6 Inch Crossette Canister Shell

8/12/2019 6 Inch Crossette Canister Shell

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Build This...6" Crossette Canister Shell

Summary:Crossettes are among the more tricky effects to master,and this article shows many of the tricks for getting themto work properly. A method is shown for making cleanbreaking charcoal crossettes without the distracting whiteflash typical of flash broke crossettes.The shell itself is constructed using a Maltese-Italianhybrid, showing one of the several ways these two shellbuilding techniques can be combined to lower costs andmake construction easier.

March, 2003 Issue

Build This:6" Crossette Canister ShellTool Tip:Making Cross Match Autopsy:3" Vulcan Canister

Materials:(1) 10" x 36" long poster board(1) 10.5" x 36" long 60lb kraft(1) 36" long x cut to width 30lb kraft(3) 24" long x cut to width 70lb virgin kraft(4) 5.5" dia. 1/8" thick chipboard disks(1) 3.5" long spolette tube(40) 3/4" dia. chipboard disks(40) 2.5" x 8.5" long 30lb kraft

Tools:Spiking horse

1-1/4" crossette pumpArbor press or malletThin metal blade

Unmeasured Materials:chinese fuse or termolite, 4Fg, 2FA, meal powder, flax twine, sawdust, black match, white glue, wheat paste


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6" Crossette Canister Shell

Figure 1:Basic crossette components.

Figure 2:Crossette pump and PVCsleeve.

Figure 3:Star shaped cavity formerwith pin at tip.

Introduction:Crossettes, also called split comets, are a special breed ofcomet that split into four pieces midway through their trajectory.

Figure 1 shows a cross section of a typical crossette, whichreveals an inner cavity where a high-energy break charge isplaced. The comet is pasted in on the sides and top so that itcan only burn from one end. When the flame front reaches theinner cavity, the burst charge blows the remainder of the cometinto four pieces (ideally).

The inner cavity of a crossette is usually a tapered hole withthe profile of a four pointed star or square. Although it ispossible to make crossettes with a rounded cavity, the weakpoints caused by a four pointed polygon help insure that thecomet breaks into four equal sized pieces. The taper isneccessary to ease the removal of comets from the pump after

pressing, where they are fragile and prone to cracking.

Crossette shells typically suffer from two problems: crossettesthat don't break properly and crossettes that don't all break atthe same time. The first step in making a crossette shell is tomake sure your crossettes break properly through repeatedtesting from a star gun. The illustration below shows two of themost common crossette failures seen when testing individualcrossettes.

"Jetting" Fragmenting PerfectJetting is the most common problem and can be caused by anumber of factors. It most often occurs when testing from a stargun, since the setback from the lift can compact the breakcharge into one side of the cavity and turn the crossette into anend burning rocket. This is why it is important to test yourcrossettes from a star gun rather than just placing them on apost or hanging them from a string. Star guns create the actualconditions your crossettes will experience when being thrownfrom a shell, whereas other methods do not and may lead youto think that your crossettes are working only to find that manyof them fail when fired from a shell.

The use of too little or too weak of a break charge can also cause jetting. Since the cavity can not holdmuch powder, a high strength flash type mix must be used. The types of aluminum used for the flashwill effect it's strength, with Indian Blackhead being the strongest, followed by German Black and thenAmerican Dark.

Another method some builders prefer is to hand roll small firecracker-like "shots" that fit into the cavity,thus insuring that the charge will have adequate confinement to split the comet apart. I personally find


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that this method adds too much work to a component that is already a lot of work as it is!

The most common trick to eliminate jetting is the use of a fuse that inserts into a small hole at thebottom of the cavity. Most commercial crossette pumps have a pin at the end of the plunger, as seenin Figure 3, which is designed specifically for this purpose. The flame front will reach the small holefirst, allowing ignition of the cavity while there is still some composition left at the bottom to help create

containment. The passfire fuse, which runs the full length of the cavity, also helps eliminate the end-burner problem by providing a fire gap through any comp that may otherwise get compacted fromsetback.

Thermolite is the most common choice of passfire for the small inner fuse, probably because it is oneof the few types of fuse that is thin enough to actually fit into the hole. However, Thermolite is quiteexpensive and is increasingly hard to find. I have not had much luck with thin diameter visco fuse asan alternative, as the burn rate is too slow.

