Shell Building
Building Tables
Basic Construction Techniques
Paper Glue and string
Building Tools
Shell Types
Video
 

Shell Building Tools.


Case Formers.
Case formers come in a range of sizes to match the size of
the shell you are building. To construct a 3'' shell (one that
fits inside a 3 inch I.D mortar tube) you will need to construct
the casing around a 2 1/2 inch OD former. By the time you
haverolled several layers of Kraft paper around the former,
spiked it with twine and applied layers of pasted paper to
fireproof it your shell should be the correct size for the tube.
Depending on the size of shell the former is 1/2 to 1'' smaller
in diameter than the finished shell size.
The best formers are made from hardwood and sanded to
a smooth finish with a slight taper towards one end to allow
the casing to be removed easily from the former. Most formers
have a hole bored several inches deep into one end. This hole
allows you to roll a casing then insert an end disc to which is
already attached a flash bag, time fuse or spolette.
After pleating the paper down onto the disc the former is then
removed leaving the fuse/flash bag sitting inside the centre of
the casing. Alternatively a plain disc is inserted and the case
closed then the fused disc inserted later after filling the case
with stars, garnitures and burst. A hole should be bored
throughout the entire length of the former to allow air into the
casing. Once one end of the casing is pleated down and closed
and the casing pulled from the former a vacuum can form
within the case making it difficult to remove. This hole allows
air into the casing to stop a vacuum being formed.
The length of the former should be around 3 1/2 times the
diameter. This should be long enough for most types of shell
including those with inserts.

Canulles.


A Canulle is simply a tube that is inserted centrally into the shell casing and filled with burst charge. The tube can be made from just about any non sparking material. It should be thin and have a smooth surface so that contents of the shell such as cut stars do not ‘bite’ into it and cause it to bind when being removed from the casing. For this reason rolled cardboard tubes do not make good canulles.
Tubes of around 1/32 to 1/16 wall thickness made from Aluminium, Copper and Stainless Steel work fine and the top can incorporate a funnel shaped section to spoon in the burst charge without spillage. The tube should be thin walled because as it is withdrawn from the casing the burst powder inside will take up the space previously occupied by the tube. A thick walled tube will require you to fill the tube some way above the level indicated by the top of the cardboard liner to allow for this. A good idea if you do not use rough powder to pack all the spaces between your stars with Polverone filler is to roll 2 turns of thin tissue type paper around the Canulle before inserting it into the casing. After fillling the case and removing the Canulle the paper core will keep the burst charge in the center of the shell and stop it from migrating into the stars and inserts.
 

Spiking Tools.


To spike your shells a device is needed to hold the twine and allow you to wrap the shell casing under tension. Traditionally a wooden Spiking Horse is used for this purpose and it is arguably still the best method today.

Simple and uncomplicated it is merely a couple of upright pegs fixed solidly to a base that can be clamped or permanently bolted to your work table. Paste is applied to the twine which is then wound tightly in a figure of 8 configuration around the 2 pegs. To spike simply unwind a few feet and wrap around the shell then unwind more as needed.

Another way is to use a cam device. They can be made from metal or wood and consist of a block with a hole running through it that pivots on a bearing. The one pictured here is made by Wolter Pyro Tools. Twine enters the block at one end is then looped around a post and exits at the other end of the block.

When pulled in an off centre direction the block locks against the post and the twine can be wound around the shell under tension. When you need to release more twine from the cam you simply pull in a direction that moves the block away from the post and the twine runs freely through the device.

This kind of spiking aid is quick to set up and use but has the limitation of being almost impossible to use with pasted twine without some kind of elaborate paste application bath for the twine to run through after emerging from the spiking tool. Since the twine needs time to absorb the paste well this device is only suitable really for dry spiking.

End Disc Cutters/Punches.


Kraft Board and cardboard end discs for shell casings are available from suppliers in standard diameters in 1/16 or 1/8 thicknesses or you can quickly make your own in any size imaginable using a tool like the Allpax Gasket Cutter.
Consisting of a heavy brass or steel block with a cutter blade in one end and an adjustable centre pivot pin in the middle this tool will with one 360 degree turn quickly and effortlessly cut through chip board and cardboard to make discs in stock or custom diameters.
An inexpensive set of hole punches can then be used to punch a smaller hole in the centre of these discs to insert time fuse or spolettes.





 
 
 
Time Fuse Punches/Cutters.


Time fuse often needs to be cut to a specific length, and a hole punched in it or the fuse cut lengthways to allow lengths of Blackmatch to be inserted into the core of the powder. Known as crossmatching this procedure helps ensure ignition of the fuse. There are a number of different tools available to accomplish this operation.
A basic punch like the one shown at top will hold your fuse while you punch a clean hole through it. Blackmatch is then threaded through the hole and crimped in place.
The precision cutting tool shown in the centre photo will cut lengths of fuse with 1/32 inch accuracy for making roundel type shells and similar devices that need split second and consistent timing.
After cutting the fuse end will need to be
primed or split / punched to allow insertion of the match.

Shown at the bottom is a tool that does it all, not only does it cut precise lengths of fuse but also punch holes or splits the fuse lengthways with great accuracy.

The time fuse is arguably the most important element in your shell and great care and attention to detail should be given to making sure it functions correctly. Should the fuse fail in any way apart from the safety concerns of having a dud shell or one that ignites in the gun all the time, money and effort put in to making the shell, stars, burst etc will have been for nothing.

 

The makers of the devices pictured in this section
Rich Wolter and Ben Smith have links to their
websites on my links page.















 
Dowels/Tamping Tools/Brushes.


Small brushes to apply white glue and paste including a wide ‘sash brush’ type to apply paste to Kraft paper when pasting shells come in handy for many manipulations. Small glue brushes with tapered ends are useful for pulling the paper down and making crisp neat folds when pleating down the shell case ends and a variety of different sized wooden dowels find use for tamping down stars and polverone.

Small dowels with triangular ends are useful for packing Polverone or sawdust into the spaces between the shell casing and rows of comets, cylindrical stars or shell inserts and shaped wooden blocks come in handy during pasting for smoothing down the edges and pleated ends of the paper.

Hammers and Mallets.


Non sparking hammers and mallets can be made from Aluminium, Brass, Copper, Lead, leather or wood or plastic. A range of sizes in weights of 100gm to 2 Kg will cover most uses.










   Spolette Making Tools.

Spolettes are the traditional way to fuse cylinder shells and if
you are going to make them a set of ramming tools with
rammers having flat and convex ends as well as a ramming base and tube sleaves will make the job quick and easy as
well as giving you consistent results in your timing.
A flat ended rammer produces a powder core flush and level with one end of the tube while another produces a concave
recess in the powder core at the other end (the end inside the shell) that will help to project a healthy jet of fire into the centre of your shell and ensure ignition of the burst charge and shell
contents.
The rammers have machined grooves around the shaft in
graduations of 1/4 or 1/8 inch  to allow you to accurately ram or press the powder in equal increments and to measure the total length of your powder core within the tube.
Tooling is available in standard spolette tube sizes or you can get custom made tooling to fit your size of tubes.



Shell Rolling and Assembly Devices.
under construction


 
Copyright Bangkok Pyro Company Thailand 2011