FRC pocketing

[GeeTwo]

Originally Posted by EricH

Or use a completely different material. Wood is nice for certain applications; PVC has its uses. You can't forget about fiberglass/carbon fiber (not the same material, but I'm lumping them together) despite the extra precautions needed for them.

And yet, each of the materials you list (and probably every reasonable FRC construction material) can produce a better load-to-weight ratio when under compression through the use of pocketing than with solid convex parts.

Tubing, angle, c-channel, and many other extrusions and sheet metal folds are simply an example of pocketing in one dimension. Monocoque is another great example of sheet metal one-dimension pocketing.

Did you ever really look at a cantilever bridge? Here's a neat example. Can you even count how many levels of pocketing appear here? (This is a 1930s railroad bridge around which another bridge was added much more recently; I grew up five miles away from it and still cross it most Sundays.)

I encountered a new construction technique for pocketing a few weeks ago. I haven't done any 3-d printing, but one of the other departments at my office 3d-prints internal parts for oceanographic data collection systems. For many of them, they use solid shells for the boundaries, but in the gaps, they trace the printer thread at what looks like about five extrusion diameters apart, and rotate between 60 and 90 degrees between layers, producing an "open foam" pattern which is much lighter but about half as strong as a solid block would be. Bird bones.

Edit:

Originally Posted by Al Skierkiewicz

2016 rules may differ, please be sure to read everything in the robot section, twice!

Twice? Twice? I notice something I missed before every time I read the rules (latest yesterday). I must have read the 2015 rules at least 10 times before bag and tag and probably 30 times so far.