It may feel like cheating but using the TS 55 to trim to size chair legs is the quickest and most accurate way I've found of creating a chair that doesn't wobble. Given the frame construction of the chairs, it's easy enough to lay the guide rail across back stile and front leg to trim both at the same time.
I first level the chair using plastic packers on a known flat surface (my table saw bed) and scribe a line around all the legs to make the chair seat sit at 18". .
I also use the TS 55 to cut out my chair seats - with a sharp blade it requires minimal work to remove the blade marks prior to rounding the edges over.
One of the projects that the 2018 Alde Valley Spring Festival is supporting is The Mendlesham Chair Residency with luthier, instrument maker and furniture maker Otis Luxton. The Festival looks after The Suffolk Chair Collection - a design archive of original 19th C Suffolk Ball Back and Mendlesham chairs. Two Mendlesham chairs have been loaned from the collection to Otis and over the next four weeks he is using wood from the farm and local area to explore the design and construction of Mendlesham chairs in order to create a new contemporary version. The Residency workshop is open at weekends - alongside Open Studios of woodturner Jon Warnes and chairmaker Jim Parsons.