I have one of these Collins coping feet that replaces the flat base of a large saber saw, like my Bosch. https://www.amazon.com/Collins-Tool-Company-Coping-Foot/dp/B00B5IPTLG . Although designed for back-cutting curved moldings, I just realized the foot could also provide support when cutting round or curved turned objects...
73 Ely
73 Ely