friquant

What jumps out at me is that the latch opens abruptly. Not sure if that's normal for this machine. I don't see the bobbin case opener..maybe it's internal?

I'm enjoying learning hidden qualities of the thread check spring. Which of these screws do I loosen on my 341 to effect #1 and #2?

I can see that the timing is off, as it moves too far clockwise / not far enough counterclockise to drag the thread around the bobbin. (Even if it did manage to pick up the thread in the first place) I have not been able to find a service manual for this machine. As @Cumberland Highpower said: "Just look over the mechanisms, you should be able to "see" what the problem is with a little careful analysis." I would start by removing/opening covers. See if you can trace the movement of the hook all the way back to the main shaft. That is, figure out which shafts, rods, gears, cams, and/or arms are involved in making the hook turn. At least of of those members will be adjustable in a way that allows you to change the hook timing. Feel free to post additional videos as you make progress. Once you figure out what to adjust to effect a timing change, try setting the hook so that in its clockwise swing the point of the hook only goes about 5mm past the needle before the hook turns around to go counterclockwise. I expect that will put you in the ballpark where it will actually sew.

Wow it's hard to see down in there. I'm used to having a vertical-shafted hook where you can see the thread take a round trip. Can you take one more video with the feed dogs removed, as close as you can but still in focus, and move the handwheel very slowly. (About four seconds to do a full turn ought to do it.) Then maybe we can see what's clunking around. If we can't see it from above, you may be able to get a shot from below the left side. (This may require partially disconnecting the arm that the feed dogs ride on so we can get a better view) If using an iPhone, Uwe made a demonstration of how to lock the focus on an iPhone for taking close-up videos: https://www.youtube.com/watch?v=twl_V_vlq2Q

Can you post links to the pieces one would need to buy in order to build this setup? I'm interested

Yes I mean the pulley on the servo motor. They are typically 75mm. If it has a 15mm cylindrical shaft, that pulley can be replaced with a 45mm pulley for about ten dollars, which will slow down the machine.

Yes, do post videos. Have you done timing on your RB5?

In practice, yes. What I really mean by this distinction is whether they have a minimum speed or not, and the ones with a digital display seem to have a minimum speed. They're either not moving at all, or they are moving at least at their minimum speed. And by analog, I mean you can ease into the gas pedal and start out at a crawl. What is the minimum speed of the servo motor on your consew? It's easy to find a "digital" servo motor with a minimum speed as low as 200 rpm, which with a 45mm motor pulley gave me 111 stitches per minute with an 80mm hand wheel pulley. Your setup may be slower if your handwheel is larger than 80mm. If you want slower than that, they you either need a speed reducer, or an "analog" servo, or both. I don't work with thick leather, so I will let others chime in regarding whether you will need a speed reducer in order to stitch the thick materials you are targeting.

Found a solution for the slack thread not jumping through the latch. That is, set the thread check spring to begin adding tension at that point in the stitch cycle. Still do not have a fix for the thread being off the shoulder.

What materials do you anticipate sewing, and how thick? With your other sewing machines, which would you rather have: A. Slow gentle startup, or B. The convenience of a needle positioner? It seems that there are two camps of servo motors. With an analog servo motor you supposedly get slow gentle startup, but not necessarily support for needle positioners. With a digital servo motor you get decent support for needle positioners but you get a jerky startup. Some have reported that their needle positioners did not work when they added a speed reducer. If your servo motor has a standard 15mm cylindrical shaft with a woodruff key in it, you can buy an aftermarket 45mm pulley (75mm is standard) for about $10 to get some speed reduction.

My digital servo motor has the same problem...the foot pedal is still hot for about ten seconds after turning off the power. I'm thinking on how to bring it to full off sooner. So far my best approach is: Turn off power Grab hand wheel with two hands so it can't move Press the gas pedal and let the motor pulley spin to scrub off the energy I imagine with a clutch pedal one could take a gentler approach...hold the hand wheel with one hand and press gently on the clutch to scrub off the energy.

Having never seen one in person, I underestimated the amount of distraction it can be when in motion. needle-guard-small.mp4

Rereading, you asked for a list of potential pitfalls: Unplug the machine before you begin When you pull the hook out, make sure the pin for the bobbin case opener (under the hook) stays more or less in place. (you don't want to lose it) If the hook is stuck, reach for penetrating oil and a hot air gun. (I broke a hook once prying it out) Make sure the hook is properly settled into place before you screw it down. On my 341 clone it's fiddly to get the hook to drop into the hole because the bobbin case opener has to also align. When you insert the hook, it can go in two different ways 180 degrees apart. One works and the other will not pick up the thread Make sure the tang on the bobbin goes into the slot on the needle plate. Be very careful turning the handwheel if the bobbin is installed but the needle plate is not Magnetize your screwdriver for getting the hook gib screws out. These screws are tiny and easy to drop Use a new needle for timing and clearance adjustments (to make sure it is not bent) Set hook-to-needle distance before setting timing. When setting the timing, note the manual specifies the stitch length you should be set to. (Easy to miss) When setting the timing, make sure the timing gear is gently pressed against the other gear. When setting the timing, note there is a little play in the hook, so make sure the timing is checked during forward rotation of handwheel. Sometimes I use one finger on the hook to apply some reverse pressure to it. Make sure you readjust the bobbin case opener so the thread can jump through the latch, and so the bobbin case opener does not bind. Set timing according to the book. After you set it, verify that it catches the thread with forward and reverse feed, with both short and long stitches. Make sure everything moves smoothly and does what you expect before you run under power afterwards. Find out how your hook broke. Did it collide with the side of the feed dog support? (You can file some material off to give more clearance where it is likely to hit) Did it collide with the needle? (You can/should adjust the needle guard to prevent this)

