Uwe

It's good form to post what you found. Here's the German Language manual for the Durkopp 241 ( Durkopp_239_241_242_541_542_DE.pdf), which may or may not be the book you referred to. You can always type a few key paragraphs into Google translate. It'll make as much sense as most other translated technical manuals. This manual is really as good as it gets for vintage machines like this. You just need one annotated graphic to explain hook timing requirements, regardless of language (hook timing position is at 1.6mm needle rise, by the way). Most other adjustments are the same as dozens of similar machines. Many parts and assemblies on the Durkopp 241 are practically identical to the Singer 111. If it looks the same it probably works the same. It's a little like riding a bicycle. You wouldn't say "I can't ride this bicycle - I've never seen a saddle like that before." If you're comfortable with the Singer 111W155, then you're 90% there for this Durkopp 241.

edited post repeating myself.

It'll sew lighter weight leather just fine: Here's the Pfaff 138 User Manual (Pfaff138_9-86.pdf) and the Pfaff 138 Service/Adjustment manual (Adjustment Pfaff 138.pdf)

And they're all photographed in the same, already-bowing table top.

Great find - thanks for sharing! And just to put those 1969 prices in perspective, the roughly $800 for the nice Pfaff in 1969 is equivalent to about $5,550 in 2018 money. So, a high quality premium brand machine costs about the same now as it did fifty years ago.

The sideways wiggle room is due to a gap/play between the walls where the parts connect. The part should be snug, but mine have play. The holes and pivot points are fine, actually. I think I'll rustle up a link in Fusion 360 and see how the dimensions come out when printed. I feel the outer legs with the holes need to be stronger on my printed parts. The inner leg with the pivot points is plenty strong. I have a YKK metal zipper from Tandy Leather that I was going to use to make some luggage. I'll try to make a link to fit that, just for practice and 3D printing fun.

Even without getting into G-Code, there's still a fair amount of twiddling with the settings to get things to print right. I printed batch of the links last night just to see if my printer was up to it and how they turned out. Turns out printer is up to the task, but the links connect somewhat loosely. The original photos look like the links connect quite solidly. On my links there's a tiny gap between the wall of the linking elements, allowing for play. They might still work, but I don't have any suitable zippers to test with. Nozzle size, layer thickness, filament material, fill, wall thickness, alignment of the planets, and other parameters may affect certain dimensions. That's not a problem if you print little Yoda figurines, but mechanical interconnecting parts require a little more precision. Like cutters, there may also be settings to print "on", "inside" or "outside" the line but the software driving my printer is not super fancy. Alternatively, the CAD model may need to be tweaked to compensate for printer variations. I have a feeling that no two printers will produce truly identical parts, only parts that are quite close. Here's a picture of my batch of links. I took just under six hours to print 27 links with PLA filament, 0.2mm layer thickness and 65% fill. Here's a picture of the sideways curvature play my connected links have::

It's nice that you got a new motor quickly and for free from The Leather Machine Co. Kudos to them for doing something they didn't really have to in order to get you out of a bind that wasn't really their fault. Every one of their customers helps pay for that new motor indirectly. That new motor may die during your next power surge. It would be misleading to give the impression that a vendor of electronic devices is responsible for your local power grid failings or that the vendor should have to bear the replacement cost. In reality, that burned out motor control board was your responsibility, not that of the Leather Machine Co. If you complain to your local power company about power surge damages, they will just say you need to take steps to protect your electronic equipment from inevitable power surges. Depending on your home insurance policy, it may cover personal property losses due to power surges or lightning strikes. But it may not be worth bothering to file a claim - I did it once, which is how I know it's not worth bothering. Everything electronic that I care about in my house is protected by a surge suppressor and/or battery backup device. I must have close to thirty of these devices around the house, either separate devices or integrated into the power outlet on the wall. I also have a whole-house generator that automatically kicks in and separates my house from the grid during an outage. The generator does not switch back to grid power until it's up and stable again. Those generators are not a viable option for many and they don't prevent lightning strikes in your backyard.