My personal secret is the use of hand rolled Chinese paper fuse made from corning dust. This type offuse is ideal since it is thin, takes fire easily and is very fast burning. For those of you who don't makeblack powder, corning dust is the fine grained dust leftover when granulating BP. It ranges in particlesize from meal to 60 mesh and burns quite rapidly when made into tissue fuse. Corning dust couldalso be made from pulverizing commercial BP by hand, or screening dampened meal through a 40-50mesh screen.

The other common crossette defect is an overly hard break that causes many small pieces instead offour large pieces. This is a simple matter of dialing in the strength and amount of break used in thecrossette. The paste wrap around the crossette should also not be too thick. Two turns of a lightweight 30-40 lb kraft paper is all that is required.

Figure 4:Pin position when loadingcomp.

Figure 5:Arbor press used to

compress comp.

Pumping Crossettes:The crossettes used in this 6" shell are made using the 1-1/4"Nituff coated crossette pump made by Rich Wolter. Note that

there are no paid product endorsements on Passfire.com.Anything that is recommended on this site is found to be ofexceptional quality, and Rich's tools fit that qualification.

The crossettes for this project are traditional charcoal streamercrossettes. The formula used is Shimizu's Tiger Tail streamer.You will need to mix up 1000g of this composition to make the40 comets required to build the shell. A 1000g batch will alsogive you a few extra comets to trial and error with beforebuilding the shell. I prefer to mix half of the required charcoalwith all the other ingredients in a ball mill for one hour, thenscreening in the remainder of charcoal afterwards. This gives anice bushy head on the comet while still leaving behind a tail ofdecent length. You can vary the mesh size of the screened incharcoal to adjust the tail duration as well.

Begin by dampening the 1000g batch of Tiger Tail with 15% ofwater that has 20% isopropyl alcohol added to it. Note thatisopropyl is typically 30% water, so your effective alcoholcontent is really only 14%. This percentage is not real critical,as the alcohol is only there to break the surface tension of thewater (for easier incorporation into the comp) and to speed updrying.

I find the fastest way to get the water completely incorporated

into the powder is to work it in a little by hand and then pound itall down into a solid mass in the bottom of the bucket. This


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Figure 6:PVC sleeve used as depthstop.

Figure 7:Composition shaved flushwith end of pump after pressing.

allows the water to absorb equally through the solid massinstead of spending all your effort kneading the powder byhand or pushing it through a screen to break up lumps. Allowthe mass to sit a few minutes, then scrape it back up andpound it flat one more time. Chip it back up into a loose mixagain and you are ready to go.

Comet pumps have a pin on the plunger that is designed as adepth stop. This allows you to pump comets that are of equallength, which is even more important with crossettes. If yourcrossettes are not all the same length, they will break atstaggered times and ruin the effect, not to mention presentproblems when stacking rows inside the shell casing.

For regular comets, the plunger is pressed until the pincontacts the sleeve, then the plunger is rotated until the pin isabove the slot so that the comet can be ejected. Crossettespresent a problem, however, since twisting the plunger in thisway will carve out the star shaped cavity and defeat its

purpose. The pin must be positioned above the slot beforepressing the comet in order to avoid this problem.

Since I think the depth stop concept is critical to getting uniformcomet lengths, I place the comet pump inside a PVC sleevethat is cut to the same length as the comet pump sleeve. Thisway the pin will hit the PVC sleeve, as seen in Figure 6, andcreate comets of equal length. If you had an exceptionally slowburning comet mix, you could make the sleeve even shorter inorder to shorten the burn time of the comet. This same trickcan be applied to regular comets as well.

The comet pump is loaded by holding the rammer such that the pin is at least a half inch above rim ofthe sleeve, as shown in Figure 4. Holding the pump in this way, simply ram it down into the loosecomp several times until it fills up. It is important to make sure the pin stays a consistent height abovethe sleeve when doing this so that each comet will have roughly the same amount of compositionpressed into it.

While a mallet can be used to consolidate these comets, I prefer the use of an arbor press because itis quieter, faster and less physical work. Figure 5 shows a typical arbor press in the 2 ton range. Thisratchet type press with the quick-position wheel is highly recommended for it's speed and ease ofoperation. Because the comet pump is so long, it must be pressed against the table under the press.

This requires that the press be firmly clamped to the table to keep from lifting itself during pressing,which is achieved with the bar clamps seen in Figure 5.

