Z artifact that's time/speed related

bot

Is your slicer modifying print speed or cooling based on predicted layer time?

droftarts

@screwyluie said in Z artifact that's time/speed related:

well I changed that and it didn't help. Thanks anyway though.

Interesting. Can you post your current config?

You are using the default thermistor settings B4138, which is likely not to be correct, so you might also be extruding too hot. The print possibly looks a bit overheated. With a slow extrusion of vase mode, there may be a build up of molten filament. In vase mode, when extrusion speed is consistent, this would release at regular intervals. What thermistor do you actually have?

Otherwise, the frequency could relate to an eccentrically turning extruder drive. What drive are you using? Bowden or direct? Try extruding 50mm slowly into air, see if the extrusion is consistent, also if the feed into the drive is consistent.

Does the filament have a consistent bulge in it?

Ian

screwyluie

@zapta said in Z artifact that's time/speed related:

I tried a nimble extruder a few months ago and had similar diagonal lines, never seen it before with any other extruder. I thought that they may correlate with the turn of the flex cable but gave up and went to a BMG direct extruder which works just great. No more bowdens or flex cables for me.

I have a completely different extruder on here previously with the same result, so it's not that. But thanks.

@bot said in Z artifact that's time/speed related:

Is your slicer modifying print speed or cooling based on predicted layer time?

most likely it is, I can look into that and see if it has any effect, thanks.

@droftarts said in Z artifact that's time/speed related:

@screwyluie said in Z artifact that's time/speed related:

well I changed that and it didn't help. Thanks anyway though.

Interesting. Can you post your current config?

You are using the default thermistor settings B4138, which is likely not to be correct, so you might also be extruding too hot. The print possibly looks a bit overheated. With a slow extrusion of vase mode, there may be a build up of molten filament. In vase mode, when extrusion speed is consistent, this would release at regular intervals. What thermistor do you actually have?

Otherwise, the frequency could relate to an eccentrically turning extruder drive. What drive are you using? Bowden or direct? Try extruding 50mm slowly into air, see if the extrusion is consistent, also if the feed into the drive is consistent.

Does the filament have a consistent bulge in it?

Ian

it's an e3dv6 hotend and the standard thermistor for it.
as for the extruder drive, I've completely replaced the entire extruder, so I really don't think it's the extruder. I'm currently using a nimble, I had a direct drive on previously... so entirely different hardware.
I've used half a dozen different filaments in this process, so it's not that either.

current config is the same as before except I moved the M584 command above the M350 command as instructed previously.

NitroFreak

did you pid tune the hotend? temperature fluctuations might cause exactly that

droftarts

@screwyluie said in Z artifact that's time/speed related:

it's an e3dv6 hotend and the standard thermistor for it.

Then your thermistor settings should be for Semitec 104, not the Honeywell. This can cause a significant difference at high temperature. I don’t have numbers/settings to hand, on phone, but they are in the firmware configuration tool.

Ian

NitroFreak

@droftarts said in Z artifact that's time/speed related:

@screwyluie said in Z artifact that's time/speed related:

it's an e3dv6 hotend and the standard thermistor for it.

Then your thermistor settings should be for Semitec 104, not the Honeywell. This can cause a significant difference at high temperature. I don’t have numbers/settings to hand, on phone, but they are in the firmware configuration tool.

Ian

The wrong thermistor values would not cause variation in temperature however. once the temp is tuned, it should stay the same and not cause a variation. It is literally only the number on the display that is wrong.

droftarts

@NitroFreak depends if he’s using the wrong display temperature to set the temperature! If it says 200 but is really 230C, it would cause regular filament vomiting like this. Hard to tell with a vase print if extrusion temperature is too high, as no moves that cause stringing. I’m looking at the print picture and it looks glossy and floppy, which says too hot extrusion to me.

@screwyluie have you got any other prints you’ve done, to compare?

