Im trying to decide on one of two systems for my Type vii, water tank ballast or piston tank. I'll probably go down the R and D route for both quite a long way before I actually decide as I am still getting the 3D concept of a submarine into my thick head. On this basis, and as I am loath to repeat other's mistakes yet make my own path public out of interest to others who may tread this path, I shll attempt to ensure that my build is "in the open".
When designing the piston tank I have found this company http://www.technobotsonline.com/index.php?dispatch=categories.view&category_id=189
which seems to supply gears. But as far as correct threaded brass goes, will standard "M" threads do the job? I.e. if I used M5 brass rod, will that type of thread be okay?
My initial thinking right now is to have (for each tank) a servo cam drive one of two microswitches - one for "in" and one for "out" on the piston. Add to this two end stop switches and I seem to have two independent piston ballast tanks with capability for fore and aft independent trimming.