Once the comet is pressed and the pin hits the PVC sleeve, the pump is removed and the end isshaved flush with a thin blade as seen in Figure 7. Again, consistent comet length is critical and thislast step insures that all comets will be the same length.

Lastly the plunger is pressed until the pin hits the bottom of the U shaped channel, then the comet isgently removed and placed on a screen to dry. Charcoal streamers are slow to dry, so allow at least aweek before testing one. It is always good to make an extra one to break apart at various times tocheck for dryness.


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Figure 8:Tapered 1" conduit used asdisk punch.

Figure 9:Punching poster board diskson a wooden block.

Figure 10:Granulated whistle mix.

Figure 11:Chinese fuse inserted andcut flush with top of cavity.

Punching End Disks:While you can buy thin 3/4" diameter chipboard disks to use forthe ends of your crossettes, you can also make your own prettyeasily. A standard piece of 1" metal electrical conduit will makethe perfect size disks for snugly fitting into the recess on top of

a 1-1/4" crossette. Simply use a grinder to bevel the cuttingedge of one end, as seen in Figure 8. After you have a nice 45degree angle around the edge, use a propane torch to heat theconduit until it glows red hot, then immediately submerge it intoa bucket of cold water. This will help harden the edge for alonger cutting life.

The disks used for the tops of crossettes do not need to bethick. Simple poster board makes good disks, and you canpunch through two or three sheets at a time. I like to use a 4 lbsledge hammer to punch disks over a block of hard maple, asseen in Figure 9.

Crossette Burst Charges:There are several burst charges commonly used in crossettes,most of them involving flash powder of some kind. Whilestandard 70/30 flash can be used to break crossettes, theamount has to be carefully regulated to keep from blowing thecrossette to bits. This type of charge also has the disadvantageof creating a bright flash when the crossettes break. If thecrossette is made from a bright mix such as silver flitter, thenthis flash isn't noticeable as much. But for low light charcoaleffects, this flash is very distracting and takes away from thequality of the streamer effect.

Several variations of what is called "Dark Flash" exist, whichinvolve the use of chlorate and antimony, with sulfur sometimesadded. Chlorate/antimony/sulfur mixtures are very frictionsensitive, so these mixtures require the utmost care whenmixing. Only small batches of about 30 grams should be mixedat a time.

Dark Flash CompositionsA B B

Potassium chlora et Antim ny Sulfide 1 4 3o Sulfur 1 1 21 1

Source:Pyrotechnica XIUse of granulated whistle mix is another way to break acharcoal crossette without creating a bright flash. This will notbreak the crossette very hard, but it will split the crossette intofour pieces when the mixture is granulated correctly. A mixtureof 70/30 whistle mix is first dampened to a crumbly consistencywith a mixture of water and gum arabic (1 quart of water per30g gum arabic). This is then passed through a 50 meshscreen and allowed to dry. The resulting granulated whistle mix

is shown in Figure 10.


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Figure 12:Cavity filled with whistle mixand glued around rim.

Figure 13:Pasting in crossettes from astack of pasted strips.

Figure 14:Primed ends dipped in 4Fginsures ignition.

Since the whistle mix is not quite as strong as regular 70/30flash powder, the entire cavity must be filled with the mixture.The finer your granulations are, the stronger the break will be.However, you can not get away with just using ungranulatedwhistle mix, as it will compact easily and result in jetting. Thefast burning center fuse shown in Figure 11 is also important to

insure proper operation.

Finishing the Crossettes:For testing purposes, foil tape or masking tape can be used towrap the crossettes prior to firing from a star gun. This allows afaster trial and error period, since each crossette can betweaked and fired one at a time without waiting for a pastedwrapper to dry. Simply apply two turns of 2" wide tape aroundthe crossette and fold it over on the top. Make sure there areno gaps under the tape that would allow fire to travel up theside of the comet. Hot glue can be used to glue on the end diskfor each trial. You can try different center fuses, different breakcharges and different amounts of break charge until you get a

properly working crossette.

Once your crossettes are dialed in, it is time to mass producethe rest of them. To finish them off using my whistle mixmethod, first insert a piece of the Chinese fuse and cut it flushwith the top of the cavity, as shown in Figure 11. The cavity isnow filled with the granulated whistle mix, a bead of white glueis run around the rim and a paper disk placed on top.

