Ive also been using metallic thread to decorate some bug jars for my daughters quilt. I have put a thin layer of fleece batting on the back side of the jars for 3D effect But I think it is also working somewhat as a stabalizer for all the thread work and quilting since I havent yet pieced them together or sandwhiched it yet I started using a 90/14 heavy duty needle it worked great, Im using the spool up and down, supreme slider and I believe my feed dogs are still up because the slider covers them and I think when you lower them you start to have more issues with your machine make sure the thread isnt getting caught on something along the path I keep my spools on a stand slightly to the side/back of my machine I hope I could help.