|
|
 |
|
I have been experimenting with the idea of using core drills for pre-forming spheres,
particularly spheres of 1.5" and less in diameter. I've had enough success to report on the method. This
approach eliminates the need for a rock saw and greatly reduces the use of the grinder. As you can see in the following
pictures, the process is to first use the core drill to make a core of the desired size. The first picture is a simple
clamp that can be used to hold the rock for the first drilling. press.
|
|
|
|
The above picture is mostly stones that have been drilled once. The one in the bottom center has been
drilled 3 times. You can see that it would require only a little hand grinding to be ready for the sphere machine.
This process works very well with rocks that are easy to cut, such as onyx, sodalite, garnet, and corundum. Corundum,
ruby and sapphire, lend themselves very well to this process and the core drills seem to last a long time (I have yet to use
one up on corundum). However, agate is not so cooperative and seems to ruin my core drills quite rapidly. It is
possible that I am running them too hard and too fast. More experiments are in progress. At any rate, this approach
is the fastest way to make several sphere pre-forms in a very short time. It typically takes about 30 seconds to drill
a stone with a 1' core drill. And, of course, you can be doing something else while the glue sets. I have used
many kinds of glue, but plaster of paris seems to work the best.
Recent experiments in this area have shown the following results;
1. The drill press needs to have a minimum amount of sloppiness sideways. Cheap little Harbor
Freight drill presses are too sloppy and too fast for stone drilling.
2. The water feed has to be down through the center of the drill. This means that a rotating
water feed has to be made or purchased.
These 2 improvements have resulted in a much longer life for the core drills in agate. Further
experiments are in progress.
|
|
|
|