Once the glue has completely dried, the comets are pasted inwith two turns of 30-40 lb kraft paper. The paper can be virginor recycled, it doesn't matter. The pasted paper should be as

wide as the height of the comet plus it's diameter, and longenough to make two turns around the comet. Figure 14 showscrossettes being pasted in from a stack of pasted paper strips.

Note that some builders simply use the tape method for all theircrossettes. I find the tape is actually more work when doingmany crossettes, since it has to be smoothed down and ismore prone to wrinkles along the sides that will cause timingdefects. Some builders avoid wrapping the crossettesaltogether and simply dip them in hot wax. This produces aperfect fireproof seal around the sides and top, and is a quickmethod as well.

Once your crossettes are fully dried, apply a slurry prime overthe exposed end and dip the end into a container of 4Fg grainpowder. This last step provides a primed surface that takes firevery easily and quickly.


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Figure 15:Tamping sawdust aroundgaps behind crossettes.

Figure 16:All crossettes loaded into aMaltese style can.

Figure 17:BP on puffed rice breakcharge filled in around a spolette.

Figure 18:Closing the can in theMaltese style.

Constructing the Shell:This shell is constructed using a Maltese style can. The posterboard strip is 10" x 36" long, while the 60lb recycled kraft stripis 10.5" x 36" long. These are rolled around a case former thatis 5.5" in diameter. This is a single break shell, so the bottom

disks will not contain the hole shown in the article linked toabove.

Since the traditional Italian method would require six turns ofkraft paper around the former, pleating down this amount ofpaper can be a chore. Not only is the Maltese style canstronger, it is made from cheaper materials (virgin kraft is notrequired) and is quicker to produce for larger shells.

When many cylindrical inserts are loaded into a canister shellof this type, be they comets, salutes, tourbillions, shells etc.,the symmetry of the break is proportional to how solidly theseitems are loaded into the shell. The shell contents should notbe loosely stacked against the walls. Large gaps between thecrossettes should be taken up using wedges, and the spacebehind the crossettes should be rammed with sawdust. Aftereach row is loaded, the sawdust is poured around the edgeand tamped down with a dowel rod, as seen in Figure 15. Thislocks the crossettes into place so that they do not fall out whenthe shell is inverted to dump out the remaining loose sawdust.

The crossettes are stacked into the shell like a brick wall, using10 crossettes per ring running four rings tall. Figure 16 showsall four rows of crossettes loaded.

The remaining space left for the break charge is rather large,and using straight commercial black powder would beexpensive, heavy and overkill to break this shell. A moreeffective break charge is the use of home made rough powder.Iprefer the use of puffed rice coated with BP in a 4:1 ratio, whichconsumes less BP and is a little stronger of a break chargethan rough powder. The puffed rice type charge also makes theshell lighter than if it were filled solid with rough powder, thusreducing your lift charge requirements.

A hand rolled spolette is made from a 3.5" wide x 14.5" long filefolder paper rolled around a 1/4" former. This should produce arock solid tube with a 1/2" outside diameter. The tube is

rammed with enough meal to give a 3.5 second delay, which isa 1-1/4" long charge in my case. You will have to time your ownpowder to find the exact charge required for your own spolette.Otherwise Chinese time fuse can be substituted for thespolette.

Figure 17 shows the shell prior to closing. A disk is placed overthe spolette and the remainder of the can is sliced into tabs andpleated down with glue. Note the white glue around the base ofthe spolette prior to applying the second end disk over thepleated tabs.

Now we finish the shell using the Italian method of spiking andpasting. This is done to avoid the more tedious Maltese spikingprocess, which tends to consume a lot of twine and takes


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Figure 19:Can is spiked with flaxtwine as for an Italian shell.

Figure 20:Pasting an initial 30lb wrapto insure a good gas seal.

Figure 21:Leader to passfire fusing.

longer to apply. Figure 19 shows the spiked shell finished with26 verticals of strong Italian flax twine.

One thing to be aware of when using Maltese cans is the gapsthat lead into the can from the outside where the tabs were cut.Extra care must be taken to seal the outside of the spiked shell

to ensure that lift gases do not get under the paste wrap andenter the shell through these slits at each end of the can. Aninitial paste wrap of 30lb kraft is used to form a good seal,since the thin paper lays down better and fully conforms aroundthe spiking twine. Make sure this first paste wrap lays tightlyaround the base of the spolette.

The final paste wrap consists of three 24" long sheets of virgin70lb kraft, grain short as usual.

