Hi there, I recently started using clear monofilament and trilobal polyester threads for some of my projects. Right now I'm trying to free motion quilt with invisible thread on top and poly on the bottom. Every few inches I seem to get a loop of the invisible thread pulled under to the bottom, causing my motion to sort of "stick". If I press the fabric to keep going I end up breaking a needle or at the least the monofilament thread. I slowed it down to see exactly what is happening, and it seems a loop of clear thread is pulled down into the bobbin area and catching (I have a drop in bobbin). I have lowered the tension to around a 4 and am using a size 14 needle. I tried using the invisible thread with regular 50 weight cotton on the bottom but have the same problem. I have a similar issue when I use poly on the top and bottom together, but if I use poly on TOP and invisible on the BOTTOM I don't have the problem anymore! Lol* I don't seem to have any issues when using 50 wt. cotton on both the top and bottom either. I have changed the needle several times and adjusted my tension all over the place and still am having issues.
Does this sound like a timing issue? Tension? Any idea what I'm doing wrong? I have a back up sewing machine and was going to test out the thread combination on that one but cannot find my powercord and foot petal! Lol*