Build Your Own SLA/SLS

I downloaded an STL from Thingiverse a few years ago and printed it in PLA; I want to print a small version in resin. You can find a copy of the file here

www.jonbondy.com/Voronoi_Klein_Bottle.stl

It is fairly large and complex. It takes CW quite a while to absorb it. I scaled it by 0.5 and then sliced it. This is where things get strange. I've tried it a number of times, with varying results, as reported below. I rebooted my computer (XP, unfortunately) and restarted CW, without fixing the problem. I am not running out of memory, according to Process Explorer (1.5 GB out of 2 GB, with a working set of 600 MB)

- prints the first 1/4 inch, and then stops printing. The printer is still going through the motions, but the projector is displaying a black screen. The projector is fine (I can see the red grid if I wish). So, the slice information is not making it to the projector

- printer goes through the motions but nothing shows up on the projector at all, ever

- if I try to inspect in the Slice View, I can see the first 12 slices, after which I see the 12th slice, no matter which slice I ask for (either greater than 12 or less than 12). It is as if the Slice View froze up.

- if I try to inspect in the Slice View, I can see the first 18 slices, after which I see the 18th slice, no matter which slice I ask for (either greater than 18 or less than 18). It is as if the Slice View froze up. That is, the location where the freeze occurs is variable.

- if I try to inspect in the Slice View, and drag the slider to the middle, I can see a reasonable slice (so the slice data is present). But nothing prints anyway (black projector output)

- BTW, I cannot get the Slice View to show the current slice on the projector at all (by clicking on the icon on the lower left)

My sense is that CW is overwhelmed by this STL.

Would one of you try this and let me know if this is a reproducible bug, or if there is something wrong here, please?

I know that the CW UI runs extremely slowly on this computer, so it is struggling. OTOH, I have made perhaps 20 prints so far, so the real-time aspects of CW have been working fine. I did not expect this kind of erratic behavior.

Jon

I tried slicing the same STL on a Win 8.1 system with 16 GB of RAM. Same failure. I guess CW is only useful for small and simple parts.

I've sliced plenty of complicated models- if I had to guess this one is corrupt or something. Run it through netfabb and see if it works better that way. I'm not on my CAD machine so I can't try it until tonight, but I bet that's your issue.

I don't have CW installed on this computer so I couldn't run any tests with it, however, I couldn't find any problems with the STL file. I did reduce the triangle count by 50% so you can try that and see what happens. https://www.dropbox.com/sh/hbmev2a2xgab ... c7J2a?dl=0

I've sliced STL's that were over 35mb - 40mb and never had issues...just a bit slow to move the camera around in real time. I'm also thinking there's problems with your STL file and not CW. If it's not the STL file then it could be our PC? Maybe not enough RAM or you're having display problems? I can take a look at the file this weekend and will post an update. I'm also using XP, since I'm old school...I updated to windows 10 and reverted it after 2 days...couldn't stand it lol.

Ok so I'm checking it out in Maya and the thing that jumped out at me is that the normals are reversed. This is a problem because the faces are facing inward and not out. Here is a screen cap show little dots in the middle of each triangle but the dots are supposed to be little spines sticking out representing the direction of the faces.

I will reverse the normals and take it home to try it out in CW. I dont have CW at work so yeah I'll post an update again.

PS: Here is what it's supposed to look like with correct facing normals.

I ran the file through SpaceClaim's mesh integrity checker, Zbrush's mesh integrity checker and Nefabb's analyzer and none of these reported any errors of any kind. If you find any errors let me know what software you are using.

Hi James,

I'm a professional 3D modeler for 10+ years. I mostly use Maya and 3DS Max. In this test I used Maya and again I can see right away the normals were reversed. I've had holes and black slices due to reverse normals before so this is the first thing I checked for.

I'm not familiar with the softwares you used but reversed normals are not normally considered an error so that's probably why it's not showing you this.

Hmmm... I just loaded it in Max 2015 and the normals are correct in the viewport. I don't have Maya. I'm wondering if Maya's STL importer might have inverted the normals on the import. Let me know though how your CW test comes out. I think I'll install CW on my main machine too and see what happens.