Z-Banding (not Z-wobble...because Delta)

[M-P Spierer]

I just finished a decent size print with my Rostock Max with KISSlicer and have very consistent banding in Z. The first picture makes it look way worse than it really is, but it isn't insignificant.

I'm going to try a second one with "Loops go from inside to outside of perimeter" unchecked to see if there is any improvement, but in the mean time....any ideas what could be causing this? I don't ever remember seeing this in Slic3r.

Print settings are in attached text file.

Thanks.

[Peter Gregory]

It looks like the bands are weak layers.

If you print a thin walled structure, does it de-laminate?  Pull apart easily?

Not sure why they appear at regular intervals.

[toranarod]

Do you have and where using a heat bed?

I have seen this before on my printer.

[M-P Spierer]

Yes, material is IC3D red ABS at 230C and heated bed at 90C.

[toranarod]

I have spent a lot of time on the banding issue since i first saw it.  I am still not quite able to explain it. But I bet if you don't make any other changes just turn off the Heat bed

the bands all vanish.  

The other way to eliminate this is to make a change to the X Y print speed faster or slower usually will not matter just change the frequency of the the stepper motors. 

The reason they appear at regular intervals is because the band you will find coincide the switching of the heat bed. The on and off will match the bands.

But why is something I only have a theory on.     Do you know about resonance at frequency.   remember the steppers are coils and coils pick up RF, The heat bed is also a coil of wire like a radio antenna. some how if all the conditions are correct this is what happens.   

it appears that if by accident you hit the right frequency driving your X, Y step signal and the heat bed is drawing the right amount of current it creates a resonate harmonic in the printer.   

All you can do is un tune the radio RF by changing the drive frequency or change the heat bed.    I have seen this before and have also spoke to others who have observed the same thing.

This is one time we cannot blame the software. 

That's what my banding issues was. I can tune my printers to do it any time I like. 

[Joris [van Tubergen]]

It could be wrong PID values. Can you see the temperatures during printing? If that goes up and down then colour changes could be visible...

Cheers \ Joris

Op 2 nov. 2014 20:10 schreef "toranarod" <tr7v8r...@thehydrogenshop.com>:

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[WarrenE]

I had this issue too for quite a while. For me, it was the heater bed, and was caused by the glass plate expanding and contracting when the heater turned on and off.  It was fixed by decreasing the heating cycle time on the PID for the heating bed.  The heater goes off and on more often now, but no more banding.

W

[M-P Spierer]

Interesting, I actually just updated my PID values when I updated firmware. I'll have to redo my PID calibration and try again.

[Tom Tumilty]

I had the same problem and when I reduced the heat I started having almost perfect prints so now I keep the heat low for both Pla and Abs

[M-P Spierer]

Odd thing is that I have never seen this before when running Slic3r. I'm going to try and retune my PID tonight and see if that helps since I did retune it at the same time that I installed KISSlicer. I like my bed at 90C because I find it greatly reduces warping on ABS compared to 80 or 85C.

[toranarod]

 That's how I first observed this phenomenon.  I first thought it was the heat bed expanding and contracted but I couldn't find any measurable evidence to support that.

Also if it was the bed expanding why did it just start all of a sudden out of the blue.  never did it before.  also i have the same heat bed on my other printer and printing the same object no ripples in those prints. I looked at the voltage driving the bed on an oscilloscope, this is when I was like what the@#$&. 

What you where really seeing in the side of your printed object was a physical manifestation of a 3D printed wave form of the screen on the oscilloscope. 

At that point I thought Well that's EASY to fix The power supply has way to much AC ripple in the DC supply under load.  Same Problem you here in your audio system when-you amplifier gets old and  the Capacitors start to fail. And after all the coils in the stepper motors are really just like the coils in your Audio speakers YES. so why cannot the printer hear the same noise.

Lets 1 get a better power supply or beef up the filter caps in the power supply. So that's what I did bought a new power supply and upgraded the Capacitors. YES that fixed the problem.    

I was very proud of my self, I thought I fixed it.  took the old power supply and though it into the second box in the shed.

A few weeks went by and all of a sudden the lines in my prints came back. shit, how is what. You got to be joking.  

I was related to the heat bed  power supply that was for sure but there was other factors also causing this.    I then looked at the Printer power supply and doubled it wattage and current capabilities.   Also improved it DC supply rating. This improved the lines on the printed objects but didn't eliminate them. Also noted it really Changed the noise of the steppers. Made the hole machine more silent. 

That's when it became more about what I have already posted there is a resonant harmonic  of some kind taking place between the to power supplies and the load place on the system when the Heat bed kicks in. The Head bed draws large amounts of current and also produce's an intense electro magnetic field. On further looking into this there is obversely many issues when you incorporate a heat bed into a printer that was never designed to have one.     That's why I would say 3D system never put one in the first place.     

If you want to totally test my theory power your Heat bed from a car battery and see what happens.  A pure DC source. ?

[Peter Gregory]

Did you try any noise suppression or isolation techniques?
A ferrite bead on the power cable to suppress high frequency noise?
Or on the DC power cables leading to the bed?
Trying two outlets from different circuit breakers?
Just curious.

[M-P Spierer]

I adjusted my bed PID values last night and now have it running with a set point of 90C within a range of 89.85-90.13C. I don't know what it did before because I didn't want it that closely. I haven't printed anything yet, but will see tonight if it fixes anything at all.

Also just to add more fuel to the fire, here are a few pictures of other prints. The two that are identical parts were printed on different days with only one change in kisslicer....perimeters go from outside to inside on one and inside to outside on the other. 

The other part you can see finer pitch banding on the thin surface and no banding at all on the tall (smaller) surface.

This is also currently being discussed on the SeeMeCNC forums... http://forum.seemecnc.com/viewtopic.php?f=41&t=6747

[M-P Spierer]

Did another part last night after tweaking my PID settings for the bed. The banding is better but still quite evident.

I did pay closer attention to my bed temps, however, and it seems that the temperature varies more than I would expect/like. During a large print like I have been doing it drops from 95C to 92C extremely quickly (maybe 10 seconds), then takes several minutes to reheat to 95C.

I have only had this issue on large parts...never on small parts.