Lyle uses a “D” shaped handle torque arrest method because it spreads out the considerable twisting forces with a broad brush. When the cutter is positioned around to the left to undercut a shoulder or reach into that hard to reach spot through a small hole, the torquing forces can get intense. Lyle wants the fingertip control to clean up tool marks and smooth the inside contour of the vessel.
It can’t get any easier. The Jamieson system allows you to stand comfortably in front of the lathe with fingertip control to reach any desired hollow form shape. No need to get a stiff neck and sore back leaning over the lathe looking into the entry hole. No need to sit on the lathe and hang onto the handle with a death grip. It is all about the fun. You do not need to work hard hollowing any more.
An ongoing difficulty of woodturning has been the ergonomics of getting the hollowing tool into the vessel. Traditionally, a turner would have to bend over the lathe during hollowing. This position is often hard on the back and can cause damage to back and neck muscles over time. This problem is further antagonized by the need for proper tool placement to achieve a perfect finish. It was this problem that led Lyle to create the Jamieson Hollow Form Turning System for safer, in-control hollowing that is fun, too.