Extrude without a Hotend

Hello RepRap Community.


I am not very experienced in coding and 3d printers but i am eager to learn.
so i bought a diy 3d printer (a prusa i3) and it was a success. However, now i want to make it in to a paste extruder.
the thing is i have been struggling to change the code so the extruder motor would work without a hotend. as in use the extruder motor to drive the syringe.
its getting really frustrating now
if there is anyone who knows what im doing wrong or have any advice i gladly welcome them
thanks

Edited 1 time(s). Last edit at 05/01/2017 11:10PM by Viko.

You can use a simple g-code command to allow cold extrusion. (dont let the name fall you, g-code is not coding just machining commands)

M302 P1 ; Allow cold extrusion

Just enter the above code from your host software (pronterface or repitear) and you should be good to test the paste extruder.

Here is a handy list of g-code commands [reprap.org]

Hey Scotty,
Thank you for the reply i sure did try that but when i enter the Gcode for cold extrusion it says "sending.." and thats about it. However, other Gcode commands work fine.. for instance homing all axis and all..
i wonder whats wrong with this.
So, lets say even if i get this working (Thanks to your help) how can i control the extrusion via RAMPS 1.4 with out the hot end attached. Like say i want to print something, and X. Y, Z steppers work fine.. will the E0 extruder work like normal without the hot end? or is this just a one time command to test the E0.

Sorry if i sound dumb xD but this is the only hope i have in figuring it out.
Thank you for your time Scotty

Edited 1 time(s). Last edit at 05/04/2017 11:26PM by Viko.

odd that it just displays sending, Do you know what version firmware you are running?

Yes this would be a one time solution, you could include it at the start of your g-code.

Once cold extrusion is enabled the printer will not wait for the hotend to reach temp so yes the E0 will work like normal.

If you dont like that idea then you can modify your firmware, all you should need to change is min extruder temp from something like 170 to 0

#define MIN_EXTRUDER_TEMP 0

To be honest with you I have not looked much into past extrusion but there is a sub (http://forums.reprap.org/list.php?180) that is dedicated to paste extrusion, have a read around and you might find some info. Also have a google, lots of people have added paste extruders like RichRAP [richrap.blogspot.com.au]