Metal mortars

[Pretty green flame]

Ok, since proper sized paper mortars for small cakes and stuff are almost impossible to find localy and if i do find them it is usually in small (too small) quantities, i was thinking of using aluminium tubing for a reloadable comet cake.

 

I know the dangers of shrapnel from metal tubing but would this be a possibility? I mean, quick, "cheap", easy to clean and long lasting.

 

How dangerous would it be to fire comets (solid and with cavitiy, no crosettes or anything with exploding properties for that matter), the comets would have 1/8 clearance so they are not tight fitting.

 

Just looking for some safety advice.

 

Thanks

[pyrochris]

Ok, since proper sized paper mortars for small cakes and stuff are almost impossible to find localy and if i do find them it is usually in small (too small) quantities, i was thinking of using aluminium tubing for a reloadable comet cake.

 

I know the dangers of shrapnel from metal tubing but would this be a possibility? I mean, quick, "cheap", easy to clean and long lasting.

 

How dangerous would it be to fire comets (solid and with cavitiy, no crosettes or anything with exploding properties for that matter), the comets would have 1/8 clearance so they are not tight fitting.

 

Just looking for some safety advice.

 

Thanks

well, pyrocreations has 36" tubing for sale that they sell 5 36" long tubes that you could cut down to size, and you get the items within 2-3 days! I see no problem with comets because they use metal tubing as comet testers, i would advise against using it for cakes though.

[Pretty green flame]

Yes, i know pyrocreations sells 36" tubing but those will wear out eventually and wet grass from where i fire from will severly effect their life time. I'm looking for a long term solution.

 

Why do you think it would be unwise to use them in cakes?

[weknowpyro]

Personally i have read about metal mortars before in books and i think if the size is small they are ok.Because if you get a tube that has a visible thread I.e. you can see were it was wheiled together then it should be ok.

The logic behind this being if you have a metal tube with no thread if it blows it will shatter and send shrapnel, but with the threaded one if it blows it will only blow out on its thread and this means you can point it away from you.

 

But like everything there can always be a risk.

[joe609]

To be honest unless you are launching really heavy stuff and putting enourmous strain on the tube it should be ok, like weknowpyro said if it has a seam runnig along the side then in the unlikely case it did burst it would blow along the seam and shouldnt turn to shrapnel also i think it would blow a comet to pieces in the tube before the tube actually gave way itself.

All said and done though it's up to you to judge what is safe and whats not.

[BigBang]

If you must use metal mortars:

 

Use seamless tubing. Most tubes have a seam, and it is very weak, which could lead to a rupture.

 

Aluminum tubing is preffered over steel because, in most cases, it won't frag. If you can, get 6061 T6 tubing, it is what is used in HPR casings, and should fit the bill.

 

Steel tubing is acceptable, but it MUST be burried if you plan on being near the mortar. Steel will frag if it ruptures, and this is bad.

 

You should be fine if you use metal tubing, just use common sense.

[weknowpyro]

But surely without a seem thats asking for pieces of metal to fly off in any direction. Yes a seem makes it weaker but atleast if it blows it would be better to know which way it would send shrapenl instead of any old direction.

[itwasntme]

This is kind of related, but do you think that it would be safe to use CPVC tubings for sugar rockets? I used it a few times and worked greatly. The reason I ask this is because they are cheap strong and I saw it on an E-book liked from here. Thanks

[Mumbles]

I personally wouldn't use it, but in all reality, there are worse ideas. Of all the metal tube explosions I've seen, about 70% were just the bottom of the tube blowing off. All the others were just a split down the side and some defomation. Short of the bottom blowing off, I've never personally seen any fragments. All of them were of course properly burried so that may have helped. If you do use this for comets and such. I would definatly bury it, or put it in a box and place it in the ground.

 

My personal preference would actually be with steel, but for something as small as comets, Al should be ok. PVC would be another option. I will use PVC sometimes for things 1" and under.

[rocket]

How about a 4-5mm walled steel tube for a 2” shell. I feel it would be safer than using PVC, and it would be well in the ground. I’m not willing to take risks with this sort of thing.

Buy the way I would use HDPE if I had some its just that I already have steel tube.

[Pretty green flame]

Cheers, i'll check out T6 6061 aluminium tubing, 6061 is aircraft aluminium right?

[Rocket007]

i have also a qestion. i will make a 4" shell. for the mortar i will use a

tub (thin wall) only so that i can wind round paper and a lot of glue and wet past i will use. the wall will be then 5-10mm.

 

 

what do you think??'

