Wizcrafts

Any walking foot machine I've seen, read about or watched videos of can sew 2 layers of 3mm (~1/8") leather. Most modern compound feed machines can sew up to 3/8", or about 10mm. Look into a used Juki DNU-1541, or better yet, a LU-1508NS (inches) or LU-1509NS (metric). These machines are expensive when new. Another good source of used but functioning walking foot machines are upholstery shops. That is usually the only type of machine they use to sew furniture covers. Old ones will be rode hard and put up wet, but usually keep going like EverReady batteries. IHTH

Probably a Seiko frame.

Yes. The hole will be round, not slot shaped, or oval, or triangular. Round point needles are meant for paper, canvas, cotton, denim, vinyl and most other non-leather materials. Leather point needles are specifically designed to penetrate leather for the best results in otherwise difficult material. A benefit of using round points is that the stitches will lay flatter on the top and bottom surfaces, rather than getting pulled in on the leading and trailing edges, as slicing needles tend to do.

Okay, no harm done. Buy some #23 needles (round point!) and use #138 bonded nylon (22 pound test), or bonded polyester (21 pound test). That should hold a 3/8 inch stack of book papers together. If you need more strength, buy #207 (aka: T210) bonded thread and use the #24 needle you already have. Just make sure you use round point needles, unless the covers are of leather.

Please, for the love of God, do not put a #27 needle in that machine. It is meant for use with a #24. You may be able to squeak in a #25, but watch out for impacts with the feed dog hole and hook. If you break the machine it will be very costly to ship and repair it. The hook clearance is insufficient to pass 1/2 mm thread of any kind. Your idea of buying #138 thread is fine. It may even handle #207, which is what the #24 needle is sized for.

Yes, I lower that thread guide as far as possible. Some machines will have more room to move the guide than others.

If you must use 1/2mm thread (aka: 4 cord, or #277), you'll need a machine meant for heavy thread, like the Juki TSC-441, or the Cowboy, Cobra and Techsew 441 clones, or the Adler 205 heavy stitchers, or a Union Lockstitch, or Campbell Lockstitch machine, or even a Puritan chainstitch machine. The latter three machines are actually built for use with linen thread. If you need a flatbed machine, look for a used Adler 204-370 (long out of production, but out there), or a new Cowboy CB243 - both of which sew at least 3/4 inch with thread sizes up to #415 (.7mm), using needles up to a #27. These machines have an open frame shuttle and huge cylindrical bobbins.

I found the pdf with the specs for your machine. It is not clearanced for that size of thread and is only rated for up to a #24 needle. You must use smaller thread than 1/2 mm. I would go down to 3 cord linen (Chinois #832), or #207 bonded nylon.

I looked up your thread and found that it is a little over a half millimeter in diameter. Your size 532 hand sewing thread is about the same as #277 bonded nylon. This calls for a #25 needle. In your case, you may need to move up to a #26 needle to poke a large enough hole for the take-up system to pull the lockstitch knot into the stack of paper. Lockstitch sewing machines with a standard closed eye needle are not meant for use with any prewaxed thread. The thread path, guides and tensioning disks are not optimized for sticky thread. Use bonded nylon, bonded polyester, or even heavy cotton or poly core button hole thread.

It kept the thread deep inside the disks, which was not happening before. Bonded nylon and polyester thread is much more slippery than unbonded thread. Slippery thread that moves around in tension disks needs to have a greater angle of entry and exit from the disks to keep it centered. If the angle can't be changed, double wrapping it will help. The theory of the multi-hole top post on some industrial sewing machines. Because some sewing machines, like 441 and 205 types, have their tension disks on the top of the head/faceplate area, the incoming angle of incidence of the top thread can be almost inline. This is horrible for maintaining dependable top tension. Bonded thread is not only slippery, but is often twisty. That is a two way fight for the guide in front of the disks. So, vendors of these machines usually hammer in a thread guide post that has 2 to 4 holes, drilled at different angles. The idea is that if the thread is moving around in the disks, providing some back pressure will predispose the thread to stay down in the disks. By feeding the thread through holes at different angles, you build back pressure. The closer the wrapping and greater the angle of wrap, the greater the back pressure. It can be so great that it overrides your tension spring entirely. That is counterproductive. So, if your machine has a top post with even one hole going through it, feed the thread through the hole and turn the post with pliers so the exit angle is not inline with the tension disks. If it has 2 or more holes, feed it in the top, then around, then out the bottom hole. Back off the top tension spring to balance the knots. If you back it off all the way and the knots are too high and the bobbin spring can't bring the knots down, go back to using one hole with an offset angle. If your machine lacks a top post with holes, try to move the steel loop thread guide in front of the tension disks down as far as it will go. I did that on my CB4500 and it really helps secure the thread inside the disks. When really twisty thread causes trouble, I feed it through the top hole, around the post, then down and out the lowest (4th) hole, which is inline. I can still use the top tension and bobbin tension springs to fine tune the knots. IHTH.

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Why don't you head on over to the 3D Printers and Lasers forum and start a new topic there?

I have owned two Union Lockstitch machines. The driving wheel on the back weighs about 50 pounds. I called it a flywheel.

No comment of the 15 class clone, other than the presser foot, which is a roller foot. Good luck! The Singer 31-15 is a tailoring machine. Yours is missing a lot of parts. It must be set in an industrial sewing machine table that has a 7" x 17" cutout, four rubber corner pads, hinges and hinge mounts for the head, a tilt back peg, an oil pan, a parts drawer, a knee lever for a 31-15 and a floor pedal with a motor linkage, plus a clutch or servo industrial sewing motor rated at between 1/3rd and 1/2 horsepower, with a 2" pulley. Additionally, the table to will need a thread stand, flex lamp and bobbin winder. I believe that you can buy an entire table setup for your machine for about $350, plus shipping. Upgrading to a servo motor will add another $50 or more over a clutch motor. Considering how many parts are missing from the 31-15 head, you could buy a reconditioned sewing machine for what you are going to have to put into this one. Even if you totally rebuild this machine and buy a table for it, the poor thing will still be a tailoring machine. It can only sew a few ounces of soft leather, and only up to #69 bonded thread.

Ah yes, the old thread stub trick.

@Clintock Try this. Pull the top thread out of the second hole in the top post and just run it through one hole. Then loosen the screw on the thread loop in front of the tension disks and push it as far down as it can go, then lock it in place. The rational is that by lowering the thread guide it will feed the disks from a greater downward angle, better securing the thread inside the disks. Pay attention to whether the disk separator is interfering with the full closure until you lift the feet. It should not push them open at all until you lift them, nor should the point hit the thread as it feeds down to the roller disk. Resetting the tensions means remembering how tight they were when you got the machine. Just set the bobbin tension for a moderate pull (not too tight, nor too loose), then balance the knot position with the upper tension nut. You can play with the bottom roller tension to see if it makes any difference. But, to have any tensioning affect, it needs at least 1.5 full turns before it exits over the pin. Anything less and the thread will just slide around the roller disk.

It could be a problem with the leather varying in density as you sew. Or, the bobbin thread could be getting twisty, forming microknots as it passes under the tension spring.

My answers are as follows, based on my personal experience with both Cowboy and Cobra 441 clones. Question 1, you are concerned about how hard it is to turn the wheel. This is because of the 3:1 speed reducer between the machine and motor. Going from bottom to top is easy. Going from the top down is not. The motors currently in use have a cork brake that is engaged until you press down on the speed pedal. It disengages when you press on the big pedal. It stays off until you take your foot off, or heel down. If the motor switch is on, you can feather the pedal with your toe to help turn the hand wheel. Question 2 deals with the presser bar sticking in the up position. This can be caused by a slightly off center hole in the pressure adjuster screw. If you just turn the screw slightly with the foot up, it will probably let it drop down. If this is the cause and you find a best position, use the locknut to keep the pressure adjuster in that position. This makes it a crap shoot if you are constantly changing foot pressure, as I do. I just used a round file to open up the diameter of the slot a little bit. Now, my presser foot never sticks in the raised position. Oil that sucker! Question 3: The right foot lift floor pedal is used to temporarily lift the feet. It is not locking at the top. For that, use the hand lift lever with the ball knob. Make sure that the lift chain from the machine to the pedal has a very little slack when the feet are lowered. I set mine to about 1/2 inch free motion with the feet down. Question 4: If your edge guide is a swing away guide that slides right and left in a T shaped plate, it should sit at the level of the throat plate when in use. Try loosening the screw on top of the roller to let it drop down, or ask for a replacement guide. It could even be that the T plate for the guide is not perfectly inline, or its mounting screws may have come loose. Tighten the two screws that secure the T plate to the body and see if the edge guide roller comes down. If you bought the drop down edge guide that mounts to the back of the head, it has two set screws that raise or lower it, plus two screws that let it move forward and backward. I hope this helps.

