First 2" Canister "Style" Shell

[BlastFromThePast]

I got a lot done today. Made my first shell ever which is awesome, and I was amazed by how much work goes into making just one of these things. I also made my first mortar rack. I've posted pics of both below. I'm planning on setting this thing off tonight once I find a relatively uninhabited area via google earth hahaha. I'll make sure to get a video of it. I have a question though. My total shell weight is approximately 105g. I don't really know why I did this without referencing anything, but I put in 16g of lift on the bottom of the shell. Let me know what you think. Thanks!

 

edit- forgot to add what the effects are haha. I had some cut C8 stars, pumped D1 glitter 1/4" and some rolled stars that are about 3/8" dia which at D1 to C8 cores. Those last stars are pretty whack. They were the ones that ended up looking like raspberries and I definitely didn't make them big enough to have any real effect. They burn like a D1 for less than a second and then flare up to a flame for another second or too and then just smolder. I was using a toilet paper tube as my cylinder former and pretty much just packed it with everything I had, which obviously isn't much, but thats because I'm limited with the chems I have.

Edited April 25, 2013 by BlastFromThePast

[Bobosan]

Mortar racks are next on my many-pyro-things-to-do list. I'm no expert on rackmaking but think you should have some chipboard lower cross members at mortar bottom, both sides. Also, I've read where 3/4 plywood endplates are also advised.

 

Looking forward to the shell video.

[BlastFromThePast]

Yeah, I'm definitely not done with making the rack yet as I'm planning to add a piece of 1x6 across the bottom to cover it. Bobosan, I meant to mention you in my post but I forgot, so I want to say thank you for helping me out with making my mortar plugs. I definitely feel confidant that they're gonna work well, so again, thanks!

[nater]

Racks are easy to build. I have used dimensional lumber as well as plywood in the past. The racks we use on commercial shows are all dimensional lumber and withstand plenty of abuse. There are plenty of theories about safe rack design, especially concerning the materials used and the use of spacers. People can say what they want about a rack, but the truth is if there is flash in the shell, the rack will most likely be destroyed. Distance is your only key to keeping your spectators safe.

 

I would recommend a solid lumber rails and bottom from 2 X s. 1" solid lumber or 3/4" plywood works for the side rails on the top and bottom. I think a 1 x6 would be overkill on a small rack. The bottom rail only needs to be tall enough to prevent the mortars from bouncing out.

 

The base on your rack is probably okay for a 2" shell, but the bottom is best flush on the ground. With larger shells, the recoil from the lift can be significant. If the lift caused the mortar to punch through a poorly supported base, your could be a low break. Even with 2" thick bases, we have cracked them if they were angled or otherwise poorly supported. Just something to keep in mind when you make racks for larger shells.

 

http://www.amateurpyro.com/forums/uploads/1301329517/gallery_9966_86_47596.jpg

[BlastFromThePast]

The bottom rail only needs to be tall enough to prevent the mortars from bouncing out. .

 

http://www.amateurpy...66_86_47596.jpg

The thing is that the hole cutter I used to drill out the plugs had a 1/4" pilot bit in the center. Therefore, the plugs I drilled had a 1/4" hole in the middle. So when I glued the plugs together, two of them, with their grains at 90degrees, I used a bolt to bolt the two plugs together, but the bolt extended a good 2 inches beyond the bottom of the plugs. So the bottoms of the mortars are actually bolted to the base, and I used the two 1x1's one the bottom to allow for the bolt to protrude by 3/4" below the base plate. But yes, a 1x6 is overkill, however I don't have to worry about the bottoms jumping around in the first place.

 

What I'm really wanting to know before I do this is whether or not 16g of lift is too much for this shell, not enough, or just right.

Edited April 25, 2013 by BlastFromThePast

[psyco_1322]

Glad to see you are getting some shells built. The rack looks like a fine piece of work too.

 

I have rolled some stars that were Tiger Tail, changing to Win20 glitter. With that arrangement, it does make a nice effect, and the core doesn't need to be overly large. It's like a charcoal break, with little glittery/flashy tips.

[guntoteninfadel]

What I'm really wanting to know before I do this is whether or not 16g of lift is too much for this shell, not enough, or just right.

 

Assuming, and we all know what that means, it should be a great lift charge!

 

What I dont know is did you make it yourself, how hot is it, did you corn it, was it pressed? Is it commercial, 2fa, 2fg?

