Tips for Fountain Tooling

Some of my first successful pyro projects were fountains. I still enjoy the simplicity and quick reward of making a finely crafted fountain. I prefer choked fountains because, in general, the higher internal pressure produces a greater height of fountain spray. In other words, a bigger effect is achieved for your efforts. Consequently, my fountain tooling is very similar to rocket tooling. A choked fountain is, after all, an inverted rocket with fuel designed for special effects. I offer here a few tips for making your choked fountain tooling. The illustrations depict tooling for a 3/4 inch I.D. fountain.



There are only two basic tools in the tooling set for fountains. One is the nozzle former, or spindle, and the other is the rammer, or "drift" if you want to use a nice buzz-word. The first step in making this tooling is to drill a hole into the end of a dowel to serve as the rammer. The hole is the same diameter as the spindle which, in this case, is 1/4 inch. The dowel is the same diameter as the I. D. of the intended fountain tube. Getting this hole perfectly centered and aligned is a challenge, even with a drill press. The hole is made about 2 inches deep because a 1 inch piece is then cut off to serve as the spindle collar.
To construct the spindle, I start with a 1 3/4 inch length of metal rod. Ideally, this rod should be made from a soft, non-sparking metal such as brass or aluminum. The diameter of this rod determines the throat diameter of the resulting fountain nozzle. A general rule of thumb is that the nozzle throat diameter should be about 1/2 of the fountain's inside diameter. This tooling uses a throat diameter which is 1/3 of the fountain diameter because I tend to push my fountains to their limits. Consequently, I always use very sturdy tubes for the fountain body. The length of this spindle is designed to extend only a short distance beyond the clay nozzle material and into the fountain composition. The desire is to create a small cavity where enough surface area of the fountain composition is exposed to enhance ignition. If the spindle is too long, the fountain becomes more like the typical black powder rocket which has a long core for high thrust.
Now, I am about to reveal tip number one.... get out your pencils and pay close attention. The part of the spindle rod which extends beyond the spindle collar should have a few degrees of taper in it. If you don't have a $5000 milling machine, you can accomplish this easily the poor man's way. Put the spindle rod in an electric drill and use a sanding block to wear away a little bit of the spindle surface. Start with about 320 grit sandpaper and finish with 600 grit to add a nice polish. This little bit of effort will greatly ease the extraction of the spindle tooling from the fountain when you are done ramming the contents into it.
To complete the spindle tool, a 3/4 inch hole is drilled into a piece of hardwood to a depth of 1/2 inch. The spindle collar is glued into this hole with epoxy and the spindle rod is inserted into the collar. Here comes tip number two..... apply epoxy in the spindle collar hole and on the top of the spindle collar. The epoxy should adhere to the spindle rod and form a nice, rounded fillet between the rod and collar. This effect is visible in the picture of the spindle above. The purpose of this enhancement is to create a rounded edge in the fountain nozzle.
Before I started using the epoxy fillet, the sharp edge of the nozzle throat would usually crumble in a few places as the spindle tooling was extracted. Now, as shown in this picture, the nozzle throat comes out perfect every time. Your fountain nozzles will be the envy of all your pyro buddies.




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