i have noticed that, while printing fast, different patterns in X and Y start appearing. the patterns on the print wall parallel to the Y axis resemble that of a longitudinal wave, while the pattern parallel to the X axis resembles a transverse wave. I hope one can see the compression and stretching in this pic. I added the sketch to make it easier to visualize.
The transverse wave is easy to see in the top, horizontal aprt of the print.

After thinking it could only come from the bed, where the plates that hold the bed are only 2mm titanium and can flex in the Y axis. Unfortunately this is also the direction in which the heavier gantry rides, further amplifying the paper stiffness problem.
I already had plans of replacing that 2mm titanium with some 6mm stainless steel, but i ran into problems. Also, this would only reduce the problem, not totally eliminate it.
Active damping the bed is not easy due to the chamber temperature, adding another guide is also impossible due to space restraints.
This video inspired me:
https://www.youtube.com/watch?v=Ofg21LDNxdU&list=PLV4isz0nRXU3GnEECwNQKYsIve-Zo85Ks&index=39&ab_channel=RogierdeHaan

I wanted to see if this would work in the real world. I am very aware of the force cancellation test that deckingman made, however i saw some flaws.

1. He ran very low acceleration and jerk settings (like 500mm/s²) so there was nothing to really exacerbate the effect and no way to be able to easily see it.
2. the cancellation weight was on the wrong plane. He assumed the frame to be infinitely stiff, and the floor make a pivot point around which the higher up position of the cancel gantry would cancel out the forces from the print gantry due to the lever effect. However i believe those assumtions are not valid.

So, after some thinking i came up with a dynamic force cancellation design of my own.
Fortunately i built a basic cartesian machine with separate belts for X and Y. So i tapped directly into the "returning" belt path. I installed two MGN12 rails onto which i bolted 3kg of steel each. 6kg is roughly what my gantry weighs. I gave it my best effort to make the center of gravity of the steel weights the same height as the gantry.

Here are the tests. Same Gcode, on the left without and on the right with the weight.
It is a 60mm cube with only 1 perimeter, normal print, no vase mode ( to exclude artifacts caused by the Z axis)
Print speed 100mm/s, jerk 100mm/s (yes, that is right) acceleration 5000mm/s² ( not that it matters, printhead changes direction instantly)

Here on the left print you can also see the longitudinal wave against the light. the nozzle travels at differing, oscillating speeds throughout the line to create this effect. I attribute Both waves due to the bed moving, because of the Y axis either accelerating or stopping.

Here is a video of the print
https://www.youtube.com/watch?v=dPtld7a66VA&lc=UgzxiPtrtzqDPCfiGIZ4AaABAg&ab_channel=faxxzc

here is one at 200mm/s ( but still at 100mm/s jerk) I did not bother to show because it looks the same, just that the wavelength is longer and therefore harder to see.
https://www.youtube.com/watch?v=sKAI4nb9tZc&ab_channel=faxxzc
I couldn´t increase the jerk to 200mm/s because then my X axis (yes the two super whoppers at full torque) would start skipping. The Y servo is fine, even with double the weight.

Issues and problems: Yes the force cancellation is only in the Y direction, but this is because i had space problems in X, also there was hardly any overshoot in the X direction. The bed is really stiff in this direction.
Also, technically, if i am not printing in the middle of the bed, the cancellation is uneven, creating a rotational force that wants to twist the printer around the Z axis.
Also, the (center of the) counterweights are ~8mm too high up to be on the perfect plane , so they cause a slight rocking or tipping motion around the X axis. However i think this is negligible.

Conclusion: i think there is a visible difference between the prints with and without the cancellation. I would say, as it sits, it was cut in half. I still have to fine tune the weight.
Also, i think the servo now requires retuning since i doubled the weight it has to accelerate. This may also partly be the reason there is still a wobble (overshoot and correction). I will do this and report back, but i was really eager to share this.