Figure 21 shows the passfire connection to the spolette, whichis made by baring a few inches of match and tying it over theexposed powder core using several turns of twine. I preferwaxed twine for its strong grip on the spolette, reducing thechances that the match could get torn away from the spolettebefore it takes fire.

The leader is connected to the passfire by looping exposedmatch around it and back up into the leader pipe for about fourinches. This helps prevent the leader from getting yanked outof the shell when being lowered into the mortar. It also doublesthe amount of match present at the connection point, producinga bigger flash of fire to help ignite the match passing over thespolette.

If you used charcoal crossettes and BP coated puffed rice asthe break charge, you will only need about 100g of 2FA to liftthis shell. Use an ounce of 2FA per pound of shell weight todetermine the correct amount of lift for your own shell.


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Tool Tip : Making Cross Match

Figure 1:Sizing up the spool bracketswith the slurry bucket.

Figure 2:Bracket placement aroundslurry bucket.

Figure 3:Making spools with brasstubing and 3" end disks.

Introduction:Cross match is a thin diameter type of fuse used to pass fireinto a piece of time fuse. The time fuse is punched through with

a small diameter hole into which a short segment of crossmatch is inserted. Black match is most frequently used forcross match because it takes fire easier than other types ofsmall diameter fuses such as visco or thermolite. Black matchcan also take fire at any point instead of just at the ends suchas with visco. This side-ignite characteristic helps reduce thetime required to pass fire to the main time fuse.

Because the reliability of the cross match is detrimental toinsuring quick and effective ignition in shells and inserts, it isimportant to be able to make good cross match. Thin matchthat only contains a shell of powder around the outside tends tobend easily when inserted, resulting in the outer powder layer

cracking off and creating a void in the powder train. This littleinch of fuse can make the difference between a lot of effortworking properly vs. smashing to the ground.

While the method for making black match described here canbe used to make smaller diameter cross match, the methoddescribed in this article produces a more consistent diameterfuse with good powder saturation. While this technique requiresmore effort in fabricating the initial tooling, it is generally fasterand less messy at producing match than other methods.

Making the Spool Rack:

The basic idea here is to feed four individual strands of cottonthread down into a bucket of black powder slurry, where theythen merge as one strand up through a diameter regulatinghole and onto a rotating frame. This way each strand is coatedbefore merging into one strand, insuring that there is powderon the inside of the fuse as well as on the outside.

The first component you will need to make is a bucket aroundwhich four spools of string are situated. The actual dimensionswill depend on whatever bucket you can find, so Figures 1through 5 show the basic design. The bucket should be at leastsix inches in diameter, but no larger than 8" or you will wind upwasting a lot of slurry per fuse batch. The depth of the bucket

should also be at least 6".

You will need to make four brackets that look similar to the oneshown in Figure 1. The hole near the top is used to hold a rodaround which the spool can spin. The bracket should be madeso that the hole is about 2" above the lip of the bucket whenplaced next to it. The wood block at the bottom of the L shapedbracket helps hold the pieces together and gives yousomething to screw into when fastening the brackets to thebase board. The width of each bracket face should be about 2",while the height will be determined by your bucket.

The brackets should be spaced around the bucket as shown inFigure 2. The spacing between each bracket pair should beequal to the diameter of your bucket. Use wood glue and


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Figure 4:Spools mounted in brackets.

Figure 5:Thin cotton twine fed intonotched bottom of PVC pipe, then upthrough a 1/8" hole in the capped end.

screws to secure each bracket to the base board, screwingfrom the bottom side of the base board up into the brackets.

The four spools are made using brass tubing and chip boardend disks for 3" shells. The length of the brass tubes, whichcan be found in the K&S Metal centers of some hardware

stores, will need to be equal to the diameter of your bucket,minus about 1/4". I use 1/4" rod as the axle, so the brass tubesare 3/8" O.D. and easily slide over the axle. Drill a center holein a set of end disks such that they make a tight fit onto thebrass tube, as seen in Figure 2. The disks can be secured withhot glue if they are not a tight fit. Be sure to leave at least 1" ofbrass tube sticking out on both sides of the disk, which you willneed for fitting into a drill chuck when loading them with string.

You will need four axle rods for the spools to spin on, which arecut 2-1/2" longer than the length of the brass tubes. This canbe something like 1/4" threaded rod or 1/4" aluminum tubingwith threads cut onto each end so that a nut can be threaded

on. Figure 4 shows all four spools in place. The nuts at the endof each axle need only be hand tight so that the spools can beremoved without the need for any tools.

