Hemstitching woes continue to plague me. Thread breakage with the left needle thread continues to be a persistent problem. The breakage is preceded by skipped stitches that cause the thread to wrap around the pierces where the piercers or needles eventually cut the thread. I have run through various scenarios trying to diagnose the problem. The timing of a machine is absolutely critical or no stitches form. In the case of a hemstitcher, the timing is a bit more complex. The position of the needles relative to the piercers and how they move as the fabric moves under the foot is all a part of the timing. A hemstitcher has two bobbins which must be separately adjusted to work in time with the needles as they descend with the piercer. For a while I have thought there was a timing issue with the left needle.
Or maybe not. I have set and checked the timing and it appears to be right on. I have adjusted nearly every possible adjustable part. Even the pitmans that control the needle position and angle - something I dreaded touching. I adjusted the check springs. I have spent countless hours making one fine adjustment after another, studying the manual over and over. I feel as though I have hit a brick wall. It is rather frustrating to be stitching a customers blanket and have the left needle thread break every 5-12" for no apparent reason.
So off to browse the net to try and find some kind of solution. American and Efird is probably one of the best technical websites for manufacturers. They have an excellent article on thread breakage that has given me some insight. A checklist of things that might be causing some of the problems. One thing that I had observed the last mechanic to work on this machine do was wrench down on the tension discs. I have maintained tight tensions ever since. Tonight I loosened the tensions until the bobbin tensions took over than edged back to a balanced stitch. The stitch is better and perhaps that will solve some of the problems.
The next step was to look at the orientation of the needles, in particular the rotation of the needle in the needle clamp. Most every blog entry I have read says to turn the needle out to help avoid thread breakage. I think that is the wrong approach because it affects how the hook interacts with the needle. The needles should be aligned with the eyes opposite each other in a straight line. This may not make a lot of sense if you are not familar with the machine, but mechanically, it does.
In any event, I still must plug away at stitching some customer orders with my fingers crossed that I will have fewer problems. If you are having stitching problems because of skipped stitches or thread breakage, I highly recommend the American and Efird article.
Oh and did I mention I had to fix the belt. Leather belts have a tendency to wear out. I used my last clip, so I must order some more just in case. I have extra belting because my machine can be used as either a treadle or with a motor. I don't have the fancy tool that punches a hole in the belt and compresses the clip. I learned a neat trick of using a drill to create a hole for the clip. It worked great.