Constabulary

There are 2 basic types of 51w sewing machines, an early type with thread take up lever on the left side and the later type with thread take up lever on the front side. You can download the manual for either type here. They should help to figure which one you have.

Looks like an H4 machine, that means it should have 14mm foot lift!!! Before you let this machine go better test it to see if it suits your needs. Not having a drop feed does not mean that it only can do binding work. Pfaff 335 and Adler 69 also no not have drop feed (some do but most don´t) and they are very common in leather work. Back in the old days there were leather sewing machines with only needle feed meaning they had no feed dog at all and they worked! So if I was you I would test it before I make a decision only by the digits on a brass plate. Keep in mind that these digits just show how the machine was set up when it left the factory but it does not tell you if the machine has been modified. Test it - then make a decision. My 2 cents.

Yea the 211 are a pain when it comes to hand wheels. I failed to remove it on my 212 (same as 211 but double needle). The 111´s are easier to work with IMO. But you can add a speed reducer instead of installing a lager hand wheel if you want to slow down the machine. Anyway - If I had to choose between the 2 above machines I would go with the 211. Are you sure the 230 is a walking foot machine? To me it looks like a plain drop feed machine.

maybe you should tell us what thickness (all layers in total) you want to sew or what product. The 236 have a rather short stitch length and are meant for sewing shoe uppers and the like.

looks like a 29K70 or 71 or the like but W/O front wheel or is and an earlier model in the K60´s subclass?

Seems several parts are missing and machine has no reverse. Table top is bad and motor for sure is an old clutch motor. Not what I would buy.

I don´t think you can get the OEM wheels anymore (well maybe... you never know). If I were you I would probably take a wheel from a different bobbin winder then wrap a piece of leather or PU flat belt around it and adapt it to the spindle. Spindle is present I guess? Other than that I would buy a table mount bobbin winder https://www.ebay.com/itm/143422223667 But it may need some modification as well.

30-10 is the newer version of the 30-1. Technically there is no big difference. Both are small bobbin patcher machines with the same stitch length and foot lift. Spare parts are expensive.

not all new machines are necessarily clones of "old / big name" manufacturers.

Or the needle size is too small so the needle hole is not big enough for the bottom an top thread and the thread knot cannot be pulled into the material. Try a bigger needle or smaller size the bottom thread.

Thats right. The original question was for a 111w.

PE means Polyester I`d say and 35 could be thread size TEX 35

Maybe the discs with the stitch length numbers has slipped. I´m not in front of your machine so I only can guess. I would try this. Open the cover plate on the top. Loosen the set screw of the stitch length dial. Push the button in the flatbed and turn the hand wheel towards you until you feel resistance. Then the longest stitch length dialed in. Then rotate the stitch length dial until you see the 5 in the window in the casting and tighten the set screw again.

@kidbeey I just recalled this thread here. Maybe this is interesting for you. Contact him by sending a PM cause he only made 2 post here.

check what diameter the bobbins have that come with the machine, small ones are approx 16.5mm the large ones are approx 20mm in diameter.

Your stitch length adjuster is installed upside down. The arrow has to point upward. Also make sure the gib is instilled correctly.

BTW - hope you are aware that is is not a heavy duty leather sewing machine. It was used for sewing garments and maybe some lightweight leather. What leather thickness (all layers together) do you want to sew and with what thread size? Those who think it is a heavy duty machine usually come form domestic sewing machines and think because of size and weight it has to be a "Hevay Duty" machine.

There were pre wound bobbins for barrel hook machines? Can you post some pictures please? Did the machine come without bobbin winder? That surprises me. This one should work: https://www.ebay.com/itm/143422221569

If the needle for your machine is 16x231 then you need a round shank needle. The needle system 16 (as from the Singer 16) is also called System 34 or 287 or 1738. Here you can find different leather needles for the mentioned needle system: https://www.thethreadexchange.com/miva/merchant.mvc?Screen=CTGY&Category_Code=NDL-34

I agree with nylonRigging. Pfaffs are excellent machines - no doubt. But finding gauge sets for different needle distances is a pain. When you are looking for a double needle machine I would look for machines based on Singer, like JUKI, SEIKO, Mitsubishi, Brother (they often share the same gauge sets) or the Singer 212 or 112 it self. On the other hand if the machine has the needle distance you need and you are sure you will need no other then go for it. My double needle choice was the Singer 212G141. To give you an idea of which machines share the same "Singer Type" needle feed gauge set check the description here: https://www.ebay.com/itm/153439679127

True. As Kafka said: Better to have, and not need, than to need, and not have. But this one actually goes on to a new setup.

I finally used the above shown pats for making a box type speed reducer. I have used 15mm coated plywood. It still needs some work.

Patcher machines can become quite handy for repair work or certain sewing operations. if it is cheap and it works and you have enough space for it - why not. My 29K71 does not see much work but I love it and I´ll keep it.

It basically is a shoe and boot repair machine and not designed for really heavy work / heavy thread. 138 pretty much is the max. is can handle. The 29-4 is probably 100 years old and has some (a few) parts in common with the later 29K models. Some parts remained the same bust most of the important wear parts are obsolete. You may find some but they are hard to find nowadays. Its a different story for the later 29K models like 29K71 - the later models are still made in China / far east so parts are usually not a big problem. Servo motor is possible but you have to figure how and where to install it. You may also need a counter spring cause the 29K´s have a heavy cast iron foot pedal. The Adler 30 machines (a similar patcher model but made by Adler in Germany) had optional motor brackets for the treadle stand. I can post picture of one later. Lots of information on the 29 / 29K Singers when you do a google forum search: https://www.google.com/search?client=firefox-b-d&q=singer+29+site%3Aleatherworker.net%2Fforum

I barely need one but I´m using the one fredk shows as well. They are cheap on ebay like 6 bucks or so. Well they all come from China anyway. I have polished / sharpened the blades with jewelers rouge on some scrap leather and I´m actually very pleased with it. F.i. https://www.ebay.de/itm/364005525549