How to lower amount of extrusion under the minimum?

[heqe95 2]

Hi all!

I'm using a paste extruder with a 2mm nozzle. It doesn't have gearing so I'm needing about 2,5% of flow to get proper extrusion. Cura however counts under 5% flow as an error. I can make the first layer right by using Initial layer flow, but I'd be interested in making 3D prints with paste.

Stuff I've tried:
-Increasing compatible material diameter from machine settings. (Didn't do anything)

-Setting "initial bottom layers" to 100 so every layer would be initial. (Turns out that there are multiple settings for "initial layers" that are independent, this setting was for shell and the flow setting is independent.)

-Trying to find a way to disable error checking in Cura (no luck yet).

 

So, any other route to achieve less extrusion with Cura?

Thanks for the help!

[P3D 46]

What about reducing the steps/mm for the extruder stepper in the firmware?

[heqe95 2]

The printer is Zmorph VX, haven't found settings for steps/mm in the firmware.

Will try to add instruction in the start of the gcode to alter the steps/mm.

Edited March 12, 2020 by heqe95

[burtoogle 514]

Increase the filament diameter so that will reduce the extruded lengths for lines.

[heqe95 2]

3 hours ago, burtoogle said:

Increase the filament diameter so that will reduce the extruded lengths for lines.

If you meant "compatible material diameter", this didn't have any effect.

But I solved this by adding command M92 to the start of my gcode. (Reseting printer will return extrusion setting back to normal.)

Info for other zmorph VX paste extruder users through Cura:

Right now I'm using code M92 E11 in the start of gcode with a flow setting of 45%.
This is with original 100ml syringe and 2mm nozzle.

Thank you for answers!

[MatheusCCF 0]

@heqe95 I've started to play with Cura on my Zmorph VX yesterday. I had the exact same problems, and tried the same settings that you tested. As you mentioned, nothing change. Today I'm going to try the M92 E11 on my Start G-Code to see if i can extrude properly. I'm going to use a 100 ml syringe  with a 4 mm nozzle. Let's see if it works.

If possible, can you share your experience working with Cura and the Zmorph printer since your last post? 

[GregValiant 1,287]

Another setting you might consider useful is M221.  It's the global flow percentage setting for the printer.  M221 S100 would leave the Evalues in the gcode alone.  M221 S50 would cut all Evalues in half.  So setting the Cura flow to 10% and then putting M221 S25 in your start gcode should give you 2.5% flow.

Edited February 26, 2021 by GregValiant

[MatheusCCF 0]

Brilliant Greg, I'll definitely try that on latter. Now I'm just having some doubts regarding the difference between those 3 parameters: M93, M221 and Flow. 

 

Are they changing the same thing? 

 

Just registering my progress,

 

- The adjustments on M92 + Flow 45% worked perfectly. Fine clay passes through the extruder like butter. However, cement pastes keep segregating from water and clogging the nozzle. I guess I'll have to rework my paste mix. 

 

 

[GregValiant 1,287]

Cura calculates the volume required for an extrusion as {line width * layer height * length-of-extrusion} (there is more to it but that's close enough).  When you put Flow numbers in Cura they are percentages of the calculated volume and it is those numbers that go into the Gcode as "E" values.  Cura knows nothing about steps/mm, only the calculated flow (which in my world is known as Volume and Flow = Volume/Time).

When the Gcode is read by the printer, the printer refers to it's own flow setting and adjusts every (a global change) E value it comes across by the percentage.  If you Tune the flow on the LCD it is adjusted with an internal M221.  It's the same as putting an M221 line into the actual Gcode file, you are asking for a global change and don't care what the settings were when the file was created.  All are adjusted by the printer/planner to the percentage set by M221 whether internal using the Tune Flow menu setting, or as an M221 command in a gcode file.

When you calibrate the E steps for filament you set them so that when you ask the printer to extrude 100mm then exactly 100mm is extruded.  Let's say your calibrated E-steps are 93steps/mm.  If you were to use M92 E46.5 then when a line of Gcode asks for 100mm of filament only 50 would actually be supplied by the extruder motor.  You are fooling the system by deliberately misstating the E-steps to 50%.

You mentioned setting the Cura/printer flow to 2.5%.  That provides 100% flow for your system.  I think it is right and proper to use M92 and adjust the Esteps so you get YOUR 100% flow.  Using my example of 93steps/mm - if you were to set M92 E2.3 then you would be very close to what you want.  That leaves a lot of adjustment both up and down using the Tune Flow adjustment on the LCD.  If you were to put M221 S105 in your Start-Gcode in Cura then when you go to Tune Flow on the LCD you will see it at 105%.  Using the knob you could over-ride that.

I think I'd want a different stepper motor.  A typical printer stepper is 1.8 degree step angle or 200 steps/revolution.  A motor with a .36 step angle is 1000 steps/revolution.  You would be able to tune in finer increments.