Drill a 1/2" diameter hole in the rock about 18" deep. The hole should be placed so that it is 12" - 18" in from the rock face that you are trying to break. Use a hammer drill with a masonry bit to do this.
Clean out the hole. You can get it mostly cleaned out with the drill. For better results, attach a 24" long, 1/4" diameter aluminum tube to a bicycle pump. Stick the tube in the hole and blow it out by pumping the bicycle pump.
Pour about 3/4 of a fluid ounce of gunpowder into the hole using a small funnel. A graduated cooking shot glass works well to measure the powder.
Place an appropriate length of cannon fuse in the hole. Be sure to know the burn rate of the fuse, and use more than you think you'll need to get out of the area! Also, be sure that you have good fuse / powder connection by corkscrewing the fuse into the powder by an inch or so.
Backfill the remaining hole by balling up modeling clay into 1/8" balls, dropping them into the hole, and tamping them down with a 1/4" wooden dowel. Tamp down the clay every 5 to 10 balls.
Place sandbags tightly around the hole.
Make sure that nobody is in the area, light the fuse, and then EVACUATE.
Notes: You can adjust the hole depth, powder charge, and hole distance from the rock face to meet your requirements. A good blast will just crack the rock. Too much charge or placing the hole too near a rock face will result in 'air burst', where rock flies into the air. This is dangerous and wasteful. Too little charge, or placing the hole too far away from a rock face will result in almost no rock breakage. This method works well when you can drill a hole straight down, or close to straight down. It will not work for placing a charge in overhead rock.
Comments
0 comment