Lightning Protection

[lalberts]

Dear Path/CAM readers and programmers,

I am trying to 'misuse' the functions of CAM to apply it to lightning protection.

From internet maps on can import stl files of Buildings into Blender. From there make a solid into Freecad.

Pycam can handle a stl directly, but also there, those 'castle' stl files are complicated and it takes an eternity to have an automatic gcode path for it.
pycam is not really actual anymore.. but a pycam import into Freecad would be welcome.

The proper way would be the path calculation within FreeCad.. But as I have no clue about pockets and other strategies of cutting 3D surfaces, I am asking here for support.

One needs this relief as stl or solid. Then check the scaling of it.
Depending on the ligthning protection class, one starts to check where a rolling Sphere of 30 to 90m diameter is rolling over the surface and where the collision points are.
At those collision points on has to setup some thunderconductors to evacuate the currents to ground.
The assessment of those positions is the job of a Lightning Protection agent.

A path of a spherical endmill is exactly the envelope of such a rolling spherical thundermodel.

The problem is probably the very uncorrelated mesh surfaces a tool would have to follow.. but the strategy should not be the exact cutting of the 3D-model.
It is very much more a 'roughing' of the site.. go into the shape until collision. This applied to some area mapping.

I wish I would be more a programmer..

Thanks for your suggestions

Lukas
Esslingen

[freman]

I'm not sure that I fully understand what output you want it but it looks like you could do something with 3dSurface path and large (90m) ball-end milling tool.

go into the shape until collision.

I think you need to better define the criteria of what condition you are trying to detect.. Maybe post on German forum, if language is a problem.

I am asking here for support.

Yes, this probably should be in the help forum.

[DeepSOIC]

The easiest thing I can think of is to offset the shape outward by 90 m, then offset it back inward. Then you find the points where the surface of the offset-unoffset solid coincides with surface of the original.
Unfortunately, offset tool almost certainly isn't robust enough to handle such a complicated shape. We often have problems even with the simplest of shapes...

[lalberts]

Thanks for your advices..

I am trying to set-up the drop-cutter 'path' as an option to the 3Dsurface operation. But it is difficult to understand, which comes after which.
I am trying first on some very simple model, like a cone and cube on a plane.. in mm scale.
I can cut one top layer for some mm in a zig-zag mode.. but it won't go further down.
I made a boolean merge of all solids (parts) as a starting object for 'path'..
is this the mistake? do I need to define there the surface shape on the model?

What I need is this drop-cutting.. I cut the starting block down until there is collision with the model. No X or Y path, only Z. Come back to a safe Z level, move X, and cut down again into Z until collision..and so on.. back up, move X or Y, cutiing down..

The real models are of course of complicated shapes..some google shapefile/export out of Blender.. ('rdc' files)
Perfect will be when some ifc-building model is placed into the osm/google landscape..

An end result should look like:

Clipboard01.jpg (21.58 KiB) Viewed 1708 times

everything under the blue surfacemesh is lightning 'protected'.

Lukas

Dropcutter.FCStd

(350.76 KiB) Downloaded 40 times

[lalberts]

Sorry... got it.. at least one step further..
I was using pocket3d and not surface3d..
Need some tuning..

lukas

Clipboard01.jpg (92.52 KiB) Viewed 1704 times

[<Charlie_root>]

If the end result is a 3D field or limit and not the actual path itself, I'm pretty sure this problem can be solved entirely in Blender and in realtime

I'll take a stab at it sometime

[lalberts]

Hi,
yes the end result should be this 3D field, this dress-up surface in blue.

I am fighting with the transformation of the horrible mesh file out of Renderdoc/Blender to a solid, that is needed to create a path..
Pycam can accept the stl as is..
Trying to simplifly and clean up the mesh of my landscape. So that FreeCAD can make a shape out the mesh, and then a solid of the shape..
but for now no results.. get some some shape after some hours..but no solid for now.
so, no path..
Lukas

[<Charlie_root>]

well, yeah, whenever your workflow requires converting a mesh to a solid ... you know you're going to be in a lot of pain

as an update, I'm not sure I can do it entirely using the default Blender Shader editor

there might be some volumetric tricks I'm unfamilliar with but the way I see it, the simplest way would be to convert the geometry into a height map and then do a simple separable* kernel convolution-type operation (it's not a real kernel convolution because it requires using a min() function )

* I'm actually not sure it's separable, my intuition just tells me it should be ? ... so, maybe ?

[<Charlie_root>]

https://en.wikipedia.org/wiki/Grassfire_transform

maybe this will work, but with a different distance metric