Two ideas.
Fist, it is common in the States to make fiberglass constructs without benefit of molds. A foam shape is produced, the fabric is laid over it, and then wetted with the resin. Makes for a good finish, with minimal fuss. That is, if the part doesn't need to be hollow... Carving foam is even easier than carving wood.
Second, a truly huge machine could be made with elatively low cost parts, if your precision doesn't need to be extremely high. Garage door openers use a suspended track and rollers which fit into it...with reasonable precision. Mounting these on the ceiling could produce an X axis which would work quite well. By hanging the gantry from the X axis, most of your materials will be in tension...lighter weight and stiffer, if you do it right. The Z axis might be a little tricky, but shouldn't prove to be too difficult.
The drive screws could be handled 2 different ways. One would be to use garage door opener ACME threaded rod, which is easily available in 4 or 8 foot lengths. The other would be to implement a rack and pinion system...either is workable, given proper design.
This would let you build, with relative ease, a machine with as much as a 20x24 foot X-Y area, which is the size of a 2 car garage in the US. Surely that would be big enough for you...
-- Chuck Knight  |