Editing .STL Files

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Editing .STL Files

This topic has 10 replies, 8 voices, and was last updated 10 January 2019 at 19:40 by Jeff Dayman.

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9 January 2019 at 20:53 #31591
Colin Heseltine
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@colinheseltine48622
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9 January 2019 at 20:53 #390233
Colin Heseltine
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@colinheseltine48622
Has anyone played around with editing .stl files they have downloaded from sites such as Thingiverse. I have looked at a few Youtube tutorials where people are using Tinkercad and it looks as though it is worth a try. Has anyone on here used it for this purpose?

Are there better options. I do have Turbocad 2018 Professional but struggling with the learning curve.

Colin
9 January 2019 at 21:04 #390238
Jeff Dayman
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@jeffdayman43397
In my opinion, time would be better spent learning a good 3D modeling package like TurboCAD or many others, rather than a "repair" or "doctoring" editor for stl files.

A good 3D model can be modified at will as needed and from it you can output clean stl anytime. I'd be hesitant to do a big complex time-and-filament-intensive print from an iffy doctored stl file.

(but I do have the advantage of owning a Solidworks license)
9 January 2019 at 21:41 #390243
Steve F
Participant
@stevef
Yes i've had a dabble with stl files……..Yuck

First thing is an stl file is a mesh and the object is made up of triangles. Loads of em. If it's something engineering rather than artistic you can open it in designspark. Select the object and do convert to solid. You can then sometimes mess about with the file. Then resave as and stl or designspark file for future editing. If its something artistic then head for meshmixer. You can muck with all the triangles pushing and pulling the shape. It's best if you can download the file in it's native cad format rather than stl.

regards

Steve
9 January 2019 at 23:37 #390254
Fergus Stirling
Participant
@fergusstirling62506
STL files are a garbage fire of a format, used to use them in a former GovT job. There are many standalone convertion programes you can use to put them into somthing more usable, modify in your program of choice then output to a clean STL (or somthing else if you can)

I used to use them in solidworks and 3DSMAX (but i had to write some custom tools to import them properly) The biggest problem is that the format simply defines a list of unconnected triangular faces, so when you import them into a program, it has to undertake a 'vertex welding process' and assume that vertices within approximately the same location are connected to form contiguous mesh faces. So each final vertex point in a mesh may be made up of many triangular "corners". this obviously falls over when you have very complicated STLs with high levels of detail because there has to be an assumed tollerance when doing the weld process…. so nearby verticies that should occupy the same 3d co-ordinates can get pulled together forming a big broken meshy blobfest….. Blaa bla bla….sorry bored myself…

admittedly you can (with the likes of both of thes programs import them unwelded, but then you just end up with a big pile of triangles, which makes any hope of modifying the object unrealistic.

The early commercial Stereolithography 3d printers that we used to have, would only really work with STL files, and back then (ironicaly only about 10 years ago) small models would cost thousands of pounds each to print. Do newer 3d printers work with other file formats or is STL still the only format used?
10 January 2019 at 08:06 #390270
Gary Wooding
Participant
@garywooding25363
STL files can be edited in Fusion 360 which, as you know, is free for hobbyists etc. F360 is my program of choice for producing models for 3D printing.

I've been using TurboCAD for years (since V2 in fact) but have basically ditched it in favour of F360.
10 January 2019 at 08:35 #390277
Brian G
Participant
@briang
Perhaps it also depends on what else you do? If you also like punishing the brown stuff, SketchUp seems to be the woodworker's preferred software, and although it doesn't directly manipulate STLs it has excellent add-on import and export functions and is simple to use. Its interface is pretty intuitive and you can be creating models (or modifying models imported from STLs) and exporting to STLs within an afternoon.

Brian
10 January 2019 at 11:31 #390308
Neil Wyatt
Moderator
@neilwyatt
The only way to edit an STL meaningfully is to treat it as an amporphous lump and either cut bits off or add bits on. TurboCAD will do this but it's a ghastly process. Even a cube becomes at least twelve triangles as an STL and the potential for creating 'non-manifold vertices' and other trauma is huge.

There are alternatives to STL for 3D printing, but the only advantages of other formats are adding properties like colours and textures.

The reason for STL is that it is a purely geometric representation made up of straight lines and vertices which makes generating one from a CAD program straightforward and processing for printing easy, but editing a nightmare (for example a sphere defined by just a centre and radius becomes a huge geodetic construction as an STL.

Neil
10 January 2019 at 17:35 #390378
Enough!
Participant
@enough
Posted by Jeff Dayman on 09/01/2019 21:04:10:

In my opinion, time would be better spent learning a good 3D modeling package like TurboCAD or many others, rather than a "repair" or "doctoring" editor for stl files.

A good 3D model can be modified at will as needed and from it you can output clean stl anytime. I'd be hesitant to do a big complex time-and-filament-intensive print from an iffy doctored stl file.

(but I do have the advantage of owning a Solidworks license)

That's fine (and I'd agree) for models that you design yourself, Jeff, but many of these STLs are lifted from, say, Thingiverse without any accompanying native file. The STLs contain no history so they can only be edited in gross fashion in a cad program.
10 January 2019 at 18:47 #390393
Colin Heseltine
Participant
@colinheseltine48622
From all the views above it looks as though I had better have another go at Turbocad and do it properly rather than try to edit/play with .stl files.

Colin
10 January 2019 at 19:40 #390406
Jeff Dayman
Participant
@jeffdayman43397
Posted by Bandersnatch on 10/01/2019 17:35:08:

Posted by Jeff Dayman on 09/01/2019 21:04:10:

In my opinion, time would be better spent learning a good 3D modeling package like TurboCAD or many others, rather than a "repair" or "doctoring" editor for stl files.

A good 3D model can be modified at will as needed and from it you can output clean stl anytime. I'd be hesitant to do a big complex time-and-filament-intensive print from an iffy doctored stl file.

(but I do have the advantage of owning a Solidworks license)

That's fine (and I'd agree) for models that you design yourself, Jeff, but many of these STLs are lifted from, say, Thingiverse without any accompanying native file. The STLs contain no history so they can only be edited in gross fashion in a cad program.

Hi Bandersnatch – I understand your point about Thingverse and other stl libraries. My experience with such stl libraries has not been good overall, there have been some good models and a number of really bad ones. A number of people have insisted I get their parts from Thingverse and other stl libraries. I've had much better luck importing CAD files for the needed parts in native or step format into SW or other CAD. I can modify features if needed , then generate clean stl with resolution dialed in to the process capability and dimensional needs, or I can model items from scratch with SW or other CAD. In many cases for simple parts it is far faster to model from scratch and this has the added benefit of being able to dial in dimensions to exactly what is needed. There are huge libraries of existing CAD models out there, maybe same amount or more than for stl. My point is I prefer CAD based 3D print projects rather than depending on stl libraries. Just my opinion. Your mileage may vary. Many many ways to get the job done.
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