Wizcrafts

The thread should be taut until the needle meets the top of the fabric. From there it depends on the material. I usually keep the thread taut until pickoff time.

Rotate the hand wheel a little more to clear the thread from the shuttle. Also, it looks like the thread is getting caught on the tab on the bobbin case. Adjust your check spring to leave more slack in the top thread. It should go around the bobbin case and shuttle without binding, snapping or getting hung up. Your last photo doesn't show how you have threaded around your check spring assembly.

Adjust the bottom stop bracket under the check spring for more travel downward. The adjust the position of the check disks to reduce the slack to the minimum needed to go around the bobbin case and shuttle without making a snapping sound. This adjustment is done by loosening the little screw in the slot and moving the disks one way or the other. Finally, the tension of the check spring is adjusted by loosening a screw in the body that holds the shaft that the spring is mounted upon. With the screw loose, turn the shaft anti-clockwise to strengthen, or clockwise to lighten the spring action. Then tighten the screw to hold that spring action.

Clutch motors have a large bolt on the front that can be adjusted for free play before the clutch engages. There is a spring and thumbscrew on the right side of the lever that sticks out to control the motion of the clutch. Tighten up the thumbscrew on the spring to get a little more control over the foot action and keep the lever as high as possible until you press down. If the clutch is grabby, smear a little grease on it (partial disassembly may be req'd) or sand it smoother. A well adjusted clutch motor can be feathered accurately by a steady foot. Sewers have done this for a hundred years. My Dad feathered the clutch on his Singer 31-15 for 60 years.

In reality, you can probably get better use from a standard walking foot machine, with a cylinder arm. There are many brands that made and make these machines. Here is what a typical cylinder arm walking foot machine looks like and sells for new, in the USA. This one is a clone of a Consew 227R. These machines use a common system 135x16 and 135x17 needle and can sew up to 10mm thickness with Tkt 20 (or under) bonded thread.

There is a world of difference between the Singer 45 models and domestic/household sewing machines. The 45 series was built to withstand the forces and pressures exerted by heavy thread and thick dense leather. Some 45k sub-classes were used to sew soles onto shoes. Others are used in saddlery. It is literally a case of apples and oranges. The 45k is a very good leather sewing machine with few parts that can go out of wack. If you plan to sew hard or thick leather, or even thick stacks of cloth, the 45k is an excellent machine. What is won't be good at is sewing thin or soft leather or cloth. The feed dog teeth are aggressive, then needles are long and the springs are very strong.

That .heic image file requires a special, non-standard codec to open it. Can you re-upload the image as a .jpg or .png file?

Have you asked Raphael Sewing in Montreal, aka: Techsew? They import parts that are in Metric measurements, as is forced upon Canadians by law.

To this day, most upholsterers use clutch motors that are geared 1:1, or higher, with the machine pulley. They are used to sewing flat out at 2000 stitches per minute. In upholstery, time is money. Furthermore, until the servo motors became commonplace in the last few years, everybody had a clutch motor on their industrial sewing machines. Most of these sewers have learned how to feather the clutches. I still have clutch motors on a couple of machines and have no problem feathering them to one stitch per second. But then, I used to drive clutch cars.

With a #18 needle it will sew with #69 bonded thread. Leather points are available if it uses the common domestic System HAx1 needles (with a flat on the shank). Your uncommon machine was made in Germany in the early to mid 1950s (reference). Parts may or may not be a problem.

Here is a link to a pdf for the Singer 138w101 post bed machines.

As for changing the gauges on the Singer post machines, there was a topic about this as recently as March, 2018. Bob Kovar (@CowboyBob) found compatible parts in a catalog for the 138, but it required changing the needle bar before they would go on.

The non-walking foot machine was likely used to sew chrome tanned shoe uppers that don't have much drag. The teeth on the bottom really dig into the flesh side. If the original owner used small needles and thread, there wouldn't be much foot pressure required, making easy to feed shoe leather through it. Machines like the above will not be as good with veg-tan leather and thicker thread/bigger needles. You will be fighting to hold the leather down to avoid skipped stitches. But, if you are sewing seat covers and they aren't grabby on top, you should be good to go, with #92 thread and a #19 or 20 needle. It really depends on how the hooks are built and set from the needles. They may or may not allow #138 thread to pass around them. Plus, the throat plate holes, or feed dog holes must be large enough to clear #23 needles to use #138 thread.

If, as is being speculated, the top thread is overheating and burning, it can be run through a silicon lube pot that sticks on top of your machine (magnetic base). Factories with high speed machines have forced air tubes that they aim at the needle and blow cool air constantly as the machines spin at 90 stitches per second. Finally, you can buy titanium coated needles that are much more heat resistant than plain steel. I use these needles in all my walking foot and patch machines, not because of heat, but to resist the grab of the 3M leather tape I use to hold things together for sewing.

On the post machines, I believe you move the posts apart when you change the needle spacing. This will be tricky and may not even be doable if the needle bar or clamp cannot be changed. This is old tech.

When you sew fast the thread flops around the take-up area more so than at slow speeds. You may have to adjust the check spring setting, or lengthen the throw of the spring by moving the stop bracket down. Consult your owners' manual to see these parts.

What brand and model is your post machine?

Even I can't find a Singer 153 walking foot machine for sale at an affordable price in the USA and I live here. They were all sent into Outer Space in Elon Musk's Tesla Roadster space car.

Weaver Leather?

Like what models?

I have a Singer 31-15 that handles up to #69 bonded nylon thread and sews up to 1/4 inch of compressed material (not leather). It can sew wallet interiors made of thin pigskin or calf skin. If converted into a roller foot machine it can sew Chrome Excel shoe uppers. It doesn't like veg-tan leather at all. The pressure and tension springs aren't strong enough for veg. The Singer 31-15 and 96k40 are both tailoring and dressmaking machines. It can be used to do decorative stitching on shoe and boot uppers before they are assembled.

Yes and no. A new topic is actually the correct designation. The difference is that the designation "thread" usually refers to an ongoing topic with many replies. A new topic that has no replies is not actually a thread in that sense of the meaning. I refer to a new topic as a new topic, or new post. Once a discussion is underway, it becomes a (not new) thread. Hope that explains it adequately!

I buy most of my thread here. It is sold in matching colors across multiple sizes. For instance, straw color matches from #69 through #346. They stock 69, 92, 138, 207 and 277 in most primary colors and several shades of brown.

I use #69 thread on wallet interiors that are up to 4 ounces thickness. I move up to #92 thread for 5 to 8 ounces. I use #138 thread for 8 to 10 ounces. As a reference, #69 thread has a breaking strength of 11 pounds. Number 92 has about 15 pounds strength and #138 has 22 pounds test. I usually sew wallet interiors with #69 and combine them to the back with #92.

CowboySew already makes a synchronized binder attachment for their CB4500 and related machines. Ask Bob Kovar for the details.