 

ten percent I believe is the rule of thumb, but if your like me my bp is batch sensitive. Some batches I can use a little less, some a lot more. I generally make bp at about 7lbs per batch and I am sure there is a way to make so-so bp better, i just have not gotten around to learning that and just adjust as necessary.

 

Looking forward to the video!

Edited April 25, 2013 by guntoteninfadel

[BlastFromThePast]

Guntoteninfadel, yes this is homemade BP, milled for about 5 hours and then pressed through a 7 mesh screen. (the only sized screen I had at the time). It burns fast but I'm not too worried. Didn't get a chance to set it off last night, so I'm going to go do it tonight but well see. The only problem I forsee is the timing. I made a 1/4" spoolette with about and inch of rammed BP. Never made a spoolette before so I don't know what this amount equates to in timing delay.

[Bobosan]

@ Blast - I use a wood dowel to fill the hole in center of the plugs. The dowel helps align the wood discs to each other during gluing and screwing and just cut it off flush when ready to mount to tube.

 

3" HDPE preplugged tubes are getting so cheap that became uneconomical to continue building the cardboard ones.

Edited April 25, 2013 by Bobosan

[BlastFromThePast]

Bobosan-Ahhh, I was wondering why yours had no obvious center hole from the pilot bit lol. I'll have to do that next time. The thing is, the plugs I made aren't very big at all, less than 2" dia. For your plugs I see that you filled the hole with a dowel and also had 3 drywall screws offset at 120 degree securing the plugs to one another. The ones I made were so small that I probably would have compromised the structural integrity of the plugs had I tried securing them together using screws, so I just used the bolt. And it worked out conveniently that like I said before, I had an extra inch and a half or two of the bolt coming out from the bottom of the plug, so i just bolted that to the base plate. It would be too hard to fix now but I will do it your way in the future as it would make it MUCH easier to change the mortars in the rack if need be instead of having to unscrew a nut But thanks for filling me in on how to deal with that hole in the middle, no pun intended hahahah

[Bobosan]

You wouldn't necessarily have to screw the discs together on a plug that small. A good wood glue and clamp should do it with the center dowel acting as a filler and alignment pin. The commercial plugs are solid wood and are usually stapled to the HDPE tube walls.

[BlastFromThePast]

Gotcha. Yeah I was into carpentry and such for years and I'll tell you, I know that when glue dries that it's pretty damn strong, however even when something ONLY called for glue, I would always use small finishing nails just so I could sleep at night. But yeah, I know the bolt is overkill and to some extent, the drywall screws are too, but I've never fired anything from a mortar with 16g of lift before so at least what I did is putting my mind at ease to some extent.

[BlastFromThePast]

Can someone please give me an idea on spolette sizing and burn rate/timing.I don't have access to time fuse or even visco at this point and i'm broke. All I have is white lightning fuse (like .5sec/ft), pink quick fuse (maybe 2 sec/ft), and crackling fuse (2 sec/in). None of these are good enough IMO to use as a timing for shells. So, I would be making 1/4" spolettes hand rammed. I know that there is a lot of variability involved, namely the quality of the BP and how much force is applied to compact the powder. But for those of you who make 1/4" spolettes, can you tell me what you have found as far as length of powder packed in relation to time delay. Any feedback is much appreciated as I'm planning on making a couple more shells today.

[nater]

*My* BP burns just under 3 seconds per inch when pressed into a spolette. It is very important that you test your spolettes to confirm their timing and consistency before you use them to ignite a shell.

 

https://www.youtube.com/watch?v=TlHINv9LG-w

[BlastFromThePast]

And I assume your using a press to compact it? You're right that I do need to test it, and I'm probably going to take that shell I made apart just to do some fine tuning tonight. However back to the topic, is there a sizable quantitative difference when hand ramming versus using an arbor press or equivalent?

[nater]

I do use a little arbor press to make the spolettes. I have not compared ramming one to pressing one. I can't do it tonight, but I might be able to make a few as a test soon.

[Mumbles]

I never noticed too big of a difference between ramming or pressing spolettes in terms of timing. They will be slightly different though, so it's not good to mix and match the two kinds if you're going for some synchronized event. It will probably burn for between 2.5 and 3 seconds per inch. That might be a little long for this size of shell. I'd probably go with 3/4" or so of a column of BP in a spolette for a shell this size.

