How to Construct Blasting Caps Discliamer . Blasting cap manufacture is illegal and very dangerous. The author and provider of this information take no responsibility for your actions if you decide to follw the directions in this text. There are several safety precations that should be taken. Load caps from remote, keep large amouts of water near by, and use a blast sheild. FUSE USE CAP MANUFACTURE Being totally realistic one cannot hope toproduce a blasting cap comparable to commercial products. The precision of modern manufacturing can produce caps cheaply and safely. The actual loading process is a dangerous one, but can be made relatively safe by taking the precautions outlined in the processes below. The home producer, can however, manufacture a cap that will work 99% of the time. These "homemade" caps will detonate most of the high explosives that their commercial counterparts will. Fuse caps are blasting caps that are fired by the flame from a safety fuse. This flame ignites the flash charge of loose black powder. This, in turn, ignites the primary explosive. This primary explosive makes the transition from burning (deflagration) to detonation. These caps can be loaded as a simple cap or a compound cap. The simple cap has only the flash charge and the primary explosive. The compound caps have both these ingredients plus a high explosive base charge. The compound caps are usually a good deal stronger due to the high explosive base charge. To manufacture these caps the explosives are simply pressed into the cap container. This container should be 1/4 inch in diameter (or larger) copper or aluminum tubing 1.25" long or a 5.56 mm N.A.T.O. spent cartridge. The tubing can have one end sealed with a wooden plug or simply be crimped closed with a pair of pliers. The burr should be removed from the open end of the tubing. After removing this burr, these tubes would be ready to load with the explosive charges. When using a 5.56 mm N.A.T.O. spent case the primer would need to be removed. After this has been done the flash hole would need to be enlarged enough to accept the fuse. This could be accomplished with a hand drill or by using a nail. The cap case would then be ready to insert the fuse and load with the explosive charges. The copper or aluminum tubes would need the base charge to be pressed in first. This pressing should be done with a close fitting wooden dowel. This should also be done with the tube supported rigidly from underneath and surrounded with bags of sand to absorb the explosion, if necessary. Find in this section a drawing of a loading apparatus. This apparatus would be safe as the operator would be remote. This press would be simple to make and would be highly recommended. Next the primary charge should be pressed into the tube. CAUTION: Primary explosives are very sensitive to friction and impact! Extreme care should be taken in this step of the procedure. A foul up here could be very dangerous! After this primary charge is pressed a very small amount of black powder is placed on top of the primary charge. This will ensure the ignition of the primary charge. The fuse is then placed in the mouth of the filled tube so that the end contacts the black powder ignition charge. NOTE: Use only good quality safety fuse available from: Westech Corp. P.O.B. 593, Logan UT. 84321, Zeller Enterprises, P. O. Drawer W 2, WickenburgA Z. 85358. Good fuse can be made by soaking cotton twine in a saturated solution of potassium chlorate. This, however, will not be as reliable and therefore not as safe. A small wad of cotton is then pressed on top of the fuse and igniter charge so that the fuse can exit the tube on one side. This is then crimped with pliers. Care should be taken to ensure the primary explosive is not present in the area of the tube to be crimped, as this crimping with this primary in between the tube walls could very well cause the premature detonation of the cap. This cap would then be ready to use. Simple caps can be loaded similarly with the deletion of the base charge in the loading. They can also be loaded into a .22 magnum spent cartridge case in a manner similar to the method above. These small caps will not be as powerful as the larger caps. Some of the primaries would not be suitable and all of the others would need their primary charge doubled for maximum performance. The 5.56 mm cartridge case would be load is the exact opposite of the copper or aluminum tube caps. The fuse would be inserted into the case through the flash hole. The black powder ignition charge would then be place in the bottom of the case. The primary would then be placed in the bottom of the case. The primary would then be pressed into the case carefully and of course on top of that would be the base charge. After these were pressed into the case a small ball of cotton or paper would be pressed into the case to fill the remaining portion. Thenthe end of the case would be crimped with pliers to close the cap. This cap would then be ready touse. 1/4" aluminum or copper tube. Igniter: Black Powder .20 G. PRIMARY: HMTD .75 G. DDNP .50 G. Mercury Fulminate .75 G. Double Salts .75 G. Nitromannite . .50 G. BASE: RDX 1.0 G. PETN 1.0 G. Picric Acid 1.0 G. TENN 1.0 G. Nitromannite 1.0 G. MMAN (3/8" tubing) 3.0 G. Nitroguanidine 2.0 G. Tetryl 1.5 G. As you can see by the above chart the nitromannite is listed as both a primary and a base charge. The reason for this is, that while it is not actually a primary explosive, it tends to function as one. Nitromannite.s use as a base charge makes use of the 8000+ M/sec. detonation velocity. This nitromannite is a very touchy substance with sensitivity approaching that of nitroglycerin. It would be best used as a last resort. 