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.

Wrapped tubes

Turns out that topologist Herbert Edelsbrunner founded a company for 3D object manipulation. He has a large series of knots and tori that he has generated in STL. I'm trying the square torus in -10/4 time: Ten rotations of the tube during four rotations around the hole. The minus sign means the tube curls towards the middle in the clockwise direction. It is a very nice model and turned out great with minimal clean up.

Possible revisions:  I might have been able to print it without supports, but I was worried about the parts which wouldn't touch the bottom, so there were supports on the bottom. And ten is too many rotations. It sort of looks like a fancy donut instead of a mathematical shape. Next time I would like to try the -4/4 time torus without supports.

Update: I found out what kind of fancy donut this is - it is a French Cruller.

Catalan wireframe polyhedra

I tried mathgrrl's entire workflow for producing Catalan wireframe polyhedra. It gives a chance to try meshlab,  TopMod, and edit a custom profile. During the Prepare stage, I discovered the very useful command "Lay Flat" in the Turn menu.

Here it is while printing:

And here's what I see on my screen while printing. The camera means I can watch it while sitting in the other room:

Here it is in its finished state ready to be cleaned up:

Follow up note on clean up: mathgrrl shows a photo that looks something like this, followed by a cleaned up version with the comment "removing the support is not all that difficult" and only takes 5 minutes.  Obviously she knows something I don't because  I have already broken one of the edges, but still have not managed to get all those supports out of the middle! Hopefully one gets the hang of it after a while. Here it is at last after 5 minutes… in turtle minutes anyway:

Notes for next time: I tried this whole workflow again on a buckyball, but there I ended up with all sides triangulated. Have to work out why they didn't remain pentagons and hexagons.

Setting temperature in custom profiles

Quick technical note for future reference: To set the temperature in the custom profiles, you need to set it in the file start.gcode (not in  miracle.json).

Update: Even when I set it this way, it didn't work. I will be looking to find how to set it in custom profiles. In the meantime I will set it using the GUI profile maker.

Silly Doodle Printing

Today I am printing a silly doodle that I made on a piece of paper, as per these instructions by mathgrrl.  I started with the following doodle:

Which I processed to to give a 3D stl file  that looks like this (this is a still image in the open source program meshlab, which runs through XQuartz):

I sent that to the printer. The result is this:

I believe that this process would work fine to generate 3D versions of one-dimensional functions.

Half Menger Cube

Yesterday's I printed a half Menger cube by owens, using the order three model. It was estimated to take 3:30 hours, and took more like 5. Usually the estimates are pretty accurate, but I suspect the fractal nature causes misestimation.

Possible revisions: This half Menger cube particularly interesting because of the beautiful cross section on the inside piece. Unfortunately, it is very hard to see in the white material. Next time I will either try printing in a different color, printing just the flat cross section to add on, or printing the other half to see if that angle shows better.

Welcome to the GMU Math Makerbot Lab

Lab Members: Evelyn Sander and Chris Manon
Mathematical Sciences, George Mason University

Welcome!

We have just gotten a 3D printer: Makerbot Replicator 5th Generation to use in the calculus classroom.
In order to keep ideas in order, I will keep a blog. Initially this will be mostly technical details of how to use the printer, but it might get interesting after a while.

Makerbot in action:

Some prints:

Everyone's first print: Mr. Sharky

Chain prints linked

Queen Anne table

Nut and bolt

Table needed a teapot

Final print from movie above

Rolling knot

Hyperboloid pencil holder

Makerbot support line: If you need to call Makerbot for technical support: 347-334-6800 ext 2. 

How to avoid a mothy quality in printing: 

Three suggestions on how to avoid mothiness. Try in order

1. Lower temp to 225
2. Lower print speed to 80 mm/sec
3. Lower travel speed to 140 mm/sec

Software:

Have downloaded MeshLab and TopMod, but of which seem like nice open source tools. Worth trying. They are post-processors for a Mathematica generated file. So if you use the canned Mathematica polyhedra, you can for example remove faces and just leave the edges and regenerate a mesh. Still haven't tried any CAD software, but I am messing with some custom profiles to see how to modify the supports. For example, "hexagon" is only one fill option. 

How to replace the blue tape on the build plate: 

Replacement blue tape rectangles are called kapton tape. They sold by Makerbot, sold on Amazon, and according to the website also at any hardware store. 

Posted by Evelyn Sander