Ian

screwyluie

@droftarts

sorry with the holidays this has been on the backburner. I will be getting back to this soon. I appreciate the help, just wanted to update.

screwyluie

@droftarts ok after a long hiatus, working on it again... I have adjusted the thermistor settings, didn't fix it.

@NitroFreak I did not pid tune it but it's rock solid at +-0.1

I have tried modify stuff in the slicer, even tried several other slicers all with similar results. At this point I'm pretty convinced it's either mechanical or something in the duet config I've screwed up... but I have no idea where to start.

Phaedrux

@screwyluie said in Z artifact that's time/speed related:

At this point I'm pretty convinced it's either mechanical or something in the duet config I've screwed up... but I have no idea where to start.

Your config looked ok. I'm inclined to think it's mechanical. I would start with disassembling the Z axis, checking things over, and reassembling.

The pattern on the vase looks like something is slipping/binding every few layers. Maybe a loose coupler? Tight lead screw nut?

screwyluie

@Phaedrux except that it's not layer specific, it's time based. if I speed up the print they get further apart, and likewise if I slow it down they get closer together... so it's not your typical z banding

Phaedrux

I notice in your config that the M307 line is commented out. Is your bed set to bang bang mode? This can lead to some bed warp that can cause fat layers like this.

screwyluie

@Phaedrux said in Z artifact that's time/speed related:

M307 line is commented out

honestly no idea. I do know that it heats up like it should and the temp is very steady.

Phaedrux

If you send M307 H0 in the console, what does it reply back with?

screwyluie

@Phaedrux said in Z artifact that's time/speed related:

If you send M307 H0 in the console, what does it reply back with?

M307 H0
Heater 0 model: gain 90.0, time constant 700.0, dead time 10.0, max PWM 1.00, calibration voltage 0.0, mode bang-bang, inverted no, frequency default

I have tried so many things and so far nothing has had any effect on this... I've gone over and replaced basically all the hardware that could affect it except the duet... I'm wondering if I should get a different board and swap it out to see if that fixes it

Phaedrux

As I suspected you're using bang Bang mode for the bed. I suggest changing to PID mode and do an auto tune of the bed heater. This can help eliminate changes in the bed shape due to the heater which can cause issues as you're describing. Worth a try.

https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control

screwyluie

@Phaedrux said in Z artifact that's time/speed related:

As I suspected you're using bang Bang mode for the bed. I suggest changing to PID mode and do an auto tune of the bed heater. This can help eliminate changes in the bed shape due to the heater which can cause issues as you're describing. Worth a try.

https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control

so as a quick test of the theory I just disabled the bed heater and put down some glue instead and what do ya know.. it worked. Now read that link you sent and figure out how to setup PID and hope it doesn't do the same thing. I can't thank you guys enough for the patience and help provided.

Phaedrux

@screwyluie said in Z artifact that's time/speed related:

Now read that link you sent and figure out how to setup PID

This may help: https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+4:+Calibration/40#s161

jmshep

Now you have established that the fault is connected with the bed heater and it is in bang bang mode it may be that it is a power supply issue?
It could be that when bed heater switches on, the voltage dips and causes the problem. The solution would be a new more powerful power supply.
To test this you would need to connect a volt meter to the 12v (or 24v) output of the power supply and watch the readings. (I doubt the Duet voltage reading will respond fast enough).
PID tuning may mask the problem because the heater is not being switched from 0 to full power all the time as is the case with bang bang.

droftarts

@jmshep said in Z artifact that's time/speed related:

PID tuning may mask the problem because the heater is not being switched from 0 to full power all the time as is the case with bang bang.

Actually, it IS being turned on full power, and off again, just very quickly, with a MOSFET. It’s not able to vary the voltage.

@screwyluie But yes, I’d suspect an under-performing PSU, or an underpowered one, that’s causing voltage drop issues, such that the hot end can’t maintain temperature. Do you notice a variation in hot end temperature? Have you tuned the hot end with M303?

But could also be the bed warping while heating. Check bed thermistor is making good contact, as if it’s not, the actual bed temperature will swing more than the thermistor is reporting.

Ian