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HELP! is this a bump? Z scar?

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Hey guys!

So here goes my 20th print of a pyramid shaped tile and dents form when the Z axis is lowered. I have attached a photo, please see.

5a33173f75613_Ultimakerforumtile.thumb.JPG.6606445ceaa8dfdf10d9bc46737d1e6e.JPG

ultimakerforumtile2.thumb.JPG.241bf29d08cabdc5ab555ab6cd70bc8c.JPG

My settings were:

Ultimaker 2+

nozzle 0.4mm

layer:0.2mm

Shell: 2.4mm

fill density:20,40 100%

Print temp tried 200 and 210 but no difference

initial layer thickness 0.2mm

Lowered the Z speed to 5mm/s

Acceleration 100 and also tries 1500 and 3000 (but no difference)

Thank you, any advice is appreciated!

5a33173f75613_Ultimakerforumtile.thumb.JPG.6606445ceaa8dfdf10d9bc46737d1e6e.JPG

ultimakerforumtile2.thumb.JPG.241bf29d08cabdc5ab555ab6cd70bc8c.JPG

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You might want to try the new cura beta since it has coasting. Coasting turns off the extruder at the end of a loop and let the 'blob/preassure' be part of the print. I haven't use it but I use options alike on s3d to remove the z scar.

Also printing cooler/slower? generates less preassure.

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Neatko: I tried to download Cura beta (15.06) but it seems that it is not available yet, hopefully soon? Will definitely want to try out coasting.

Owen and Yellowshark: I am printing at very slow speeds between 20 to 30mm/sec and fan comes on after 3-5th layers.

Thanks for your replies so far

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Neatko: I tried to download Cura beta (15.06) but it seems that it is not available yet, hopefully soon? Will definitely want to try out coasting.

 

You might want to try the new cura beta since it has coasting. Coasting turns off the extruder at the end of a loop and let the 'blob/preassure' be part of the print. I haven't use it but I use options alike on s3d to remove the z scar.

Also printing cooler/slower? generates less preassure.

 

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Ok then if you are at 20/30mm/s then with .200 you can probably go down to 190c, especially if your drive/feed system is 100%. I would certainly push it down until you see under-extrusion. Also make sure your wall and infill speeds are all the same.

If you can make your .stl available I do not mind having a try with it.

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Neotko, I may be having newbie syndrome but I downloaded 15.04 last update was 29th jan 2016 but I could not find coasting option.

I also tried 15.06 but that does not support Ultimaker2+ and was only updated last year.

Do you know which one I should download?

Thanks for the link!

 

 

Neatko: I tried to download Cura beta (15.06) but it seems that it is not available yet, hopefully soon? Will definitely want to try out coasting.

 

Try here

https://software.ultimaker.com/Cura_closed_beta/15.10/

 

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Hi I had assumed it was a single print but looking at it again I am wondering if you are printing more than copy? The apex area say top 1/4 of the print has come out very well, which given the small layer area at the top is maybe a bit surprising for a single copy. Trying to get my head around it versus the lower part of the model

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Hey, I was just printing one copy at a time. Because the tile has sloping sides, it changes the slicing path in cura and the bed moves down at different locations (the tile was printed vertically). It looks random in the picture above but those scars appear when the bed moves down. Unfortunately in cura there is no option to select the location where the z-move happens.

Hi I had assumed it was a single print but looking at it again I am wondering if you are printing more than copy? The apex area say top 1/4 of the print has come out very well, which given the small layer area at the top is maybe a bit surprising for a single copy. Trying to get my head around it versus the lower part of the model

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Hey, I was just printing one copy at a time. Because the tile has sloping sides, it changes the slicing path in cura and the bed moves down at different locations (the tile was printed vertically). It looks random in the picture above but those scars appear when the bed moves down. Unfortunately in cura there is no option to select the location where the z-move happens.

 

Hi I had assumed it was a single print but looking at it again I am wondering if you are printing more than copy? The apex area say top 1/4 of the print has come out very well, which given the small layer area at the top is maybe a bit surprising for a single copy. Trying to get my head around it versus the lower part of the model

 

 

In Cura 1.99 yo can select where the z scar happens

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Ah now that I did not know, as a 15.4 user. But is that a z scar? I can see overlaps where the scar appears on the same layers at different corners. I am wondering whether it is caused by the deceleration and acceleration coupled with too high a temp. As I said earlier I think .200 at 20s is too hot at 20mm/s or 30mm/s.

I am still trying to get my head around why the top of the model looks perfect, compared with the earlier layers, but where the layer print times will be a lot lower.

o I am not convincedhave not seen anything said in the thread about retraction and print head movement. Also, to me it does not explain the partial presence of the scar and the scar occurs in more than one place.

Edited by Guest

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I agree that its not solely z scar. but i don't think its because its to hot as if it was the top would be overheated or worse then the bottom.

Could it be due to the infill? seeing that is sloped the position that it would meet the infill would change as it goes up? But also unlikely.

Have you tried turning the object 45deg on the bed?

Have you looked in x-ray mode to see if there is an issue with the model?

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