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Ballista Bolt Fin Construction

Ballista Bolt Fin Construction

The instructions below are to help you to construct a SCA legal Fins for Ballista Bolts. There are also directions for how to mount the fins at an angle to help the bolt fly better.

Supplies needed: Yellow Duct Tape, 2" inch Strapping Tape, Scissors, foam pipe insulation for a 1/2" copper pipe. Optional but helpful: Carpenters Square, long 1/2" rod of some type. I found it easiest to work with foam lengths that were about 4" shorter then the rod, so about 34" long.

Inserting the rod down the middle of the foam helps working on foam by making it more ridged.

Hook the carpenters square on the edge of your table with the foam also aligned along the edge. Then line the strapping tape up with the 45 degree edge of the square. While the square is not requred it helps get the tape started at the correct angle allowing you to lay it smoothly down the entire length.

Photo of the foam after the first piece of strapping tape has been put on.

Add a second wrapping of strapping tape in the same manner so that it covers the foam left by the first wrapping.

Cover the whole thing in yellow duck tape run down the length of the foam pipe.

Cut off one end so that the rough end and excess tape has been removed and it is nice and square.

Again hook the edge of your carpenters square on the edge or your table with the foam pipe also aligned along the table edge. Measure off 3" past the 45 degree side of the square. Line up the square end of the foam with this mark, then using the sissors cut along the 45 degree side of the square.

Line up the first fine at the short side of the 45 degree cut and then cut a perfectly matching second fin.

Finish cutting the lenght of taped up foam pipe. Be sure to keep the matched pairs of fins togeather. If you end up with a odd lenght at the end of the pipe, hang on to it you will get another one at the end of the next pipe too, use them togeather.

Run a 1/2" wide piece of strapping tape through the middle of both fins for one bolt.

Mount the first fin approximately 1.5 to 2 inches from the end of the siloflex pipe. I suggest aligning it with the printing on one side of the siloflex, this assures you that the fin is straight. Stick the strapping tape down as best you can, don't worry if it pulls off some.

Align the second fin directly opposite the first, as well as aligned to the front and back are as even as possible.

Take a lenght of 1/2" strapping tape and wrap it tightly around the siloflex pipe immediately in front and behind the two fins, be sure that you catch the tape running through the fins and pull it down tight. The wrap should go around the pipe at least twice.

The fins are now complete for this ballista bolt, repeat for the rest of your ammo. When firing off a "Docmo" style ballista be be sure that you have a hold down finger mounted on your trigger loop, it *WILL* misfire if you do not.


If you are looking for how to construct the other end of your ballista bolt here are  two links to articles on ballista tip construction. Any of these instructions will create tips & bolts that will pass the new rules.  LINK A  LINK B


If you are looking for how to mount the fins at a consistant angle here are those instructions.

Written by Baron Jonathas Reinisch

(Permission is given to copy as long as credit is given to the author)

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