How To Make Saxon Spark Wheels
By John Werner
Saxon spark wheels are a very simple ground based revolving device similar in effect to a wheel but much more basic in construction. Imagine a long, tubular propeller shape spinning about a central pivot, being driven by the exhaust from nozzles located on the sides of the item. In ground displays, saxon spark wheels are used as a stand-alone item mounted on a pole like a wheel, either singly or in multiples. However, they are very often used in combination with lance work, gerbs, fountains, and candles. Saxon spark wheels spin rapidly; their purpose is to lend animation and movement to set piece work. Depending on the pyrotechnic compositions used, their effect can range from tight, compact circles of delicate, lacey orange sparks to huge, brilliant silver and white displays twenty feet or more in diameter (often complimented in the center with color changing rings). Due to their very compact design, saxon spark wheels are easy to transport and set up on the display site, requiring nothing more than a few nails and a 2x4 support post.
Smaller saxon spark wheels are made up of a single, heavy wall convolute wound tube, solidly plugged at each end and filled with an appropriate driver composition. Larger saxon spark wheels are more conveniently made using two tubes connected in the middle with a dowel or stick. Nozzles are merely holes drilled or punched through the wall of the tube close to the plugged ends, at right angles to the tube axis. A pivot point is provided at the midpoint of the device to allow the saxon spark wheel to rotate on a support member. As such they offer the pyrotechnic craftsman a relatively safe and very easy weekend project that can be developed into many spectacular variations all made with a minimum of experience, tooling and materials. Saxon spark wheels can be made in a wide range of sizes and effects.
For the purpose of this article, a medium size, two tube, gold glitter to silver transformation saxon spark wheel will be described. Gold glitter is often difficult to make work in a fountain or driver, however in this application the supplied glitter formula works beautifully and makes for a very elegant effect.
Although this is an excellent project for the beginner, it is recommended that they have some previous experience with mixing pyrotechnic formulas and are familiar with standard safety procedures.
- Label tubes as "A" and "B". Using one of the wood dowels, ram a 3/4" thick clay plug in tube "A" and tube "B".
- In each tube, drill a 1/4" diameter hole as close to the clay plug as possible; these holes are the spark wheels nozzle orifices. Leave one of the wooden dowels in the tube while drilling to facilitate making a clean hole.
- In tube "A", drill a 3/16" relay hole, 5-1/2" up from the plugged end, and on the opposite side from the previously drilled nozzle orifice. Place a small piece of masking tape over the spark wheels relay hole.
- In both spark wheel tubes "A" and "B", insert a piece of black match, 1-1/2 " long, into the nozzle so that approximately 3/4" of black match remains outside of the hole. If the match is thin, two pieces should be inserted to more completely fill the spark wheel holes. Bend the match down so that it lies parallel with the axis of the spark wheel tube and tape it in place. The tape should cover the hole and the match.
- Ram spark wheel tube "A" (the one with two holes) with the gold glitter pyrotechnic formula and the single hole spark wheel tube "B" with the silver titanium pyrotechnic formula, leaving 1-3/4" of each tube empty at the top. On spark wheel tube "A" with the additional 3/16" hole, the powder should be just filled past this hole, and there should be powder in the hole itself (peel back tape to check).
- An additional small charge of clay can be rammed in each spark wheel tube if desired to prevent powder from accidentally leaking out until the separating dowel is glued in place; one and a half inches of empty tube should still remain at the top. This extra step is useful when large numbers of spark wheel tubes are being made up, and the spark wheel tubes are being moved around a bit before final assembly.
- White glue or hot-melt glue the 10" wood dowel into spark wheel tube "A". Before gluing spark wheel tube "B" on to the opposite end of the dowel, carefully line up the nozzle holes of each spark wheel tube so that they are pointing in opposite directions. Make a reference mark on the dowel and the unglued spark wheel tube "B" once you are satisfied with the alignment. Remove spark wheel tube "B" from the dowel, apply glue, and slide the spark wheel tube back in place, realigning the reference marks.
- Measure to find the midpoint of the spark wheel. Mark this point and drill a 3/16" diameter hole into the dowel at a right angle to the plane of the 1/4" nozzle holes in the spark wheel tubes. This is the pivot point and should accommodate a 16-penny nail.
- Cut a length of quickmatch to go from the relay hole in spark wheel tube "A" to the nozzle hole in the spark wheel tube "B" (both of these holes should be on the same side of the saxon spark wheel, and in a straight line parallel to the axis of the device).
- Starting at the nozzle on spark wheel tube "B", remove the bit of tape from the black match. Slip the black match up into the sleeve of the quick match and tape the match down to spark wheel tube "B". Run the match down the length of this tube, down the wooden dowel, and up to the relay hole on spark wheel tube "A". Tape can be used at intervals to secure the match to the spark wheel tubes and dowel. Finally, remove the tape from the relay hole (make sure you can see powder in the hole) and tape down the end of the match over the hole.
