Wednesday, February 29, 2012

Iris Door Test Print Video #1

As I mentioned in a previous post, I really wanted to have a working mechanical iris as an exit for the divers.  This was not as hard to design as the tentacles but it wasn't a picnic.  There are lots of irises on the web, but not too much covering the mathematics to design one from scratch.  I built everything myself but I have to send out props to emmett on Thingiverse.com for inspiration. His design helped me figure out some of the mechanics and layout.  Thingiverse is run by MakerBot industries and is a community forum for uploading and sharing 3D printing design.  You like something, just download it and print.

This was also exciting because I was actually able to prototype it on my MakerBot.  The final version will be printed on the fancy Objet printer at the NYU AMS lab.


I also need to submit a public apology to my wife Kate.  In the video I failed to mention the hours she spent helping me figure out the geometry to make this thing work.  She's much better at math than I am and I couldn't have done it with out her.  Thank you Kate!  Please let me come home now.

McMaster of the Universe! - Free CAD Models

Here's a great tip for my fellow modelers.  Go to McMaster-Carr, look up screws, bolts or some other type of hardware. Pick one at random and you will notice a 'CAD' tag pop up for the item.  Click and and download a CAD file of the item. Now open your modeling program and import it. Nice. You now have mechanically accurate parts to detail stuff with or to use as a guide for designing real-life parts.  That's what I have been doing. I downloaded the exact screws I wanted for the iris and used them to size the holes and tracks correctly.   I've been using IGS files successfully in C4D.

This is also great for my fellow MakerBots out there. You can take this file and print plastic screws. PLASTIC SCREWS! They don't have CAD files for everything, but there's still plenty.


Also, McMaster-Carr is the most awesome place in the world.  Their catalog is about 6" thick. When I order something, it's here the next day with standard shipping.  If you want to learn about rubber, plastic or static eliminating blowers, this is the place to go.  Each section has an 'About' preface that will give you a good primer on hardware.  If you email customer service, you will hear back from them in less than an hour.  It's like Christmas.

Mosquitopod

I should build this as a companion piece to the Octopod.  According to Dr. Gustav Luchy, the mechanical mosquito will help us to conquer Antarctica.  Of particular interest is the "Sheath Containing Fully Equipped Ocean Liner".  Via The Salt Lake Tribune, 1913:
 



Thursday, February 23, 2012

Tentacle Test Print #3 - Modeling Video

Kind of a test print, but in reality it's probably the start of final printing for the tentacles. As long as these two turn out ok I'll be printing the other six using the same model.

I had so much to cover since my last major update that I just made a video of it.  Topics of interest include: final (?) tentacle design, tentacle mount, file prep, rubber webbing and iris doors.  I'd recommend going full screen to see everything clearly.



Wednesday, February 22, 2012

Printing LEGO Video

This is my dream job.  A short video showing how LEGO uses 3D modeling and a 3D printer to quickly test new parts.



Saturday, February 18, 2012

Master of the Octagon Video

Unfortunately not a post about my Cage Fighting career but a quick post with extraordinarily valuable modeling tips.


Tuesday, February 7, 2012

Lye Bath! - How to Clean Prints

As discussed before, when parts come out of the printer they're covered in a rubbery, wax-like support material that has to be cleaned off.  Typically a water jet is used for cleaning but even after that I've had a lot of residue left.

This is a particular annoyance with my current tentacle design.
After some research, I found that the printer manufacturer recommends a sodium hydroxide bath which will loosen and remove the support material.  I have access to an ultrasonic cleaning tank which would work great with the solution.

The problem is sodium hydroxide, also known as lye, is kind of hard to find due to the fact that it's used in crystal meth production. Yay!  Typically, you can use drain cleaner but I couldn't find any that was pure lye.  The good news is it's also used in darkrooms and I was able to pick some up at B&H Photo. (Pick up only, no mail order).

Monday, February 6, 2012

OPUS V Design

I've been getting asked a lot about the aesthetic design of the octopod which always triggers a little anxiety.  This usually stems from the fact that I consider myself more of a builder than a designer.  I am most comfortable when presented with a mostly finished design that needs to be built and elaborated on rather than coming up with my own thing from scratch. It's just how my brain is wired. But I wanted to challenge myself and chose to try and design something from scratch.  I have been pretty comfortable with the actual modeling and mechanical design and stalling a bit with the aesthetics.

From the beginning I knew I wanted a nuts-and-bolts, mechanical design.  My first thoughts were WWII and  Cold War era design.




Friday, February 3, 2012

Tentacle Test Print #2 Video & Pix


With lessons learned from the first try, I put together another test print before the semester started.  I wanted to make the new tentacle sleeker, more flexible and bigger.  I wanted to try the fused rubber and acrylic one more time as well.


I started from scratch with a totally new knuckle design.  As you will see in the video, the rivets were way too small to print well.  Right now the knuckle is solid and I use the rubber core to cut a hole through the middle.

Thursday, February 2, 2012

Octopod Rough Draft



A rough build of the Octopod showing basic design and proportions.

The look of the tentacles is more or less done but will require another rebuild to fix a few details.

The body shown here is just a stand in and will be completely rebuilt.




Cutaway of rough interior layout with figures for size reference.

The front will be a one-man cockpit with the engine compartment underneath.

The rear is the cargo area with a moon pool for access to the water.

Wednesday, February 1, 2012

Tentacle Test Print #1 Video & Pix

Having done a print before, I knew that there were many things to consider when modeling parts. You can't make details too small or they won't print or might break off. You have to maintain a certain wall thickness so the structure is strong, etc. I'm also using a printer and materials which are new to me, so I have to figure out the capabilities and limitations of both the printer and materials. So I felt that I HAD to get a test print done during the pre-production semester.

I felt that the tentacle was the most important part to figure out or the model would be a flop.  I went ahead with the rubber core/plastic knuckle design but I still needed a way to to pose the tentacle. While the rubber core would make it super-flexible, it wouldn't hold a position.  I decided to insert a brass rod through the length of the tentacle much like they do for stop motion puppets. The rubber would give it flexibility while the brass rod would hold the shape.

I took precise measurements of the brass rod so I could model the correct size hole through the rubber core.







I built a base knuckle, making sure to remove any software smoothing since the printer will only print pure geometry. I created a cylinder at exact scale to stand in for the armature rod and then used it to boole a hole through the tentacle core. 











Tentacle Design

From the beginning I felt that designing articulated tentacles would be one of the biggest challenges and one that I needed to tackle immediately.

My initial plan was to make a super-articulated tentacle using many joints like a traditional action figure.