Posts made by Twigz

@deckingman said in problem with switching to seperate Z axis drivers:

@Twigz said in problem with switching to seperate Z axis drivers:

@Phaedrux said in problem with switching to seperate Z axis drivers:

@Twigz said in problem with switching to seperate Z axis drivers:

i plugged the X axis into the z motor to confirm the motors are ok and this works as it should rulling out defect motors.

Can you describe your test a little more? Which motor did you connect to which driver?

the X axis motor is close to the left Z axis motor, so i switched the connectors around so an input on the X axis would result into a movement on the Z axis and visa versa.

The result is when i try to move the X axis via the webpage it moves up and down without any issue. no vibration and no weird noises.
On the other hand the X axis then displays the same issue where it vibrates but does not move.

jeff

If I've read that correctly, it's the motor or the wiring between the Duet board and the motor. Possibly a bad crimp?

i went ahead and replaced the cables today and that resolved the issue. i don't know how the cables went bad but either way its fixed.
Thanks a lot to you and others for the suggestions.

jeff

@deckingman said in problem with switching to seperate Z axis drivers:

@Twigz said in problem with switching to seperate Z axis drivers:

@Phaedrux said in problem with switching to seperate Z axis drivers:

@Twigz said in problem with switching to seperate Z axis drivers:

i plugged the X axis into the z motor to confirm the motors are ok and this works as it should rulling out defect motors.

Can you describe your test a little more? Which motor did you connect to which driver?

the X axis motor is close to the left Z axis motor, so i switched the connectors around so an input on the X axis would result into a movement on the Z axis and visa versa.

The result is when i try to move the X axis via the webpage it moves up and down without any issue. no vibration and no weird noises.
On the other hand the X axis then displays the same issue where it vibrates but does not move.

jeff

If I've read that correctly, it's the motor or the wiring between the Duet board and the motor. Possibly a bad crimp?

i dont think it is the motor as they do work on other drivers, i didn't touch any cables but i will check the cables and see if they are alright.

edit: i think you're onto somthing, i now used the x axis wiring on E1 and this works flawlessly.
placing both Z axis motors on Za and Zb again now works and moves the z axis but is just very noisy, getting closer
jeff

@dc42 said in problem with switching to seperate Z axis drivers:

What happens if you connect the Z motors back to the Za and Zb connectors, then connect the X motor to the E1 connector, and change the M584 command to:

M584 X4 Y1 Z2 E3

Does the X axis move normally?

i just tried connecting driver E1 to the X axis and it has the same result. connecting it back to Za and Zb also doesn't work anymore and gives the same result.

jeff

@Phaedrux said in problem with switching to seperate Z axis drivers:

@Twigz said in problem with switching to seperate Z axis drivers:

i plugged the X axis into the z motor to confirm the motors are ok and this works as it should rulling out defect motors.

Can you describe your test a little more? Which motor did you connect to which driver?

the X axis motor is close to the left Z axis motor, so i switched the connectors around so an input on the X axis would result into a movement on the Z axis and visa versa.

The result is when i try to move the X axis via the webpage it moves up and down without any issue. no vibration and no weird noises.
On the other hand the X axis then displays the same issue where it vibrates but does not move.

jeff

@Phaedrux said in problem with switching to seperate Z axis drivers:

I think you're going to need to add the second Z driver to your M906 command because right now I think it may be using the motor current for the extruder.

Try M906 X900 Y1200 Z900:900 E700 I50

i tried as you suggested, the issue remains the same, it just makes a bunch of noise and does not turn.
Using a different motor makes the same noise with no spinning of the motors.

one thing i noticed is that after i tried to move the Z axis one side is resisting movement while the other side is spinning easily.

i dont know what changed to cause this behaviour, i only took the plug from the second Z connection and placed it onto the E1 connection and then used the jumpers on the Z connection.
besides that i updated the firmware but i dont think that would make a difference?

jeff

@Phaedrux said in problem with switching to seperate Z axis drivers:

If you send M906 in the gcode console, what does it reply?

Thanks for your help, it replies with the correct values:
M906 X900 Y1200 Z900 E700 I50

It is also at 100% current.

Jeff

i forgot to add that before i made the switch i changed to the latest stable firmware on the duet as well as the browser, i dont know if that has any influence?

jeff

i am trying to switch from 2 motors in series on the Z driver to 2 serperate drivers on my cr10 with duet wifi.
i've connected the motors to the Z driver and to E1 and set it up in the config file but when moving the Z axis it just vibrates. i plugged the X axis into the z motor to confirm the motors are ok and this works as it should rulling out defect motors.

can someone check if this file is correctly set up?