[Pretty green flame]

i have also a qestion. i will make a 4" shell. for the mortar i will use a

tub (thin wall) only so that i can wind round paper and a lot of glue and wet past i will use. the wall will be then 5-10mm.

 

 

what do you think??'

I wouldn't feel comfortable using home made tubes for shells of that size.

 

I suggest that you go to a shop where they sell fabric and stuff, they have tubes ranging from 2" to 4" usually.

 

Ok, prevod

 

Pejt pogledat v kkšno trgovino kt so merkur al pa bauhaus pa mal vpraši če majo kkšne cevi k so gor naviti kkšni tepihi al pa blago, js uporabljam te cevi pa so super .

 

Lp, Jaka

[BigBang]

It is infact aircraft aluminium. I spose steel would be a better choice due to 6061 beign a pretty penny.

 

Just bury all of these mortars and you'll be fine. PVC will work, metal, cardboard, as long as it is set up in the proper fashion.

[TheSidewinder]

I'd suggest dropping the idea of using metal mortars COMPLETELY. Way too dangerous. Keep in mind that they use steel mortars professionally for large salutes, and they still blow up occasionally.

 

Was anyone else at the PGI when that huge (12? 16?) shell detted in the tube?

 

Sand made it all the way to the Public crowd at the West end of the grandstand and VERY lightly showered some people, although only "people in the know", knew what it was from. A relatively small piece of mortar shrapnel was later found embedded in a building of some sort BEHIND the grandstand. Given that this was the PGI, AND we were the required distance away, it's sobering.

 

Think of what could have happened, even there. And then consider that most of us routinely violate the distance rules when shooting our goodies for friends and neighbors. I damn sure wouldn't use metal mortars for anything that didn't require it, and even then would be uneasy doing so even if distances were strictly observed....

 

Consider the "what if's?".....

WHAT IF, your shell malfunctions and dets?

WHAT IF, the tube ruptures during that det?

WHAT IF, someone is injured or, god forbid, killed.

 

It isn't worth it. Forgive me for being an old fuddy-duddy, but I don't want to see anyone get hurt.

 

M

[weknowpyro]

That puts quite a new light onto the matter completly. I wonder how much it takes for a pipe to blow i mean i personally use a 3/4" steel pipe with a dowel cap fitted to shoot off tiny shells that only use bp as break would the small amounts of bp blow open the tube still?

 

I Know that after prolonged use the barrel wears down, buts still i would like to know. Although i have had one shell go off prematurly inside this mortar and it just gave a mine effect but that was propbably cause its new.

But anyway give your point of view.

[h0lx]

People, please don't use the word "detonate" with low explosives, thank you.

[Pretty green flame]

@The sidewinder

 

I'm guessing that your response was aimed against rocket's question about using a steel tube for a 2" shell which is really not of my concern.

 

Do you feel the same with launching comets from metal mortars?

[TheSidewinder]

People, please don't use the word "detonate" with low explosives, thank you.

This is a pyrotechnics thread, and "detonate" is the term that is used, albeit technically incorrect, in the industry. An in-tube EXPLOSION of a salute might actually BE a detonation, btw, since flash CAN detonate (as defined by the feds, again perhaps incorrectly).

 

Pure comets should be ok in a steel tube, but there *IS* a lift charge involved, and therefore *IS* a danger of a tube rupture. Low danger perhaps, but re-read my "What if's". Are you willing to take the chance? Personally, I'm not, unless at an approved shoot site, with bunkered mortars and blast shields, and for accepted devices (usually just salutes).

 

Same goes for weknowpyro's question. Very low risk in that case, but it's still there.

 

This is a matter of personal opinion when we're talking about accepted uses for steel mortars vs. "experimental" uses. I use the term experimental for want of a better term, but I think you see what I mean?

 

M

[optimus]

I heard of an incident where a battery of large-bore candles was contained within a steel tube at a pro display. Something went wrong with the candles, and the tube shattered. Can't remember if there were any casualties, but a whole load of schrapnel would've been hurled at the spectators. If the candles had been contained within a paper tube, the malfunction would've caused a load of paper confetti, but the potentially fatal schrapnel...

 

I wouldn't feel comfortable using metal mortars, unless they were barricaded, buried, and a long long way away from me.

[moonshot]

On the 06 4th of July shoot that I helped set up we used steel tubes to launch 4" round shells but the tubes were buried in sand. The multishot 2.5 and 3" cake boxes were all paper tube construction. I would seriously not consider aluminum tube unless it were very heavy walled. It seems the latest tech is fiberglass tubes but if your building a multishot cake I would stick to paper tubes. It must take a lot of time to roll the tubes but thats why the Chinese use tube rolling machines and build their devices in factories.