designed infill patterns
June 30, 2008 12:39PM
So, I'm at the point where I'm almost ready to extrude (heh, that sounds rude), and I'm fighting my way up through software issues, sorting through many versions of code trying to get something working.

A thought occured to me - I really like the concept of the infill patterns, and I think they could be used to strengthen the finished product. Since we're making all the fancy internal patterns, why not line them up so that they are aligned with the expected stress loads on the parts? There's a guy making some neat surfboards out of cardboard, using a similar idea:

[www.sheldrake.net]

His boards have a honeycomb interior structure, that turns out to be pretty strong once you glass it. Lighter than the foam shapers have been using for years, which has a bit of a honeycomb structure itself. I imagine we should be able to do the same thing with our software; make interior infill patterns such that they actually improve the strength of the finished product. Honeycombs, or radial ribs around bolt holes, even tilt the ribs at 45 deg to improve rigidity, that sort of thing.

This is a big project though; I think we're going to have to be able to specify the specific pattern type and orientation in the design stage, not as an extra processing step done afterwards to the solid models.

I'm no graphics programmer, but I imagine one could model reprappable parts out of line segments with a fixed diameter, 0.5 mm say. Modelling each line as a cylinder would be CPU intensive, but maybe we can use a line segment with a fixed radius? If we could get AoI or Blender to convert a solid object into an array of line segments, instead of triangle meshes, it might make more sense. The line count might even be comparable to the triangle count for a given object, or near enough to make it feasible. One could then look at the 3d array of lines and see if it was what you were intending.

Anyway, this is a pie in the sky idea, and I know ideas are plentiful around here - so I'll be hacking at this myself in the future. I just wanted to throw this out there to see if anyone had any comments on it.

I'm also wondering how long before I can start making kiteboards on my reprap. smiling smiley
Ru
Re: designed infill patterns
June 30, 2008 05:04PM
Skeinforge already has some code to do more cunning infilling, such as running filaments parallel to the side of slender construction elements. I'm not sure how useful it is yet, however.

Radial ribs around boltholes sound interesting, though. I think that one of the current issue is contraction around holes causing delamination, though I don't recall enough of the discussion to know how it is happening or if this idae might assist.

Quote

even tilt the ribs at 45 deg to improve rigidity./quote]

45 degrees which way? out of the plane? running long filaments in the z direction is going to be tricky, to say the least.
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