Repeatable small gap in between layer

[Dythe]

Hi all,

My printer is an anycubic i3 mega and I am using Hatchbox orange PLA.

When using a 0.2mm layer height with this model, I only saw one small gap per print sometimes but to try and accelerate the process. I tried a 0.3mm layer height. You can see the result with the photos.

IMG_20200325_002216.jpgIMG_20200325_002229.jpgIMG_20200325_002244.jpg

The inside of the box is full gap between the layer only on the exterior layer and on the outside of the box it's all clean, nothing.

I tried slowing the speed from 60mm/s to 35mm/s and also tried a higher temparature, from 200 degre C to 225. In comparison, I use 50mm/s with 0.2mm layer height
Those modification did improve the quality but not enough.

In the title, I say repeatable because no matter the speed, temparature and even the orientation on the bed. The gap always seems to be on the same layer.

I suspected a problem with the model but I have no issue printing with a 0.2mm layer height. I tried to print a calibration cube to see if the same error occurs.
The result of the calibration cube is that yes it did it again but only one time and a really small one but I still think it counts.

What do you think is my problem, I would like to know what you think.

[plastizone]

What is your nozzle dia? Because layer height couldn't be half of nozlle diameter. It could be wrong layer height, much more extrusion, wrong bed leveling and high temperature.

[Dythe]

My nozzle diameter is 0.4
I'm using cura base setting for 0.3 layer height.
Did a leveling test and it looks good, I also don't have any problem with bed adhesion when I clean my bed.
High temp ? What I readed is that a higher temp is better and I also saw a small improvement with a temparature of 225 degre C compared to 200 degre C
One thing I forgot mentionning is that I tried the same model with the white filament that came with my 3d printer and also tried it with a black filament coming from a local manufacturer and in both case I still get some gap but the difference is day and night.

Thanks for answering me plastizone. I was starting to think nobody would answer me.

[plastizone]

Hello; If your nozzle dia 0.4 your layer is good but bed leveling is important because x axis moves linear but your bed slope your part gets gaps. If your extrusion value is much and first layer height is high than other layer height, bed adhesion seem good but your part gonna get gaps. I prefer UBL for bed leveling. It crates your bed plate and saves. High temperature not good every time. If your printing speed slow and linear advance feature not active, there are lots of bubbles on your part surface. And your filament is too runny. Also it could be some gaps. There are little bit relationship between extrusion multipler,temperature and speed. And different brand's filament has different chemical and physical effects. Even different color. In this case, you should adhere to the manufacturer's recommendations.