I would watch how the thread uncoils off the spool. Maybe it is hitting sticky spots, then loosening, then grabbing? Twisty thread can also cause the knots to move. I also recommend that you wind a different bobbin with the same thread and see if the problem persists. Some bobbins have a longer end to end profile than others. Over-length bobbins squeeze the bobbin thread against the shuttle driver frame at certain points of rotation, as the thread feeds out. I I've actually had to sand down and polish a few over-length bobbins for my harness/holster stitcher.

Anne Bonny would be proud of you, Darren! Harrrr

I don't know anything about other locations for Thoroughbred than Kentucky. But they are part of a group of companies belong to Tasman, one of the largest hide brokers anywhere. Thoroughbred is an old school, wholesale leather tannery business (not for hobbyists). You call on the telephone and talk to one of the people running the business. If they don't answer, leave a message with your name and phone number. You get the details on the phone, prices on the phone and place your order on the phone. Once you are on- file in their system, all you do is call and order what you want. Not all weights are in stock at all times. You may have to wait for them to receive the tanned and finished leather of that color and thickness. Ask for long backs if you make belts, as there is less waste and no belly to throw out. Some backs I get exceed 105 inches with one reaching an incredible 110 inches from the butt to neck! PM me for the phone number. If you are a wholesale customer with Weaver, you can buy Thoroughbred bridle leather from them. It is slightly more expensive, but usually in stock.

I will take your word that the machine is threaded properly. But, are you using the proper needle system? I have seen patchers that had a needle that was too short and would never sew. You should be using either system 29x3, 29x4, 135x16, or 135x17. The scarf side of the needle must face due right and the ribbed side due left. Adjust as necessary and try sewing. If happy happy, rejoice. Otherwise, move on down. That still leaves three other things that must be set right for proper sewing. Two of those affect the stitch quality and one determines if the machines sews or skips stitches. Later, I'll describe a fourth item. That's were you need to focus first. If everything on the top is set as per factory specs and the hook is not picking off the thread loop, the hook timing is off. It is adjustable on your machine via a screwdriver hole in the right front of the lower section of the machine. Inside that hole, around the center of the base, there is an eccentric screw connecting a shaft coming down to a shaft running to the far left, through the cylinder arm. That eccentric retards or advances the hook to get the best timing. There is supposed to be a locking nut on the back of these coupled shafts. You will need to loosen that nut using the proper size box end wrench before the eccentric can be turned. Do so. After loosening the lock nut, swing open the throat plate to expose the hook. Hold the top thread upfrom the needle, between the legs of the foot and hand wheel the needle down. When you reach BDC, slow down. Carefully watch the needle until it slightly raises up and halts, just before it starts back down. It is during this slight jog that the hook needs to intersect the loop that is formed by the jog motion. If the point of the hook has not reached, or has passed the loop before it starts back down, use a long, wide, flat blade screwdriver through the hole in the body to turn the eccentric screw until the hook does meet the needle while there is a noticeable loop. Hand tighten the locknut, raise the needle, close the throat plate and try sewing again. If it sews, tighten down that locknut and rejoice. If the hook has been timed correctly to the needle, but the thread loop dissolves so the hook can't pick it off, One of two common problems exists. One that is easy to fix if the flat spring on top of the take-up lever (trapeze) is too tight. There should be a thumb screw on top of the spring that you can back off until it stops pulling the thread loop up before the hook picks it off. If that doesn't get the loop back, the only thing left is the paddle shaped check spring inside the needle bar, which is either bent, worn out, or missing. It is an operation to replace and will take some time and skills.

Thus, it should accept the same bobbin cases, with a positioning tab on top. Correct?

I recommend that you start a new topic for this, please.

In that case, yes, it is a good buy. New, it would have sold for 2 or 3 times what a 1541 sells for.