Welcome from Ontario, Canada.
If the thread is shredding at the needle, I think you are pulling the needle slightly to the side when you are moving the quilt. If the needle is pulled to the side\front/back etc, it will shread the thread against the throat plate. A stronger needle may not bend as much and you might have better luck.
Are you using Machinger or similar gloves to help move the quilt? The gloves help to grip your ruler and help move the quilt without having to press too hard. It is also helpful if you can adjust the machine speed so you can quilt slower along the ruler edge. Get out some practice squares and keep at it. You will get the hang of it.
Last edited by Tartan; 08-02-2018 at 06:51 AM.