Software suggestions and requests

[DoulosDS]

The amount of 'drawback' is IMHO negligible, as it will be an extremely tiny amount compared to how much is needed to raise the fluid level...

You are probably right, however, any periodic irregularity becomes glaringly obvious when viewing the surface quality of a smooth print; e.g. the rocket. Let me crunch some numbers before I conjecture further...

Assume the pump tube has an inner diameter of 0.25" which has an area of 0.049 in2. If the pump roller pinches a section of tube 0.5" long, beginning and ending at 100% open and pinched entirely closed in the middle, we could estimate the displaced volume of the pinch as half the volume normally enclosed by the unpinched tube, or 0.25" x 0.049 in2 = 0.0123 in3. Converting to Canadian units: 201.56 mm3. If the print tank is approximately 3" in diameter or 75 mm, the area is 4418 mm2, and the pinch results in a Z error of 0.0456 mm. A fine human hair is approximately 0.04 mm to 0.06 mm in diameter.

Yeah, that might be negligible, especially in a larger print tank. One way to avoid any error is to force the model slicer to use an integer number of motor turns, divided by the number of lobes in the pump (assuming direct drive by a stepper motor) per slice. The pump should be started and stopped about halfway between pinches. That would eliminate the drip counting system, and the pump could speed up the printing process. If the surface tension and viscosity of the resin is a limiting factor, the pump could transfer sufficient extra brine to ensure all the areas printed previously are covered with fresh liquid resin, then remove the excess brine leaving only the amount required by the slice Z increment. A pause before printing the next layer would allow any resin flow to cease.

I hope the pump and motor can be implemented for less than half the cost of the printer... anybody know where to get an inexpensive peristaltic pump?