5.56 mm Empty cartridge case: Igniter: Black powder 2.O G. (3 grains) PRIMARY: /> HMTD .75 G DDNP .50 G Mercury Fulminate .75 G TACC 1.0 G Double Salts .75 G Lead Picrate 3.0 G Nitromannite .50 G TACN 4.5 G BASE: PETN 1.0 G /> RDX 1.0 G TeNN 1.0 G Nitromannite 1.0 G Picric Acid 1.0 G Nitroguanidine 2.0 G MMAN (7.62case) 3.0 G Tetryl 1.5 G TACN is listed here as a primary. This is given due to the ease of manufacture. This primary is stated in literature to detonate T.N.T.. The need for a heavy wall thickness detonator capsule would limit this to 5.56 mm shell detonators or larger empty shells. The use of MMAN would require waterproofing the finished cap by dipping in molten wax or paraffin. ELECTRIC BLASTING CAP MANUFACTURE Electric blasting caps offer a good deal more versatility to the blaster. This allows better and more remote blasting operations and the possibility for timed blasting applications are great but cannot offer the versatility of application. The electric blasting cap (EBC) can. EBC.s are very simple in their function. Current is passed through the two wires leading from the cap. This current, due to resistance, heats a small "bridge wire" which in turn fires an ignition mixture. This, in turn, fires the primary explosive and base charge respectively. The problem with improvisation is finding a suitable performing bridge wire which will give reliable performance. Earlier literature has stated that the "guts" from light bulbs will work. They will work but cannot be expected to resist corrosion produced by some situations and could not be expected to give stable reliable detonation instigation. Take a spent 7.62 mm N.A.T.O. case. with a small pin punch, nail or other small slender rigid object, reach into the case and knock out the fired primer. Enlarge the flash hole with a 1/8 inch diameter drill. Deburr this enlarged hole so that the wires passing through will not have their insulation cut by these burrs, and thus causing a dud. Pass two sections of 22 gauge insulated wire, twelve inches long, through the 1/8 inch hole so that they go completely through the case, and their ends are free of the case mouth. Strip 1/8 inch of the insulation off the wires protruding from the case mouth. Cut a 3/8 inch section of .01 inch "nichrome wire", which is available at any hobby store or from nearly any electronics supplier. Nichrome wire is the wire inside toasters and other appliances that gets hot when current is passed through it. Discarded appliances could be another source of this wire. This piece of nichrome wire is spliced into both of the wires at the case mouth. Splice the 22 gauge wires to bot h ends of the nichrome wire bridle. This splice can be formed by twisting the nichrome wire around the upper part of the stripped 22 gauge wire and the lower part of the 22 gauge wire bent up to form a loop. A drop of solder is placed on these splices to ensure a good circuit. Outside dimensions of this improvised "bridge wire" should not be greater than .28 inches. A small wooden support should then be placed above the junction of the bridge wire. This will help the improvised bridge resist deformation and breaks from loading the cap. This wooden support could be made of a wooden match stick cut to length. This support should be 1/4 inch or less in length, with the ends notched out for the 22 gauge wire. These wires should be glued on the support stick. This whole bridge wire unit should be narrow enough to allow it to be pulled inside the 7.62 mm case even with the priming mixture on it. The wires should be twisted together on the other side of the wooden support after the glue on the ends of the support sti ck have dried, securing the wires in place. These bridge wire units are now ready to have their igniter composition placed on them. We will give three different compositions for this. #1 Match heads (ground damp with acetone) 50% Smokeless powder 50% #2 Black powder (improvised will work) 50% Smokeless powder 50% #3 Potassium Perchlorate 60% Sulfur 38% White glue (Elmer.s) enough to form a pasty mass The first two of these compositions should be used by mixing and slightly dampened with acetone. This will form a putty type mixture. This is pressed very gently around the bridge wire assembly. Remember, you have to get this back into the case, and when dry this priming mixture will be as hard as rock. It should also be said that great care should be taken to ensure the continuity of the circuit. This can and should be checked by using a ohm meter. Let these dry, and they are almost ready to load with explosives. You may want to test one of these before loading to see how they work. In tests, these bridge wires when used in ignition squibs, where 98% reliable. They are also sensitive to 2 "C" batteries or larger. Gently pull the bridge assembly into the case with the wires extended from the other side: When firmly in the case as far as possible, put several drops of "model airplane glue" in the recess where the spent primer was. This is allowed to dry. When dry, these are ready to load. These are loaded with the same amounts of explosives as the fused caps so use the table in that section of this book to find the quantity to load. The only difference is the amount of black powder igniter used. Use 1/8 to 1/4 gram of black powder for the igniter charge. This is done to cushion the bridge wire when the primary and base explosives are pressed in. After the addition of the black powder igniter, tap the case to settle this charge. The primary explosive charge is very carefully pressed on top of the igniter charge with a wooden dowel and remotely if possible. Best results will be obtained with the press apparatus. See the drawing. The base charge is then pressed on on top of the primary charge. Check the circuits, one at a time, with a OHM meter from behind a barricade. Press cotton in the remaining part of the case, a crimp with cotton, in the part of the case that is being crimped. These can be water proofed by dipping the completed cap in hot wax for just long enough to immerse them completely. These caps are ready to use and will equal a #8 or #10 blasting cap.