I did not catch the start of this thread but here is how my sphere
machine is made. I just kept the description on file so I would not
have to retype it if ever needed again. I hope this can be of some
Hello, my name is John. I am fairly new to the list and I do not
have very much experience to contribute to the list. I make cabs,
silver smith, do casting, make chains, do filigree, micro mounting,
fossil fish preparation, facet and make spheres.
I have a home made sphere machine. I finished a sphere that was all
ready started and now I just finished one that I started from the
beginning. I do not know a lot about spheres but know a club member
that makes spheres. So if I cannot answer your questions I am sure
I have seen one commercial machine, it had two heads directly across
from each other. I was told that they have a tendency to just spin
on the sphere and make it out of round. In other words the sphere
itself stops turning. I have had this happen on my three headed
machine. Lucky for me I was watching and just adjusted the head
pressure by removing a rubber band. I was told if I did not catch it
in time and the cups had worn grooves into the sphere I wound have
to down a size on the cups and start over.
My machine has three Bodine Electric Company motors, Type
NCC1-11RS2, 1700 RPM, 1/70 HP. They all rotate CCW.
They are mounted on a 1 in. thick 16 in. diameter wood base. The
base is divided into thirds where three grooves are cut into the
base deep enough to clear a bolt head with a flat washer. On each
side of these grooves are 6 in. long 1 1/2 in. wide steel plate over
hanging the groove in the base. This allows a bolt to hold the motor
mount to the base and when loosened can slide the motors in or out
for different diameter spheres.
I will try to describe the motor mount from the base up. There is a
3 inch wide by 1 inch deep hinge bolted to the base. To that is
bolted a 8 inch tall 3 1/2 inch wide steel plate. The motor is
mounted so that it’s shaft comes through the steel plate 6 inches up
from the bottom. There is enough room left at the top of the steel
plate to weld on a 3 1/2 inch long bolt.
The head of the bolt is in the air. You stretch a rubber band across
to one other bolt. Then put a rubber band from the second bolt to
the third bolt then a rubber band from the third bolt to the first
bolt. The tension of the rubber bands hold the cups to the sphere
and hold the sphere in the air between the cups. I start with 1
rubber band on each bolt then as the sphere rounds out I work up to
three rubber bands. I use the heavier rubber bands found on the
The cups are a reducing pipe fitting made of galvanized cast iron or
PVC. The large end is changes with sphere size. The object here is
that they cannot touch each other while grinding a sphere. I used 1
1/2 inch to make a 3 inch sphere. The small end of the reducer is
3/4 inch. This is threaded onto a 3/4 inch plug that is mounted to
the motor shaft. The plug was drilled with a 1/4 inch hole for the
motor shaft. The plug was also drilled and tapped on the side to
accommodate s set screw used to hold the plug to the motor shaft.
Now for the drip tank. At the edge of the base is mounted a 2 inch
diameter adapter. The hardware store is closed and I do not know
what is called. It is a flat round base with 3 mounting holes and a
threaded center. It has a 32 inch tall 1/2 inch diameter copper pipe
in it. There is an elbow at the top and it goes toward the center of
the machine for 5 inches. From there hangs a plastic medical IV bag.
The base is cut open and you put water in it.
From the base of the copper stand go up 13 inches. There is a tee
with a pipe going toward the center of the machine for 7 1/2 inches.
There is a 1/2 inch wooden board going down through a Tee at the end
of the pipe. The hose from the IV bag is feed through a hole drilled
diagonally through the lower end of the board. This lets the water
drip over the sphere without the hose getting caught in the machine.
The IV hose has an adjustable slide wheel that changes the drip rate
of the water.
The grit feed box stands on a 11 inch base that slides under the
machine. The machine has three 1 inch tall 1 inch diameter dowels
for feet. The feed box is on a 19 inch tall 1 1/2 inch square board.
The box is 5 12 inches long 3 1/2 inches wide and 4 inches deep.
Inside the top right hand side of the box is a 1 1/4 inch thick 5
1/2 inch board. There is a hole drilled in the middle for the grit
feed motor shaft. The motor is WB-27 80-1, 6OC 4.5 W, MFD by
International Register Co., Chicago Ill. I do not know what that is.
In layman terms it is a 120 volt slow turning motor.
There is a 3 inch long 1/2 inch wide aluminum strip attached to the
shaft of the motor. The strip will start out longer. This total
length will depend on the grit cups you use. Mine had 22 cal. shells
but I changed to 2 red plastic wire nuts to hold more grit. The
strip of aluminum wraps around the grit cups. They rotate in a CCW
direction. They rotate down in to the box filled with grit. As they
come off the top of their rotation they dump the grit out over a 1/2
inch diameter tube coming up through the bottom of the box at a 45
degree angle. The bottom edge of the box has a triangle shaped board
in it to add thickness to support the tube coming into the box.
I have seen machines with 2 or 4 grit cups on them. I have seen them
with larger cal. shells and with different size wire nuts. I cut the
bottom off a gallon plastic milk jug. I use it as a catch pan under
the sphere to catch the grit slurry dripping off the sphere. The
grit is not broken down much so I let it dry and reuse it on the
next sphere. I have a separate jug for each grit. Some people reuse
the grit in there rock tumblers.
You use 60/90 grit until the sphere is totally round. Look closely
for little flat spots. Then progress to 600 grit ant 220 grit for
two hours each. Then go on to the final polish of Cerium oxide. Go
for a couple hours and then check the polish. If you can see the
writing reflected off a light bulb in the polished sphere you are
done. Not all parts of the stone are the same so not all of it will
show the reflection. As long as you see it in some of the stone is
all that matters. I am not talking from experience. This process is
from a man that has polishes over a hundred spheres.
You must be sure to get all the grit cleaned out of the grit box
before you move on to the next finer grit or you will get scratches
from the larger grit mixing in with the finer grit. On the final
polish change to wooden cups.
To make these you use a hole saw the same diameter as the galvanized
or PVC cup to cut a round plug out of a block of wood. Before you
cut the plug out of the board use the smaller size saws to cut a
hole in the center about an inch deep. That way you can hold the
board in the vise. Then cut the plug out of the board last. Mount
the same type adapter used to mount the copper pipe to the base,
onto the wooden plug. Then screw the adapter into the plug that is
on the motor shaft.
The 600 grit and the Cerium oxide are a fine powder. They will not
feed in the cups very well. They tend to pack in and stay in the
cups. You will probably have to make a slurry out of them and feed
them by hand with a paint brush. I plan on changing the grit feed
system to a large fluted drill bid turning slowly through a large
capped PVC pipe. I just have not found the time to put it all
I am sorry this is so long. I hope you understand what I am trying
to describe. If you have any questions I will try to get you the