control 4 axis cnc machine

Heisl

Hello everyone,

first about me. I am a mechanical engineering student and I am currently working on a project involving winding resin-soaked carbon fiber onto a cylinder. These are later the basic body of a model rocket.
Our machine has two linear and two rotary axes. The linear axis X travels along the cylinder and the second linear axis travels towards and away from the cylinder. The rotary axis A turns the cylinder and the other rotary axis B turns the guide head of the carbon fiber.
We have a Duet3D - 6HC board and a PanelDue display for control. RepRap 3.3 is installed on the board. The machine works in CNC mode with the M453 gcode.
The question I have for you is, does anyone have experience with such a control? How are the rotary axes controlled? step/mm or step/degree? Is CNC modus the right modus for the machine.
The linear axes work great and do everything that we specify via gcode. We only have problems with the rotary axes. Can someone help me there?

Many Thanks!!
Matthias

3DPMicro

@heisl filamemt winding, eh? Yes, CNC mode is correct. Its really steps per unit. Those units can be whatever you want them to be. It's been a couple years since I used the 4th axis rotary on my mill so i will have to go back and see how i had the FW and gcode set up. I wasnt doing any simultaneous 4th axis, just using it as an indexer. What software, CAM are you using or are you going to piece the gcode together yourself?

Heisl

@3dpmicro Right, filament winding. Ah ok, so step/unit means it doesn't matter if I choose step/mm or step/degree!?
Well, the gcode is created by "x-winder design" software. But for the first, we have our own gcode to to adjust the config.g file for reprap 3.3.Once all settings are fine, we let "x-winder design" create the gcode for the winding.
Thx for your answering!

3DPMicro

@heisl cool project. Post a picture of your finished product if you get a chance

Heisl

@3dpmicro Sorry for the late reply, something went wrong. My answer was not published a week ago and I was wondering why no email came about it.
So now again.

Thank you, yes that is really an exciting topic that we have here. I'll ask our professor if that's possible

We have another problem. The B-axis (a rotation axis, which the cfk-filament runs along to the cylinder) can only be homed once. With further homing, the axis is misaligned more and more. Homing only works as it should after a reset.
Any idea why that might be?
The B-axis gcode is the same as for the other axes where homing always works.

Furthermore, we would like to see in a live script on the duet paneldue (display) in which line of gcode the machine is currently working. Does anyone have a solution as to how or which gcode is used to solve this?

Thanks again for your answers

...I am attaching the gcodes here...
config.g
homea.g
homeb.g
homex.g
homey.g
homez.g
homeall.g

3DPMicro

@heisl is it possible the B axis is skipping steps. I cant think of any reason for your home issue other than the axis not being calibrated correctly but that should repeat.
I have been using a host called Repetier host to control my 3d printers. It allows me to control it on the fly and also shows the line of g-code it is reading. There are other hosts out there that probably do the same but that's the only one (since 2013) I've ever used. It's for 3d printing but maybe it could be useful. There is also Chilipeppr which is a cnc milling interface. It may do something useful if you load your gcode in to it. There may be a better chance of tweaking that than Repetier.
How many rotations does your B axis need to turn to run a complete winding cycle?

SpoonUnit

@heisl Is the B end stop a physical switch and do you rely on an inability to rotate beyond a specific point based on the machine design?

Heisl

@3dpmicro Now, as you can see in the next picture, there isn't much torque on the B-axis for skipping a step. Of course, the stepper motor could also be defective. But we're not assuming that for now. Yes, the error repeats itself. First homing after restarting the machine works. If you press homing again, the axis moves by 3-4 degrees. And that every time you continue to press homing. Really strange...
Yes, we have already thought of another host, but unfortunately this project will be over for us at the end of July, so there is no time for a new host

The B axis can rotate a maximum of 340 degree. In operation it should (depending on the direction of travel of the x-axis) only ever move back and forth by a few degrees. It only controls that the filament is wound onto the cylinder (A axis) in a defined position.
Here's another picture with a caption. (in purple you can see the way of the filament)

Thank you for the reply

Heisl

@spoonunit Yes, the Endstop of the B-axis is at a physical switch. Not really, the B-axis should only turn back and forth a few degrees during operation.

Heisl

...here is a further problem with the Duet3D PanelDue 7i that we don't understand to solve:
https://forum.duet3d.com/topic/24040/delete-y-axis?_=1658297009772

Many thanks!!!

o_lampe

@heisl The stepper of the B-axis has a gearbox which might have backlash? This error could add up everytime you home...

Heisl

@o_lampe Hm, well I din't think so. Cause the Y-axis Stepper also have a Gearbox. (the same) And there is no problem with the homing.

Heisl

Finished! We solved our Problem with the Homing. The Problem was the Wire of the Stepper. We had to shield them. Now the Homing does its Job as well!

Thanks for all your ideas and help!!