3D STEP File Compatible: For supports export and import file


I still fail to understand how Autodesk was somehow responsible for the design of Formlabs Preform. Autodesk did not acquire NetFabb until late 2016, and the software was redesigned in mid to late 2017. By then Preform was in full swing, and had gone through nearly 30 revisions.

So please tell me how was Autodesk involved in the development of PreForm?

Last but not least, what is it that makes NetFabb a red herring? Is there something deceiving about it (or about its use) that we should all be aware of?

Edit: Preform uses the NetFabb engine for fixing defective models when they are loaded. Even if there is more to the NetFabb core in Preform, this is NOT the Autodesk Netfabb, it’s the original German NetFabb, as this functionality inside Preform predates the Autodesk/Netfabb merger by more than 3 years.


500,000 polygons is quite a lot. and the ability to see the individual facets is dependent entirely on the size of the object.

Here is a 37K triangle object. one at normal size, the other at 5x the size. Obviously you can see the individual faces at the larger size, but the normal size of the object is 20mm in length, there’s no way you’ll be able to see any thing, simply because the printer cannot resolve faces that have edges smaller than 0.2mm

Additionally, many programs like Solidworks do smart tessellation. They assign (break down the curves) into more triangles to achieve a smoother curve, while the flat surface have very few triangles. So a properly tessellated object can still have less than 500K triangles, yet look perfectly smooth.


I’ve spoken to Autodesk to enquire about the purchase of Fusion360 or Netfabb, because Pre-Form isn’t full proof when it comes to basic STL repairs.

Which is annoying in a professional environment as I don’t have all day doing tweaks, because time is money.

Also, if Preform isn’t an integrated solution it isn’t a long term solution it not a real solution.

I suggest you speak to them too, because there are some similarities between some of the Autodesk UI architecture e.g. Recap Pro & Print Studio. We already know that Netfabb involved with Pre-Form repair tools, but to what extent is something I couldn’t get a straight answer. Netfabb was developed in Germany and said direct there “was” involvement, but other Autodesk members said Formlabs only acquire the their OEM version for development.

While Preform have told me about their software development process and couldn’t tell me about the lead-time or scheduling or even an approval process when & how to treat a reported bugs or add improvement features.

In another word, if there is a software issue with Preform, there doesn’t seem to be anyone I could speak to directly anywhere in the world. I’ve tried.

One positive note is that Formlab is still very young and very willing to listen to communities concerns, unlike the older and more professional companies, which doesn’t tell you anything for product improvement. Unless you show them $$$



Not for me, it common to have professional 3d models with intricate details for print (especially injection moulding parts) and it usually runs into few millions of polygons or else end up with a pixelated prints.


If it isn’t an Integrated solution, it isn’t a long term solutions, especially in a professional environment, because time is money.

Most graphic designers I know (directly) prefer working with raw data e.g. Vector vs Jpeg similarly when capturing in raw than JPEG in cameras.

Are you saying jpeg is more important than raw or adobe illustrator? Eventhough Jpeg are designed to remove workable data, unlike raw.

STL file where never intended to be modified (invented before windows) and the only reason 3d printing industry uses it because it free, not because it easier to work with compared to raw data.


Not for me, it common to have professional 3d models with intricate details for print (especially injection moulding parts) and it usually runs into few millions of polygons or else end up with a pixelated prints.

That sounds like it is a memory limitation. Though I’m not sure I understand how a laser tool path could result in a pixilated print.


Does Solidworks have any control over tesselation on export? MOI has outstanding controls on curvature while minimizing faces on flat surfaces. FormZ has more of a global approach but also does a very nice job. I made some threaded parts and fit was tricky but I was able to do it. I actually had more of an issue with an acme thread drooping rather than the resolution of the model. You really need to not go courser than 50 micron when doing threads from my experience unless your making super course threads. Finest thread I was able to do was a 28 pitch screw and that was difficult. As far as dimensional accuracy the prints seem pretty good and I haven’t had any issues with that.
I do agree injection molded parts you may need to tweak the files to handle the better tolerances. I assume most if not all resin based prints are subject to shrinkage as they cure to some degree and 3d printing in general you have to contend with the stepping of the layer thickness that affect surface quality even if not easily noticeable. Just the nature of the beast. This is probably why subtractive prototyping is still more accurate for FFF but not always practical or possible for all shapes.


I think Kevin is not referring to pixels, but Voxels.

STL is triangulated geometry. The triangles describing curved surfaces are planar; where large enough, those planes can become visible in the print when using a printer with the resolution of the Form2.

