Monday, June 8, 2015

Square Wheeled Boat Building

When I first caught wind that there was going a People's Sculpture Race in Cambridge I proposed the idea, to the Wednesday physics lunch gang, that we put our heads together and come up with a design that we could build together.  "Think people+sculpture+wheels" was the pitch.  


After much banter, brainstorming, and abandonment of seriously ridiculous ideas we came up with the notion of a square wheeled boat (I think it was Wolfgang that we can mostly credit) that would ride with a pulley system over an inverted catenary track. 



Once our proposal was accepted and I mocked up an 1"=1' scale model which we exhibited with our 'competitors' at MIT.  


Wolf crunched the numbers, created templates, then left to go watch Dancing with the Stars live in LA while we...  


cut up the luan with a jig saw,


used a hot wire to cut the rigid insulation,


created triple-decker-luan-insulation sandwiches,


set up an assembly line for gorilla gluing,  


slid the stack into a long Polyethylene bag, sealed it, 


applied atmospheric pressure by evacuating the bag with a vacuum pump while the glue set up,


and repeated the process five more times for three sets of tracks.  


Next came the wheels...

  
four more triple-decker-luan-insulation sandwiches, 


evacuated in a vacuum bag while the glue set up,


a test roll...


a forstner bit to drill the holes, 


times four.


While we had the drill press revved up and running we cut the holes in the tracks with a hole saw.  


Wolf returned from LA to work on the drum... 
a 30" diameter sonotube with plywood on the sides, an aluminum axle, 


bushings made of high density polyethylene, U-bolts, flanges and an aluminum union, which serves as a "stop" 
(the union snugs up against the polyethylene bushing to prevent axle from moving laterally).


All the while Rob was working on the flanges, for the tubes that support the tracks, 
on the Shopbot CNC machine, made from 1/2" thick PVC sheet, hole diameter 1.915" to make a slip-on fit to the 1 1/2" sched 40 PVC tube. 


drilling holes in the PVC tubes and sheet and pinning for easy assembly.


Nils was cutting the platform, 


David was painting the wheels and drum, 


Daniel was painting the cycloid track, 


and I was wondering if we were going to pull off this crazy project.  


There was buzz of activity and everyone had their areas of expertise.  We agreed to divide and conquer.  We were working together, towards a common goal, putting our heads together when we hit a snag and problem solving collectively.  


Things really starting to look like they might work out when we put the wheels and drum together.  

video

We set it all up in the Science Center and gave it a push.  


Next came the pulley (a spliced line), wrapped around the drum 2 1/2 times,


the stays, the 'rigging', the sail, 


and the sign for the stern.  

 "Sisyphus", who in Greek mythology, was punished for chronic deceitfulness 
by being compelled to roll an immense boulder up a hill, 
only to watch it roll back down, repeating this action forever.  

Yup, that sounded fitting.

video

We gave her a test roll again and were all delighted that everything worked!


We were ready to take on the competition!


Thanks to our enthusiastic 'wave slaves' we were not short-handed the day of the race.  

 

As we rolled along, they picked up the tracks, and laid them down ahead of us repeatedly...


ad nauseam.


 Before we were 1/4 of the way through, 
we realized that it would take us an eternity to roll Sisyphus to the finish line. 


So, we carried the boat around the race course, 
laid down the tracks and rolled to the finish line in grand style, dead last! 
Did it matter?!


No!  
We may have lost the race but we had a boatload of fun, 
not to mention the fact that we were a big hit all afternoon with the four years olds.

Does Sisyphus struggle in vain, still?
Rolling his rock up that same hill?
Applying some physics
to problems of mythics,
We roll up hills without rolling uphill.

Click here to see lots of great pictures (courtesy of Greg Cook and WBUR) 
of all the other zany sculptures on wheels and read about the People's Sculpture Race.