|On my older machine (Bernina 830) I can only use the narrow twin needles. I usually have problems with tunneling and wanted wider spacing between the lines of topstitching, so I have been looking for other methods for the side seams of pants or jeans jackets. Experimenting with presser feet has resolved my problem.
For the first line of topstitching, I use the edge stitching foot (#10) with the blade resting against the well of the seam and the needle set to the far left. For the second line of stitching, I use the quilter's 1/4" foot (#57); the new one has a longer guide that runs on the edge of the fabric. I set the needle as far left of center as the foot will allow, which is one click left on my manual settings.
Using these two feet give me two really straight lines of topstitching that are spaced correctly for jeans or jackets.