Hi All,

As you all know the new Silhouette tool has been discussed here and as explained, Michael's implemented this tool mainly for visualisation for AI, like OSTexo shows here, Michael also mentions,
Which I thought, was the only thing it was used for, now I know of two uses :)

I modeled a basic spoon (3dm attached) and if I was designing a mould for it the first thing that would be done would be the parting faces for the mould to establish the two halves, using the Silhouette tool produces the 'parting lines' very easily, indicating any potential undercuts in the product, which requires additional mechanical movements in the mould to release which increases the cost of the mould, also useful when designing plastic products.

The spoon is straight forward for moulding and the part line is generated in the TOP view (Line of draw), which is the way it will be seating and ejected from the mould, the part line would of been pretty labour intensive to do without the Silhouette tool.



Below is one half of a four cavity Spoon Mould once establishing the part line.
I started this just to check out the Silhouette tool and got a bit carried away, I might try and finish it, so it's a WIP.

As usual, any questions, feel free.

Thanks for this very useful tool, Michael.

Cheers
~Danny~

Thanks for posting the example Danny!

It's great to see Silhouette able to be used for this purpose as well.

- Michael

Hi Danny,
Thanks for posting this. I am interested in how this is done even though I wont be doing plastic injection. I know it's more involved than just "boolean'ing" away a spoon from a solid.

So you actually "part the spoon" down its center of mass to create the surface of the mould?

Hi Burr,

> So you actually "part the spoon" down
> its center of mass to create the surface of the mould?

Yes that's how I did the Spoon mould, but you could do what you said also, where you establish the mould parting face make it a solid block and Boolean the product out, with 'keep objects' option checked so you can use the product again for the other half.

Cheers

Hi Michael,

Just wondering if the Geometry library you use handles offsetting curves on a surface, this would be another useful tool for product and mould design.

Cheers

Hi Danny,

> Just wondering if the Geometry library you use handles
> offsetting curves on a surface

I don't think that there is anything built in for that currently.

But how is that supposed to work, is it supposed to produce an offset by "distance as traveled along the surface", or "distance measured directly from point to point"?

For the latter I guess creating a tube and then intersecting it could give that result, except probably some difficulties with corners or tight bends and stuff like that.

Do you happen to have an example file for this?

- Michael

Hi Michael,

Yes, "distance as traveled along the surface", the attached file of the spoon shows a red curve using a 'offset on surface' tool at an offset of 0.75mm from the edge of the blend.

-

Hi Danny, thanks for the example.

But unfortunately that curve is fairly difficult to calculate. It can't be done by just an offset in 3D space or an offset in UV space either, it has to be done by a kind of "surface tracing" process that steps along the curve and analyzes which direction to go as it marches along.

There is some surface tracing infrastructure in the geometry library that MoI uses, which the silhouette generation actually sits on top of already.

But it is not exactly trivial to create a new tracer method, it involves a fair amount of pretty specialized work.

So it's something could be possible in the future but probably not until quite a ways out.

- Michael

That's OK Michael, it's not a tool that we can't live without, I just raised the question to see if it was possible with the current geometry library and if it makes it in V6 that's fine too.
Thanks for looking into it.

Cheers

Hi Danny,

Are you try to create parting surface ?

Thanks !

Hi Anis,

> Are you try to create parting surface ?

Yes, that's what I'm showing there, the spoon shape may look simple but I think without the Silhouette tool it would take you a lot more steps to establish the correct parting line.

Cheers

So attached is sample of parting surface.

Hi Anis,

Yep, that's the parting face, you've got the idea, the only thing I did was to smooth out the area shown in the picture, there is sort of a kink in this area resulting from the offset, this is not nice for mould makers in regards to machining the face and fitting afterward so I refined this area a little to get more of a smoother surface that follows the spoon shape.



I've attached that part of the surface with a refined version for you to have a look.

Cheers

Hi Danny,

How do create those surface in MoI ?
Or are you create the offset surface in NX ?

Hi Anis,

Everything is done in MoI, I offset the part line and smooth it out using the control points.

Cheers