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bastienb

Why are the first layers of my cubes shrinked on my UM2+?

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Hello everyone!

First post so I hope I won't get it wrong ^^. I made some researches but I had difficulties to find an answer to this issue... (better see it on the pics):

1.thumb.jpg.3dc002604a7d2e645fdc0e3dcc4f20ac.jpg

2.thumb.jpg.ccb0e3202932366ec6373ece9f9bf36f.jpg

3.thumb.jpg.0e9ba6c7f274efab56d65046f42036e0.jpg

As you can see on the previous pics, the base of all the parts is shrinked.

Same problem on another part

5.thumb.jpg.2764c91314c78fc7502f854b1668a7bf.jpg

explication5.thumb.png.a52e990d3c0e90031525e1fbc79b40b3.png

For this one, the print goes back to normal as soon as the walls are printed... For the parameters I use this in Cura:

4.thumb.png.54d05e3b5e6b862112e126be5d912702.png

The bed is 60°C, PLA, 0.4mm for the nozzle, 210°C for the nozzle too. I built the Closed chamber ('green house') UM2 by Kris.

Thanks a lot for your help =))

Edited by Guest

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Ok, thanks to the tutorial and your comment I have deducted I have two problems:

- Elephant's foot (common and needed for adhesion, not really a problem then)

- Lower wall cave in

This last one is interesting. The printer is brand new, my prints are with a bed temp of 60°C BUT, I know it had fallen from 50cm when I was away... I saw nothing bad (ran test prints) but it could be the Zbearing that took a hit... I will test the cooling thing and keep you updated (and if you have any other advice, do not hesitate!)

Thanks for your help btw

Edited by Guest

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Nothing obviously wrong there.

 

 

Not seen anything like that before. Doesn't look like a Z artefact to me, looks like both the X and Y are printing too small. What does the object look like in Cura layers view?

 

The heat explanation suits me but... should be smg else... here are the layers (is it good for you?)layers.thumb.png.c916ad8f2dbdb38ba94ebbcd517908ca.png

 

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The problem is still there... I stopped making those kind of parts so...

Problem:

P1040686.jpg

All the parts with the same structure (Xmm filled, then Ymm with walls) have the same problem: X first layers are shrinked, the Y next are OK.

Printer

Ultimaker 2+

Cura (latest version) layers:

1.png

2.png

3.png

Parameters

settings.png

- Regular fan speed at height 0.27mm (layer 1)

Misc

- repRap PLA white, new spool

- 1000hours of printing

- very recently cleaned and lubricated

- door and top cover

- not the Z-bearing -> it depends of the heigth from which the "walls" start to be printed

Things tried

- Still a problem with this method

Ideas

For me, it's all about cooling the first layers more effectively. Somehow it would be nice to adapt the cooling flow to the density of material for each layer. It would mean more cooling for the first Xmm and less cooling for the last Ymm. Simply because the first X are harder to cool than the Y next (less stuff to print).

So the work would has to be done by the slicer... but I do not know how to tweak it!

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