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Sketchup file to STL

Posted by gemors 
Sketchup file to STL
August 04, 2016 04:09PM
G'day all,

I've drawn this up in Sketch up and then exported it to a STL file with CADspan, when I then add the stl to slic3r I lose most of the outer and top walls. I've read a bit about the inner walls being an issue. Should I be removing all the inner walls and so that only exterior facing walls are visible?

The two attached file: Sketchup and then the resulting Slic3r file...



your thoughts would be much appreciated.
Attachments:
open | download - sketchup preview.png (32.5 KB)
open | download - slic3r preview.png (110.8 KB)
Re: Sketchup file to STL
August 04, 2016 06:37PM
There is a plugin for sketchup that will allow you to export STL files. That said, Sketchup is a piss-poor CAD to use for 3D printing. I know it is easy- I used to use it, but it produces poor quality models that usually require repair using programs like Netfabb before they can be printed. The problem comes from the way Sketchup handles curves. In Sketchup, curves are actually polygons. The result is that when you try to connect objects the connections can only happen at vertices. If the vertices don't meet exactly, you get a gap or an overlap that will cause problems for the slicer. In a real CAD program, curves are mathematical curves, and that prevents a lot of the sort of problems you get with Sketchup.

Look at DesignSpark Mechanical for CAD that has a user interface similar to Sketchup. It is free, easy to learn and use, and much more powerful that Sketchup. It is crippleware- they leave out a few features like lofting and text, but it will do most things you'll need without requiring 6 months of study to use it. Oh yeah, it produces very high quality STL files that I have never had to repair before printing.

Some Sketchup fanbois will say "STL files are polygons, so it doesn't matter if curves are polygons in Sketchup". But it does matter. While you're designing the part, you need mathematical precision and accuracy. Once the design is done, converting to STL polygons is no problem. Sketchup is the only "CAD" program I know of that produces errors in the CAD models that lead to errors in the STL files that will prevent slicing without prior repair.

Here's a simple test that illustrates the problem: in Sketchup, draw two circles of random sizes and then try to draw a tangent line to the two circles. After you draw the line, zoom in to the place where the line meets each "circle". Notice anything strange?

If you want to learn and use a more professional CAD package, look into Fusion 360 and OnShape. The learning curves are a lot steeper, but they are both free and fully featured.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Sketchup file to STL
August 04, 2016 06:48PM
Thanks for the repl! Much appreciated!.

How does Blender compare to: DesignSpark Mechanical for CAD, Fusion and Onshape?

thanks heaps
Re: Sketchup file to STL
August 04, 2016 07:14PM
Blender isn't CAD. It's for doing "organic" modeling like sculpting characters/objects for games and animation. You can do precision modeling in Blender, but it isn't easy.

OnShape was developed by the guys who wrote Solidworks. It is cloud based, which has advantages and disadvantages. You can use any screen with a browser to do 3D CAD with it, including your phone if you must, but you're dependent on their servers, and must have an internet connection to use it. You get limited storage for "private" projects and 5GB storage for "public" projects. The learning curve, like that for any professional level CAD, is steep, but there are plenty of on-line tutorials available.

Fusion 360 is an Autodesk product, fully featured, professional level CAD with the standard steep learning curve and tons of tutorials available. It probably needs an internet connection to run, like most CAD software these days.

If you're really going to get into CAD, consider getting a 3D mouse (3dconnexion.com). I use one with DSM and I would hate to give it up. It will work with almost any CAD software that runs in Windows, including OnShape. Watch some of the Youtube videos of a 3D mouse in use and you'll be hooked.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Sketchup file to STL
August 05, 2016 12:04PM
Blender is a polygonal modeller, just as SketchUp, under the hood, really is.

These modellers produce polygon mesh models. [en.wikipedia.org]

Quote
the_digital_dentist
Some Sketchup fanbois will say "STL files are polygons, so it doesn't matter if curves are polygons in Sketchup". But it does matter. While you're designing the part, you need mathematical precision and accuracy. Once the design is done, converting to STL polygons is no problem.

You summed up the problem quite nicely. And "Sketchup" in "Sketchup fanbois" could be replaced with any polygonal modeller's name IMO.

But as for myself, I do not trust free commercial products like DesignSpark Mechanical, OnShape or Fusion 360. I do not want them to monitor my usage (which you can bet they do). You have to ask yourself the question: why are they free? Developing software (or licensing one like RS Online did for DSM) costs money. As a matter of principle I don't use crippleware. They really disabled lofting in DSM? On top of not being able to export a model to an open exchange 3D CAD format, for me that's unacceptable.