Since i only retrofitted my machine to do this, there were some shortcomings.
If i were to build a machine from scratch that was to use this, i would put them on both X & Y and really make sure that they match perfectly and the center of gravity lies on the same plane. If the gantry is sturdy enough to only flex in the micrometers when full force is applied, and the servomotors are strong enough to accelerate the weight, it could make for a machine that can jerk/accelerate at eyewatering speeds while not sacrificing print quality.
maybe also make the Gantry of Magnesium to further reduce weight. Magnesium also has amazing vibration absorption properties.

I think this can start up where M572 DAA stops. M572 is an amazing tool, but it only really works with zero jerk. This however is especially good at cancelling the forces that jerk produces.

Let me know what you think
Max

Try the benchy with the fan at 100%, and crank the temperature up to 210-215 to get rid of layer adhesion issues.
Just try it and report back

I guess my 230°C heated chamber printer is sort of unusual? It´s got an auto lifting dual extruder. I won the Solvay AM cup with it, printing PPSU at 400 °C in a ~220°C chamber. Here is the interview, you can see it in the background.
https://www.solvay.com/en/article/2019-am-cup-3d-printing-winners

here´s a bit of footage from the lifting hotend.
https://www.youtube.com/watch?v=KYCNw_LuCM4&t=38s

What footage exactly are you looking for?

I had a similar problem. Please try disabling any "Combing" and "use combing instead of retract" in cura.
Basically, at any point that the extruder wants to move from A to B without extruding, have it do a retract and Z hop, and rapid to that position. The problem is that cura usually defaults to using combing without retract ( to eliminate stringing) which means that especially on cases with thin walls the extruder travels a lot without retracting and it oozes out on the part. When it arrives, there is too little plastic to be pushed out (because it oozed out on the travel move) so on the start of the layer there is underextrusion.
I know this topic is old but anyone looking for this is at least finding a solution.

Funny i have the same problem.

I really hope that at some point, someone that does know firmware stuff has the same problem and will add the vertical layout to the options. I really think that the vertical layout would make a lot of sense in a lot of printers.

@mrehorstdmd said in Layer shift detection?:

@zapta A closed loop motor/system wouldn't be able correct for all errors. If a print warps and stands up and blocks the nozzle, a closed loop system is going to try to force the nozzle to the correct position. That could cause problems.

I think a closed loop stepper is best used in a system where an object has to move to a target location, like maybe a pick and place machine, as opposed to something that is moving continuously along a specific path.

Sorry but this is so much misinformation.
I can´t help but disagree with that. The print head (with a servomotor) will always try to reach the position given by the microcontroller, and as long as the printhead is held up it will stay there, and as soon as the dictated direction changes and the print head can "slip by" it will go to the new correct location.
Also, all servos can throw out an alarm when there is a specified lag behind the commanded position. I have configured my JMC servo to throw an error if either a specified Amp draw is reached (in my case 9A) or it lags at least 200 steps behind the commanded position. It will throw an alarm and stop, and wait for a reboot.
You can connect the alarm to a free endstop and configure that as an E-stop.

I have long said that steppers are long overdue for being phased out, with servos coming down in price so drastically.
Just take this for example, this is the servo i`m using.

https://www.ebay.de/itm/V552-version-180W-3000rpm-0-6Nm-57-Integrated-Servo-Motor-NEMA23-36VDC-Fur-JMC/312996165948?hash=item48e006793c:g:YgcAAOSwHv1d~Ilt

It´s a 180W nema 23 size servomotor with an included onboard driverboard.

It costs 106 € including shipping (70 without, for when buying multiple)
Now, considering that a good quality stepper already costs 40€ plus the stepper driver (I dont know how much, maybe 10-20€ for the chip?) which equals to 50-60€, you begin to question the reason behind steppers, apart from "it´s always been steppers".
Just some of the benefits:

