Necessary to cross-match?

[Merlin]

Is it really necessary to cross match small 1.75" -1.91" inch shells. The time fuse is pretty short on these. I can see cross matching on 3" or larger shells both for safety and who would want to lose a bigger shell to a failure to cross match. I just tried a 1.75" and it worked perfectly just dipping the end of the time fuse in NC lacquer and BP prime. I used 4 grams benzolift for break and no flash was needed.

[BillyBobBodean]

If it's working for you then go for it, I see no reason to change it up. For me, I always cross match even 1.75" shells, just makes me feel better.

[Wiley]

I crossmatch all mine, but braddsn doesn't, and he's built a few hundred more shells than me.

[GMetcalf]

The smallest shells I make are two inch and I always crossmatch them. I figure it's not going to do any harm so I might as well.

[Richtee]

I didn't ever bother. I'd split the end of the fuse maybe .125", dip in NC then fine BP.

[Arthur]

Crossmatching is used to improve the certainty of passing fire from the lift to the fuse. If you are already at 100% then there is no point, If you get the occasional misfire then do the crossmatching.

 

With even moderate shells then two or three time fuses can be fitted, the damage caused by a 6+" shell falling from the sky soon outweigh the time and effort to crossmatch two or three bits of time fuse.

[fredjr]

I have made a lot of shells and have never crossmatched. I use a drop of what I call BP glue (NC laquer mixed with BP mill dust) and then dip into fine BP (-20+30). I have never had a shell fail to take fire. I use the same method on all my shells from 1" to 16" shells, including the 2008 PGI best exhibition ball shell winner.

[Andres1511]

I also never crossmatch, just dip the end in meal with dex slurry and then in fine pulverone... Has always worked up to now !

[mikeee]

Small shells down and dirty, quick and easy.

Larger shells deserve the extra effort and insurance from the cross match.

No-one wants to run for cover when a bigger shell is a no fire and is heading back down.

[Merlin]

I have made a lot of shells and have never crossmatched. I use a drop of what I call BP glue (NC laquer mixed with BP mill dust) and then dip into fine BP (-20+30). I have never had a shell fail to take fire. I use the same method on all my shells from 1" to 16" shells, including the 2008 PGI best exhibition ball shell winner.

You must be kidding. A 16" shell? That is gigantic! I am just about to move up to 4" max. A sixteen inch shell you will need a audience, better yet a paying audience! The resources and time that would go into a shell like that must be incredible. Not to mention a lot of hard work. That must be the kind I have seen, heard, and felt at professional shows put on by municipalities. The "normal person" has no idea at all what goes into such a shell. I salute you!

 

Now I remember, we got a battleship down in Mobile bay that shot those 16 inch shells...........

Edited May 20, 2015 by Merlin

[Merlin]

Small shells down and dirty, quick and easy.

Larger shells deserve the extra effort and insurance from the cross match.

No-one wants to run for cover when a bigger shell is a no fire and is heading back down.

You are absolutely right. My conception of a large shell is 4". My small ones would just bounce off and my wife is my audience so it dont matter so much I think. Baseballs and golf balls used for testing lift is another matter. Better put a bit of an angle on the mortar!!

[marks265]

I've seen shells do the return trip from the best of some of the builders. You just never know when Karma will get you. Because of that I always add a cross match where possible. One day if something goes wrong I can discount crossmatching as a problem.

 

Or can I? I once saw a good builder have a return tripper on a ball shell. Both ends were cross matched. The taking fire end did work and I could see it burning going upwards and back down. Its when the crossed matched end on a WASPed shell was jammed into the passfire tube the problem occurred. There was so much material jammed in the tube that a fireblock was actually created.

 

Then we have a guy that can work with time fuse that just astounds me with his method.

 

So I guess I'm on the fence on this because any manner can work so long as caveats for each system is not forgotten. Personally, as I've said, I would crossmatch when possible regardless of shell size or device.

[nater]

Merlin, a 16" shell during a public display for a municipality in the US would be a very rare sight.

 

Manufacture, transportation, storage, distance and cost are all difficult for such large shells. The ports will not ship 12" and larger shells any longer, so they must be domestic or from South America if they are not already in the States. The safe distance is a big problem too. Not many towns have a 1600' radius clear for a show AND the proper place for a crowd. The cost of a shell roughly doubles for each step up in size. For your town show budget, do you buy 1 10" shell or 2 8s?

 

 

For the OP, I cross match small shells too, or use spolettes. I am glad you prime the fuse as you do, that should certainly help prevent a dropped shell.

Edited May 20, 2015 by nater

[braddsn]

I have built in the neighborhood of 500 shells, like Wiley said. I cross matched my very first shell, then never again. I have never had a dud shell. I make my lift bag, make a small slit in it, then take a utility knife (with razor blade) and split the last 1/4" of timefuse in half, pry it open a bit, then immediately plunge it into the lift bag. The odds of it 'not' taking fire, would be the same odds as a grain of bp not igniting, because there is now direct contact between the bp inside the fuse, and the lift bp. But I will also say that if cross matching makes you feel better, then by all means I would do it. It doesn't take long, nor does it cost anything. For me, I wanted to cut that process out to save time when I am making a lot of shells. Knock on wood, so far 100% success!

[fredjr]

On large shells 12" & 16" I do use multiple time fuses but I do not crossmatch. And yes 16" do take a lot of time and chemicals (about 75lb finished weight). I have made 4 of them and all were shot at PGI conventions. The first in competition and the rest as part of BPG shows at PGI. The 2 in the attached pic were fired together as the final shot of BPG show at PGI in Iowa last summer.