Thank you @Northmount! Here's a brief rough cut of a video snippet that shows how to adjust the friction gib on the feed driving eccentric. This snippet is just temporary and has some audio and focus problems. I'm still working on a "proper" video that goes over the whole assembly. I'll delete this temporary video once I get the final version published.

Just a picture of what you were describing at the end of your video. I think it's a good approach to keep your thread from popping out from between the tension discs.

And since he asked for "best", here's the reigning champion, the Durkopp Adler H-Type 967-100 (if you have to ask, you can't afford it):

I'd say the Singer 144W design is one of the most capable for sewing heavy canvas and wrangling tarp size work pieces. Used Singer 144W heads can be had for under $1k, modern equivalents like Consew 744RB30 run close to $10K new. Singer 144W: Consew 744RB30:

Thanks for that dose of comic relief on a Saturday morning, Bob! One more cup of coffee should do it. That feed eccentric mechanism is indeed a confounding, yet brilliant, piece of engineering. I've been procrastinating making a video about it because the task is daunting. I do have a Singer 111W155 on the workbench with a stuck feed eccentric. Maybe I'll get the camera rolling as I work on it this weekend.

Yes, the quilting machine in the video below is what I was thinking of. Mounting the Chandler on a frame would give essentially the same effect, minus the computer wizardry.

Indeed, quilting is very similar to darning - the main difference is what moves and what is fixed. On quilting machines you freely move the whole machine around and the material is fixed. On darning machines the machine is fixed and you move the material around freely.

So it appears the check spring then really performs two distinct functions on machines with a thread regulator: 1. Keep thread taught while the needle is above the material to prevent the needle from accidentally piercing the thread on the way down 2. Apply very slight tension to the thread as it wraps around the farthest part of the hook The thread regulator device allows you to make sure the second function is indeed happening. Normally, you adjust the check spring resting ledge so that the check spring hits that ledge just as the needle enters the material. Then you can use the thread regulator to make sure the check spring just barely lifts off that ledge as the threads wraps around the farthest part of the hook. You learn something new every day. I'll have to check that out on a real machine when I get a chance.

The Adler machines of that vintage and design are very good machines in general. Whether or not this particular subclass suits your needs depends, well, on your needs. The machine is not designed for holsters and heavy belts, but it may be perfect for wallets. Here's a PDF of the original Adler 67-372 Brochure (Adler 67-372-373 Brochure.pdf) with specifications and other relevant details. The Adler 67-372 is a light/medium duty version designed for needle sizes ranging from 90-120 Nm (Singer size 14-19, indicating a max thread size of T90), and a max stitch length of 4.5mm (about 5.5 SPI)

Chandler sold some re-badged machines made by other manufacturers. They may have contracted a few machine to be sold solely under the Chandler label. They produce some machines themselves, too. I'd say this is an original Chandler since the plate clearly states "MFD by CHANDLER MFG Co. Aver, Mass. U.S.A." You can always ask them directly since they still exist: http://www.chandlermachineco.com/ In any case, you probably know it's a darning machine, others may not. No feed mechanism at all. You move the material by hand. Below's a video of how to use one of these machines. Great for repairing jeans, not so great for sewing leather.

I have a new, old-stock Juki LS-341 and it took me nearly two days to figure out the root cause for a bind when I first got it. It turned out the machine had - for some unknown reason - a set screw on one of the hook driving cone gears that was a tiny bit too long.The set screw was touching other cone gear teeth nearby - not a good thing. With a proper, shorter set screw installed the machine is the buttery smoothness you expect from Juki. I mention this because even the tiniest part can turn a perfectly good machine into grinding, thumping mess. I'm glad I found the screw before I ran the machine under motor power. On the sub-topic of oil drip pans, I ordered an inexpensive Honbo HB-8B (copy of Seiko CW-8B/Consew 227R) to develop a table attachment for this machine class - eventually. It was a gamble but it turned out to be a surprisingly nice and well made machine. It even came with a metal oil drip pan insert - yay!

