Clay 3D printer Extrusion calculation

[BBogdan 0]

Hello, I am student of fine arts in Belgrade. We have made massive clay 3D printer which uses Cura slicer.

 

Extruder is stepmotor with auger and pressure tank working on 4-6 bar (depending on nozzle size and clay moisture). Material thickness is left to 2.85 and flow is 30-60% depending on nozzle and clay moisture. That is working perfect and its fine tweakable with pressure inside tank.

 

What is problem? Long straight lines:

 

For example making half cylinder. Circle part would go perfect. Straight flat part won`t be printed. If you look at Gcode curcular part would be made of a bunch of code lines where it would extrude (for example) 2 then 4, then 6 and so on. When it comes to straight part, it would want to extrude value of 20 in one line of code. In reality head just pass over that segment but with increased speed as it is travel movement. In slicer preview it looks like it is normal extruded line, not a travel movement.

 

I can fix this by tweaking model itself to force it to generate Gcode of flat surfaces in a more of smaller steps.

 

Problem is for example with portrait, if you want to have auto generated infil, it would not print parts of grid that is longer than for example 10cm(I dont know in Gcode which extrude value is that yet).

 

I have attached one Gcode (for example check lines 299-300   365-366).

 

Is there any limitation of amount of extruded material per line of code or? Why is this happening and how to solve this? Thank You!

Edited September 15 by BBogdan