when they see a shop full of big sewing machines!

I would contact some industrial sewing machine dealers and see if any of them have that model as a parts machine. I've done that in the past. Bob Kovar, owner of Toledo Industrial Sewing Machines, has tons of old Singer sewing machines in the back of his warehouse. Gregg from Keystone Sewing has been in business since the Ark landed on dry ground. Raphael Sewing has been in business in Quebec for decades and is known here as Techsew. Nick-O-Sew has lots of parts too and I suspect that Cobra Steve has accumulated a bunch too.

What serrations do you have on a Consew 206RB? It uses standard type 111 presser feet, most of which are totally smooth on the bottom. The feed dog on the 206RB always has teeth, used to grip and move the flesh side of the leather, or whatever material you have on the bottom.

Try looping the thread through all three guide holes. If the thread guide is currently set to horizontal, loosen its set screw and rotate it so the holes face down and re-tighten the set screw. Loop the thread around all 3 holes and come out the bottom. This increases the angle going to the tension disks and will help keep the thread inside them.

To be fair, I have managed to get a Cobra 4 to sew with #69 bonded nylon thread. I used a #19 needle, which was the smallest I could get at the time. I reduced all tensions, including the check spring. Finally, I had to remove the feed dog and throat plate and install the narrow slotted plate in its stead. With minimal top tension, I was able to sew a canvas bag and a zipper in a vinyl jacket. The time it takes to transform such a machine into a light duty stitcher is only worth it if you only do it once in a great while. It is simpler for those in business to acquire other medium and light duty machines for thin, soft materials.

Welcome back, Steve! I'm glad you survived the butchery.

The practical lower thread limit is really #92, top and bottom. Use a #20 needle with it As mentioned already, there are no leather point needles in stock below #23 in system 7x4/794. Getting smaller leather point needles would require placing a very large minimum order with the needle manufacturer. If your Cobra is already set up for #277 thread and sewing normally, you will have to reduce the tension to almost nil on the top disks and the check spring. Balance the knots using the bobbin tension spring. The travel of the check spring may also need to be dinked with to get a suitable loop at the eye of the needle on the upstroke. Of course, the top pressure spring will need to be adjusted almost all the way out. Sewing things that look best with #69 thread may indicate that some of the material if very soft and thin (4 ozs and under). Such materials tend to get shoved into the huge slot in the throat plate and feed dog. So, it is best to remove the feed dog and standard plate and replace it with the optional flat slotted plate (with a narrow slot).

Since you are now using a minimum needle size for the thread, I would reduce the bobbin tension first and increase the top second. Less tension on the bottom makes it easier to pull the knots up. Just make sure there is a little back tension on the thread.

My Family Sew motors have multi-position rotary switches, with resistors coming off the terminals. The highest 4 speed settings are all the same speed, having no further effect on the top speed. The remaining positions (5th and under) each have an obvious effect on the top speed. When I set them at the 350 RPM position and floor the pedal, the walking foot machine turns over at about 2 stitches per second (without a reducer) and the CB4500 at about 1/2 stitch per second, with a 3:1 reducer.

There is a spare cork brake in the bag of accessories. There is always one pre-installed. If you remove the brake cork, the motor will not stop on its own until it runs out of inertia. You would have to use your hand on the flywheel to halt the machine if the speed was over 2 or 3 stitches per second. At 5 sps, the machine might run on for an extra 2 or 3 stitches on its own. You can sand the brake a little thinner to get more free motion before it engages. One of my FS550s has virtually no free motion while another has over 1/2 inch on the pedal. Both turn on very gradually, with no jumps in the speed. My FS-550s have rotary switches, while the newer models have pots. You might want to buy a new model with a pot.

I bought one for my former Singer 15-91 and it enabled the machine to sew a Naugahyde bag that I couldn't keep aligned or feed without dragging with the regular flat foot.

This is valuable information. Thanks for posting it. Perhaps other manufacturers will eventually upgrade their self-oilers to pump at slow speeds. I guess it would be a good idea if the oil flow adjuster is external and labeled (more/less, or slow/fast), rather than hidden on the bottom. Is yours under or on the outside of the machine?

From my experience, those so-called walking foot attachments cause you to lose about 1/8" under the feet. If the machine only has 5/16" lift (pretty standard for old straight stitch machines) you would end up with only 3/16" with that attachment. Since the feet must alternate to move the material, you have to take away another 16th or so. This leaves you with no more than 8 ounces (1/8") of sewable clearance. A better option is to find a complete roller foot conversion kit and install all three parts: the roller foot, the slim feed dog and matching throat plate. You will keep the machine's full sewing clearance under the foot and see exactly where the needle is hitting.