Hi all,

I’ve been experiencing a file conversion/upload to Shapeways problem for some time. I’m not sure if its an MOI problem or a Shapeways problem, so I thought I’d start here.

Basically, when I upload the finished STL or OBJ file to Shapeways, what is there on my MOI screen does not show up on the Shapeways upload. Usually, small bits like the piping and whistles atop the ship’s funnel simply disappear. When I change the polygon count up or down, other random bits appear and then disappear, the problem not fixing itself; I had hoped that the polygon count was somehow affecting the render and that by adjusting it the missing parts might appear. Again, they’re there on the MOI model but apparently not when converted to a printable file format, or at least not when Shapeways processes the file. I’ve also tried uploaded the OBJ in all three forms (tris only, tris and squares, and N-GONS) and the results are the same.

So... Any ideas on how to fix this? I’m well aware that the model isn’t up to professional standards (I’m a home hobbyist) but man, I’d love to finally print it. I should add that I’ve redone the piping several times thinking that perhaps there was an issue with the sweeps and such used for it, but I get similar results no matter what.

Thanks for any pointers.

Bob

PS. I'd upload the file for everyone to look at but the upload function seems to be having hiccups. The following error keeps coming back:


500 - Internal server error.
There is a problem with the resource you are looking for, and it cannot be displayed.

Hi Bob, I'll probably need to see the file in order to get any good idea of what might be wrong. Maybe the details are very small in numeric size and getting collapsed down?

re: Internal server error - if the file you're trying to upload is pretty large you'll probably need to upload it to a file sharing service like dropbox or Microsoft OneDrive and then just share the link to it here rather than uploading the large file directly here.

You would probably want to use STL format, it's pretty much the most simple format and there's less that can go wrong it it. OBJ should be ok too except probably not N-gons.

What you may be seeing is some model processing that Shapeways does to your file in order to account for limitations in the printing process - the printers have a limited resolution and so you can't print really tiny fine details that are below a certain size. Maybe they just sort of blob together things that are below a certain size threshold because of this limitation. That's probably my best guess.

- Michael

What units are you working in?

Shapeways does offer materials that produce fine detail it's a matter of following the recommendations for the particular material in use http://www.shapeways.com/materials/frosted-detail-plastic, so as Michael suggests if it's beyond the accuracy of the machine it's a no go.

-

I'm using milimeters. The parts and assemblies are VERY small, so I'm not shocked that parts aren't printable; the little details are right at the ragged edge of what is printable. I've been revising the design to get it printable over the past month. What's odd is that parts of the design simply vanish. This doesn't happen when converted into a STL from Geomagic, just MOI, which made me wonder if it was an MOI issue.

Hi Bob, maybe Geomagic is applying some scaling factor to your object and that's why there are different results.

That's just a guess though - if you could post the 2 STL files you are talking about - the one from MoI that you're having problems with and the one from Geomagic that works better, I might be able to look at them and potentially find out what the differences are between them.

If you want to keep them private you can send the links to me directly at moi@moi3d.com, you will probably need to use a file sharing service like Dropbox or Microsoft OneDrive to host the files if they are fairly large, then just send a link instead of trying to send the entire large file directly.

- Michael

Okay, I broke the model into smaller files to make it uploadable. I made the piping and other things rather simplified and they now more or less show up when uploaded to Shapeways. The two problems areas are the forward gussets and the funnel cap grill work.

The after gussets come through fine. However, the forward gussets are all ragged and bunchy. I've tried lofting the curves, extruding and sweeping along curves, etc. Even when the gussets look properly lofted in MOI, they appear ragged and torn on Shapeways.

The funnel grill work is another issue. The innards inside the funnel cap sometimes appear, sometimes disappear. I'll upload the same basic model, changing only small details unrelated to the funnel cap area, and the grill work, or parts of it, will or will nor be there.

So, any ideas on how to correct these issues? The gussets are the real problems. I can deal with the grill work or simplify things to reduce problems, but the gussets are some of the defining points of the Sims-class funnel.

Many thanks for any help.

Bob

Hi Bob, by 3D printing standards that's unfortuantely an extremely difficult part that you're trying to send to Shapeways.

One problem is that the 3D printer ideally wants to have just one single solid in the file to print, but instead you've got 113 different objects all in the same file there, with some of them not being closed solids and even the parts that are solids are partially overlapping on top of each other. It's rather doubtful that the 3D printing prep software is going to be able to make sense of such a complex multi-object model like you've got. The printing software is going to try to calculate the outlines of planar slices through the object and it wants to form a uniform closed boundary line for each slice. When you've got non solids and parts running into each other it makes it very difficult for it to arrive at a good slice through it.

So that's one big problem - your entire structure there is very complex and difficult to process from the standpoint of what 3D printing software expects to receive, you've got to try to get things into just one solid rather than so many separate and overlapping pieces.

The other problem is the tiny size of some of your details. The shapeways materials chart here shows the minimum detail size for different materials:
http://www.shapeways.com/materials/material-options

You can see that the minimum detail size there ranges from something like 0.1mm to 2mm depending on the particular material. But in your model you have many features that are quite a lot smaller than that for example this little area here has a thickness of only 0.03 mm:






So those are some of the problematic things, I think you'd need to probably significantly simplify and unify your model here before it's going to be very feasible for it to get printed...

- Michael

That's what I've started doing. The potential buyers for the part are so far okay with a simplified part without railings and whistles and such, so the entire part is being detailed down, and the funnel base and the funnel itself will likely be two different parts for the modeler to simply glue together. The big thing is the gussets. Any idea on how to accomplish that?

Bob

Hi Bob, re: gussets - I'm not familiar with what a gusset is so it's difficult for me to help you on that.

Is it the 3 sided area that you're trying to fill in? I'm unsure if that's what you are talking about because it looks like you have that in your model you posted. Are you trying to make it different than what you currently have?

- Michael

Its that roughly triangular area on each side of the forward funnel, left and right of the piping. I'm trying to get it to look like the picture. Sweeping the various edges hasn't worked - some REALLY funky results. Lofting works best, but then it seems to sag, or lack of a better word. The result isn't smooth or organic, with bots and pieces all raggedy.

Hi Bob, I'd think you would want to do a sweep there, but currently the edges don't really match up directly with one another, like for example you'd want this edge to span all the way across:



Currently that edge does not meet up with the other ones, there is a significant gap between their ends:



If you could post a 3DM file with just the curves you are sweeping and the all raggedy result from it, it would be easier to give you some advice on what's going wrong with that - it's difficult for me to pick out these things from your full model file that has everything in it.

Are you maybe selecting multiple edges all across the same station for the profiles? That will make for bad results because Sweep thinks that each profile curve that you give it should be one station along the rails - if you have multiple segments selected it will try to use each one of those as a station independently. You've got to join things like that up into a single curve so that you have just one profile curve per station along the rails.

Here's an example (also see attached 3DM file) where the curves are ready to sweep - select the profile, then run Construct > Sweep and then pick the other 2 curves as the rails:



The more narrowed down you can make your example the easier it is to give you advice on it, so for example if you have a question about why a particular sweep is weird, if you extract just the geometry that's directly involved in producing the sweep and the weird result and then post only that, I'd be able to figure out what you are running into a lot easier.

- Michael

Thanks, that helped a lot. The forward gussets now look fine and the after ones are a little bit problematic, but they're coming along. Seriously, I hadn't noticed the curves not matching up. I suspect I'm still thinking parametrically in terms of solids than in terms of MOI curves. In other words, operator error!

Bob