 

I don't like HDPE mortars with stapled in end plugs. I make sure the ones I buy are screwed or bolted in. I've seen too many HDPE guns lose a plug due to staples bending or coming out of the plug. If I'm going to blow a plug out, I want to know it's because I exceeded the limits of the gun, not due to cheap materials. With screws or bolts, the plug literally rips itself out of the gun, leaving streaks where the bolts of screws tore down the wall.

[BlastFromThePast]

I don't like HDPE mortars with stapled in end plugs. I make sure the ones I buy are screwed or bolted in. I've seen too many HDPE guns lose a plug due to staples bending or coming out of the plug. If I'm going to blow a plug out, I want to know it's because I exceeded the limits of the gun, not due to cheap materials. With screws or bolts, the plug literally rips itself out of the gun, leaving streaks where the bolts of screws tore down the wall.

I'm assuming you're talking about really large shells here, with enough force to rip out the end plug, bolt and all.

 

Pertaining to the spolette, theoretically even if my 1" of BP does make for a 3 second delay, with 16g of lift, it's not as though my shell will start to be on the way down when the burst goes off. It's just that with this size shell, and thus smaller stars, a 3 sec delay might make the effect less noticeable due to ignition at a higher altitude, right?

[nater]

It does not take a large shell to blow out a plug. I had a consumer shell blow the plug and base of the mortar out which was not properly supported on the bottom. I have also seen small shells blow out plugs that weren't secured properly or had been exposed to the weather.

 

Assuming the shell survives a harder lift, it will not necessarily reach a greater height. There is a point where a shell can only go so fast and reach a given height, after that the excess lift is just burned off and wasted. I can't tell you what that point is, but it is wrong to assume that greater lift always equals greater height.

 

You are right about the effect being the best when viewed at a certain height, although I would be more concerned with the longer delay resulting in a break on the way down than breaking too high. With a single break shell, probably not a big deal. When you are timing a bottom shot, the correct timing is essential to prevent the bottom shot from breaking on the ground.

 

I am curious, did you use the toilet paper core as a former for the casing or as the casing itself? Is the shell spiked and pasted in? Any pictures of the construction?

[BlastFromThePast]

Yes I did use a toilet paper roll as the former for the 2" shell. The shell isnt spiked, but like I said, I do believe that it has enough tape, excess IMO that I'm pretty sure will keep it together during the inital force of lift. Admittedly, I definitely used way too much tape on the shell, and it was constructed using various aspects that I remember from Pyrotechnica XI, such as using a cannula, which is overkill for a 2" shell and such. I have no pictures of cunstruction sadly, but I'm hoping this thing will hold together and NOT flowerpot upon exiting the mortar. But there's no way of knowing until I set it off.

[dan999ification]

To get higher lifts you need a few things, longer gun to make use of the or more than usual bp, tighter shells ( if they survive ) or heavier shells.

A 100g shell fires from the same gun with the same bp as a 200g shell, the 200g shell will go higher, the reason is "terminal velocity"

The propulsion time in a longer gun will give the shell more muzzle velocity but once that slows

Or stops only the shells weight is keeping it going.

 

Dan.

[PyroCube]

If you have fast BP, 16g is too much.

I dont know how hot your BP is, but canister shells require less BP than same weight ball shells.

With my BP, I would get to a good height with 6-7g lift for a 100g canister shell.

But if you dont know your BP that well, I think its better to put too much in than too little.

 

Greets

[BlastFromThePast]

My BP is very hot. After taking into account what everyone has had to say, I think I'm gonna tear that shell apart and do it right, No reason to waste all the stars I put in it when I'm unsure of the lift amount, the fact that there is way to much burst for a 2" and it might blow blind and that I'm not sure how well/the timing of my crappy spolette. Better do it right and get good results than do it quick just to set it off faster. I watched 50AE's video tutorial last night on making 2' cylinder shells and I'm going to use that as my guide. I should have a properly completed 2" with the same effects by the end of the day, but we'll see

 

-Blast

[pyrokid]

I'd almost recommend that you just fire the shell and observe the results. You can learn a lot from a failure, and if it works properly then you know what works.

[BlastFromThePast]

I'd almost recommend that you just fire the shell and observe the results. You can learn a lot from a failure, and if it works properly then you know what works.

 

Yeah after I said the above I thought to myself what the hell, I'll try it anyway. I guess then that I'll make a second shell today properly and do a side by side comparison. Its perfect that my mortar rack has two 2"