This is my favorite way of sewing darts. I did not invent this method, I believe I first learned it from Nancy Zieman. There is a major benefit to sewing darts this way: You do not need to fasten the thread at the point of the dart, so you don’t need to tie knots that could come undone, or backstitch near the point of the dart (which can make it look messy from the right side). This is especially useful for sheer fabrics, where backstitching could show through, but I use this method every time I sew a dart on any fabric.
All you need to do is remove the needle thread, and pull out a few feet of bobbin thread. Now thread the machine with the tail of bobbin thread, but thread it backwards. The last step becomes the first step, so start by going through the needle. If you normally thread front to back, thread it back to front. If you normally thread right to left, thread left to right. Continue through the thread guides, takeup lever, tension spring, etc, all in reverse order from how you normally thread your machine.
When you’re done, you should have a tail of thread at the top of your machine, where the spool would be. Follow the thread down from the loose tail; it should follow the same path that the thread does when you thread your machine normally, and then disappear into the bobbin area. Make sure that there is no slack between the bobbin and the needle, and that you have a long enough tail of thread at the top of the machine to sew the full length of your dart.
Now you’re ready to sew. Starting at the point of the dart, begin sewing without backstitching, and continue towards the seam allowance. You can backstitch the ending of the dart in the seam allowance. The stitching at the tip of the dart cannot come undone because there are no ends, it’s just one continuous length of thread.
You will need to pull more bobbin thread out and re-thread for every dart you sew, so it’s not as quick as other methods. But I think it gives superior results, and that’s why I prefer it.
Elena has an article on her vintage sewing machines blog from a Singer manual that recommends tying the needle thread to the bobbin thread and using the needle thread to pull the bobbin thread through the threading path. I think this is a great idea, and although I have used this method to change colors of thread on my serger, I’d never considered using it to thread the machine for sewing darts! Thanks Elena!