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Z banding when ever I use infill - what's wrong?

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Posted · Z banding when ever I use infill - what's wrong?

Oh about if that's the issue. It might be. I had them replaced by warranty but I also moved to misumi shafts.

Check my posts about how to check them etc. the best way imo it's using high tech flat stuff or by setting the shafts between two bearings and... Well read the posts it's a long story.

https://ultimaker.com/en/community/16964-umo-woobling-x-block-sometimes-y?page=last#reply-115820

Aftet this I moved to gt2 and misumi shafts.

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Posted · Z banding when ever I use infill - what's wrong?

thanks everyone and @neotko for the great ideas to check. here's where i am today.

1. The print head bearings are fine and snug, no tack tack there.

2. The slight Y block movements in my video is in the "normal range" when compared to the UMO+s I have at work that do not exhibit the issue.

So I think today I'm going to try to focus on my extruder assembly. I think I'm going to try to see if there is a relationship between the slow speeds and teeth marks on the filament and maybe see if I can correlate rotations on the hobbed bolt or wood gear to extrusion differences.

I suppose I could try swapping the entire extruder assemblies with a functioning machine, but that seem like a bunch-o-work so I'll start with more test prints and measurements before resorting to that.

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Posted · Z banding when ever I use infill - what's wrong?

If you are going to reassemble the hotend. Just please try to remember to not tiiiight the wooden parts 4 long screws. They must be 'ok' but never overtight, or the ptfe cuopler will get all that preassure, bend overtime, die faster and ofc kill the quality.

For me that's a banana shaft, my 3 printers don't wooble even a bit. If you can't get a warranty replacement I would think about buying misumi or igus (cheaper) shafts.

About changing the hotend fast, you could move to chopmeister twisterblocks, they have fast release of the central axis and they make stuff like this much faster.

But one mod at the time XD

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Posted · Z banding when ever I use infill - what's wrong?

OK I did a bunch of printing this weekend. Makeing different files to try to measure what was happening.

5a331a460377a_zwavegroupshotJPG.thumb.JPG.8a2bcc3142ac73d5d0377008c142ad88.JPG

I got pretty close to thinking that this comb pattern could help me identify the period of the zwave.

5a331a4693e56_wavecombprint.thumb.jpg.2efb96c99e9704edf42baa4e414730a3.jpg

I did get a working UMO+ and tried swapping the extrusion assembles and the zwave did not follow the extruder, so I eliminated that as a source! Progress.:)

I did see some under extrusion. So I ran some temperature tests and discovered the temperature where under extrusion starts on the home machine was about 200C but on the work machine I printed at 180C with no issues.

THEN I printed everything hotter on my home machine and things started to look a lot better.

5a331a472b094_zwaveTEMP-words.thumb.jpg.a3b6185a041265b3ef7e2b5d80003098.jpg

So Apparently the z banding is due to some extrusion issues at low speeds???

Possible causes....

1. Nozzle is not reaching reported temp, and actual temp is probably lower then reported.

2. Something in the print head is causing more friction at lower speeds (old Teflon coupler maybe).

I have watched the temp while it prints and is not drifting a lot, or jumping around. Maybe I need a new PT100.

5a331a460377a_zwavegroupshotJPG.thumb.JPG.8a2bcc3142ac73d5d0377008c142ad88.JPG

5a331a4693e56_wavecombprint.thumb.jpg.2efb96c99e9704edf42baa4e414730a3.jpg

5a331a472b094_zwaveTEMP-words.thumb.jpg.a3b6185a041265b3ef7e2b5d80003098.jpg

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Posted · Z banding when ever I use infill - what's wrong?

The results your tests produce appear to indicate that there is a condition in which the pressure gradually builds up and then is suddenly released. Increasing the temperature alleviates this condition by reducing the viscosity of the plastic.

I had this issue and was always printing PLA at 210C for 0.1mm layers at 30mm/sec. Just recently I bought a "pimp" 40 watt heater from 3Dsolex and what a difference that has made! It leaves me to believe that the previous heater was woefully underpowered, and no doubt Ultimaker genuinely believed that it was a 25 watt heater, but it was probably a lot less than that.

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Posted · Z banding when ever I use infill - what's wrong?

Of all the photos - the most interesting to me is 2 photos up - that photo if you click on it - the part on the right side - the overhead view you can clearly see cycles of over and under extrusion. That particular print seems to coincidentally have it such that the underextrusion occurrs in a very repeatable pattern time-wise such that it occurs in a particular spot on one layer and then goes away for a while and then comes back when it is doing the layer above but a bit to the left.

I'm pretty sure your temperature is cycling. You say it's stead but I don't think it is. Something is making the temperature go up and down by at least 5C. probably more like 15C.

I thought about mechanical things that would interlink X and Y with extruder or X and Y with Z but nothing I can think of would make that pattern other then temperature cycles. Which is very plausible. But I'm very surprised you didn't see this pattern in the temperature display. If you did see the temperature moving by 5C or more then I would try to fix the PID values. But if not then I would blame the sensor or the sensor circuitry. To me this looks so much like bad PID values but again you would see the temperature changing slowly every minute.

This also explains why the hotter prints are fine - they aren't underextruding so much because the temperature is higher so it's not so bad.

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Posted · Z banding when ever I use infill - what's wrong?

@gr5 I'll triple check my temps and PIDs.

What I really find interesting is that even at the same temperature I only see these patterns when printing in the 18mm/s to 25mm/s range. What would cause these temp cycles only at slow speed? Does the slow speed allow heat to creep up the filament too much and cause some weird pressure resonance in the hot zone?

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Posted · Z banding when ever I use infill - what's wrong?

Two theories:

1) When printing slower there is less plastic being melted so less heat is needed. Because less heat is needed it might be easier for the PID to not get out of control (to not oscillate).

2) It is doing it but because you are printing slower the cycle happens more often per layer so it's not as noticable. For exampe - 2 photos up - it does it on both prints but because the left print is slower it happens more than once per layer whereas on the print on the right it happens almost perfectly once per layer (but slightly earlier/later - not sure which if printing CW or CCW - each time).

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Posted · Z banding when ever I use infill - what's wrong?

I have not been printing slow for a while. I think after changing the Teflon Coupler things got better. I should re-test and post results.

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Posted · Z banding when ever I use infill - what's wrong?

I have not been printing slow for a while. I think after changing the Teflon Coupler things got better. I should re-test and post results.

 

Hi Peter! I was facing the exact same issue in my DIY printer, the issue was caused by the HeatBed.

This issue got me crazy as you too so check out this post, it will surely help you! ;)

https://groups.google.com/forum/#!topic/kisslicer-refugee-camp/ro86SEuZ17w

"turanarod" got it! Let me know how it goes!

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