What I dont understand about shell halves and pasting...

[usapyro]

Is how your supposed to get an even break with that circular seam around the entire shell. Sure, if you paste in a zillion layers or use a stinger you get an okay break... But there is a giant circular weak spot in the shell.

 

I have recently gone through the effort of using expoxy around the seams of my shells... You can get a decent break with only a few layers of pasting with a boosted shell using 5 minute epoxy to glue the seam. I also extra reinforce the seam area before pasting. After analysis of the shells still shows they break in the seam area first... But not easily!!!

 

If only I had a type of glue that is real strong and absorbs into the cardboard a bit... Hmmm... Maybe I could pre-treat the cardboard in the seam area with some kind of hardener beforehand then expoxy it...

 

For ease of construction... I use tissue paper on the outside of both halves so that black powder doesn't leak into the glue when I'm holding the seam slightly open for gluing.

[Potassiumchlorate]

I paste one layer around the seam only for each layer that I paste around the whole shell. I also use H3 as the break charge, which gives very powerful bursts.

[usapyro]

That sounds like a good solution, but wouldn't it be better to just find a way to simply and completely remove the weakness at the seam?

 

Treating a quarter inch of the shell halves with some kind of wood hardener before epoxy might be a perfect solution! Heck, why not treat the entire shell so you only need to paste a few layers for a strong break! Haha... Gonna go pick up a pint of Minwax wood hardener and see what the results are...

 

I paste one layer around the seam only for each layer that I paste around the whole shell. I also use H3 as the break charge, which gives very powerful bursts.

Edited October 24, 2012 by usapyro

[superspike23]

I use 3 g of flash powder to make a good break

it compensates for poor welding of the shell

 

KClO4 5

magnesium 5

 

This gives a strong break

 

look at my video of the flash powder:

4g not confined

 

http://youtu.be/45sO5mp1sHQ

Edited October 24, 2012 by superspike23

[usapyro]

I prefer doing minimal boosting. The stars are ignited better and easyier with a high pressure BP driven burst instead of using a fast flash boost.

[Potassiumchlorate]

That sounds like a good solution, but wouldn't it be better to just find a way to simply and completely remove the weakness at the seam?

 

Treating a quarter inch of the shell halves with some kind of wood hardener before epoxy might be a perfect solution! Heck, why not treat the entire shell so you only need to paste a few layers for a strong break! Haha... Gonna go pick up a pint of Minwax wood hardener and see what the results are...

 

There are plastic shells, of course. There you only use xylene or similar, and the plastic "melts" together.

 

Also: a hard break like with H3 shatters the shell so thorougly that it really doesn't seem to matter that it's weaker at the seam.

[Potassiumchlorate]

I prefer doing minimal boosting. The stars are ignited better and easyier with a high pressure BP driven burst instead of using a fast flash boost.

 

I prefer H3 for my own part. 75% potassium chlorate, 23% "hot" charcoal and 2% SGRS. Very powerful and cheap at the same time. Priming the stars with pinball prime +5% silicon will guarantee that the stars ignite anyway.

[usapyro]

I use to use a lot of H3, but my black powder is much better and faster than my H3 nowadays.

 

I should probably get some more rice hulls and not use large rice crispies in my 4" shells...

[Col]

The equatorial seam isnt that much weaker with 1/16" wall newspaper hemi`s.

[bob]

I agree with col Edited October 24, 2012 by bob

[laserkoi]

has any one tryed the "4 part paper/cardboard hemisphers " it should help as then your seem are spred on all sides at right angles .

[AirCowPeacock]

Those seem brilliant! Less shell volume per morter diameter, but a small price to pay

[Algenco]

has any one tryed the "4 part paper/cardboard hemisphers " it should help as then your seem are spred on all sides at right angles .

 

am I missing somrthing? Those look like standard strawboad hemis too me.

I use a wrap of 1/2" strapping tape around the seam

[Col]

If you take the hemi strength out of the equation, the break rests with the pasting job. I dont know what a 4-part 3" hemi weighs but its prolly more than 8g and thats with the passfire and masking tape The big plus with newspaper hemi`s is they cost almost nothing.

[usapyro]

They are four part hemi's. A smaller hemi inside a larger one... OMFG... I WANT I WANT I WANT!!!

 

Where did you find those laserkoi?

 

am I missing somrthing? Those look like standard strawboad hemis too me.

I use a wrap of 1/2" strapping tape around the seam

[Mumbles]

They're called nesting sets or nesting hemis. The only place off hand that I know of who carry them is Precocious Pyro. They're pretty nifty, but you pay for them. They really only need a couple of layers of paper over the top to ensure they're fireproofed. One guy told me he only uses 3 layers on an 8" shell with this type. I've only used them once in the 3" size. I think we only put 1 layer of gummed tape over the surface to seal it up. The interior set had a layer of masking tape put around the hemi. It was then slathered in white glue, and the second set was pressed on with the hemis 90 degrees off set from the first set. Then a layer of gummed tape was added, and they were fired probably 10hr later. I doubt if they had enough time for all the glue inside to dry. With H3 on rice hulls they broke pretty well I thought.

 

If I ever make a hemi mold or something, I'd want to make a second set to make nesting hemis. Alternatively you can also always make 2 shells from each set if you don't want to double them up.

[Algenco]

ok, that make sense, I had heard of them but not seen.

