Printed object thicker than model

[Yowan 0]

I'm playing around with settings and printing some small test pieces to establish the best parameters for printing parts and keep finding the printed parts are thicker than the modelled part.  It looks like some of the initial layers aren't as close to each other as they should be which when accumulated increases the overall thickness of the part.  Any ideas on how to address this please?

The thickness of the part in each photo should be the same (5mm).  I've attached the stl file for reference as well.

Test Cube.stl

[SandervG 1,135]

Hi @Yowan, welcome to our community! 

Could you elaborate a bit more about your goal? Are you trying to establish a standard to print a lot of one particular model, or a certain type of material?

It is likely that the best parameters may very depending on the size of your model and what material you use. 

If you use your Ultimaker professionally, it makes sense to establish a benchmark but just wondering what your scope is. 

 

Could you in your photo include in which orientation it is printed? I can guess based on a hint of layers I see, but it is better to be sure. 

 

Do you have active leveling enabled? This feature compensates for any offset during the first 10mm of your print. Have you tried rotating your print by 90º so it stands rather than it lays flat? I think 4.94mm is not a very bad outcome, there will always be some shrink/expansion because of the material being thermoplastics. 

[Yowan 0]

I have a machined component which has various curved surfaces that I've be trying to re-create with a 3D print, so that I can have it machined in-house.  However, getting the settings correct to ensure an accurate dimensional replica is printed is proving problematic!  I suppose it's more about establishing some standard default settings for printing using PLA (with PVA support where applicable)

The actual piece I'm looking to print is approximately 150mm x 150mm x 90mm but whether I print a small test cube 20mm^3 or the main part, there gaps between the layers that increase the overall dimensions.

I've tried orientating the part in different ways but that just means it#s thicker in a different axis.

Active leveling is enabled and I'm happy with the 4.94mm dimension - it's the 6.21mm which highlights the problem; 1.2mm over a 20mm is far too much and when you apply that to the main part I'm trying to print - it results in being 3mm wider than it should, which is not acceptable for my application.

The expansion is only in the Z axis - X and Y axis are spot on.............bit of a head scratcher!  I'm wondering if it's because of speed or temperature or something else?!

[SandervG 1,135]

Would you be willing to turn of Active leveling for a print, and see if that makes a difference? 

[Yowan 0]

Yeah, absolutely - will try anything! Will give it a go and let you know - thanks.

[Yowan 0]

@SandervG - That certainly made a difference - will continue with some larger test pieces but printing WITHOUT Auto levelling has produced a far more dimensionally accurate part - much appreciated!

[SandervG 1,135]

No problem happy to help! Active leveling is really great if you start prints through Cura Connect and are not sure about the calibration of your Ultimaker, or when you have a print with a thicker base plate. Active leveling corrects an offset during the first 10mm, and reduces the compensation to 0 during the next 10mm. Which means after that, you should have the desired dimensions again. 

If it had to correct an offset which caused your dimensional inaccuracy, you may want to manually level your bed if you haven't already. 

 

How? 

You can find some tips on the second half of this page.

 

Good luck!