Next you will need a segment of 2" diameter of PVC that isabout 2 feet long. An end cap with a 1/8" hole drilled in thecenter is placed on one end (not glued). The bottom end isnotched with four equally spaced channels for the string topass through. This is easily done with a thin kerf pull saw orhacksaw blade.

Figure 5 shows a cutaway of all components being used to

feed string down into the slurry bucket, into the bottom of thepipe and up through the hole in the top. The pipe is stirred inactual use, which further helps coat the string with slurry.Excess slurry scraped off the string at the sizing cap falls backdown the pipe into the slurry bucket, making the operation quiteclean.


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Figure 6:Match loom dimensions.

Figure 7:Details of center pivot.

Figure 8:Details of tie-rods at eachend of frame.

Making the Frame:The frame used for this process is a little smaller than theceiling mounted frame described here. Because the operatorsits in front of the frame when making the match, a large framewould get in the way and be too difficult to manage.

The first step in making the frame piece is to cut the threadedrods and aluminum tubing to the following sizes:

(2) 29-1/4" long 1/2" O.D. aluminum tubing(1) 30-3/4" long 1/2" O.D. aluminum tubing(2) 31-1/2" long 3/8" dia threaded rod(1) 36" long 3/8" dia threaded rod

You will also need the following components for assembly:

(4) 3/8" washers

(4) 3/8" hex nuts(6) 3/8" lock nuts(2) 38" long 1x2 lumber(2) 39" long 2x4 lumber(1) 40" long 2x4 lumber(4) 3" long 1/4" lag screws(4) 1/4" washers

A 3/8" hole is drilled on center one inch from each end of the38" long 1x2s, which is easiest to do by clamping themtogether and drilling through both of them at once. A 1/2" holeis drilled on center at the midpoint of the boards, which will bethe pivot point.

The frame is assembled by putting a lock nut onto one end ofthe two shorter pieces of threaded rod and feeding them boththrough the top and bottom of one frame board. A washer isnow slipped onto each threaded rod, followed by the shorter1/2" tubes, another washer, the other frame board and finallyanother lock nut. After the lock nuts are tightened snugly, bothends of the frame should look like Figure 8.

Before placing the second frame board onto the threaded rodsas mentioned above, it is a good idea to insert the longer 1/2"tube into the center hole of one board so that it will fall into

place when the two halves are put together. Otherwise thecenter tube will have to be slid into the side of the frame once itis assembled.

Next you will need to take the two 39" long 2x4s and drill a 3/8"dia hole on center at two inches from the end of each one. Laythe frame flat on the ground and run the remaining threadedrod through the center tube, then spin two hex nuts onto eachend such that they do not actually contact the frame. Thereshould be enough threaded rod remaining that each 2x4 postcan be fitted on each side and secured with a lock nut asshown in Figure 7. The two nuts on the other side are tightenedagainst each other and are only there as spacers.

The remaining 2x4 is used to connect the support posts at the


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Figure 9:Fixed wheel dolly foroperator to sit on.

bottom using the lag screws as shown in Figure 6. The framemay be fitted with feet to keep it upright, but I prefer to leavethese off so that the frame can be stored flat up against thewall. I attach bar clamps to the bottom board to act astemporary support when I use the frame. Some hinged piecesthat fold out could be used for a similar space saving purpose.

Making the Dolly:The last component you will need is the dolly shown in Figure9, which is simply a 33" x 16" piece of 3/4" thick particle boardwith some 1x4 support planks on each edge so that it will notbend. Four fixed position casters are attached so that the dollycan only move side to side. The purpose of this platform is toallow the operator and the slurry bucket to easily movesideways as the frame is loaded with match.

Figure 10:Loading the spools using adrill press.

Figure 11Loaded spools and threadedaxle rods.

Match Making Procedure:

The first step in preparing to make a batch of cross match is toload your spools up with string. The type of string I use is a thinmercerized cotton that is sold for crochet in arts and craftstores. You can sometimes find it in large balls, but typically itcomes wound on smaller 3" dia. cardboard tubes in variouscolors. Each spool will require one of these smaller balls.

The thin cotton twine used to make commercial match will notwork for this process because it is too weak. You should not beable to easily break the string with your hands if it is to survivethe tension of being pulled under the PVC and up onto therotating frame.

