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Nicolinux

Walls delaminating

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Hi guys,

I noticed another issue lately and I don't know what could cause it. The outer walls seem to not stick to the rest of the object and start delaminating. It is not everywhere around the object and it varies with different objects.

Bad shells

 

  • layer height: 0.2
  • walls: 0.8
  • top/bottom: 0.6
  • infill: 20
  • speed: 50
  • temperature: 200

 

I also noticed that the skirt already shows these signs.

skirt

My first idea was to chech for loose pulleys and belt tension. But everything looks alright. I tightened all pulleys and my belts have a fairly high tension. The short belt on the x-motor though has a lower tension than the y-motor. That's because I can't increase the tension anymore when I push the motor down (didn't want to overdo it...).

I have also switched filament, but the issue remains.

Thanks.

 

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I had to file the slots out more on the X-axis motor mount so that the short belt could be tightened. That helped a lot with similar problems to yours.

Also, you can try increasing the filament flow % from 100% to 110%, or use a smaller filament diameter setting than 3.00mm (try 2.85mm). Measuring the filament diameter in one spot is not always accurate since some filament might vary a lot.

 

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Sounds familiar to me. It may come from the unevenness of the bed. Are you working with the standard Ultimaker bed?

Ideally the cross-section of any line drawn would be a rectangle with the layer height and about the nozzle size (or a bit more) as width. If there is a valley in the bed, the cross section of the line becomes more like a half circle or similar. Consequently it becomes narrower and could detach from other lines. However, the effect should disappear after a few layers as the height difference between last layer and the nozzle balances out...

So maybe a re-check of the bed leveling might help you?

 

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@owen: I played with themerature (and speed) quit a lot lately, but this issue didn't show up after changing something significantly about temperature.

@AnthonyT: Alright, that's what I would try next.

@Dim3nsioneer: I don't think it is the bed. I got very good (and fast) at leveling and it is spot on. I checked the distance in several locations and it is mostly constant.

Just a little update - I tried to tighten the short belt on the x-motor (with slightly more excessive force while hoping that it won't break) and the issue is less pronunced now. So I guess it is related to the tension of the short belts. I will follow AnthonyT's suggestion and file the screw holes for the motor a bit so I can push it further down to increase tension.

 

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I second on the short belt tension. When one short belt is not as tight as the other the axis of the print starts leaning to one side. I had the same problem before and solved it by installing the adjustable mounting bracket illuminarti linked.

 

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I think it's a little of two things: belt a little too loose (backlash/play) and a little bit underextruded. I would also recommend increasing flow to 110 or reducing filament diameter by 10 or 20% area (multiply by square root of .9 or .8). Alternatively reducing speed or increasing temp should increase flow a little. But I would stick to fast printing and instead increase flow.

 

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[...] So I guess it is related to the tension of the short belts. I will follow AnthonyT's suggestion and file the screw holes for the motor a bit so I can push it further down to increase tension.

 

You're right, I mixed it up with another issue... sorry! I was lucky the tension was just enough when I moved the x-motor as far as I could along the holes. Did you use threadlocker for the motor screws?

 

[...]

An adjustable mounting bracket helps a lot with fine-tuning the tension... http://www.thingiverse.com/thing:34785

 

That looks very promising...! Thanks!

 

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I have printed the adjustable mounting bracket (thx Simon). I have seen these things before but I didn't want to drill holes in my Ultimaker. Right now I "solved" the issue by loosing the other motor/short belt a bit to match the x-motor. Works fine so far but I will mount the adjustable thing anyway.

One thing to note - if you have a newer Ultimaker, select the "four screws version" because it is designed to pull all screws down and this plays nice with the delrin spacers.

 

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I think it's a little of two things: belt a little too loose (backlash/play) and a little bit underextruded. I would also recommend increasing flow to 110 or reducing filament diameter by 10 or 20% area (multiply by square root of .9 or .8). Alternatively reducing speed or increasing temp should increase flow a little. But I would stick to fast printing and instead increase flow.

 

George, I am affraid of the flow setting. I have no feeling for it and no idea what it really does. To me it looks like a valve that increases plastik flow. But there are no hard values to follow. I guess it is another of these settings that needs to be discovered empirically.

 

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affraid of the flow setting.

 

Flow is very simple. If you set flow to 200, you get double the normal amount of plastic. If you set it to 110 you get 10% extra.

For example if you are printing .2mm layers and your first layer is also .2mm and you did a bad levelling of your bed and are off by .1mm, you can increase flow to 150 and you will get enough plastic for .3mm (instead of fixing the levelling).

 

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I get that - that's easy. But flow does also influence the later layers. So increasing the flow would lead to higher pressure and I don't know if that's what I want. I mean, I can imagine that changing the flow is useful, but I didn't have an opportunity to try it and see improvements in my prints.

 

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I sometimes print with 0.65mm layer height with 300% flow rate. That gives me thicker than 1mm wall, which is pretty strong, but it is only successful with single walled objects. Anything with infill, nozzle hits the bumps created by large flow rate and lose its position.

In other cases, I increase flow rate for about 5% when I print with over 150mm/s speed to prevent underextrusion.

 

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