how to make a flight of screw
I made a helical surface, extruded up to it, knit surface on that, then thickened the knitted surface. It's probably a little weird in the holes, but perhaps it is close enough for what you're doing.
1. make a swept surface of desired pitch and revolution
2. extrude the outline of the plate up to this swept surface,
3. "knit surface" on the new face
4. "thicken" this new surface (un-check "merge result")