1. Closed loop
2. Automatic e-stop when an alarm is detected, within microseconds, not at the end of the layer and without homing
3. You only need to route power, step and direction to the servo, which means you can share power lines.
4. You won´t get als much electrical interference due to inductance like with steppers. Which means you can run thermocouple lines closer to the rest.
5. They can rev much higher than steppers, the nema 23 can do 3000 rpm with full torque up to 2000 rpm.
6. They have a very smooth motion profile from the start, no 256-interpolation necessary. You can configure them with up to 160.000 steps per revolution if you wish. Not necessary though, i run mine with 5000 steps per rev.
7. Dramatically lower power consumption, the servo only consumes power when you accelerate it or turn a load.
   Steppers always consume the specified amperage x voltage.
8. You can configure the servos to deliver more power for a shorter period of time (duty cycle). They are rated for example for 180W at 100% duty cycle. You can run them at 540W, or 300% for a duty cycle of 10% Which means normally 1 minute running at 300%, then 9 minutes cooling off at reduced load.
9. (added) They are DEAD SILENT. Not a whisper coming from them, even going at 400mm/s or accelerating at 5g. No stealthchop necessary.

I could list some more, but i think that is enough for now.

Also, you can get the nema 17 version for 62€.

https://de.aliexpress.com/item/32896698637.html?spm=a2g0o.productlist.0.0.6a3444f2bH99NV&algo_pvid=7c2a10ae-dc1d-40e6-8600-59874100d578&algo_expid=7c2a10ae-dc1d-40e6-8600-59874100d578-23&btsid=0be3769015853152671736861e72d3&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

I have long asked dc42 why he focuses so much on integrated stepper drivers.
A cheaper board with no stepper drivers and only the pinouts for external drivers would be a real seller.
I am so happy with my nema23 servos, my next printer will have all axes equipped with it.
The servo is so powerful, it can accelerate my 5kg gantry with 5g (~50.000 mm/s²) if i want it to, and not a single skipped step in sight.

I think it´s a shame that the industry is moving towards linear servomotors already, and we can´t even adapt normal rotational servomotors yet.

@Danal said in For anyone still using endstop switches...:

Yah, my Prusa 3 with Pinda probe, I set Z once when I built it about 8 months ago. Haven't touched it since. Prints almost every day.

Using the Pinda probe is cheating! We´re talking about true level here

https://youtu.be/Q1zBtJhgwBI?t=30

I think that´s pretty overkill, the easiest solution is to use 4mm ID PTFE tube for, like the 3mm filaments.
That will already reduce friction by alot.

Hi,
I know this has been asked once or twice before,
But is it possible to add the vertical layout of the PanelDue to the wishlist?
My printer is close to done and this is the only way the screen can fit.

I bet a lot of other people would also choose this layout if they could.

It would be great if there was some sort of "bounty" that we could attach to the feature wishlist,
and the more people add a few bucks to it, the more incentive there is for the developers to include that feature and earn the "bounty".
I would be more than happy to throw in 15-20€.

Thank you
Max

Ok so I think I´ve got it. I tinkered around and it seems that if i do the Z Offset as negative in the config.g file, it works. Which is weird, because the offset should really be positive.
I will post the config.g, as well as the tool change codes tomorrow (if my DWC decides to work again) for future people who have a similar problem to find.

Cheers
Max

i have noticed that, while printing fast, different patterns in X and Y start appearing. the patterns on the print wall parallel to the Y axis resemble that of a longitudinal wave, while the pattern parallel to the X axis resembles a transverse wave. I hope one can see the compression and stretching in this pic. I added the sketch to make it easier to visualize.
The transverse wave is easy to see in the top, horizontal aprt of the print.

After thinking it could only come from the bed, where the plates that hold the bed are only 2mm titanium and can flex in the Y axis. Unfortunately this is also the direction in which the heavier gantry rides, further amplifying the paper stiffness problem.
I already had plans of replacing that 2mm titanium with some 6mm stainless steel, but i ran into problems. Also, this would only reduce the problem, not totally eliminate it.
Active damping the bed is not easy due to the chamber temperature, adding another guide is also impossible due to space restraints.
This video inspired me:
https://www.youtube.com/watch?v=Ofg21LDNxdU&list=PLV4isz0nRXU3GnEECwNQKYsIve-Zo85Ks&index=39&ab_channel=RogierdeHaan

I wanted to see if this would work in the real world. I am very aware of the force cancellation test that deckingman made, however i saw some flaws.

