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Cura not up to task ??

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  Trying to print a an ACad File  (stl) that was used as the basis for CNC'ing of a full scale WW1 aviation engine.

The file/design is credible ..  and the resultant engine has Flown. 

Trying for days now to get Cura (3.2.1) to  Slice this  File... 135 mb though so i can print a reduced scale model. 

Wellll It slices.. sort of.. but it  keeps missing sections of the engine.  Even got a 25 mb STL for it to "slice' ... More like it chops it up... in truth

V annoying .

Is this file Too Complex for this pgm to deal with?

 Is there any way to get Cura to do a credible job of this?

Edited by danilo

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If it doesn't crash then it's up to the task.


The problem is almost certainly that there are errors in the model.  STL format is just a bunch of unordered triangles.  Likely you have wall inside of solids or you have holes in your walls such that cura can't figure out what is inside and what is outside.  If you look at the model in xray view you may see some red areas - if so then those are problem areas.


In addition each triangle has a "normal" which indicates which side of the triangle is "inside" and which is "outside" aka touching air.


I would try this - first I would decimate the model a bit so it's easier to work with - this step is optional though:



Then I would repair the model:

netfabb free repair service is here (but you have to create an account):


Do those two steps and it will probably slice fine.  Or at least the second step.


If you created the model yourself and you did it in sketchup then I can give you a guide to repair sketchup models which is a better route (if you plan to make changes to the model later) than using netfabb.


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Thank you gentlemen:

Here is the STL  (it was reduced from 134 mb to 25mb STL by makexyz.com)    ( file attached) Can supply the original 138 mb file if wanted/needed.. please advise

Oddly the first 3 print tries were  very poor but at least it was printing Yesterdays' Slices printed Without any Z  .. sigh.

Cura doesn't crash but it does seize up for a few mins, maxing out my i7 processor to 100% in process. So somethings amiss somewhere I suspect.

Here is a Cura file 65mb. I'm wanting to print this 37.2" diameter (real life size) as a 1:12 scale model) so detail will obviously suffer

AA63DP_Le Rhone Engine.curaproject.3mf

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OK, got a chance to look at it. You have a few issues with the file. Mostly stemming from being designed for CNC Milling and not for FDM printing.


CNC Milling's objective is to make parts that will then be assembled and have all the working parts designed. Here you can see that the heat sinks (A) for a piston is removed, it has openings for all the parts from rods to piston to spark chambers and when the flywheel is removed (B) you can see it has all the interior structure as well. This is designed to be a working metal engine.


This will give you a few problems to start with.

  1. You wind up printing an huge amount of unseen internal detail that actually weakens the parts printed.
  2. Because the design is to be mated up and not fuse as a whole, you run the risk of it coming apart after printing.
  3. At scales you are working with, the walls become super duper thin.

So, if you enable print thin walls by unhiding options in the preferences, you can get this result.



This will still have the problems of all the internal structure. But all that yellow is Cura trying to compensate for extremely thin walls and will not be a sturdy print.


I removed the  Heat Sink portion of a piston and some hosiery (Pun intended) from the model and capped them off. This was not an easy task, but it will show the difference in how it looks for CNC Milling and FDM printing. The capped version of a model can be much printed much quicker due to working on the outside structure and not all the super thin walls and unseen parts. I am including a file that produces this result for you to see the difference like this:


(A) Is the original file. It still has a bit of yellow thin wall to it, but not nearly as much.

(B) Is the same file, but put a small (0.2mm) Horizontal expansion on it in "Per Model Settings" and it perks right up.


One last problem with a file with this thin of edges is that the nozzle size greatly impacted the ability of the sampling process to get the thin details. This file is Cura 3.2.



Edited by kmanstudios

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Wow... I'm both Flattered and Humbled by your Efforts..  Thank You! 

New at this being my only credible excuse :-)

I knew that it was a CNC type file and that It would print all the Internal bits,   albeit  unnecessarily for my needs, I assumed / thought that was unavoidable baggage.

 I'm only after  a simple, looks like the real thing facsimile version..  viewed  from the outside

 Your provided File is interesting.... I had  given thought to Printing the individual bits But Frankly had zero idea of how to separate them into  pieces I can post printing assemble into my desired model.  No idea of how to tho.

IF I could get One Cylinder Complete with it's Valve gear (pushrod is unlikely to print well in any event and a Bit of ali tube/wire could easily be retrofitted)

 It's the detail of a Complete Cyl that  is all that I'm after/ need tbh.. If it becomes a case of Simplifying.

The crankcase is simply a Hollow can shape devoid of any significant detail.. That I can fabricate manually ...fairly easily .

Thought was that I could print 9 cyl assemblies then glue them onto my diy cranckase

IF? I could trouble you further on this  Can you provide some "how to" info on how I might  get this file  to Print One almost (no pushrod) complete  Cylinder?



vancouver canada


Edited by danilo

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17 minutes ago, danilo said:

Wow... I'm both Flattered and Humbled by your Efforts..  Thank You! 

First, you are quite welcome. Second, do not be flattered as I just like to solve problems. Advances my knowledge and helps others. I do this sort of thing here as well as others. I think I jut got to it first :)


Now, I will have to put on the thinking cap as for the easiest way for you to get to your goals. I mean, most of my knowledge is centered on modeling and some high end programs that are expensive. But I wonder if a few people here could chime in and offer some easy ways to do this.


Edit: What programs and type of modeling are you using now if any? That would help :)

Edited by kmanstudios

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Erm... None.

As above:  Komplete Newbie I'm after an engine model for a 1;12th scale DH2 model (ww1 aircraft)  I'm attempting to build.

Tripped over this Le Rhone engine  file and was delighted.  sadly it's proven not nearly as simple an exercise as I anticipated

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 OK Small issue tho (beyond having to guess where the front door was :-)


It won't let me register? 3 separate Email addy's...3 seperate User names.. said All were in use.. As if

 Will try it again a bit later. hoping traffic at least might lessen

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