I believe your #9 part just looks like and is called a thread guide, but is really an around-the-hook thread tension regulator. With the thread take-up lever in the bottom-most position, the regulator #9 allows a very subtle adjustment of exactly how much slack or tension the thread has as it is wrapped around the farthest part of the hook. Too much tension: thread snaps around the hook and may cause more thread to pull from the spool when it shouldn't. Too little tension: thread is not taught enough to nicely pull through the gap between the bobbin case tab and throat plate cutout at the right moment, potentially causing a snag that pulls more thread from the spool when it shouldn't. Just right tension: thread consistently and smoothly pulls through the gap at exactly the right time. The Durkopp Adler 867 has a similar device, except it is adjusted horizontally. It essentially has the same function as your #9 part: The DA service manual simply states to observe the thread getting wrapped around the hook, and to adjust the red regulator until it's just right. On older machines that do not have this regulator, the bottom position of the thread take-up lever alone (and relative timing with hook rotation) determines how taught the thread is when it wraps around the hook. I remember topics where the thread take-up lever seemingly arrives at the very bottom a wee bit too early or too late. This regulator eliminates that potential problem. The regulator allows more freedom to adjust the around-the-hook thread tension somewhat independently of the thread take-up lever timing. Anyways, that's my theory.

The only two machines I can think of that will handle your desired range of thread and materials in a single machine is the Juki LS-2342H and the Durkopp Adler 869. Both run well over $7K and are probably worth every penny. Our collective views of what something is worth or should cost have been greatly distorted by the multitude of clone machines.

I'm voting for the TechSew 2750, Cobra 26, or Cowboy 7341. All three are copies of the same original - the Juki LS-341 (the predecessor to the current model Juki LS-1341.) It's a great design and should serve you well. I suspect you'll be hard pressed to tell the difference between the three in actual use, other than paint color. Pick a dealer who's close and gives you good vibes.

I'm guessing your zipper foot is a few millimeters shorter than the piping foot. The rear presser bar height can be adjusted, but it's not entirely trivial and you certainly don't want to do that everytime you swap feet. All the "correct" Pfaff 145 feet (also fit Pfaff 545,1245, 335,etc.) should be the same height, regardless of H1/2/3/4/ subclasses. My Pfaff feet measure 27mm from the bottom of the feet to the center of the mount hole: Assuming your zipper foot is the "correct" foot, it would make sense to adjust the rear/outer presser foot bar to work with that foot. That lowered presser bar setting may also work with the taller piping foot. Don't start loosening screws just yet! Spring loaded parts may pop out of position and really ruin your day/week. Post some measurements of your feet and perhaps some photos.

You must not have looked super hard - the topic of presser feet leaving marks has been discussed ad nauseam in this forum. It all comes down to pounds per square inch of foot pressure. To get below the p.s.i. level that leaves marks, you can either lower the spring pressure or increase the square inches on the feet. The discussions generally boil down to this: 1. Use the lowest possible spring pressure that will still adequately hold the material (modifying the spring may be required.) 2. Use feet with the biggest possible smooth footprint that still allow you to see what you're sewing. 3. Use a big, smooth feed dog, or skip the feed dog entirely and use a throat plate with a needle feed slot.

So that statement turned out to be not entirely true, only partially. I'll have to have a word with my fact checker . . . It sounds like your hook timing is retarded, (hook arrives at the needle too late). I'd try advancing the hook timing a little and adjusting needle bar height to suit. Can you post a picture of the top of the hook when the needle is precisely at bottom dead center? To my knowledge, there's no way to adjust the relative movement between needle bar and take-up lever on this machine. But I have a history of being wrong on occasion.