I don't know if they would be worth the price.

A good paste job will do fine

[FREAKYDUTCHMEN]

Why not just using a bit of flash powder to give your shell a nice break?

[usapyro]

Some of us like breaks that are not so hard, but are symmetrical.

 

You can't get a perfect break from a boosted shell... If you boost it enough to get a perfect break you end up blowing up stars in my experience! Well... Not with colored comps, but with glitters you often do.

[Mumbles]

I'd suggest getting more experience then.

[usapyro]

I don't think you understand the limitations I am talking about in the topic post.

 

I need a symmetrical burst out of a standard two piece brown paper shell. The shell must only have ONE layer of paper tape to seal and ONE layer of pasting.

 

 

The only way I have been able to achive a decent symmetrical burst without boost is to use epoxy to seal the shells well around the seam. One layer of tape. Two layers of pasting. I refuse to do more than that.

 

It's still not perfect though.

 

 

I hate pasting and I simply refuse to past more than one layer of paper tape on a shell from now on. If those four hemisphere shells become more available at other suppliers that will be awesome! Those will be the godsend for those that hate pasting. The other choice is to buy a wasp. That will still need the shell to be expoxied around the seam to get a solidly symmetrical strength even then.

 

 

Finishing and pasting a shell good enough for a symmetrical break should take as much time as loading it with stars or less... Otherwise it's just not practical!!!

 

 

I'd suggest getting more experience then.

Edited October 25, 2012 by usapyro

[Mumbles]

Well, good luck in your quest for inferior shortcuts to satisfy your laziness.

[usapyro]

I don't think there is anyone who has enough free time to spend a couple hours pasting 12 layers onto a shell for a perfect break...

 

I am not even sure how someone could handle that without going insane. I mean just look around. Pretty much everyone who makes many shells has gone to stingers because pasting is simply too impractical to be used.

 

Edit: I mean wasps... And variants of wasp type pasting machines. But, even with those pasting machines... That circular seam in the hemispheres is a weak spot that has an effect unless it's dealt with!

 

 

Hobbies are not supposed to be work, they are supposed to be FUN!

 

 

Well, good luck in your quest for inferior shortcuts to satisfy your laziness.

Edited October 25, 2012 by usapyro

[Potassiumchlorate]

I also hate pasting, and I'm slow at it too, but I don't think there are any shortcuts but using plastic shells.

[Seymour]

Some of us like breaks that are not so hard, but are symmetrical.

 

You can't get a perfect break from a boosted shell... If you boost it enough to get a perfect break you end up blowing up stars in my experience! Well... Not with colored comps, but with glitters you often do.

 

I would agree to a point that you cannot get a perfect break with a boosted burst, but only to the point that I agree a perfect burst is an ideal and thus impossible. You can get very close to perfect with boosted and unboosted shells with a multitude of methods for each.

 

Your blind stars problem is not due to the booster, but, from my perspective, from deficiencies in those particular stars.

 

If you boost with a reasonable, but heavy quantity of good flash (70/30 with Dark flake), say, two and a half grams per inch of shell, you will not have stars smash unless they are insufficiently bound. You will not have them blow blind because they did not have time to light if they are primed, and if they subsequently went out because they were going too fast, they needed more prime, or some kind of charcoal layer to give a frction of a second delay.

 

All that applies to hard breaks in general, be it a flash boosted BP burst 4", a KP burst 6" or a BP burst 16". It is from this perspective that stars should be able to handle hard breaks that I say this.

 

Flash boosting is often portreyed as having a lot of problems that quite franky amazes me, and to am extent amuses me. I can only assume that people having had problems with early experiments, having read these things, decide that since the generalisation covers their experience, then it, and perhaps, by extension all the others are true.

 

Such generalisations; 'you cannot get a symmetrical break with boosting', 'flash will cause a bright flash of light when the shell bursts', 'flash makes the shell burst too loud' 'flash smashes the stars' and so on, are all reflective of realities that flash CAN bring, but you can avoid and minimise them.

 

I don't think there is anyone who has enough free time to spend a couple hours pasting 12 layers onto a shell for a perfect break...

 

I am not even sure how someone could handle that without going insane. I mean just look around. Pretty much everyone who makes many shells has gone to stingers because pasting is simply too impractical to be used.

 

Well, we all have the spare time, it's just a matter of how we want to spend it. You obviously don't want to. I get really Obsessive when I make a huge shell like that and really don't mind pasting it at all.

 

I would like sto dispute that it takes hours to paste one to get an excellent burst, though admit that with all the messing around to try to make it look pretty it might. However if you want to slap it together a bit ugly pre firing but functionally sound Its going to take half the time. Split the pasting in to several sessions and you can be looking at four or five 15 minute blocks. Considering all the time spent on stars, burst, inserts and so on, I think that is quite reasonable.

 

I agree that it shoulds be fun, and am fully aware that I have my own preferences that won't match everyone elses, and that pasting is a bottle neck in the process. Although I'm disagreeing with you a bit in this post, Overall I understand your desire to find efficiencies, and wish you the best of luck.

 

I do wonder though... screening powders, pasting, all methods of star making, rolling tubes, and a lot of the processes we do, are really quite boring when you think about it. I get past this because I'm obsessed and feel like I have an intimate connection with my mixes and devices. Essentially, this hobby is a lot of work, which I find fun, but if you don't find work fun... what do you?