Hi Pete,

Cutting the top off the 6 panels above the ramp could create some issues:

-The ramp sectors would become the top of the cyclone casing, so they would need to be 100% sealed on every edge to avoid sucking in air. They would need to be strongly joined to withstand the atmospheric pressure when the internal vacuum is on.

- The cyclone outlet tube would only be held in place by the ramp, so the circular helical hole formed by the inside edges of the ramp pieces would need to be accurately cut and securely joined to the outlet.

If a flat hexagonal top was used above the ramp, air sealing would be easier and the outlet cylinder would be simple to secure.
This would also eliminate the need for an air seal on the inside edges of the ramp pieces.

The beveled edges of the 6 casing panels would create a gap when the panels were laid out flat, causing a slight mismatch when trying to rule a line for the slope of the ramp.
This could be overcome by using direct marking : hold 2 pieces with edges together and mark where the the line crosses the edge of piece 1 onto piece 2.

Bill Pentz strongly recommends making a cardboard model before starting work on the cyclone. This would be even more instructive for a hexagonal construction, and would give a preview of any issues which would arise.
It is much easier to cut cardboard and refine the design before cutting wood or metal. This would save time and probably produce a better result.
The model could be full size if you have suitable material, and the pieces could then be used as patterns for the wooden version.
A smaller scale model would still give a better appreciation of the issues before starting construction.

Rob