1. He ran very low acceleration and jerk settings (like 500mm/s²) so there was nothing to really exacerbate the effect and no way to be able to easily see it.
2. the cancellation weight was on the wrong plane. He assumed the frame to be infinitely stiff, and the floor make a pivot point around which the higher up position of the cancel gantry would cancel out the forces from the print gantry due to the lever effect. However i believe those assumtions are not valid.

So, after some thinking i came up with a dynamic force cancellation design of my own.
Fortunately i built a basic cartesian machine with separate belts for X and Y. So i tapped directly into the "returning" belt path. I installed two MGN12 rails onto which i bolted 3kg of steel each. 6kg is roughly what my gantry weighs. I gave it my best effort to make the center of gravity of the steel weights the same height as the gantry.

Here are the tests. Same Gcode, on the left without and on the right with the weight.
It is a 60mm cube with only 1 perimeter, normal print, no vase mode ( to exclude artifacts caused by the Z axis)
Print speed 100mm/s, jerk 100mm/s (yes, that is right) acceleration 5000mm/s² ( not that it matters, printhead changes direction instantly)

Here on the left print you can also see the longitudinal wave against the light. the nozzle travels at differing, oscillating speeds throughout the line to create this effect. I attribute Both waves due to the bed moving, because of the Y axis either accelerating or stopping.

Here is a video of the print
https://www.youtube.com/watch?v=dPtld7a66VA&lc=UgzxiPtrtzqDPCfiGIZ4AaABAg&ab_channel=faxxzc

here is one at 200mm/s ( but still at 100mm/s jerk) I did not bother to show because it looks the same, just that the wavelength is longer and therefore harder to see.
https://www.youtube.com/watch?v=sKAI4nb9tZc&ab_channel=faxxzc
I couldn´t increase the jerk to 200mm/s because then my X axis (yes the two super whoppers at full torque) would start skipping. The Y servo is fine, even with double the weight.

Issues and problems: Yes the force cancellation is only in the Y direction, but this is because i had space problems in X, also there was hardly any overshoot in the X direction. The bed is really stiff in this direction.
Also, technically, if i am not printing in the middle of the bed, the cancellation is uneven, creating a rotational force that wants to twist the printer around the Z axis.
Also, the (center of the) counterweights are ~8mm too high up to be on the perfect plane , so they cause a slight rocking or tipping motion around the X axis. However i think this is negligible.

Conclusion: i think there is a visible difference between the prints with and without the cancellation. I would say, as it sits, it was cut in half. I still have to fine tune the weight.
Also, i think the servo now requires retuning since i doubled the weight it has to accelerate. This may also partly be the reason there is still a wobble (overshoot and correction). I will do this and report back, but i was really eager to share this.

Since i only retrofitted my machine to do this, there were some shortcomings.
If i were to build a machine from scratch that was to use this, i would put them on both X & Y and really make sure that they match perfectly and the center of gravity lies on the same plane. If the gantry is sturdy enough to only flex in the micrometers when full force is applied, and the servomotors are strong enough to accelerate the weight, it could make for a machine that can jerk/accelerate at eyewatering speeds while not sacrificing print quality.
maybe also make the Gantry of Magnesium to further reduce weight. Magnesium also has amazing vibration absorption properties.

I think this can start up where M572 DAA stops. M572 is an amazing tool, but it only really works with zero jerk. This however is especially good at cancelling the forces that jerk produces.

Let me know what you think
Max

I had the same exact problems on my JMC servo,
I guess you are not using the duet expansion breakout board? That fixes it.
You need the 5V logic for the steps to arrive properly, the 3.3v logic from the mainboard is enough to trigger some steps to run normally but not all of them.

So yes you need the expansion breakout board. here is my thread on it
https://forum.duet3d.com/topic/8948/3-3v-logic-for-5v-servomotor-optocouplers

The compensation is really just an intermediate step towards good axis accuracy.
Industrial cnc machines have linear (glass scale) encoders that correct for this anyway. The best have liquid cooling on all axis for extended reliability and repeatability.
However, i think most shouldn´t even worry about that because most printers have a repeatability way waaay worse than this could ever compensate for in accuracy.

