Make outside of print thinner

I have not been able to make the walls/shell of a print thinner. I have used different Cura but just installed the latest. Cura 4.1.0I amusing Cocoon Create/Wanhow Duplicator i3 V2 printer.

I just changed in Cura Shell Wall Thinkness from .8 to .4 but that did not make the shell thinner.I am printing the attached small Canopy for a mini quadcopter. It is only 40mm/1.5 inches wide.It is currently going around the perimeter possibly twice in width and does a wriggle around the perimeter.

It is probably two rows wide. I am looking for one row wide.Anyone help in making the shell of the canopy thinner?

if you change the wall thickness to the same thicjness as the nozzle - you need to make sure the nozzle extrusion diameter is actually set for 0.4mm. Also that allowing single thick ness walls are selected.

By default most slicers assume that the bead extruded by a 0.4mm nozzle is actually larger than 0.4.
So they won't allow you to print a single shell wall that is thinner than the extruded filament.

The best approach is to actually measure the diameter or the extrdued filament with digital calipers - and set that as the actual bead diameter, and set that as the wall thickness.

I don't like cura and use simplify3d, so no clue where all those settings would be. But that's most likely what's happening.

Thanks curious aardvark for the comments. Much appreciated.

I'll have a go at what you mentioned tonight and advise the outcome.

Just having a few problems with the printer so have not gotten to make the changes to make the shell thinner yet.

One question I have wanted to know for years is when you start a print the head goes to the home position and does the head read the height of the bed or is it just going to the home position to start. Mine is a Cocoon Create/Wanhow Duplicator i3 V2.

I put the yellow film on the bed but sometimes not at the home position. I put diluted wood glue on the film.

Does it matter that I do not put the film on the home position?