Show simplifying THE POWER DRILL 11 I 1 the expectations of the inventor J J brossoit of salt lake city are realized mechanical rock drilling in mines quarries marries etc should become much less expensive and greatly simplified mr brossoit who is the inventor of the numa roc sharpner and as such is well known to the mining b fraternity has just patented a new rock drill bit which he also has christened the numa and for which he cairns many advantages over the old style machine frills drills instead of forging shaping b and tempering the end of a piece of drill steel to secure the t he desired rock cutting bit mr Bross oits new idea contemplates the forging of permanent shanks on the ends of the drill steel and the cuttin cutting tf a groove through the shank for reception and holding in place of a separately made specially designed cutting bit that can be inserted used and changed without loss of time as often as may be necessary during a shifts work and thus secure the same or better results at a fraction of the cost than is obtained by the old fashioned Ineth methods through the introduction of drills of this character many advantages are to be gained over present methods instead of lugging large numbers of drills into various part of the mine for use of the machine men doing the drilling all that will be necessary with the new scheme will be to supply each drilling crew with a pocketful of bits weighing only a few ounces each when it goes on shift and supply new bits at trifling cost as needed then there is the simplicity of making the small bits of the desired shape the refinement of the steel by pressure the facility of handling heating and tempering the small bit as compared with the old method and the better results obtained it is claimed that the small bit can be better given the proper shape and gauge than is possible by attempting to make a bit on the edge of a steel bar that it can be tempered better as the cutter is regular and uniform in shape that no uneven expansion and contraction occurs as all surfaces are exposed to the atmosphere at the same time thus minimizing the chance of uneven shrinkage and liability to fracture when in use the new drill and bit were given a severe test a few days ago in the presence of a number of mining men drilling experts and engineers after drilling hole after hole through a block of solid granite with a perfect score the bit and holder stood up firmly under pounds pressure using a jackhammer mounted on a bar and using steel then a heavy steel casing was mounted so that the drill could play on that after several hours of continuous hammering under pressure carrying from 75 to pounds with a stop every twenty minutes to determine that tile the bit was in place just as it was at first inserted it was found that tile the constant hammering of steel upon upon steel had in no lio way injured the bit or the shoulder in which it was mo mounted tinted but as proof of the force of the impact the shank of the drill that portion fitted in the recess of tile the hammer had started to c rumble crumble |