DAA (M593) has an inherent flaw in that it only really works perfectly when there is 0 jerk.
Unfortunately it´s usually the jerk that causes most of the ringing...

You should try running a retraction test or "torture test" with your printer.
Bowdens have an inherent design flaw that makes them less capable printing such things by default.
They need very well tuned retraction length/speed values to work with this.
If you use too much retraction, it pulls the filament up too far into the heatbreak, molten filament solidifies and it clogs.

@Gerrard said in How do you get rid of these ridges?:

@deckingman - thanks, I've been playing with pressure advance today but I didn't get anything I was happy with. I'll try a more structured approach tomorrow.

I tuned linear advance on my marlin machine and it helped with hiding the Z seam a lot, but didn't help with this problem... I was hoping for a slicer parameter that would fix both machines...

Since you´re running a corexy, i´m going to guess that you are also running a pretty long bowden tube setup.
Chances are good that you just haven´t tried a big enough M572 (PA) value, it can easily approach 1.0 or above for long bowdens.
Just try a really big value (like, 1.5 or so) and see what it changes. If it´s too much, just dial it down.
Beginners are quick to dismiss PA because they say it doesn´t work when in reality they underestimate the amount of PA they need.

@metty you have 1600 watts of heating power and it raises the temperature 1 degree every two minutes? Something is dead wrong with your setup, big heat capacity or not.
For reference, i use a 2000w heating coil and it heats the chamber to 90°C in under 30 seconds, so a little more than 2°C per second.
Also, you absolutely need active convection, preferably a duct that blows hot air directly from the heating elements on the print. The sensor should be directly in the air stream, however not have line of sight to the heating element to prevent misreads due to radiation. The hot air should be between the HDT and the Tg of the printed material.

Trying to tune the chamber temperature with no active convection will never work properly and stable because the air will be very inhomogenous without mixing. It´s luck what temperature the air will be around the sensor.

Another thing you can try is just use bang-bang for the chamber heater.

@dc42 said in Duet 2 Pro 4 U:

I can release a little more information about the new board.

When we designed the Duet WiFi and Duet Ethernet, our aim was to make one board that would be suitable for nearly everyone. So it needed a lot of expandability and high current stepper drivers.

We now have Duet 3, which covers situations requiring high expandability and/or high current stepper drivers and/or increased processing power. So the new board does not need to offer those things. Instead it will provide features that the Duet WiFi/Ethernet lack, such as more modern stepper drivers, simplified wiring for BLTouch, a 5V output for laser devices and VFDs, on-board 12V supply for fans, Neopixel support, and a Raspberry Pi connector. The processor will have about the same power as Duet 2 but more flash memory and RAM to make room for firmware improvements. Like Duet 3 it will be capable of running either with a Raspberry Pi, or standalone using on-board Ethernet, with a WiFi version too. There will be no expansion connector like the one on the Duet 2, but there will be an optional daughter board to carry additional stepper drivers, similar to the one for the Maestro. We will likely offer an alternative daughter board to provide 5V signals for up to three external stepper drivers. Other expansion will be via I/O connectors similar to the 5-pin ones that we use on Duet 3.

Please just make a high CPU powered version with no internal stepper drivers and integrated 5V signals for external servo (or stepper) drivers. They can make use of the CPU speed. If that board is cheaper it can aid in the adoption of servos.

@wdenker said in Slow Chamber Heater:

@NitroFreak what size breaker are you running it on? I was worried about having too much watts. Between the dual hotend of 80w the bed of 900 watt and another 500 watts for the chamber heater getting close to a max for a 15 amp breaker.

they usually don´t all run at the same time, but i also don´t run a bed heater. The chamber heats up the bed anyway so it doesn´t make sense

Another possibility is to just use bang-bang for the heater. Heat it full time until it is at temp, then switch it off etc