Monthly Archives: January 2017

three iterations of light weight, organic building blocks for robots

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In this post I compare all three versions of my light weight structure experiments, with a couple of pictures an descriptions that were not given in the video below:

Version 1 had no roof and floor holes and that created the problem for the printer, also, I was printing the PLA at 200 degrees. I learned that lower temperatures are better for bridge structures. Download both files on Thingiverse.

solid thinkercad 2solid thinkercad 1 voro 2  voro 1

So, for version 2 I decided to work with round holes in all three planes, cylindric holes always yield a more organic appearance compared to triangles / prisms and I want to get more organic looking structures. Download version 2, solid and vorony version on Thingiverse.

tinkercad ungrouped rounded box v31tinkercad 2 ungrouped rounded box v31tinkercad rounded box v31tinkercad voro 3 rounded box v31tinkercad voro 2 rounded box v31     tinkercad voro 1 rounded box v31

Version 3 is a refinement of version 2 in that the smaller holes are bigger in diameter to better distinguish them better from the Vornoy holes generated automatically. Also, a greater diameter yields more surface to add the organic structure. Finally, I reduced the center holes to get a better average “wall” thickness, i.e. the distance between a hole and another hole or the sides from the box. In this way, the printer had a better chance to actually realise the Voronoy holes between the cyclinders.

v4 solid tinkercadv4 solid top

Finally, I produced the Voronoy version with a thicker structure, meaning that the lines were thicker and ideally the printer has a better chance to “find” them again in the next layer:

v4 voro1 v4 voro2 v4 voro3

Final versions for download here.

Learnings when printing:

I also reduced the printing temperature to 190 degrees from layer 3 on. The first layers I printed with 200 degrees to allow for a better sticking to the heat bed. I changed the bed to glass and used glue stick. These delicate structures have only a couple of touch points with the headbed so it is of outmost importance to have them sticking well. The servo housing shown in the end of the video was printed on pure glass without glue or spray, but the organic structures need more attention…

 

 

 

 

non-reversible reverse engineering of an electric toothbrush

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i always wanted to study how the inductive charging in such devices actually works and i decided to open an old braun tooth brush to study it.

here’s two gifs:

toothbrush standing

toothbrush

 

you can open the toothbrush by destroying the snap-ins underneath the plastic protection:

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this is the final charging setup, in the end it didn’t work anymore, the battery is probably dead, i may connect a standard 1.2V NIMH battery to it and see what it does. the multimeter showed about 300mV on the receiving coil which seems a bit too low to me but that might also mean that the battery is dead?

20170121_170341

here’s the chips, if anyone’s interested:

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Diving into 3d printed light weight structures

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I recently bought the cheapest a Prusa i3 clone on the planet, an Anet A8 at gearbest. Lovely to build and certainly great for an electronics hobbyist / maker. I never would buy a 600 or even 2000€ printer today, since I don’t think to have many usage scenarios.

But there was always one dream: to print “bones” for my walking robots to make them lighter and more “bionic”. So one of the first things I designed on Tinkercad was this structure:

light weight structure

 

I’ve been searching for a while to make structures more “bone”-like, i.e. some kind of organic or cell-like holes into them. That’s not too easy.

One tutorial I found is working with Autodesk Meshmixer. a software that is really nice to work with 3d models and view them. The tutorial leads to such structures:

The problem is that this depends on the amount of points given in the 3d model itself and tessalating them is cumbersome imho.

Another software I found is the Voronoization Online service which is EXACTLY what I want (upload STL, set parameters, download STL, bang!). The point is that you don’t care about the points of which your model consists:

meshed box

And here’s the video comparing the solid version and the Voronoy version:

This 6x3x3cm structure has a weight of five grams, it’s 20% infill, 3×1.5×1.5 solid sibling has six grams (but of course the solid one is MUCH sturdier).

I’ll now get into testing these parameters and understanding them in the context of 3d-printability. Exciting!