gaufde

Update: So I took apart the feed regulating mechanism to check for wear. The butterfly shaped block (4 in the last image above) is shiny but not noticeably worn. I also played around with the feed timing a bit to see if I could make any changes. The main thing I noticed is that the feed dog timing in reverse was slightly off even though it looked good when going forwards. Adjusting the feed dog timing at the maximum stitch length while holding the machine in reverse did make a small improvement: Here you can see that at stitch length three it is almost perfect. However, at 4.5 it is off enough that it would not pass the standard test of sewing back and forth in the same holes for five stitches. It also wouldn't pass at stitch length two. At this point, the only thing that I can think to change is the butterfly shaped block since that sets the angle of the feed mechanism. However, doing some custom grinding to that part seems like a bit of a drastic move. So, I really only have two questions left if anyone can chime in: Is this amount of variance in stitch balance normal in a machine with needle feed? I'd be very interested to see how close other people can get at a variety of stitch lengths on either a needle feed or compound feed walking foot machine. Is there anything else in the system that could make the stitch balance change as a function of stitch length?

Hi all, I just joined be this seems like one of the best places to get information about industrial sewing machines. I have a Juki DLN-5410N-7 and I am trying to get it perfectly tuned so that the forward and reverse stitches line up perfectly at all stitch lengths. The Juki has this adjustment that I can use to balance the stitches: If I adjust this at stitch length 3 (range is 0 – 4.5), then I can get it dialed in perfectly. However, if I change the stitch length to 4.5, the reverse stitches are short. If I change the stitch length to 2, then the reverse stitches will be too long. Alternatively, if I balance the stitch lengths at 4.5, then as I go down in stitch length the reverse stitches get longer relative to the forward ones (I think that is the same relationship as above). I have double checked that there is zero feed dog motion with the stitch length set to 0. I have tried adjusting the timing of the feed dogs so that the feed dogs and the needle both meet at the base plate when the needle is on its way down. I have played around with the height and the angle of the feed dogs (before setting the timing). I have tried playing with the adjustment that changes the needle feed rate relative to the feed dog feed rate, but I don’t think that is the right answer (though I’m not too confident). This adjustment is shown below: I have also adjusted the spacing of the needle bar and the presser foot bar to be 8.8 mm when the stitch length is 0 and the needle is at the bottom of its range (this is described in the engineers manual). I have been measuring the forward vs reverse stitch lengths by sewing in some card stock so that I can measure using some calipers. This machine has a synchronizer so I’m always starting the reverse stitching from the same place in the cycle. This machine doesn’t have much use (it looks almost new inside and out!) but I’m getting to the point where I’m thinking that maybe I should try replacing some parts. The two that come to mind would be the huge stitch length adjustment screw or the “butterfly” that the screw contacts. I have noticed the stitch length dial wiggles ever so slightly when switching directions, so I also tried shimming the screw with a bit of aluminum foil to see if that did anything. At this point I’m open to any advice. I can’t tell if I have done the adjustments in the wrong order since I have jumped around a lot trying to figure out relationships between different adjustments and the behavior of the machine. Or, maybe there is another adjustment that I haven’t tried yet! Does anyone here have any additional ideas or thoughts for me? I’m also happy to take any photos or videos as needed to help figure out what is going on. Many thanks!! Here are the feed components for reference: