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Help modifying Marlin - Syringe Extruder

Posted by Jrowell27 
Help modifying Marlin - Syringe Extruder
May 08, 2021 06:48PM

I am modifying marlin so I can run a syringe on my printer. I will use pin 13 to turn on and off a solenoid valve that will control the syringe. What is the best way to have pin 13 turn on and off instead of having the extruder stepper turn?
Re: Help modifying Marlin - Syringe Extruder
May 09, 2021 04:35AM
... I'm using the extruder motor to move the syringe-piston or the extruder STEP-pulses to control a paste-jetter -- so there is no modification and the dispensed/jetted media amount is totally synchrone with moving speed and path length ... otherwise you'll get "bumps" at line start and end, or you have to move so slow, that no acceleration occurs ...

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Re: Help modifying Marlin - Syringe Extruder
May 31, 2021 04:24PM
I wanted to bump this thread in case anyone searches for it and could benefit from finding out what my solution was.

I used two solenoids to control air pressure from my compressor to my syringe. One solenoid is used to control air pressure going to the syringe, the other solenoid is used to vent the syringe when the extrusion is finished. I used a nordson efd syringe. Kinda pricey but it’s good quality. In order to control the extrusion rate, I installed an air regulator upstream of both solenoids.

I used the enable pin logic to control my solenoids by making the following changes to the firmware:

In the appropriate “pins” h file I set my E0_ENABLE_PIN to pin 12 which is wired to my extrusion solenoid. My venting solenoid is wired to pin 13.

In Configuration.h, I defined E_ENABLE_ON as 1, DISABLE_E as true, and DISABLE_INACTIVE_EXTRUDER as true. This makes pin 12 high when the extruder should be running, and makes pin 12 low when the extruder should be off.

In order to make pin 13 vent at the appropriate time, I set up an if statement at the beginning of the main marlin loop that sets pin 13 to the opposite value of pin 12.

So far this has worked for me and I hope this helps someone else at some point.
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