Quote Originally Posted by Slatye View Post
Hmm, not quite sure that I fully understand that bit. I was assuming that you'd have an O-ring around the bottom of the main tank so that the "printing water" (in that tank) is completely separated from the "support water" (in the lower cylinder). You use up the support water, but the printing water remains fixed so you've got a constant volume of that. This should just result in the green cylinder/piston moving down, lowering the print bed into the printing water and resin.


Regarding the weight, there are two problems with making it really heavy. One is obviously that it'll be a pain to ship it - you might have to ask end users to attach big steel bolts or something to make it heavy enough. The other is that there'll be a lot of pressure in the support cylinder which makes it difficult to find a suitable valve setting. Still, it might be that this is just what has to be done to make it work. It'd be a small price to pay to get a nice printing platform.
slatye..... there is no problem with the user adding the weight, so it is not shipped. You will see with your sketch that the volume in the tank will drop as the platform drops.... the whole concept is that the level in the tank does not drop.... therefore the expelled volume must be into the tank, so that the level in the tank does not change. The heavy weight takes friction out of the equation, and to compensate, the orifice is quite small.