Once we had a decent working opening to the basement, I made my fourth and last iteration of the plan for the staircase with the actual opening dimensions. This is where the parents saw it starting to pay-off: we bought for 250€ worth of nice heart pine boards (five 2m40 by 60 cm) to build the whole thing, and I got the sister involved in helping me out to cut the lumber into the needed parts.
crazy sist kept seeing funny critters in the boards’ patterns ;) we aren’t a family of artists for nothing!
I made the stairs in blocks of two, using the grain direction to add extreme strength where I needed it to be and keep the vertical walls/supports to a useful minimum. The steps are 20 cm deep each, and once the dados and endgrain supporting portions are taken out we remain with ~35 cm wide cabinets for the shelves, which has proved to be perfect. I used glue, screws and dowels to secure each pair of steps to the connecting things which name I don’t know in EN (“contre-marche” en français, baby)
You can see that all the horizontal rails are supported on the endgrain of the vertical separators. Those are heavily screwed in place and don’t move at all.
This last picture shows the last two steps, which form a 90 degree angle to the right while keeping a 60 cm wide step size. This block will also be used to hold the ventilation system and the control computer (I’ll use one of our old laptops with a USB sensors and control board). The staircase is installed in the left side of the basement, and the right side wall is fitted with wooden shelves with plywood backing boards, and to prevent moisture from developping I installed computer fans between the wall and the backs to move the air, and it works great.
Here you can see all the finished parts ready to be installed in their home. I’ll take pictures of the finished basement this summer when going back there.
-- Pondering the inclusion of woodworking into physics and chemistry classes...