a "7-11 inch" deep slot directly under the seed in the spring may not be "deep ripping" but in heavy wet northern soils in the spring just ahead of planting there are many soils and conditions where that will still be a smeared open slot down under the seed regardless of what rolling baskets etc are used.

We were working with a mole knife in the spring at just 5-6" deep and in some conditions there was crop damage from fertilizer burn or drying from and open smeared slot below the surface.

It may work in some times and some places but there is a risk to spring planting directly over a spring made knife slot of about any normal depth.  Shank type strip till, in the north, is usually best done in the fall.

For building your own strip till machine, depending on the width and fold vs rigid, I would start with a good sturdy, heavy duty often "ridge till" type planter toolbar.

A point to keep in mind is that the success or lack of  in strip till by many of our customers is largely determined by the toolbar they mount our row units to.  I think this also applies to many other manufacturer's  strip till units also.

Jim at Dawn

PS - I have been on this board and its predecessor since about 1995 or maybe 1994 - I didn't write it down. I'm glad you approve.