Friday, February 8, 2013

Octopod Reprints

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.