Hi, I'm new to MOI; I got it with Alibre Design. I've used Alibre Design for several years, so I probably have some habits and preconceptions that are contrary to best practices in MOI and I need some help to recalibrate what I'm doing.

The attached file shows the shape I'm trying to create. As it stands, the shape is defined by surfaces; it's not a solid. But to import it into Alibre Design and be able to do any operations on it (like Extrude-Cut text into the flat surface) I need it to be a solid and not just surfaces. You can delete the faces to see the skeleton that I'm trying to use.

You can see that there's no axis of symmetry to this part; it's got profiles that change in every direction.

However, the design is not really critical; I could tolerate small tweaks here and there to make it usable in MOI. It's a wedge for face masks to help prevent air leak by the wearer's nose.

Any suggestions on how to proceed would be most welcome.

The surface needs to be cleaned up...so that they can be joined together.
The top area of the nose has a sharp ridge. It is not a connected "network".
- Brian

Hi Jay, there are a few inconsistencies with the curve setup, like one area goes to the bottom of the plate and the others at the top of the plate:


It would be good if those all were ending at the same level. I've attached a result here where I moved one curve's end control point up to that same level as the others and also cut the pieces in half and moved them so they intersected at the top. I also added in an ellipse and then this curve setup can be built with one network:





then I joined it to the bottom plate, 3DM file is attached, is that close to what you need?

- Michael

Michael,

Great work! Now can you help a noob out by explaining a bit of your workflow? I'm really trying to learn to use the program.

I get it that my curves were attached to different planes. Actually, that thin bottom plate was really not necessary; it was just a way for me to get a surface on the bottom.

So once you cleaned up the bottom and had all the elevation curves attached correctly, then what?

What was your reasoning to add the ellipse part-way up?

What command(s) did you use to convert the skeleton into a solid? It doesn't seem like Extrude or Revolve would work. I have watched the videos about creating the "starfish" and the "octopod" but they don't seem to help me understand how to work with this model.

Now that the model is working, is there a simple way to "stretch" or "compress" the elevation? This wedge is basically 9mm tall, and I'd like to create wedges 7, 8, and 10mm tall also.

By the way, this model imported into Alibre just fine and I was able to work with it as I had hoped. Thank you so much!

-Jay

Hi Jay,

First of all http://moi3d.com/resources


Then take time to see this post :
http://moi3d.com/forum/messages.php?webtag=MOI&msg=9816.1
A member of our community shares 48 videos on each tool and options of each tool of MOI.
He adds tips and concrete case to explore how to use MOI features.
Those videos can have subtitles in many languages.


You could take time in Pilou's site too. https://moiscript.weebly.com/
You'll find in this site more and more tips, videos and explanations.


With all of this help, you will find many paths to help you on MOI's modeling.


Have fun !

Hi Jay, I'm glad that worked!

So the first step was to use Edit > Show pts on the one curve that ends below the others, and then drag the end control point up so it is on the same level.

Then I decided that for this case I would use Construct > Network command for the construction. The Network command takes a grid of curves as input. You can't give it just any bunch of curves though, they have to be arranged in a regular grid pattern. Think of lines of longitude and latitude on a globe for example.

So to make a regular grid the 2 upper curves needed to be split so they are 4 separate curves that come up to meet at a "pole" point at the top.

Also after splitting the curves using the Edit > Trim command, I moved some more control points at the top to make the curves exactly intersect at the top pole point, that will help avoid some kinds of shaping problems.

You should be able to repeat the surface creation by selecting all the curves in that file and running Construct > Network.


> What was your reasoning to add the ellipse part-way up?

Well that's from prior experience with "pole" points using the Network command. When a shape like the closed base curve collapses down to a single point, if it has any uneven distribution in shape like some more tightly bent corners in it, those will tend to make a result like this when they collapse down (kind of an "X" like pattern):



This can be reduced by getting a more uniform shape as it goes into the collapse down to a single point, an ellipse or circle as another section for the network can help out with that.


