Ok,
The D-swirl has had a facelift over the weekend. In fact it went through a complete redesign. Its 100% my design. The new design is much better and can handle alot more flow. There is no linkage to bind and is not limited in rotation. Its adjustable 90/L 90/R 180/F 180/R and of course 360.
There is no funky link arm and no orings, just one special easy to get seal.
You will have to have good well adjusted router table, table saw and drill press. All must be adjusted so that their tables are perfectly square to the blade/bits.