Swapping traditional extruded with solenoid valve

Hello everyone,

This is my first post here and I'm looking for some knowledge. I am doing research that involves extruding a liquid rather than filament. To do this, I am swapping out the extruder for an electronic solenoid valve. The valve is controlled by a spike and hold driver that receives 5V TTL signals from the board. I want to operate the solenoid according to the traditional g-code at a certain flowrate milliliters/second, which corresponds directly to pulses/second. I would like to know what the best way to accomplish this is.

Can I just limit the current limiting stepper driver to 5V?
Can I take the stepper driver off and just run a jumper from a 5V and a ground pin?
If I did it either of those ways, could I still execute the program the same as with a traditional 3D printer extruder but with an adjusted mm/s?
Would I be required to run my jumpers directly from the micro controller rather than from the shield?

Thanks,
Adam

Hi Adam,

I've developed a Piezo-driven pastedispenser with a common mechanical setup, ArduinoDue+RADDS for electronics, Marlin4Due firmware and heavy modified Pronterface for controlling/printing.
Posted here (in German) the progress with some images and videos - especially on the next pages - [forums.reprap.org] )

The valves are controlled by TTL-pulses (up to 3kHz max.) and the dispensed volume is defined either by pulses/pad (many droplets on the same position) or by pulses/mm for lines with varying width. The volume per drop can be set with the controller too, but I'm using the pulses/pad for this ...

The controller needs "inverted" 5V pulses with min 5µs pulse width, while the ArduinoDue gives 0,5µs long pulses with 3,3V -- so I've fed the extruder motor step pin through a 74HCT123 "monoflop" to define a longer pulse width and set it to 5V.

Wouldn't be a problem to define longer (or "endless") pulses with the first pulse of a line and reset the output with line end, but then you'll need another analogue pin to define the volume rate per time ... the pulse-driven volumetric output is simpler and conform to common FDM-3D-printing ...

Edited 1 time(s). Last edit at 11/10/2016 12:08PM by VDX.

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Viktor
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