The spools are easily loaded if you have a drill press. Simplychuck up a spool as shown in Figure 10, put your ball of stringin a bucket on the floor, tie off the string to the spool and runthe drill at a low speed while guiding the string with your hand.Make sure you wear a glove or you will get some serious ropeburn!

Figure 11 shows all the spools ready to go. A fully chargedspool will do more than one frame but not quite two frames. Sonext time around you will have to tie on to the existing stringwhen you recharge the spool. The knots will not cause anyproblems getting through the 1/8" sizing hole.

Prepare a few pounds of meal powder with 5% dextrin and addboiling water until it is a thick, muddy consistency. The bucketneeds to be at least half full with the slurry so that the stringswill be exposed to more of it during their passage through thetube.

Figure 12 shows the full setup ready to go. The small stool iswhere the operator sits during the process. A five gallon bucketwith some padding on top works just as well for a seat.

Remove the cap from the PVC pipe and feed the four strands

of string from the side spools up through the bottom and outthe other end. Bring the ends together and run them through


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Figure 12:Match making station withslurry bucket loaded and PVCthreaded.

Figure 13:Stirring slury with one handwhile spining the match onto the framewith other hand.

Figure 14:Fully loaded frame readyfor drying.

the hole in the cap, then secure the cap back onto the pipe.The group of four strings is tied off on one end of the frame andthe sliding platform is moved to that side. At this point you cansubmerge the pipe and string into the slurry, as shown inFigure 13.

Assuming you start at the left end of the frame, use your lefthand to spin the frame while stirring the slurry with the pipe inyour right hand. Slowly spin the frame and guide each strand ofblack match so that there is about 1/2" space from the previousstrand. If you start to see white spots on the strings, slow thepace down or stir the pipe more so the string is worked into theslurry longer.

It is usually necessary to periodically add more water to theslurry, since the string takes on slightly more water than it doespowder. When the slurry starts gloping up around the edgeswithout flowing back to the center when stirring the pipe, that'swhen it is time to add more water. Be careful not to add too

much water, because it doesn't take much to get theconsistency back to where it should be.

After about a half our of this, when your arm is ready to fall offfrom stirring the pipe so long, you should have a nice frame fullof cross match as seen in Figure 14. The first few feet of thefirst strand will be uncoated, but you will simply discard thatlater. Allow the match to air dry for several days until fully dry,then remove by cutting along the bottom and pulling the loopsoff at the top.

I usually leave the top loop connected and just lift all the match

off and store it in a cardboard mailing tube. Pieces of cappedPVC also makes good black match storage.

If you find that the match has problems bending when beinginserted through tight time fuse holes, you can make it strongerby substituting the 5% dextrin with 2.5% soluble glutinous ricestarch (SGRS) in the slurry. The use of SGRS will increase thedrying time substantially, but the finished match will be very stiffand less prone to cracking. It is recommended that SGRSmatch be removed from the frame after a few days and hung ina drying box of the type described here in order to speed upthe drying time from weeks to days.

A single frame of this thin black match should last at least ayear, since it can hold about 170 feet of match and youtypically only use small segments of it per shell. This thin matchwill also work fine for piped shell leaders, but it isrecommended that two strands be used instead of one. Adifferent method for making larger quantities of thicker blackmatch, ideally suited for shell leaders.


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3" Tourbillion w/Report and Red StarsManufacturer: VulcanShell Weight: 379gLift Charge: 50g 4Fg black powderOuter Burst: 54 g KP on rice hullsFlash Bag: 2g slow flash (dirty flash)Stars: 9/32" dia. round starsTourbillions: 3.75" long, 9/16" O.D., 3/8" I.D.Casing: Spiral wound, 6.5" long, 2.5" O.D., 1/8" wallTime Fuse: Single chinese time fuse, 2.5 sec delay time

Figure 1:No pasting, no spiking, just asimple spiral wound tube plugged at bothends.

Figure 2:Outer disk held on with masking

tape.

Autopsy Report:This 3" shell is part of a new line of canister shells from Vulcanthat are now on the market. Some of the internal inserts aremade in Germany, but the shell itself is assembled in China.

