Using bed sheets to back your quilts? Don’t Do It!
Sheets have a high thread count which forces the needle in your machine to break the thread in the sheet as it pierces through. This leaves holes in your backing and diminishes the stability of your sheet that you are using for the backing. Keep sheets on the bed not on the quilt.
Quilting fabric has a looser weave, which allows your needles to easily slide between the threads and keeps your quilt backing intact.
Changing the needle does not prevent this from happening. You will also find that the sheetmay pucker once it is removed from the frame.