Sunday, December 27, 2020

It's a Wrap! - Octopod Overview

Thesis was defended May 3, 2012 and passed with Distinction. Not bad for the guy who had an undergrad GPA which shall remain nameless.  I have collected the key entries here, but check out the rest of the blog for more on the process.

For those new to my project, the goal was to design, model and then 3D print a mechanical octopus vehicle, complete with working features and LED lighting.  The video is an introduction to the piece, followed by lots of pictures and construction details.  Don't hesitate to contact me with questions.

I built a custom stand with a ball-joint to allow for different of poses.

Continue on for more pictures and info...

It all went together really well. Overall I'm very pleased.

The tentacles turned out awesome; every test print was worth it.
Panels removed. The main body panel is held on with magnets.
The entire back wall was a last-minute addition but totally worth it.  It allowed me to install lights, run wiring and add some nice details.
The door and latch are fully functional and the LED switch is hidden inside.
The hoist moves back and forth and turns.  The floor panels open to allow access to the body screws and to hide the LED battery.
The iris door is fully functional.

The cockpit lights up as well, although due to a print problem, the side controls currently don't work.   I'll reprint them at some point.
Rear hatch and ladder.  The wheel and rungs are the beefier reprints which were glued on.

Underside.  You can see part of the tentacle mount and the stand mount.  This was the only place where I tried modeling actual screw threads and it worked out great.

Component parts of the Octopod.  It was designed to be assembled with screws.



I reprinted some Octopod parts for Maker Faire way back in September and forgot about posting pix.

The cockpit lid had a few problems.  Due to the nature of the material I printed with, it wasn't holding it's shape properly and the curvature of the top was acting like a spring which caused it to fit poorly.  

I added a beam on the underside which helped to keeps the shape.  I also beefed up the ladder rungs so they wouldn't snap off like the first print.  On the first lid I printed the hatch wheels too small and they broke.  I ended up reprinting beefier ones that I drilled a hole for.  This worked so well that I did the same thing for this version. The bonus to this method is the wheel actually turns when installed.

I also added magnet mounts on the underside to keep the lid in place better.
Another problem area on the original print were the propellers.  They were supposed to rotate, but I messed up the tolerances and they fused in place.  They also got in the way when trying to clean support material out of the engines and I snapped some blades off.

For the reprints I increased the tolerances and added a hole in the front so support material could be cleaned out.  The original props were snapped off, the stumps cleaned up and the replacements glued in place.

Old prop snapped off.

New prop designed to fit over stump.

And I finally figured out how to rebuild the control panels and dedication plaque so the white and black had proper separation.  It's hard to believe but these tiny little parts turned out to be some of the hardest to build for printing.

The progression of the plaque.
This is a good example of how some 3D printing materials are not meant for real production.  I used an acrylic-like material for the Octopod and over the last few months it has started to droop in places.  The front face of the cockpit has sagged and there are now gaps all around the cockpit and at the bottom of the housing.  I gave him a bit of a facelift with some rubberbands but it's not perfect.  A redesign would help but the material is not necessarily suitable for long-term use.