SWING ARM ROCK SAW   When it comes to pre-forming spheres, it's hard to beat a chop type saw.  It's just more convenient for cutting and holding the pre-form and it lends itself much better to holding jigs that help make accurate sphere shaping cuts.  The picture shows that it is quite simple to clamp the rock and that the saw can be moved to cut parallel slices. This is another design that uses wood as the construction material.  I can tell you that I have used one of these for about 6 months and it has served well.    It uses water as the coolant and will take blades up to 8" although it can easily be scaled up to 10 or 12".   All of the metal parts are available at your local hardware store.

ROCK GRINDER After the rock has been sawn to the desired shape, it is still necessary to grind off the corners.  This grinder will accomodate 6" grinding wheels.  There are some quite inexpensive wheels listed on Ebay which will work very well for shaping sphere pre-forms.  Of course, this grinder could be used for shaping and polishing cabs with just a change of wheels.  The best and cheapest motor that I've found has been the 1050 RPM air moving motor found in heating and air conditioning units.  Your local repair company may have a salvage (junk) yard with reasonable prices.

4 HEAD SPHERE MACHINE This 4 head sphere machine can easily be built with woodworking tools.  The 4 head configuration has several advantages, one of which is that its construction is simple.  It is easy to scale from 1/4" marbles to 6" spheres, and the  same machine will do a wide variety of sizes.  The small motors are quite cheap and even motors of 80 in-oz, which will handle maybe 6" spheres are not very expensive.  If you use motors other than described, you will have to devise wiring schemes, but those are not too complex.  A person could, I suppose, actually power these motors with real stepper motor driving circuits, but I did not find that necessary.  Since the smaller motors are so inexpensive, and since the machines take so little room, a person should probably build several for himself.   Also, with these plans are included the instructions, again mostly pictures of components, to build a 2 head machine using gearmotors.  The 2 head machine is quite easy to build and involves no precision cutting.

A person making spheres really needs to have a rock saw, a rock grinder, and a sphere machine.  This set will show you how to cheaply build all of them.  These plans are actually pictures and instructions rather than blueprints.  These machines are designed to be mostlt constructed of wood with no close tolerances.  The complete set is 1 CD with instructions and pictures for; 1.  4 head sphere machine 2.  3 head sphere machine 3.  2 head sphere machine 4.  Swing arm rock saw 5.  Rock grinder 5.  Marble mill $35.00 Including Shipping (CD Format Only)