|Forum topic by Col Baker||posted 09-19-2012 07:02 AM||6113 views||5 times favorited||10 replies|
09-19-2012 07:02 AM
One of the most recognizable icons is the classic soccer ball. Consisting of 20 hexagons and 12 pentagons of differing dark/light timber. To construct one from timber seems simple on the face of it but it took quite a lot of cad analysis to work out all the angles of the dangles to determine correct fitment. A first ball was a disaster as it is by nature a hand construct and the name of the game is accuracy. It is a satisfying geometric exercise but maybe just a dust collector when finished but certainly a talking point and quite decorative.
Sizing:- The hexagons have angled edges at 20.9 degrees and the pentagons at 16.4 degrees, both having an edge length of 48mm (1.9”) which will give you a finished standard soccer ball 8 1/2” dia when finish machined.
Manufacture:- print out the shapes on paper cut out and glue to the timber face. (Put glue on timber not the paper as it will swell otherwise). Rough cut the pieces out just clear of the lines and then start by linishing very carefully back to the lines at the angles mentioned before. BE ACCURATE! Only prepare a couple at a time and start assembly using ordinary white glue. Allow to set between pieces although two or three can be done at once with care. DO NOT MAKE SUB ASSEMBLIES!. Trust me they will not mate. Just build one piece at a time and you will have to trim pieces as you go to ensure a gap free fit. Tedious but satisfying.
Machining:- Machine up two circles of scrap timber with m/c centers in them, to just fit the hexagon size – sand of the paper face on two opp sides of the ball and then glue the circles in place. Mount in a lathe and turn to a sphere checking with a simple plywood template, sand as smooth as possible. Remove ball, cut off circle pieces and hand finish sand the Remaining faces. Machine up a suitable base dished stand to sit it on.
Finish:- Use a good quality spray clear varnish.
There you have it.
-- Col B.