I have a not-so-great overlock machine – a White Speedylock 1600 – that will no longer do a 4-thread stitch, but it still does an OK 3-thread stitch for finishing seams. I broke it years ago and got it serviced, but it never worked as well after that. It’s not worth spending money to have it serviced at this point – I’d be better off saving for a new machine.
I was inspired by this do-it-yourself serger repair post to try to fix it myself. I spent hours adjusting the looper timing trying to get it to catch the left needle thread, but I finally gave up. Actually, I had it mostly working at one point, but then I just had to try to get it a little better . . . you can guess how that worked out. I should have left well enough alone.
Even though I couldn’t get the looper to catch the left needle thread, I was excited to find that I could now use this machine on thin fabric, which had never worked before. I thought I’d adjusted my serger to work better than ever – I hardly had any skipped stitches, even on very thin fabric!
Well, it turns out that when I was adjusting my machine, I happened to have some black Tex 40 weight thread in it. This thread is heavier than the typical serger thread you will find at a fabric store (such as Maxi-Lock – Tex 27). Wikipedia has an explanation of thread weight and Tex numbers, if you care.
When I switched back to my regular thread, bam, the overlocker was back to skipping as many stitches as it caught on lightweight fabric. So the “fix” wasn’t from my mad mechanical skills – darn it. My overlock machine just does better with thicker thread. I only have the thicker thread cones in black and olive green, so I just ordered a Tex 40 cone in white (yay, on sale!). I probably won’t use this thread too often, so I’ll just split up one cone of thread. (Update – I got the thread, and it was disappointing, so I now I use regular spools of Gutterman thread in the needles and serger thread in the loopers, and it works pretty well.)
So really, my overlocker is back to working just like it was before I tried to fix it. Sigh. At least I didn’t break it. And I did learn something.
The lesson here? If your serger/overlocker is skipping stitches on lightweight fabric, try using thicker thread (like regular sewing machine thread). It seems counter-intuitive, but it’s what worked for me.