For these reasons I prefer to use open source software FreeCAD. Granted it's not as intuitive, it has its quirks, bugs and limitations, but the latter were not wittingly introduced by the developers, who are volunteers working in their spare time.

Edited 1 time(s). Last edit at 08/05/2016 12:05PM by NormandC.
Re: Sketchup file to STL
August 05, 2016 05:06PM
CAD can be hard enough without adding all the problems that come with FreeCAD. If you're committed to open source at any "cost" (i.e. your time to work through the weird user interface and all the bugs) it's fine, but many of us just want to create a model with the minimal effort and don't care about philosophy.

OnShape specifically provides 5GB of "public" storage on their servers. Obviously, if you're designing things for commercial purposes you probably don't want it shared publicly. They have a subscription for additional private storage.

Fusion 360 has a more complicated licensing scheme.

DSM doesn't use cloud storage, but your computer seems to require check in with their server, probably to prevent bootlegging of their commercially licensed product, but who knows? Who cares?


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Sketchup file to STL
August 05, 2016 05:20PM
Hi all,

I ended up with DSM and it seems very capable and will do what I need to.

Thanks for all your help!
Re: Sketchup file to STL
August 05, 2016 09:06PM
Quote
the_digital_dentist
CAD can be hard enough without adding all the problems that come with FreeCAD. If you're committed to open source at any "cost" (i.e. your time to work through the weird user interface and all the bugs) it's fine, but many of us just want to create a model with the minimal effort and don't care about philosophy.

For one thing, FreeCAD's UI isn't any weirder than any other parametric CAD I've worked with. How many have you actually used by the way, to make such an assessment?

I'll wager than I can create a model in FreeCAD as fast, or even faster than you can on DSM. Oh, and not to brag but I can use lofts, and who knows how many tools that are disabled in DSM. winking smiley

Anyway, I figure it's pointless to argue any further, I'll only close with this comment: if you don't care about philosophy, I wonder what the hell you're doing in the RepRap movement.
Re: Sketchup file to STL
August 06, 2016 05:17AM
My level of paranoia isn't quite as well-developed as yours, I'm not in any "movement", and I don't care for any philosophy but print quality and printer reliability. Unlike many in "the movement" I place a pretty high value on my time, so I use whatever tools get the job done with minimal investment of time and effort, whether its FOSS or closed source. I design my printers with minimal 3D printed parts because they generally can't compare to the performance and reliability of metal parts. I publish a lot of information about my designs, experiments, and results (including failures), in case there are others who are similarly driven to produce high quality prints and want a reliable printer. I do not limit myself to trying to keep my designs under the magical $300 price ceiling that so many in "the movement" seem to have imposed on themselves. I came to the conclusion long ago that I cannot meet my quality or reliability goals for $300. That said, I don't throw money around like a drunken sailor, either, and I buy quality materials and parts where I can find them at the lowest prices, including scrap yards, ebay, and industrial suppliers. I am always looking for lower cost methods and sources that don't compromise the reliability of the printer or the quality of the prints it produces.

You may indeed be able to do things in FreeCAD faster than I can do them in DSM, but it didn't take me 6 months of daily effort to learn how to do them. So far, I've been able to live without lofting and text in my prints. I did spend some time with OnShape a while back- I'm not a fan of Windows or MS, so a professional level CAD package that can be accessed via a computer running Linux is very attractive. Eventually I will try to become more proficient with OnShape. Unfortunately, I am stuck with Windows for my 3D scanner, so my transition to Windows-free living is probably still a few years away.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Sketchup file to STL
August 06, 2016 11:29AM
Quote
the_digital_dentist
My level of paranoia isn't quite as well-developed as yours

eye rolling smiley

Quote
the_digital_dentist
You may indeed be able to do things in FreeCAD faster than I can do them in DSM, but it didn't take me 6 months of daily effort to learn how to do them.

I've been helping people on the FreeCAD forum for quite a while. Funny how some people can't seem to grasp the software and will say it is hard to use, while many, many others learn it very quickly - it certainly doesn't take them "6 months of daily effort". I guess some people just learn faster than others.

I have no idea where the rest of your comments about the $300 price ceiling came from. Whatever. eye rolling smiley
Re: Sketchup file to STL
August 10, 2016 06:20AM
Download this plugin, it will automatically prepare your SketchUp files for 3D printing and you'll be able to download your file in STL or Obj format.
[makeprintable.com]
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