Creating mold for CNC? (booleans)

_Check returns:

Rhino surface object is valid.

No, in my above screenshot, the object is exploded.

Following the suggestion by @2DCube, I tried _ShrinkTrimmedSurface, without effect however:

The surface is already shrunk.

[quote]Once exploded, if you run RebuildEdges on all surfaces and then Join, you will probably see a bunch of naked edges where the tolerances are out.
[/quote]

_RebuildEdges indeed makes the weird surface become visible, but then indeed I cannot join the surfaces into a closed polysurface anymore.

Yep, so your edges are out of tolerance as I suspected. If you try JoinEdge, it will tell you how far out they are - I only use this as a check, as it is a crutch that doesnā€™t actually change the base geometry and it can get you into trouble down the road. So if you need watertight, you will end up needing to remake one or more of the surfaces so they will join - or, you can try lowering the global tolerance of the file - again beware there.

If you are machining, unlike 3D printing, you may not need a watertight object - most CAM can tolerate gaps, so you could just leave the object open. You will however have to work around the various trimming and joining operations that might cross the open spots, as those may cause failures. and if the surfaces are badly defined, even if they look good in Rhino, they may cause trouble in the CAM program such as gouging where you donā€™t expect it.

ā€“Mitch

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I guess it could be that Iā€™m using the WIP version:

Take a look: http://screencast-o-matic.com/watch/cDXbQCQVrQ

It might be due to which file i opened too?

Andy

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I used: Coluna Grecoromana_01.SLDPRT

Yeah same. If you scan the model you can see lots of cut-and-shut bits all over it. It will pay dividends to remodel bits of the file, and as Mitch says, itā€™ll bite you in the ass further down the line.

Be careful of tolerances though and be careful of matching/joining edgesā€¦ I spent the best part of 3 weeks 12-14hrs per day working on one file chasing my tail trying to undo bitā€™s Iā€™d ignored or bodged at the beginning. It all looked fine until I exported it as a Sat or Iges file for the client who was using Max to render an animation. All the edges and seams split and left terrible artefacts.

Iā€™ve learned my lesson the hard way.

Yesterday, a colleague suggested to simply use Meshmixer. Indeed, I could start with the STL file: Coluna Gregoromana_.STL Instead of Meshmixer I guess I could Rhinoā€™s mesh tools just as well.

Remodeling can be fun, and NURBS is great (although better stuff appears on the horizon). But here I would like to see how to simply get a quick result.

Meshmixer is great, I use it but youā€™re not going to immediately remove the errors/undercuts etcā€¦ You have two bodies which donā€™t intersect well.

Having said that, you could fuse them together and push/pull the surfaces around the details and fill in the gaps fairly quickly using meshmixer, itā€™ll give you a better result than using Rhinoā€™s mesh tools for a quick fix.

Good luck :slight_smile:

Hereā€™s a heightmap. I did not get as far with this as I had hoped by now. It is a 16-bit image, and it does have some rasterization effects, although less than an 8-bit. The stuff I worked with before was very organic and somewhat rough, so the smoothness of the surface was not an issue as it is here. Have to spend more time with it when I have a chance.

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Thanks! What software did you use to create the heightmap? VRay?

No, I used an app called Leveller. It is a topographic application, but will accept 3d formats in addition to stuff like DEMs. The 3d model is rasterized differently than with a depth rendered image, so I think that is the issue with this.

Iā€™m going to try this with LuxRender for a comparison. I just was informed of a method to get specific channels out (such as depth/distance, and other channels are available as well).

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How does it compare with _ShowZBuffer ?

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Didā€™t know that exists, thanks for the hint! Obviously with standard graphics the depth buffer is only up to eight bits. On graphics systems supporting HDRI, it may be possible to get up to twelve bits of depth, which means up to sixteen times the depth resolution.

ZBuffer 8-bit = 256 levels
16-bit = 65536 levels

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I have taken 8-bit greyscale images and interpolated them to 16-bits, using Gaussian Blur. However, the blurring can obviously destroy small details or sharp edges, so its not going to work universally.

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I generated another depth map by ZBrush. This is an improvement, however, I donā€™t think this is a worthwhile method for objects that have crisp/hard edges. I ran this heightmap through a few different applications. It generates a very large file due to the number of surfaces and suffers from aliasing effects (ie sawtooth edges) even at higher resolutions.

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Heightfield as a tool to make relief portraits was discussed - search for "zsurf4"
https://discourse.mcneel.com/search?q=zsurf4