Vulcan's shells have been pretty high quality lately, with eachshell wrapped in a plastic bag with a moisture absorptionpacket. Their leaders are also coated in a plastic similar topacking tape, as is the fuse cap, making them extremelyresistant to moisture. If you fire shows in a damp climate orrainy season such as in Florida, then you may find Vulcan'smoisture resistant packing reduces the number of shells left in

the guns at the end of a show during which rain occuredsometime after setup.

On the outside this shell looks like your typical Italian style 3"shell, although at a length of 8" it is a bit on the long side. A 40weight paper covers the outside, which is folded and tapeddown on the bottom and tied off around the leader on the top.The leader runs down the side into a stiff cardboard lift cup atthe bottom.

Removing the outer wrap reveals the surprise shown in Figure1, which is a shell completely devoid of any spiking twine orpasted paper whatsoever! The liberal use of masking tapewould make old Italian shell builders wince, and I'm sure the


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Figure 3:Triple disk inner plug held inplace with lots of white glue.

Figure 4:Bottom fused with plastic liftbag. Note the amount of glued stringwrapped around the time fuse base.

Figure 5:Details of time fuse and flashbag components.

Figure 6:Fused end cap removed, lookingdown at the tourbillions. Note the yellowplastic end plugs.

Orientals who were assigned to assemble these shells foundthem quite peculiar as well!

This shell is basically a spiral wound tube with a triple diskedplug on both ends, as seen in the cutaway above. The top disk

taped onto the shell in Figure 2 probably adds nothing to theburst containment and is only there to cover the void beneath it.

Figure 3 shows how the end is plugged, which is really moresubstantial than it might first appear. A liberal amount of gluecovers the tube wall above the disk, which is a laminated set of3 disks that total 1/2" in thickness. The glue braces the disk atthe edges and prevents it from blowing out easily. The non-brittle nature of the dried white glue makes it ideal for thispurpose.

Figure 4 shows the lift cup removed from the shell, whichcontains 50g of fine 4Fg type black powder in a plastic baggie

tapped onto the shell leader. Note this is roughly twice as muchas the ounce per pound rule would dictate for traditional canistershells.

The plug on the bottom fused end of the shell was substantiallyless secured, and it surprises me that the contents of this shelldon't just blow out the bottom. A thick cap is fitted with threedisks like the other side, but the cap is just glued onto the end ofthe tube and was easily pried off with a screwdriver.

Figure 5 shows the details of the interesting fusing methoddevised for this shell. A piece of regular Chinese time fuse is

half covered in masking tape and then inserted half way into aspolette tube that was probably first glued into the shell cap.Cotton string soaked in glue is then used to build up a conicalseal around the time fuse and the tube, which prevents the liftgases from leaking around them and also insures that they don'tget blown into the shell. The time fuse is cross matched throughthe masking tape, then a piece of fast burning visco coated withblack powder is threaded through and tied around the time fusein a knot to keep it from falling out during lift.

On the internal passfire side of the fuse, the tube is filled with4Fg black powder and closed with a sheet of tissue paper. Afew turns of light kraft are used to form a flash bag that gets

taped onto the tube. The bag is filled with 2g of a slow burningflash (no thump when lit) and pinched closed.

Note that this method of using time fuse and a spolette tubecombined would allow the use of very short pieces of time fusethat normally couldn't reach from the inside of the shell to theoutside if used in the typical way. This is one way time fusecould be adapted for use in multi-break shells with short timingbetween breaks. While it is more work than simply ramming aspolette, the risks of blow through would be less on shorttimings.

Figure 6 shows the tourbillions lining the wall of the canister asexpected. A break charge of KP on Chinese rice hulls is mixed


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Figure 7:Tourbillions "crossmatched" withblack powder coated fast visco.

Figure 8:Break pattern is surprisinglyround with no signs of blowing out oneend.

about 50/50 with the stars that filled the rest of the shell.

The yellow plastic end plugs used to plug the tourbillions showtell-tale signs of European manufacturing. The tourbillions werealso fused completely through the casing with a fuse running

through like cross match. It would seem that two opposing jetstreams would not allow the tourbillion to do much spinning, butit works none the less.

After seeing this construction method, no doubt considered ahack by any self respecting Italian shell builder, it is surprisingjust how well the shell actually breaks. Figure 8 shows the shellin action, which looks pretty good for such a small shell! But likeany low confinement break system, the shell must be slammedhard by an energetic break for it to work. This requirementprevents this technique from being used to produce a softer,denser color break of equal symmetry.

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6 Inch Crossette Canister Shell

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