Hey, I love this program so far but I have a question. I usually union all of my parts at the end of the design so as to assure that they're all part of one structure. Is this necessary though or does MOI automatically make it a coherent structure when exporting?

For some reason if I union this design then 2 of the legs disappear(not sure why) but can I just keep them all as separate parts? That also makes it easier to modify the design later.

Thanks

I, too, use MOI for 3D printing.
For printing I export each part separately as an .stl file.
For Moi I do NOT union the parts together but I guess you could union them together, check it out, and the nundo the union with Ctrl-z.
Or save twice, once before unioning, and then again after unioning, with, obviously different file names.

Mike.

Hi danekshea,

> Is this necessary though or does MOI automatically make it a coherent structure when exporting?

MoI will not attempt to alter the overall structure of your objects when doing an export.


re:
> but can I just keep them all as separate parts?

Generally no not for STL export to a single STL file unless there was some space between them. Most of the time for STL format the receiving programs that will process the STL up into slices to send to the printer does not expect for there to be multiple triangles sticking through each other or grazing right on top of one another, it expects for triangles to only touch one another at their boundary edges only.

But like Mike mentions above if the pieces are going to be printed separately you could export each of the pieces to its own STL file rather than doing it all in one STL file. You do that by selecting the individual object you want to write and then use File > Export rather than File > "Save As". File > Export will only write the selected objects to the file rather than writing everything.

The thing that won't work properly is to have multiple different objects that are touching each other all exported to a single STL file, that will make it hard for the receiving program to figure things out.


re:
> For some reason if I union this design then 2 of the legs disappear(not sure why)

Having tubes that come together like that tends to be a difficult case for the surface/surface intersection mechanism to resolve. Are you using version 2 or version 3 though? There have been some tune ups to that particular area in v3.

If you can post your 3DM model file or e-mail it to me at moi@moi3d.com, I can take a look at it and try to give you some suggestions on how to get this unioned together. Sometimes it can work better for many tubes of the same radius to come together at a hub rather than colliding directly into one another.

- Michael

Hey,

So yesterday before you guys replied I attempted to print this piece. As you noted, the different parts caused problems for the printer and it attempted to print the legs separately even when they were merged. I eventually had to stop it because the way it was printing didn't make any sense. It probably would have finished but structurally it was terrible.

So I downloaded V3 and attempted to union everything. It actually seemed to work and MOI is treating it as a single object when I select it. There still seems to be seams along the legs and that is what caused a problem for the printer. Do I still have to make a hub for it to see this as one object in the STL file?

I posted the file of before everything was unioned in case you want to check it out.

EDIT: By the way I've been saving all my STLs with the maximum amount of polygons. That doesn't affect anything though, right? That just affects how many polygons are used on the surfaces in STL, right?

Thanks,

Dane

Hi Dane,

> EDIT: By the way I've been saving all my STLs with the maximum amount of polygons. That
> doesn't affect anything though, right? That just affects how many polygons are used on the
> surfaces in STL, right?

Yes, that's correct, that just controls the density when surfaces are diced up into triangles.

Sometimes it's also not a bad idea to use the additional "Divide larger than" option to force additional polygons to be created, like for your case here if you put in "Divide larger than" = 3 that will divide up polygons on curved surfaces if the polygons are larger than 3 units across. This can help to avoid getting really long and skinny triangles from being formed. You need to push the little down arrow in the bottom left corner of the meshing options dialog to see the "divide larger than" setting.


> So I downloaded V3 and attempted to union everything. It actually seemed to work and MOI
> is treating it as a single object when I select it.

I tried it with your attached file over here too and it seems to make a good result - it reads as a solid and I examined it a bit and could not see any obvious problems...


> There still seems to be seams along the legs and that is what caused a
> problem for the printer.

Do you mean you see the same problem with the new booleaned one you did in v3 ? Maybe it's possible your STL processing software does not like really long and skinny triangles, try putting in Divide larger than = 3 as described above and see if that makes it happier.


> Do I still have to make a hub for it to see this as one object in the STL file?

Nope, the hub thing was just if the tubes were refusing to get booleaned to one another directly. Crossing tubes can just be a difficult type of intersection calculation, but there have been some tuneups specifically for that in v3.

- Michael

Hi Dane

I find that when you have 4 tubes like that, that share a common top if you draw a line down the centre and cut across front and side views
When each meets at an exact surface they will union easily giving a nice clean solid.



When I draw jewellery and have printed , I do not join the individual parts , as long as they intersect each other the slicing programs are able to slice the stl file for printing.
The main problem is if you have duplicate objects on top of each other.

The slicing program for solidscape printers can handle non joined parts.


I am currently looking at a Kevvox resin printer that runs K studio which can join the parts as part of the print operation
I will let you know how I get on.

http://kevvox.com/3d-printers/sp-series/
https://www.youtube.com/watch?v=QzNDtwTYLMo

cheers
shayne

Hey guys,

So when I said that I had that problem with slicing it was in V2 and not in V3. The results that I got are attached.

So after doing the union in V3, I was able to print it and the finished results of that are also attached!

In regards to your answer Shayne, that looks like an awesome solution and would have and will be the solution I will use if I run into this in another form. I would have created a hub but I like your solution much better. With keeping the parts separate you never have problems with it treating items as separate when printed?

Thanks Mike and Shayne.

Regards,

Dane

Hi Dane, it turned out great!

I'm glad that the tune-ups in v3 were able to solve that problem.

- Michael

Just thought to add that if you make use of a 3D printing service like Shapeways, intersecting parts will be auto-Booleaned, so you don't need to do that yourself first.