Originally Posted by
Tttdoc
SID on a longarm is not hard but does require practice and good ruler skills.
Absolutely, it can be done with a ruler, but it's more time consuming than free hand work, and so it costs more. And if the ditches aren't straight, it takes even more time to stay in them. Add to that the fact that the top needs to be well pressed with the seam allowances going in a consistent direction.