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Wednesday, April 13, 2011

How to make a Single Jack Stone Drill for Prospecting for Gold

A Single Jack Stone drill was extensively used by miners and stonemasons during the 19th century, but today using one is almost a lost art, and to my knowledge they are not even being manufactured today. They received extensive use in the days before air drills that were operated by compressed air were invented. A single jack stone drill looks like a chisel with a rounded end that is very effective for drilling holes in stone. It is surprising how fast one of these drills will penetrate stone.

A line of drilled holes in rock with feather wedges in place for splitting the stone.  Notice the hairline crack extending between the holes. The hammer shown is a regular striking hammer not a Nevada Long Striker.  Along the line of holes every few holes one is left empty allowing space for the crack to develop.

In use a stone drill is repeatedly struck on its upper end with a heavy short handled hammer. A popular style of this kind of hammer was one that was called a “Nevada long striker.” that had a slightly longer head than usual allowing for greater force to be applied to the upper end of the Stone drill.

A stone drill of this sort can be easily made from a star drill that is available at most hardware and mason supply stores by grinding off two of the opposing flutes on the drill. This should be done with a grinding wheel to which plenty of coolant is applied while grinding so as not to remove the temper from the star drill. 

If the temper is removed in the process is easy to restore by heating the tip of the drill with a propane torch until the steel turns a light yellow color that is then plunged into water to make it hard again.

A stone drilling contest that was popular among miners in the past and today.
Photo by Javier Mediavilla Exquibela
A regular star drill is designed for drilling masonry that is softer than many of the stones encountered while prospecting. Because of the increase in the area of the face of the drill it is virtually useless for drilling stone. Admittedly, a star drill can be used for this purpose only requires about four times the effort.

It is much easier to drill into rock with a small sized stone drill rather than a larger one. The resulting drill hole can be enlarged by using a larger drill as a reamer. Sometimes to drill on hole several drills of different size are used.

In use the drill is held in one hand while it is being struck on the upper end with a stone hammer that is held in the other hand. Each time the drill is struck in has to be rotated about a quarter turn making it ready for the next stroke. Part of drilling with one of these drills is removing the rock dust from the hole periodically. This rock dust may be discarded, or in some cases if you are hard rock prospecting panned to see if it contains gold or other valuable minerals.

A single Jack Stone drill is especially useful when the prospector is working in remote areas where it is not feasible to bring an air drill with you. Drilling holes into rock has many uses in the field; the most obvious one is for planting explosives. The rock dust can also be used as a sample to determine the content of the rock being drilled. Finally if you drill a line of holes about 6 inches between the holes with the use of a device called a feather wedge it is possible to split rocks in a relatively straight line.

This method of splitting rock is commonly used by stonemasons even today; you can always recognize these split stones by the drill marks that go into the stone for several inches to hold a feather wedges.

3 comments:

  1. Thanks for your clear description of single-jack stone drilling. I am researching the hard rock miners of the Bradshaw Mountains - 1880-1930. I am reading an excellent book written by Frank Crampton, "Deep Enough - A Working Stiff in the Western Mine Camps". It was recommended to me as an accurate portrayal of life in the early days of hard rock mining in the west.

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  2. Here's a great video of the World Championship Single Jack contest in Carson City Nevada, Nevada Day 2011

    I thought your audience might be interested. Pass on the link if you like ...

    http://www.youtube.com/watch?v=N7zh1TF1UUs

    Thanks!

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  3. I saw this site, always going in a very nice theme.such matters is very difficult to find many great subject now is really nice, but I really liked your site.
    Stone Split Face

    ReplyDelete