# 3D Printing > General 3D Printing Discussion >  Does Layer Height effect print strength?

## QuitNoMore

This is a question that I can't seem to find anywhere.  Does layer height effect the sturdiness of a print?  I would imagine it has too, but in which direction does it go?  Would a higher or lower layer height make the print stronger?  Would a print with layers at 0.15mm be stronger or weaker than one with a layer height of 0.3mm?
Anyone ever test this, or have an answer?

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## DrLuigi

I did once use a stretch test of a piece of about 0.1 and 0.25, It was hardly any diffrence,

I doubt it would make a diffrence when we are talking about 0.5 or 0.25.

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## RobH2

One thing I have noticed is that on some prints with higher layers I sometimes don't get as good adhesion as ones with thinner layers. I think with the thinner layers each one may get pushed into the subsequent one better. For instance, I printed a conical part about the size of a D battery. It was about 4" tall and I used .25 as the layer height. I flexed it just a bit to test it and it split between layers. So I reprinted it a .18 and when I tested it, it was really tight. I even bent it pretty firmly and it did not separate. 

I'm not sure if my printer was malfunctioning or it it's just the nature of layer heights in general, but from my experience, I don't trust the integrity of prints with thicker layers as much as I do those with thinner ones.

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## MeoWorks

> One thing I have noticed is that on some prints with higher layers I sometimes don't get as good adhesion as ones with thinner layers. I think with the thinner layers each one may get pushed into the subsequent one better. For instance, I printed a conical part about the size of a D battery. It was about 4" tall and I used .25 as the layer height. I flexed it just a bit to test it and it split between layers. So I reprinted it a .18 and when I tested it, it was really tight. I even bent it pretty firmly and it did not separate. 
> 
> I'm not sure if my printer was malfunctioning or it it's just the nature of layer heights in general, but from my experience, I don't trust the integrity of prints with thicker layers as much as I do those with thinner ones.


Same experience here, my sturdier prints are all 0.1mm or lower. I do think parameter (shell thickness) plays a bigger role though.

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## Geoff

> Same experience here, my sturdier prints are all 0.1mm or lower. I do think parameter (shell thickness) plays a bigger role though.


Definitely shells. All my quadcopters require 20%infill minimum and 2-3 shells for rigidity. Layer height makes very little difference, but it depends on your force distribution. For a quadcotper arm, I print them flat - so the layers run horizontally, or the same way it's going to sit on the quad.  If I was to print them standing up, as in long and tall... they would print layer by layer in the wrong direction...

hard to explain, but print out a small tube. Print one out standing up  and the other lying down flat. 

The one standing up straight will be more round and look better, but the one you printed laying down witll be 10x stronger to flex and wont snap. 

Look at the two pictures. See the cylinder standing up is built with small cricles - these are ok but not as strong as picture 2, where it's layed down in long strips - this is much much more rigid.
basnap.JPGnosnap.JPG

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## intohim

I haven't done any 'official' tests, but from my experience, the smaller the layers the stronger it is.  However, it would also probably depend on the material used.  I'm talking about PLA here.

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## trimmedup

Layer height really doesn't effect the strength in any noticeable way.  However I'm assuming there are some small differences.   I've never used shell infill.  I'll have to try this.  Do shells work better than honey comb?

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## Davo

We like 3-4 shells with a 25-35% rectilinear infill at a 45 degrees for our printed parts; 2-3 solid layers at top and bottom.

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## RobH2

> Layer height really doesn't effect the strength in any noticeable way.  However I'm assuming there are some small differences.   I've never used shell infill.  I'll have to try this.  Do shells work better than honey comb?


I haven't done any scientific experiments either but I've definitely experienced weaker parts with higher layer heights. I've reprinted a number of parts with thinner layers and they are much stronger. They don't suffer layer separation like the higher layer versions have. Again, this is just my experience as I've done no scientific stress tests.

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## Frans

Hi 3D Print Board!

I did a master thesis project about 3D printing and durability, including how layer height affects strength. I thought you may find my results interesting! I also researched and tested mechanical properties of FFF 3D-printed PLA, ABS, PET and three Taulman nylon filaments as well as other factors affecting layer bonding performance. 

I will attach the major findings and data as pictures in this post, but be sure to check out the full report for further information about the tests, Google Drive PDF: https://drive.google.com/file/d/0Bxo...JWR2lHcFU/view










Feel free to ask any questions about the project. Hopefully this could come in handy for you 3D printing entusiasts!



Edit: Thanks for the kind feedback! I don't seem to be able to make new posts for some reason.

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## Davo

Great paper, thank you for sharing it!

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## RobH2

Thanks for posting this. It's really interesting. Your findings are the opposite of what I've experienced which intrigues me. I need to examine my methods and see what might have led to that. I trust that your experiments are reliable and will enjoy looking through your data.

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## curious aardvark

Fascinating, I've dowloaded it as pdf I'll stick it on my nook for later perusal :-)

Thanks !

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## djprinter

In my experience prints become weaker once you exceed 50% of the nozzle diameter.

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## Alibert

Really nice and high quality Master's thesis Frans, thank you so much for sharing it with us!

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## ralphzoontjens

Frans, Thank you! This is great work and very helpful to the 3D printing community.

Thinner layers make for stronger parts.
In my experience a 0.15mm layer height with a 0.4mm nozzle gives the best tradeoff in print quality vs speed.
Imagine a cross-section of a 3D printed wall. The extruded filament comes out round with the width of the nozzle, and is compressed to the set layer height.
This leaves air pockets in between layers. With a 2x thinner layer, because the nozzle size remains constant, you get half the material in half the height, which means the filament gets compressed twice as much leaving half the air pocket. Because the filament is forming more or less a flatter ellipse, the area where the layers meet will exponentially increase (at least more than linear). Also the part becomes more homogeneous overall making for a much stronger part.
This has consistently been my experience.

@Frans, for your experiments n = ?

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## Frans

Thank you for the kind feedback!

@ralphzoontjens
I think that is a good theory! Not sure if it is enough to explain the phenomenon but still. 

What n are you thinking of?

Moderator note: Late post is due to unexpected delay in obtaining moderator approval

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