G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"cr10" ; set printer name

; Drives
M569 P0 S0 ; physical drive 0 goes backwards
M569 P1 S0 ; physical drive 1 goes backwards
M569 P2 S0 ; physical drive 2 goes backwards
M569 P3 S0 ; physical drive 3 goes backwards
M569 P4 S0 ; physical drive 4 goes backwards

M584 X0 Y1 Z2:4 E3 ; two Z motors connected to driver outputs Z and E1
M671 X-20:520 Y0:0 S0.5 ; leadscrews at left (connected to Z) and right (connected to E1) of X axis
M208 X0:450 Y0:400 ; X carriage moves from 0 to 450, Y bed goes from 0 to 400

; Axis Limits
M208 X0 Y0 Z0 S1 ; set axis minima
M208 X450 Y400 Z400 S0 ; set axis maxima

M92 X80.00 Y80.00 Z400.00 E476.50 ; set steps per mm
M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation
M566 X300.00 Y300.00 Z12.00 E120.00 ; set maximum instantaneous speed changes (mm/min)
M203 X3600.00 Y3600.00 Z900.00 E1200.00 ; set maximum speeds (mm/min)
M201 X300.00 Y300.00 Z20.00 E250.00 ; set accelerations (mm/s^2)
M906 X900 Y1200 Z900 E700 I50 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Endstops
M574 X1 Y1 S1 ; set active high endstops
M574 Z1 E1 S1 ; set endstops controlled by probe

; Z-Probe
M558 P8 I0 R0. 4 F300 X0 Y0 Z0 ; set Z probe (digital mode, NO/NC, delay, speed, not used as axis endstop)
G31 X0 Y0 Z-0.1 P100 ; set Z probe trigger value, offset and trigger height
M558 H30 ;*** Remove this line after delta calibration has been done and new delta parameters have been saved
M557 X50:400 Y50:350 S20 ; define mesh grid

; Heaters
M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit
M305 P0 T100000 B4138 R4700 ; set thermistor + ADC parameters for heater 0
M143 H0 S75 ; set temperature limit for heater 0 to 75C
M305 P1 T100000 B4138 R4700 ; set thermistor + ADC parameters for heater 1
M143 H1 S230 ; set temperature limit for heater 1 to 230C

; Fans
M106 P0 S0 I1 F25000 H-1 ; set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off

; Tools
M563 P0 D0 H1 F0 ; define tool 0
G10 P0 X0 Y0 Z0 ; set tool 0 axis offsets
G10 P0 R0 S0 ; set initial tool 0 active and standby temperatures to 0C

; Custom settings
M564 H0 ; Allow movement before homing

any help is appreciated,

jeff

I wasn't completely sure on how the k factor was applied so I searched and found this:

actual_extrusion_speed = requested_extrusion_speed + (K * current_extruder_acceleration)

If you apply non linear extrution, the acceleration would ramp up slowly to accommodate for the multiplier and stay at the requested feed rate when hitting the maximum speed. (requested x multiplier from non linear extrution). If setting up the pressure advance before the non linear multiplier it would mean the result of the formula above is increasing with the multiplier and the advance would turn out to high.

Therefor I would think the non linear extrution needs to be set up first. To create an accurate extrution at all nozzle pressures.
Then set up the pressure advance to control the nozzle pressure when starting and stopping.
In theory you would then only need a tiny bit of retraction to pull the filament out of the melt chamber to stop oozing.

Any thoughts?

Jeff

@deckingman
I'm the guy that asked your help a bit earlier regarding my custom printer.
I have a 6 Input custom hotend design and when going up to higher feed rates with 6 inputs the pressure increases so drastic that indeed it gets more difficult to push the filament through, causing some degree of slip. When the design was adjusted for direct extrution (4cm bowden tubes) with a 20:1 ratio it seems I could get more pressure and thus more slip than with the bowden which would make me believe that buckling in a bowden tube is a real thing. Maybe your short tubes are still to long and have too much buckle compared to direct drive and thus the extruder doesn't slip as easy?
So I don't think non linear extrution is misplaced. But it is only needed in specific cases.

thinking back to the video you made regarding nozzle pressure wasn't the amount of pressure advance needed at high speeds greater than at low speeds? ( I believe 0.5 was good on the 300mm/s and 0.2 had better result on the lower speeds?)

