This one is going far beyond a simple technique, if you get in a couple of sentences and its too far out skip it and I wont blame you! lol.
I couldnt accept the problem of serging curves, especially tight inside or outside reversing patterns. I am using a singer 14u244 for this one. Heres what I saw the problems to be and and how they were fixed. Advanced mechanical skills are required, all changes reversible.
The first issue limitiing the ability to control the fabric is the distance from the knives to the needle, such a long path forces the material to go straight! For my changes to work you will need to scissor cut precisely the outline to be followed and drop or disable the knive. Now the issue is how to align the fabric edge to the stitch finger where the loops are formed. I made a vertical prong out of stiff wire that pokes up ahead of the stitch finger. This will act as a (bumper) seam guide that is as close to the needle as possible. This prong is held in place by the lower knife clamp.
I removed the front feed dog enitrely, the u 244 is a differential feed. This way only the rear dogs grip the fabric, allowing more control!
Finally, the presser foot was wedged or locked with the toe up so only the heel of the foot clamped the fabric to the rear feed dogs. This allows the fabric to move freely side to side under the toe while pivoting about the needle.
Now I can make beautiful curves with a radius of less than 3/4 of an inch on paper towels! I will try to upload photos later,,,,