MOST models you can download online will show planar geometry because they are modeled to render good, rather than be printed.

I routinely model at 80 million polygons- but because of preform’s 32 but memory limitations, I have to decimate the file down to under 140 mb or preform won’t input it.

It also has a bug importing several STL files in a row… claiming subsequent imports are “bad” geometry when I know they are perfect.

However- the problem with STEP or other formats that have spline surface capability is that surface modeling has real problems with solidity.

It doesn’t matter in MILLING because the mill software is only deriving a TOOL PATH in space… the cutting head doesn’t care which side of the surface is solid… it will trace the surface in free air if there is nothing to cut in its way.

But all Print technologies REQUIRE the model to qualify as a topological solid. The printer is not CUTTING a preexiuating material to form- it is deposting solid material where the model is solid… so the file need to know what parts of the model ( all the way thru ) are solid- not just the surface acutting head will trace.

STL- by eliminating all spline data- stitch data- and not having to deal with coons patches versus other types of UV geometry- has far less issues maintaining solidity, and is far easier to rectify lack of solidity.

Its no big issue to convert subD or surface data to STL- unless your software is not capable of resolving or detecting solidity issues.

Also- the idea that STEP files or IGES files are smaller is a myth.

They are generally much smaller when modeling simple shapes like engineered parts composed of cubes and cylinders… but to model a highly detailed organic figure in nurbs with any level of accuracy requires so many fit points per patch and so many patches that the file size quickly equals or exceed an STL model that can capture the same level of detail.

And the only way to reduce the file size of a surface model is to LOSE overall fine resolution- whereas STL models Can be intelligently decimated down to a target size and preserve fine details.

Used to be, we only ever created nurbs models because many milling apps would ONLY accept surface data… tho for 15 years now, most modern milling apps can mill directly from STL as well.

Parametrics and surface modelers are fine for engineering… but for anything organic, Voxel stl modelers and subD apps reign supreme.

And Preform accepts both STL and OBJ… so-

The last figure I did in nurbs ended up being a 1.2 GB STEP file… Preform can’t import that much data even if it could accept IGES or STEP.


I found that you can import files with about 6M polys (about 300MB). Anything larger than that generates an error. The cowboy STL file is about 288MB and 5.89M triangles.

However, that only applies to any single model. You can import multiples for a higher combined total. Each one of the Space Marines is a little over 2M polys. The combined total is 8.35M, the combined FORM file without supports is 718MB


I’ve been having a different issue.

I often decimate and export multiple models out of Freeform. They export as separate files.
And I know from 18 years experience that Freeform exports perfect qualified solids every time.

When I import one model into Preform- it comes in fine- but when I try to import a SECOND model… it ALWAYS returns a File Broken error.

However- if I then save the file and CLOSE preform… and reopen the file… it will import the next model without a problem.

But here’s the really weird part… this only works if I re-open the file by clicking on the ICON for the specific file on the desktop or in its folder.

If I reopen the file from the taskbar recent files list… or if I relaunch preform and then try to open the file from inside Preform… I still can’t import additional models.

I was hoping the recent update would solve the problem, but it hasn’t.


After 12 months of complaining, 64 bit is finally here:

and after some initial testing it seem to process both files (.stl and .form) twice (almost) as fast than before.

Let just hope they will add STEP import option as well, because others already starting to do this for the sake of file handling.




You can keep your “High School” mathematics & your arguments about PreForm “STL is more than sufficient to meet/exceed the resolution of the Form2.” Go get some structured light data or inspection measurement data to support you claims. Because all I have read is an opinion & my opinion is different based on my experience during the conversion process & my requirements.


I’m an Engineer 20+ years with CAD/CAM. Many don’t understand fully what you are saying because they probably have never done it in a real manufacturing environment and don not understand the processes used. I’ll put it Basic Terms: STL sucks for Engineers. The way Engineers use NEW Products is also dependent on what other industrial products stipulate (i.e. what are the current industrial standards) . I have read Kelvin’s many examples and he has given numerous industrial examples that I agree with and support his argument. That tells me FormLabs may not understand my industry and thus my needs as a Design/Development Engineer well as they think they do.


Depends on which G code they are using… Is it 100% industry standard? I have found many are not… lol


What’s the latest on this. We are now running into file size issues with STLs as well and I’m typically only exporting 100k-300k triangle models. It’s making it very difficult to send these files over email to service bureaus. During our revision control implementation we’d likely be looking at alternative file formats. We would also need support for these file formats from formlabs to make printing a bit easier.