Current Construction Details:
First the cones:
The cones are made from .015" thickness aluminum sheet metal. The outer cone measures 19.5 in. diameter at the top, and 19.5 in. tall (tip to top, not the length of the side). The inner cone is 19.5 in. diameter while being only 9.75 in. tall. The M3CD I built used inner cones that brought the pivot point up higher than center, but I'm trying this one at the same measurement characteristics as Mr. Hamel used. If necessary, I'll change the inner cones later on.
The seams of the cones are butted together and have a narrow strip of aluminum rivited in place for strength, and then they're soldered at the tip for strength. The tip of the outer cone has about 2 in. of light weight automotive body filler in the tip, again just for strength. The inner seam is then sealed, water tight, with Goop brand sealer / glue.
The magnet mounting ring is made of the same .015" aluminum. Near perfect roundness is obtained using a plywood form with a 19.5" hole cut perfectly into it. I placed the mounting ring into the hole, then rivit the ends together. Then place the cone into the ring and fill the angled gap with the same light weight automotive body filler. That layer of filler material gives a great deal of strength to the rim of the cone, and keeps it round throughout assembly.
The inner cone is fastened to the outer cone with screws, which go through both layers of aluminum and into the body filler.
I fastened a 3.75" doughnut magnet to the tip of each inner cone, on a piece of aluminum, with a 3/8" hole in it to keep the tip at the center of the magnet's thickness, they are held in place with strips of aluminum rivited to the cone, then covered completely with aluminum tape.
The magnets I used with this design are a special high strength flexible material, which is conventionally oriented, and equal in strength to a # 1 ceramic magnet. Before fastening the magnet material to the ring, I wrapped a layer of paper tape on the ring, followed by a layer of aluminum tape, then another layer of paper tape ( This gives it a kind of orgone generator quality, at the cone magnet ring area). I am using a double layer of magnet material, with no overlapping ends, on both the cones and suspension rings. I fastened the magnet material with aluminum rivits, which go straight into the body filler, then covered the magnet material completely with aluminum tape.
The tip of each outer cone is coated with a very strong clear fingernail polish protective enamel coating, to electrically separate the 3 cones. Again, I don't know for sure that this is the most effective way to build, but the enamel can be removed if necessary. Then, each tip has a small dab of dielectric grease for a lubricant in the pivot points.
I put a .25" hole in the inner cones, half way up, for adding and removing water (weight) through a siringe type device, with a long tube.
These cones are very light weight, and very strong! They weigh less than 2.5 lbs. each, with the magnet material being the heaviest part.
The Suspension Rings:
Suspension rings use the same magnet material as the cones, double layered with no overlaps. The material is rivited to a steel ring, made from .020" sheet steel, which is spot welded at the ends, using rivits would be fine. I made the material 3/8" wider than necessary, and used tin shears to cut slots into the extra material. Then I bent most of the tabs outward toward the drum area, to help block air flow, and be a place to easily put more air blocking material later on. I left 4 tabs straight, at an even distance apart, to use for mounting the ring to the drum. I used 1/4" aluminum channel for a spacer between the suspension ring and the drum, as it is 3/8" thick on the outside. I drilled a .25" hole through the extra tabs, and also through the aluminum channel spacers for a bolt to pass snugly through.
I roughly placed each suspension ring, when complete, into the drum at the mounting area and marked the drum for mounting holes. The mounting holes are drilled into the drum with a .25" drill, then lengthened vertically with a .25""saw drill" for height adjustments to be made when balancing the cones.
Once installed, I completely covered the magnetic material with aluminum tape.
The Oscillator Base:
I used a thick piece of aluminum sheet to make the oscillator base, about .050" thick. The bottom piece is 21.5" in diameter, and nearly takes up all the bottom of the 22" drum, leaving .25" at the edges for centering adjustment. The top piece is made of the same material, cut out in a triangle with rounded edges.
The cups for the oscillator balls are made from the bottom of iced tea cans, and are fastened with epoxy. The balls are ping-pong balls from the sporting goods department of a local store.
The magnets holding the oscillator base on center are the same 3.75" doughnut magnets used in the center of each cone. Spaceing of the magnets was determined using magnetic film. The magnets were brought closer together, over the film, until the line shown on the film was very sharp. They are mounted at this distance apart from one another, and this allows for a very active oscillator base.
The pivot point for the bottom cone to sit into is a 4" tall cone (6 in. wide at the top). I put a 3/8" hole in the center of the top piece, and placed the pivot piece into the hole so that the point would be in the center of the top magnet. I used epoxy again to hold this pivot piece onto the top of the oscillator base, but I made sure that it's electrically connected to the top plate.
The bottom magnet is mounted to the bottom of the lower piece of oscillator base, this would allow me to remove it from the base and re-mount it with a larger gap between magnets, effectively allowing me to have an adjustable oscillator base.
Since the lower half takes up most of the drum's bottom, four 2 in. holes were cut into the aluminum for air to pass through. One hole is in the center of the lower magnet, the other 3 are between the oscillator ball cups, at the same distance from center as the cups. Then the lower piece is mounted to the bottom of the drum with .5" steel spacers to allow enough air to flow through the vent in the bottom of the drum and up through the oscillator base without restriction.
The Drum / Shell:
This is really the easiest part. I used 2 standard 55 U.S. gallon ( 45 U.K. gallon ) drums, one of which is cut in half and used to make the original drum taller. I put a piece of sheet steel inside the edge of the drum extension, to keep it perfectly aligned and have 4 angle brackets fastened to both pieces to keep them held together tightly.
The bottom of the drum has a 6" hole cut in the center for the bottom air vent.
The bottom vent can be restricted by sliding 2 pieces of sheet steel, held by a rivit on the corner of each one, over the hole.
The Lid:
The lid and rejection magnet holder are a 1 piece assembly. The lid has a 1" square hollow bar, which goes across the center of the drum, and has a piece of threaded rod through the center of it for the rejection magnet. I fastened a hinge to each side of the square bar, and fastened the lid halves to each of these, so that I can raise them up for inspection and adjustment of the rejection magnet without removing the center bar.
Each of the lid halves has one half of a 6" hole cut into the straight edge in the center, for the top air vent. These can be closed in the same manner as the bottom air vent.
The bar is held to the top rim of the drum with "C" clamps, which allows a good hold, easy adjustment, and easy removal.
Balanceing is another subject all it's own, so I'll end this construction portion here and go into balancing at a later time. Any questions or comments can be sent via email to my address on the Main Page.