At the lower speeds having a travel move would still have filament oozing out while on the higher speeds this was almost rectified without the use of retraction with a 0.5 pressure advance.

That would lead me to believe that we also need a non linear pressure advance to be effective on all feed rates. I would think this graph would show the same trend as the non linear one?

That would effectively rule out any need for retraction as well since both your feed rate and pressure advance are calibrated over a range of speeds. Laying down the layers as requested by the gcode?

Just a thought

Jeff

@remopini you can also try to turn the bltouch 180 degrees. I had mine too close to the hotend and it acted up. Turning it around meant the board was further away from the hotend and it worked flawless.
Maybe the all metal aero has some influence?

@remopini as stated in the second post, you can set a different spacing (more or less points) for your mesh and avoid the spot all together. This will probably be a bit of trail and error.

You can take 5 step/dir signals from the expansion header and 2 from the lcd plug for a total of 7.

What you could do is use logic gates to split the step/dir signal and feed them into multiple seperate motor drivers. This would fix your need for drivers as well as open up some slots.
A guy on another thread did this but didn't really go into detail how Soni figured it out myself.
I'll do the same once I'm at the stage of wiring

As I understand there is a new version of the duex underway without the drivers. May be an idea to wait for this to come.

After some more calculations and thinking i figured the reverse might be beneficial as a replacement for jerk. To stop extreme shaking and ringing the best would be to get to a full stop before changing direction.
In this case reversing the above formula to jerk=jerk*(SQRT(T/Factor)) would start from a stop with a high acceleration where the acceleration increases exponentionally less.

You could then finetune the jerk for sharp corners and direction changes after which you can tune the acceleration to the max your printer is capable off.

I made some Ghraps to show what i mean in the hopes of it making things more clear in my explanation.

EDIT: When the jerk speed has been reached it would continue using acceleration instead.

jeff

Good morning

I've run into a problem that may or may not need a s curve.

I'm driving the x and y gantry with a brushless/ encoder + lead screw setup and am able to get speeds up to 1mtr/s.

The whole hotend assembly is rather hefty at 0.5 kg. At quick direction changes (corners of Infill at 45 degrees in a cube) it shakes uncomfortably much and I have to reduce to 500mm/s^2. At this acceleration it would take 1.5 seconds and approximately 500mm to get to its maximum speed.

I did some tests and when printing a corner in a radius of 75mm an acceleration of 10.000mm/S^2 even seems reasonable
My thought would be that the slower ramping up is what is causing this improvement. (as the direction turns from x to y the y gantry has to move exponentially faster)

At 10.000mm/s^2 it only takes 0.07 second and 25mm to get to its maximum.
If we interpolate between the two that gives 0.75 seconds and 262mm to obtain maximum speed. (in reality this would only be 25% quicker) this could decrease the overall print time on long complicated prints by quite a lot.

I think printers with either a high capability of speed or a heavy hotend assembly will greatly benefit from a ramping acceleration/deceleration.

I don't know if this is easier to setup than a s curve but perhaps it would be an idea to multiply the acceleration by time and by a factor in time to reach the max acceleration.
In this case we could ramp up to 10.000mm/s^2 in 1 second and it would look like this:

Acceleration = (acceleration*((t/factor) ^2))

After 0.1 seconds:
Acceleration= (10.000*((0.1/1) ^2)=100mm/s^2

After 0.5 seconds:
Acceleration=(10.000*((0.5/1) ^2)=2500mm/s^2

After 0.75 seconds:
Acceleration=(10.000*((0.75/1) ^2)=5625mm/s^2

After 1.0 seconds:
Acceleration=(10.000*((1.0/1) ^2)=10.000mm/s^2

Ramping up to 5000mm/s2 in 3 seconds:

After 1 seconds:
Acceleration= (5000*((1/3) ^2)=555mm/s^2

After 2 seconds:
Acceleration=(5000*((2/3) ^2)=2222mm/s^2

After 2.5 seconds:
Acceleration =(5000*((2.5/3)^2)=3472mm/s^2

After 3 seconds:
Acceleration=(5000*((3/3) ^2)=5000mm/s^2

Applying the same formula to the extruder would also ramp the extruder to not create under or over extrution during the ramping up.

I've never heard of issues caused by the jerk between acceleration and max speed so this may or may not be a problem.

Keeping acceleration and deceleration seperate would lead to even more tuneability as acceleration tends to be able to be a little bit higher.

Jeff