Today I continued on with some more planning for the helix. I settled on a method of securing the sections together that is both easy, quick, sturdy & cheap by using stitching plate & stitching screws.
I also checking the position of the helix in relation to the layout framing and also the radius again. The diameter of the helix fits within the confines of the bench work as can be seen by the black marker on the floor, this is the edge of the fascia above. The radius will stay at 28"R.
I have ordered a large sheet of 12mm (1/2") structural plywood and will begin cutting out the segments tomorrow. Once I have one (1) full ring made and the sections joined together I will setting the initial grade and working out how much alterations will be required to one section of layout bench work supports.