Is this normal?

We just recently received a Form2 and have been knocking out prints with both flexible and clear material. Some of our parts are cylindrical, and I’ve noticed that the cylinders seem to be a really low resolution. They appear well rounded in SolidWorks, and are exported as .stl files. But when they are opened in PreForm the cylinder face appears to consist of a low number of vertices. It isn’t square by any means, but it does look blocky, and prints that way as well. Orientation of the model does not matter. I have not printed under .1, but setting it up to print under .1 does not change what the object looks like in PreForm.

Is this a matter or print resolution? Is there a setting in SolidWorks that needs to be adjusted when saving a part as .stl? I’ve gone into edit while saving and selection “fine” but it does not seem to matter to PreForm. Should I save it as something other than .stl? Is there a way to say, this arc should be represented by 64 vertices instead of 32?

I took a screenshot but not sure how to upload it here.

Thanks ahead of time for your input.

The default export settings for cylinders is very low in solidworks. When saving parts to STL, make sure you set deviation very low in the options box.

When saving as an STL file there is an option box where you can set the resolution. That could help. I haven’t noticed that problem with my cylinders and I use solidworks all the time. But I think a while ago I set my stl resolution pretty low.

As mentioned above… Here is the options page, once you have chosen STL as the file type. Not only is the deviation important, but the angle. Reducing the angle creates a much finer mech. I usually never go above 3-degrees. A small deviation and angle can make a truly enormous file, so you have to be a little careful,

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Thanks folks. I had changed it from “course” to “fine” and had not noticed a difference. Going to custom and playing with those two settings helped. Is this just a SolidWorks issue? I’ll be exporting from Blender as well. Is there a better file type to use instead of .stl?

For some reason the 3D printer industry picked a terrible file format. So unfortunately, you’re stuck with STL.

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I don’t know if there’s any 3D printers that can use that type of format, it usually has to be converted to a set polygon resolution for it to be able to be printed.
Software like Blender already works in polygons so you need to make sure you turn off smoothing so that you can see what the model actually looks like and make sure you have enough segments on the curves.
STL is really basic so it’s easy to work with for the needs of 3D printing.

I use solid works only. And have not had this issue. What is the diameter of the part?

if solidworks has obj export try that. I use rhino and it makes a big difference. obj seems much smoother. then I can use a mesh repair command in Rhino 5 to convert it to stl and fix any errors

It would be nice if Rhino5 had a relationship with FL2 like it has with other printers.

I’m not sure what “relationship” would mean, but I export STL files from Rhino 5 and drop them into Preform and they work great. Rhino (and Grasshopper, their procedural modeling extension) and the Form2 make a great combination.

Not entirely. The STL format isn’t lossless so in most cases it’s impossible to export a geometry and get 100.00% the same result, except if you have only planar surfaces.

The issue with SW is that the preset settings (even on “fine”) are pretty bad. Fortunately it’s easy to tweak and you get a preview when exporting which allows you so assess if the non-planar surfaces are smooth enough. Beware that extreme precision greatly increases the file size.

TL;DR : depending on the export settings, any software will show the same issues, but most softwares probably have better default settings than SW.

So no subsurf modifier?

You can use that in some cases to increase the number of subdivisions and smooth it out, but sometimes it can make some errors on the model if it’s not designed for it. Like Hard surface models can have issues when you do that.
I use 3ds Max and in there the visual smoothing effect (which doesn’t subdivide the mesh) is called Smoothing groups, so a set of polygons can be given a smoothing group number to say that they should be smoothed together. You can drop a Turbosmooth or Meshsmooth modifier and restrict it based off smoothing groups to maintain the hard edges, but some hard surface modeling techniques will create issues where a polygon might end up overlapping another and some other weird stuff. But it’s still possible to get a good result if you mess split things more with smoothing groups or do a quick manual fix to vertices after using Turbosmooth.

At least the settings in solidworks are fairly straight foreword to find. I manually made mine extremely fine because I don’t care about file size.

In Catia the STL resolution is tied directly to your display settings. Took a bit of digging to figure that one out.

In Solidworks, all curves are handled as mathematical equations. When Solidworks exports an object to STL, it needs to tessellate the surface, it breaks the surfaces into connected triangles.

Unlike other programs that breakdown all the surfaces into (more or less) equal sized triangles, Solidworks takes a more intelligent approach. If the surface is planar (flat), it will break it down into the minimum number of needed triangles. For example a cube will have a total of 12 triangles (6 faces of 2 triangles each). Curves will be first broken up into flat surfaces of “X” number degrees (that is controlled by the export option under angle). Lower angle values will increase density of the mesh on the curved surfaces. Becuase these creates triangle edges at the edge of the model, it also forces the flat surfaces that attach to them to be broken up into as many triangles as needed.

See the image below, where I save the dish model into a coarse STL (the angle is 10°, so there are 36 flat surfaces around the base), and a fine model, where the base is now made up of 360 flat surfaces, which for all intents and purposes will print smooth, at the size of the model (30mm diameter).

The other value that can be changed is the deviation. This changes the accuracy of the tesselation algorithm, and can produces very dense meshes, yet not improve the smoothness of the curves as much as changing the angle value does.


Dudemeister is correct…

As I mentioned above the angle setting has a profound impact on smoothness, often much more than deviation. This is particularly true for regular curved geometry, such as a cylinder.

I do wish that they had an absolute tesselation edge size(maximum) setting… PTC’s Creo has this, and it is very useful!

The problem with setting the triangle edge size is that it will apply this across the whole model. So flat surfaces that don’t need to be broken up in to dozens or hundred of triangles, will be. If you want to stay within a triangle budget, it leads to a model that is excessively tessellated on flat surfaces, yet not enough on smooth curved surfaces.

Meshmixer has REMESH option, where you can take model and remesh it’s surface based on a a variety of options, triangle budget, triangle edge size, adaptive density, etc.

It’s not an issue at all.
It’s the way meshes work.

You cannot print an object composed of NURBS or similar “smooth” spline-based curves and surfaces. It needs to be converted into discrete line segments / polygons. The same way you cannot print a vector drawing with your printer (although you could, with old vector plotters) before they’re rasterized first into discrete points/pixels.

There is no magical algorithm to do this ideally for every and any application - you need to adjust the settings to suit your particular use case. There is no “single” way of exporting an STL, you adjust the parameters to get the desired output (enough polygons to yield a smooth surface, but not so many polygons the resulting STL becomes too huge and unwieldy).


It’s the way tesselated models work but we’re not all using softwares that work with such models… and in that case that’s definitely an issue.

For 3D data exchange it’s not a good idea to use a model made off triangles if your source model isn’t, as is the case for all 3D CAD softwares (Inventor, Creo, Solidworks, NX, Solidedge, Fusion360, Onshape, Catia, …) because the tesselation is by default lossy while a format like STP isn’t and that’s a shame 3D slicers don’t support such format.

Using an STL format to communicate between my CAD software and Preform is like saying “take your EPS file and convert it to JPEG to modify it with Photoshop”… that’s not a good idea.

Anyway, my explanation was aimed at a CAD used who didn’t seem familiar with the way other 3D modeling software work and the difference between a typical CAD file format and STL.