@chrishamm Thank you for your response.
I will adapt the T parameter of M669 and see how it works.

Hello everyone,

I am currently working on a 3D printer that utilizes a Duet control board to print objects by layering mortar material extruded from a nozzle. I am facing issues with the line width of the extruded mortar and need help from the forum to address this problem.

The mortar material is pumped through the nozzle, but the flow rate from the pump is not constant, resulting in some fluctuation. To address this issue, I plan to measure the flow rate of the mortar and linearly control the nozzle's movement speed to match the pump's flow rate.

However, I am having trouble achieving this real-time linear control using G-code. For example, with a G-code like:

G1 X0 Y0 Z0 F12000
G1 X100 Y0 Z0 F12000

I cannot linearly control the feedrate between X0 and X100 based on feedback. I am looking for a solution that allows me to adjust the F value with good responsiveness and in real-time. Any suggestions or guidance would be greatly appreciated.

Thank you in advance for your help.

@t3p3tony Thank you for your response.

So if I am using Duet3 in SBC mode, then
1,Duet3 control function can be obtained by Raspberry Pi.
2,If I create an OPC-UA plug-in for Linux and run it on Raspberry Pi, I can upload the Duet3 control functions to OPC-UA. (Export)
3,If you create an OPC-UA plug-in for Linux and run it on Raspberry Pi, you can control Duet3 according to the function obtained by OPC-UA.
Is my understanding correct?

If I understand correctly, I would like to create an OPC-UA plugin for Duet3 in SBC mode.
If you have detailed information on how to get Duet3 functions in SBC mode, please share it with me.
Thank you in advance.

Duet3 supports data acquisition via html and Can communications. Is there a way to support data acquisition with OPC-UA in the future, or are there any plans to do so?

My lab uses OPC-UA to manage sensors and some machines. I would like to integrate and manage the Duet information in OPC-UA.

Thank you!
Your answer is correct. I just enabled the pull-up resistor and it works correctly!

In addition to the pull-up, I also changed the connection of all end stop switches from normally open to normally closed, modified M574, and added M671.

After correction: [M574 Z1 S1 P "ystop+zstop+xstop+^exp.e2stop"]
(did not work correctly in normally open state, only exp.e2stop pin)

Thanks to you, my printer works perfectly!

Thank you for opening my question.

My printer has 4 end stop switches on the Z axis.
The Z axis end stop switches are X STOP, YSTOP, ZSTOP and also E2_STOP (exp.e2stop) on the EXPANSION pin. (X axis Y axis uses E0, E1 Stop pin)

X STOP, YSTOP and ZSTOP are working properly, but E2_STOP pin is not stable. (It turns ON or OFF even when the switch is not pressed.)

If anyone knows the solution, please let me know.

Info
The board I'm using is Duet2wifi and I'm using firmware 3.1.1.

I have added the following Gcode
M584 X5 Y6 Z8:9:10:11 E7
M574 Z1 S1 P"!ystop+!zstop+!xstop+!exp.e2stop"

The end-stop switch utilises a simple normally-open contact switch.
(Changing to a normally-closed switch and modifying parts of the Gcode did not solve the problem. (!exp.e2stop -> exp.e2stop))

There is a tiny voltage (1.4v) coming from exp.e2stop, which we think is the cause of the malfunction. However, I do not know any means to cut off the minute voltage.

@bearer
Thank you very much.
I now understand that I had only a fossil knowledge of arduino.
I would like to buy and test the Teensy that you suggested.

@theruttmeister
I have taken your suggestion to measure the pump extrusion per 30 seconds.
Specifically, I input a constant control voltage and measured the amount of extrusion multiple times during the 30 seconds between turning the pump on and turning it off. (This test was carried out with several control voltages).

The results showed a maximum error of 5g.
(I don't know what the error would be if the pump had acceleration/deceleration control...)

This means that the number of revolutions per unit time of this pump is constant!
We did it!

@theruttmeister
Thank you theruttmeister for your kind reply.

I would like to share an overview of the pump I use and the printer I make.
The PCPump I am using is a "MAI 2PUMP-PICTOR" and it is driven by an induction motor.
(The motor is made by "ABM Greiffenberger" and the model is "G80F/4D80E-4". According to this sheet "http://abm-plauen.com/file/1383_tl2_eng.pdf", the maximum torque is 49Nm).
This pump can control the speed with 0-10v input.

My 3D printer is a construction 3D printer, it extrudes mortar from a nozzle and laminates it.
Search for "construction 3d printer" and you'll get an idea of what I'm working on. (I'm making it in my garage, so it's much smaller...)
The mortar is pumped by a PCPump and extruded through a 20mm diameter circular nozzle. The layer height is 10 mm. (The hose length from the pump to the nozzle is about 5m)

@bearer said in How to use a PCPump as an extrusion device.:

I would think the "simplest" would be to add an encoder and write an arduino like sketch to act as a stepper driver - it has the benefit of not needing to maintain a fork of the reprapfirmware; and I'm pretty sure I've some instructables or youtube videos with people making cnc stuff with dc motors and diy encoders so with abit of luch there is some code out there on the interwebs.

Thanks for the answer.
I have the same idea if using a DC motor.
I used Arduino Uno for this control signal conversion, but the processing speed was too slow for an 8-bit microcontroller to give me the response performance I wanted.
I made a prototype of the control signal conversion program in Mbed and got good responsiveness.
If there are other folks doing something similar, I would like you to share the link with me. Thanks.