[Merlin]

Those are truly enormous shells. I cant imagine the display. With that kind of investment multiple fuses makes a lot of sense!

[wyzard10]

I have just started making shells, started with 3 inch ones. The time fuse I have burns at 3.5 seconds per inch if I do not cross match the fuse will only be about 3/4ths of an inch long. If I don't cross match it will I have issues with the lift charge blowing the fuse thru?

[braddsn]

Wyzard, I am not entirely sure what you are asking. You will hot glue the timefuse in place, both on the inside and outside of the hemi. The lift will not blow the timefuse through the hemi whether you crossmatch or not. You will also have a passfire of some sort that will transfer fire from the timefuse to the center of the shell. Personally, I use a 1/4 inch paper tube and it slides neatly over the timefuse. I apply a liberal amount of glue around the base of it to seal it against the bottom of the inside of hemi. I then fill it with 3 strands of perc fuse. Transfers fire nicely. Hope this helps.

[Merlin]

braddsn,

If you place the passfire tube over the time fuse on the inside with the break charge in a bag secured to the passfire tube in the center of the shell with perc fuse strands inside the passfire tube I don't see how that end could be cross-matched. Instead of a "horizontal cross-match fuse thru the time fuse wouldnt it be the same as vertical"cross"matching? By "cross matching" I thought you pierced the time fuse on both ends and passed fast fuse thru the hole and tied in place. I have only been making shells for a year- this could explain why I dont get symmetrical bursts because in a 3 inch shell a 3/4" time fuse gives correct altitude for shell burst but does not reach the center of the shell with the bag tied over the cross matched 3/4" fuse the burst is closer to the bottom of the shell.

By perc fuse do you mean fast fuse?

Edited May 21, 2015 by Merlin

[nater]

You are right. Cross matching does imply either splitting the end of the fuse or piercing a hole through it. A strand of black match is passed through it and tied in place.

 

I don't everything wrong with priming the end with a BP / NC slurry. Slipping the primed fuse in a small tube with sticks of black match gives you some of the advantages of a spolette. The bundle of black match spits a lot of fire and the added length of the tube or spolette gives you anchor for spiking or pasting. Especially with small shells, having 3/4" of timing does not give you much room to build the shell up.

 

You can also make a pipette to pass fire from the short time fuse to the center of the shell. This is just a few turns of light Kraft wrapped around the end of the time fuse and filled with a few sticks of black match. The idea is to pass the fire to the center of the burst for even ignition.

Edited May 21, 2015 by nater

[Wiley]

I cross-match the fire-giving side of my fuses as normal, slicing the TF 1/2" down an inserting two sticks of BM so as to make a cross. I then tie the split ends back together with a clove hitch and an overhand. On the fire-receiving side, I do the same thing, but insert the BM parallel to the fuse, rather than perpendicular. On my small shells, 1/2" of timing is common, and it's no big deal with my methods. I made a shell with 3/8" of fuse on the first break, and that one needed to be inserted into a tube, but 1/2" is definitely long enough.

[braddsn]

What Nater essentially said at the end of his post is what I do. But instead of using kraft, I use a little .25 inch bottlerocket tube. I buy em in packs of 50. You need to pass fire to the center of the shell. Also I dont use a bag inside the shell. I line outside of both hemis with stars, then fill center with burst, then finally dust burst with amount of booster I want.

[Wiley]

Merlin, I'm guessing you're building ball shells, yes? In that case, you don't need to try to center the time fuse in the shell on 1.75", or even 3" shells. Heck, on my cylinder shells, the time fuse is as far from the center as it can get, and they break in near-perfect rings almost every time. Just somehow prime the inside of the fuse to get your burst going.

[FlaMtnBkr]

I have used a piece of the paper outer wrap from flat quickmatch as a "tube" to direct fire to the center of the shell. It's usually from the short piece I cut to harvest small diameter black match to cross match with. It is almost the perfect size to slide over 1/4" time fuse that has been cross matched. I then tie it to the fuse with a clove hitch to hold in place. I believe Lloyd S. showed that to me many years ago and something I still do.

 

I also like splitting the time fuse and then tying closed with a clove hitch. Piercing fuse has been known to smear the tar thru the hole causing a fire block and failure.

 

I have also done the split, slurry, dredge in BP granules to the ends of time fuse and don't remember ever having a failure. But I only do this on small shells where I'm trying to crank them out and a failure to pass fire wouldn't be potentially catastrophic.

I have used a piece of the paper outer wrap from flat quickmatch as a "tube" to direct fire to the center of the shell. It's usually from the short piece I cut to harvest small diameter black match to cross match with. It is almost the perfect size to slide over 1/4" time fuse that has been cross matched. I then tie it to the fuse with a clove hitch to hold in place. I believe Lloyd S. showed that to me many years ago and something I still do.

 

I also like splitting the time fuse and then tying closed with a clove hitch. Piercing fuse has been known to smear the tar thru the hole causing a fire block and failure.

 

I have also done the split, slurry, dredge in BP granules to the ends of time fuse and don't remember ever having a failure. But I only do this on small shells where I'm trying to crank them out and a failure to pass fire wouldn't be potentially catastrophic.

[wyzard10]

If I do not cross match the end of the time fuse would almost be flush with the end of the shell. Im using plastic hemi's and only have about 1/4 inch of fuse one the inside of the shell. I do use a paper tube around it to bring it to the center of the shell. I tried using quick match in the tube but found a bit of fine BP worked better. I think I will probably stick with cross match. Any ideas on a better way to split it than a paper knife? The fibers in the fuse tend to get shredded up when I cut them.