Found two more videos relevant to this project: Uwe's Consew 225 hook timing video. (Different machine but useful for timing basics. Especially useful are putting black marker at the middle of the needle scarf (easier than measuring your needle bar height). And using a clamp on the needle bar to set your reference position. ) https://www.youtube.com/watch?v=1wNBPX8i524 Uwe's Needle Guard Adjustment video. (Different machine, but same concept applies) https://www.youtube.com/watch?v=9EWODLVlOxo

You can do this! Setting the timing is no harder than removing/installing the hook. You'll want to remove the feed dog so you can see the needle-to-hook relationship better. Do you have already the service manual? Here is a link: https://leatherworker.net/forum/applications/core/interface/file/attachment.php?id=139088 The service manual explains what the adjustment dimensions are, but does not actually go into the details of how to remove the hook. This video by Uwe will show you how to remove. (Different machine, but the removal of hook is similar.) https://www.youtube.com/watch?v=CfkGrz3OugA

Wow, congratulations! I've got a table coming to me this weekend with an old singer knee lift on it. Now I know what it will look like 😀 On my pfaff 545 I learned to grease the sliding plate that releases the tension discs when the feet are up...the knee lifter moved much easier after that.

I even drop tools onto the pedal and the machine says giddy-up. Not fair I say! Like @AlZilla, I intend to turn the machine off (and wait for the digital servo LCD to go off) before I thread the needle or touch the bobbin. If I'm doing more than that, I often unplug it from the wall.

How to buy or make a finger guard for a Juki 341 clone? I occasionally see photos of triple feed machines with finger guards, but the feet I bought do not have extra mounting holes for guards.

I've decided to give up on this quest for now. Putting the machine back together and time to get to building something. 🚶‍♀️

Is this to drive the machine or to lift the presser foot? I thought you were going to use the kick drum lever to tell a separate servo to raise the presser foot.

Ooooohhh... Can you post links to the servo you're using for this?

Beautiful table! A foot lift is activated by pressing down with your foot, a knee lift is activated by pressing to the right with your right knee. My Jiang Long came with both, but I had to ask how to install the knee lift. Here is the install video they sent me...the chain actuator reminded me of your singer. 937adbfd78d59f2d56efebcd9d6f1892.mp4

I'm in search of the perfect hundred-dollar servo motor. I've had two motors, both of them good but neither perfect. Here are some requirements that would make me happy: Distance in degrees between needle-up and needle-down should be configurable Motor should use standard 15mm cylindrical shaft with key hole, since a range of aftermarket pulleys are available for this shaft size There should be a long range of travel in the foot pedal between slow and fast The maximum speed should be configurable When the maximum speed is set to something slow such as "900 rpm", the range of pedal travel should be spread across the entire usable range. Meaning you should have to push the pedal all the way to get to 900rpm if 900 rpm is your max. Slow start, ideally, would be a gradual transition up from 0 rpm into some minimum speed. (The slow start I have used before still immediately jumped from 0rpm to 200 rpm, which was not gradual at all) When you tap the gas pedal to ask for one stitch, you should ALWAYS ALWAYS ALWAYS get exactly one stitch. If you give two stitches instead of one now there's an extra hole in the leather that I hadn't planned on. Also, giving more stitches than asked seems like a safety issue. When you heel-tap to ask for the needle to come up, the needle should come up. It must not do a full turn and then come up. That also puts unwanted holes in the leather and seems like a safety issue. The power switch must be in easy reach of the operator The power switch should light up so we can see when it's powered on When the power switch is turned off, the motor should immediately stop. (Safety) Pressing the gas pedal after the power switch has been turned off should have no effect. (Safety) Instructions for operating the manual should be provided in clear language. (I'd be happy to help you write the instruction manual) Ideally one could limit the amount of torque through the control settings There should be no settings visible in the menus that don't do anything. The settings in the menu should be numbered incrementally. No skipping numbers, as this is confusing. Ideally, needle position sensor would stop within one degree each time. Five degrees may be acceptable, but one would be better. If the gas pedal is pressed down while the power button is turned on, the motor should not start. (Safety) Rather, the motor should wait until the gas pedal is released and then pressed anew before motor starting. Ideally, the minimum speed would be 30rpm. This would alleviate the need for a gear reducer for many people. Though if small pulleys are available, 60rpm may be fine. The factory default maximum speed should be something medium slow like 1000rpm. Let the user increase it through the menu if they need it faster. If the belt slips such that the motor has to turn farther than it expected for the needle position sensor to register one complete cycle, the motor should stay in needle detection mode. Ideally, the needle position sensor should have an LED that lights up when the positioner is in the needle-down position. (Makes for easier setup) Assuming this unit comes with a needle position sensor, the controller should have needle positioning enabled by default.

Attaching pages 12 and 13 of the juki 1541 manual. After you adjust section 9 (horizontal feed cam timing), you will have adjusted it so that in a certain position, you can rock the reverse lever back and forth and the feed dog does not move. This is the position you will want to initiate your reverse stitches from. On a machine with a needle position sensor, you can set the position sensor to always stop at approximately that position. Needle positioner or not, I find it useful to have some clear markings on the machine and handwheel showing you when you are in this "reverse magic" position. Here's a picture of my alignment marks in blue tape.

Here is the geometry of the throat plate.