> Now that the model is working, is there a simple way to "stretch" or "compress" the elevation?
> This wedge is basically 9mm tall, and I'd like to create wedges 7, 8, and 10mm tall also.

Yes, there are a few different ways. You can select it and then there will be a size displayed in the upper right properties panel:



If you click it an "Edit size" menu will appear and you can enter in a new value for a height. If you want it to stretch out in only that one direction then uncheck the "Maintain proportions" option there:



You can also stretch things in one direction using the Edit frame in a side view:




Or also Transform > Scale > Scale1D will do that type of one directional scaling too.

- Michael

Hi Michael,

Thanks for that information. I'm starting to get the hang of this program and in many ways I like it.

As with any large program, there are things about the documentation that are unclear or absent for the newbie, but become routine for the old-timers. For example, I now realize that MOI doesn't really know something is truly "solid". In this context, "solid" simply means that a volume of space is completely bounded by surfaces that all meet each other (the term of art is that it's "Manifold"). I proved this theory to myself by using "Draw Solid" to make a cylinder, and then cutting that cylinder. The result was not a shorter cylinder, it was a cup. So to answer my question, "Creating this as a solid" means creating faces that all intersect, or meet each other with no gaps. Faces can be created with "Network" or "Planar" commands.

I now realize that you can constrain the two endpoints of a freeform line to be locked onto the ends or intersections with other lines in the drawing, but you can't constrain a midpoint to intersect with the end of another line. So the "ribs" of my umbrella must each be independent lines, tied to the base on one end and tied to each other at the apex.

So armed with this knowledge, I've created a new version of the wedge from scratch. The "X" at the top doesn't bother me.

But for the life of me, I can't figure out how to make the planar base properly attach to the umbrella top. Both constructions are using exactly the same closed curve, so to my mind they should automatically intersect perfectly. The "Join" command doesn't fix the problem. I even tried deleting the line around the base and using the "Planar" command with the umbrella selected; it creates a membrane on the base but it's still not correctly attached to the umbrella. The problem shows up with the use of your reveal command. I can't figure out how to fix that. It's perfectly true that the part is not manifold; if I export it as an STL and check it with Netfabb, that program also flags it as not manifold.

In another post, you had a link to a zip file that would create a "plug-in" that would help resolve this kind of problem (I guess) but I can't find any documentation about how to install a Plug-In into MOI.

So can you help me perfect my work method and know how to get the base connected to the top?
-Jay

Hi Jay,

re:
> For example, I now realize that MOI doesn't really know something is truly "solid".

Actually it does - an object that has a watertight skin will be recognized as a solid, it will show the object type as "solid" here:


it will also work with the boolean commands and in v4 you can calculate the volume of it.


> I proved this theory to myself by using "Draw Solid" to make a cylinder, and then cutting that cylinder.

Your result will depend on what tools you used to do the cut. If you use the Edit > Trim command, that one is focused on surface level operations and not on volumes. The boolean commands are the ones that work with volumes.


> So to answer my question, "Creating this as a solid" means creating faces that all intersect, or
> meet each other with no gaps. Faces can be created with "Network" or "Planar" commands.

If you have constructed several surfaces that touch each other with no gaps, you can use the Edit > Join command to glue them together into a connected watertight skin and that will result in a solid.


> In another post, you had a link to a zip file that would create a "plug-in" that would help resolve this kind
> of problem (I guess) but I can't find any documentation about how to install a Plug-In into MOI.

Check out the Frequently Asked Questions page: http://moi3d.com/FAQ#Q:_How_do_I_install_a_plug-in_script.3F


> So can you help me perfect my work method and know how to get the base connected to the top?

You would normally use Edit > Join to glue the 2 surfaces together, but you have too large of a gap between them for it to be able to join.





The gap is a result from 2 of the curves not touching the bottom one:





In the attached 3DM file I've tuned those curves up to make them end directly on the bottom one, then did Construct > Network to build a network surface then selected the surface and used Construct > Planar to fill in the planar bottom opening to make it a solid.

Hope this helps!

- Michael

Thanks again. I'm getting the hang of this!