Nice instructions for checking your STL file

Here are some useful instructions for using meshlab to make sure your STL file is watertight:

http://www.kraftwurx.com/3d-printing-community/18-3d-printing-design-a-product-advice/585-checking-models-for-3d-print-with-meshlab

Constant width objects

Here is a print of some curves of constant width that are not circles called Reuleaux polygons.

To see that they are all the same width, here they are on the spine of a familiar book.

I used the STL file from

http://www.thingiverse.com/thing:61275

Note I was able to print all four at the same time in two hours. They aren't very tall, but they were quite far apart on the build plate, so there seems to have been some time advantage in quantity.

There is a discussion in

http://cp4space.wordpress.com/2013/10/27/curves-of-constant-width/


See also the 3D versions discussed in

 http://awesci.com/constant-width-objects-not-spheres/

Transformation of functions

First of all, I have switched the extrusion color from white to yellow. The results look very nice! The current print is to demonstrate mathematical transformation f(x-c) where c is varying along an axis. The result is a shift of the function - which in this case is a sinusoidal function. It illustrates the concept nicely.

As a general observation, solids seem to work much more successfully than mesh. Here is the same thing when tried in mesh. It just doesn't work out as well. I am sold on solid!

Back in business!

The new extruder finally arrived. After fiddling and firmware updates, we are finally back in business. Here is Chris Manon's first printed design.

It is entitled Associahedron5. I will let him fill in the mathematical and technical details as to how it was created.

Ellipsoid

After a break, I am back at it. Yesterday's print was an ellipsoid. It is around 3.5 inches tall and took around 5 hours. Of course at a fraction the price,  I could have just purchased a package of M&Ms for the course demo. (First donuts, now M&Ms - is geometry somehow linked to dessert?)  In a future iteration, I plan to remove the remaining circular symmetry and make it an ellipse in every direction. No item in the candy aisle does that. 

Technical comments:
My first attempt was to print it to be short, but it is the overhang that matters. The front of this image shows the aborted print, where lots of filament was dripping down. The back  shows the bottom of the successful print - still a bit of drip.

Due to wanting to increase the size, I tried a modification  by adding a support in Tinkercad. 

I am currently reprinting it at 1.5 times the size. However, it seems this involves taking  more care than I gave it, because the supports do not seem to be touching the bottom. However, it seems to be doing well so far - estimated to take 11 hours.  

One day later update: First spectacular failure!  It seems that one must be very careful to get the supports right with a larger piece.  It seems that it fell over while printing, creating a lot of angel hair filament in the course of it. Well, back to the virtual drawing board. Planning to take inspiration from the support structure on the Sierpinski Tetrahedron by Owens. 

Paraboloid complications

I tried printing a paraboloid, but the lines were too thin, as thin as the supports, and thus the shape came apart on trying to remove supports.

Which made me wonder: How long is it possible to make unsupported bridges ie. hanging sections without any support. The following link indicates that at least for the replicator 2, 10 mm is reasonable, and here they were able to do up to 40 mm. I do not know if this is different for the 5th generation. I will find out: I am currently reprinting a fattened up version of the paraboloid without support. The bridges are more like an inch. I am printing it large side down so things will only get closer as time passes.

Here is the fattened version, printed without support:

Improvements: Perhaps too reminiscent of a famous 3D clothing item from Shapeways. In addition, more attention needs to be paid to the join points. There may be a possible fix in Mathematica. Alternatively, it might be necessary to have an intermediate step between Mathematica and printing. In case that doesn't work, here is a possible solution using Tinkercad. Here is a close up:

Catalan triangulated Buckyball

I tried making the Buckyball model in which I inadvertently triangulated all pentagons and hexagons. This taught me the lesson that there is an absolute limit on the minimum size of an opening if there is going to be support in the interior. Namely, the size of the tool you are using to clean up the shape. I had to break a few edges to clean out the shape. It is depicted here next to the previous wireframe shape (a Pentakis Dodecahedron).

Future plans: I am going to try to remove the extraneous edges to make an actual recognizable truncated icosa/Bucky/soccer ball.