- At the nozzle hole on spark wheel tube "A", secure either a longer piece of bare black match or a piece of visco fuse next to the black match protruding from the hole; tape in place. The tape should completely cover all connections at each hole to prevent accidental or early ignition. This is the fuse you will use to light the saxon spark wheel.
- A nail is inserted into the pivot hole in the dowel; it should be a loose fit and the dowel should spin freely around it. Nail the saxon spark wheel onto the flat side of the wooden block. A 1-inch length of small diameter tube can be slid on the nail between the saxon spark wheel and the wooden block to act as a spacer. A 1/8" hole drilled in the block first will facilitate nailing and prevent the block from splitting. Two additional holes should be drilled on either side of the first hole to allow the block to be screwed or nailed to a support post used to display the saxon spark wheel. Use caution when nailing that no loose powder is in the nailing vicinity, due to the possibility of striking a spark.
- Arrange the saxon spark wheel at least 6' above the ground; 8' to 10' is much better. Light fuse, stand back and enjoy.
PYROTECHNIC FORMULAS FOR SAXON SPARK WHEELS
|Magnalium, -200 mesh
Everything above is parts by weight. If commercial Meal D black powder is not available, home ball milled black powder can be substituted. In lieu of this a simple mix of Potassium Nitrate 75, Charcoal 15 and Sulfur 10 can be made up and used in the pyrotechnic formula, however, nozzle hole diameters may need to be reduced.
ADDITIONAL CONSTRUCTION NOTES
Although masking tape for attaching the quickmatch in step 10 above can be used for quick prototyping, for the most part it does not look neat and professional on the finished product. A better method to hold the match in place as described in this article is to use a strip of 30# Kraft paper, pasted with wheat paste or white glue. When dry, the paper shrinks down tight, for a clean appearance and a tight cover.
FREQUENTLY ASKED QUESTIONS
Q: Why not drill the nozzle holes after the spark wheel tubes are completely rammed?
A: Pre-drilling the holes beforehand is safer and allows you to precisely place the holes near the clay plug, and it allows the black match to be held in place by the rammed spark wheel composition. It is also much faster to do when making up large numbers of saxon spark wheels.
Q: What needs to be done to keep the spark wheel nozzle hole from enlarging as burning progresses?
A: Enlargement of the spark wheel hole is normal; usually this will not cause a problem. Saxon spark wheels turn so easily that the hole can get very large and the saxon spark wheel will still function. There are several ways to make a better nozzle orifice, but all involve more work and are generally not necessary for this device.
Q: How big can I make saxon spark wheels?
A: I have made saxon spark wheels 6' in length with 1" I.D. tubes. As the pole or dowel connecting the tubes increases in length, spin rate is decreased. The limiting factor to size and burn time is how long the spark wheel tube will hold up before burning completely through.
Q: What other pyrotechnic formulas can be used?
A: Try anything and find out. Saxon spark wheels are so quick and easy to make that the only limits are what chemicals you have to play with. Any pyrotechnic formulas for gerbs or fountains will work; also, try colored driver mixes.
Q: What is the best way to display saxon spark wheels?
A: Saxon spark wheels are most effective when fired in multiples. I make 16' support poles, with one saxon spark wheel mounted at the top and second saxon spark wheel mounted half way down at 8'. I then space 10 poles about 20' apart. When burning, this gives a wall of fire 200' by 30' high. With a slow spin rate, the effect of many saxon spark wheels is almost hypnotic.
Q: What is the best way to ignite multiple saxon spark wheel poles?
A: With multiple poles, each pole should be electrically fired. Quick match is too slow. However, you must be careful that the wire leads from the electric match do not get wrapped around the saxon spark wheel, preventing it from spinning.
VARIATIONS ON SAXON SPARK WHEELS
- The saxon spark wheel described is a 2-tube version connected with a wooden dowel. This is the best method for making large saxon spark wheels. Smaller, shorter versions can also be made using a single tube without a dowel. The ramming sequence would be: clay plug, composition, clay plug separator at the middle of the tube, composition, and clay plug, using the entire length of the tube. The clay plug separator in the middle allows you to drill a hole for the pivot point. The disadvantage of this style is that the holes need to be drilled after the ramming has been completed.
- Have both nozzle holes point in the same direction. This causes the saxon spark wheel to revolve first in one direction and then in the reverse direction as it transfers to the other spark wheel tube.
- Have both spark wheel tubes light at the same time; nozzle holes must be pointed in opposite direction. The saxon spark wheel will spin much faster, but the burn time is reduced by half.
- Use multiple pyrotechnic formulas in each spark wheel tube for more color changes.
- Attach color pots (like short, stubby lance) to the side of the saxon spark wheel; this produces bright rings of color inside a halo of sparks.
- Use longer spark wheel tubes with multiple pyrotechnic formulas in each tube and multiple nozzle holes all matched to burn at the same time. This results in a halo of sparks with several color rings inside. The Chinese make a great version of this.
- Use four (or more) spark wheel tubes. Instead of a single wooden dowel, make up a cross-shaped piece that allows four tubes to be mounted for extended effect capability and burn time.
- Try combinations of above suggestions.
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