1569 replies to this topic

[completebeginner]

The shell I just set off just exploded in the mortar I guess ill just again after I make some more bp. can rice puffs with bp be used as lift or is it going to demolish my mortar?

Edited by completebeginner, 25 December 2005 - 04:39 AM.

[karlfoxman]

The shell I just set off just exploded in the mortar I guess ill just again after I make some more bp. can rice puffs with bp be used as lift or is it going to demolish my mortar?

The problem would have been one of these 1. A leak around the time fuse 2. A weak shell 3. Too much lift. Ensure time fuses are very well sealed, i use string and pva on my paper shells and hot glue on plastic (this is the only time i use hot glue) and i always do it before the shell is loaded. The casing must be strong enough to take the massive pressure of lift, for a 3 inch shell i would use in the region of 7-10 layers of gummed kraft. This case myst be allowed to dry fully! When making lift its very useful to note down how much was used, after many tests you can make a table of shell weight/lift ammount. Also your lift must be constant, or as constant you can make it. Dont be put off by failure, it will make you a more experienced shell builder.

[adamw]

Hot glue on plastic? Does that work OK? I use xylene to melt the poly together and then strap with fibre re-enforced tape.

Oh and merry xmas! (Am I sad or what posting on xmas day morning). Just waiting for the turkey to finish cooking.

[karlfoxman]

Hot glue on plastic? Does that work OK? I use xylene to melt the poly together and then strap with fibre re-enforced tape.

Oh and merry xmas! (Am I sad or what posting on xmas day morning). Just waiting for the turkey to finish cooking.

No i close the shells with paint thinners, i seal the time fuse with hot glue. These spanish shells have a plastic tube ready for fuses, but the time fuse is smaller so i make a tube to build the diameter up then seal the small gap with hot glue.

Must mean im even sadder, i posted more

[adamw]

Right.. get ya. Me too with the time fuse. I thought you meant to seal the halves!

I had some plastic hemi's once that even had the delay spolette inserted.. but that was a bad idea if they were't well kept (moisture etc)

[karlfoxman]

Hey friends, i have just completed the 2nd break of my 2 break sun and planets shell. Its filled with tigertail 15mm stars (lots) nd burst with standard granulated bp. Remaining space is filled with rough powder. Its spiked with linnen twine 32 vert and 12 horizontal the twine is doubled up. The time fuse is 3.1 seconds the same as all the planet inserts. It weighs 920g! Its a bit of a beast, i will fire it i hope on new year or just after. The 1st break is still under construction. Will be complete soon.

Pic 1

Pic 2

Hope everyone had a good christmas!!

Edited by karlfoxman, 26 December 2005 - 09:05 PM.

[fishy1]

very neat tidy spiking.

[Karl]

Hey friends, i have just completed the 2nd break of my 2 break sun and planets shell. Its filled with tigertail 15mm stars (lots) nd burst with standard granulated bp. Remaining space is filled with rough powder. Its spiked with linnen twine 32 vert and 12 horizontal the twine is doubled up. The time fuse is 3.1 seconds the same as all the planet inserts. It weighs 920g! Its a bit of a beast, i will fire it i hope on new year or just after. The 1st break is still under construction. Will be complete soon.

Pic 1

Pic 2

Hope everyone had a good christmas!!

Deffinetley looks like abit of a beast, Karl! Hope it fires ok.

[karlfoxman]

Cheers lads, on the neat spiking reply any cylinder shell that is spiked perfectly will more than likely break the same as one that looks a tad messy. So long as you keep the little squares created fairly equal then its fine. Getting spiking perfect is a bit of a waste of time i feel. I will fill the planets up this week and load them into the 1st break. Any thoughts if the planets look good with dense breaks?

[fishy1]

Cheers lads, on the neat spiking reply any cylinder shell that is spiked perfectly will more than likely break the same as one that looks a tad messy. So long as you keep the little squares created fairly equal then its fine. Getting spiking perfect is a bit of a waste of time i feel. I will fill the planets up this week and load them into the 1st break. Any thoughts if the planets look good with dense breaks?

it might be a waste of time, but your spiking looks very nice.

[Darkstar]

QUOTE(karlfoxman @ Dec 25 2005, 12:44 PM)
No i close the shells with paint thinners, i seal the time fuse with hot glue. These spanish shells have a plastic tube ready for fuses, but the time fuse is smaller so i make a tube to build the diameter up then seal the small gap with hot glue.


There is much divided opinion when it comes to suitable glues for pyro applications, particularly when it comes to relatively modern adhesives such as hot glue and epoxy.

Some say that hot glue shouldn't be used on timefuse, as the heat will melt the bitumen layer causing it to seep into the powder core. Before making my first plastic cased shells, I tested this assumption by cutting two identical lengths of timefuse. I placed one length in a card former and pumped an entire stick worth of glue on top. Once cool, I test- fired the fuses. There was no difference in burn rate.

I've only used American hemis so far. These are moulded to take 1/4 inch timefuse and have a small well to accept glue. I've found that hot glue melts the polystyrene slightly forming a very good bond. Hot glue is certainly quicker than polystyrene cement, or shell fragments disolved in acetone/xylene for the purpose of time fuse placement.

For glueing the hemis together, I've used both shell fragments in acetone/xylene and Humbrol's Precision Poly. The needle applicator on Humbrol's product allows accurate dispensing.

[Kevin J]

I have a reguest to make, people usually post pictures of their shells before they launce them and often videos of them launching. I have slow internet so I rarely download the videos so could people please post pictures of their shells going off as well as the movies? I would apprectiat it a lot if you would.

[karlfoxman]

Hello you lot!

Well as you know i have been building the SUN AND PLANETS shell 2 break 5inch. In short the desired effect is a ring of small breaks around a large break. As many of you will know this type of shell is rather complicated to build due to all sorts of issues.

Over the past few weeks i have been building one, well tonight at around 5:30 we decided to end 2005 on a high note. And we did just that, you can wait till next year for the videos (we used 3 camera's)

I have a picture of the shell after it was complete HERE

I must take this point to thank Waz for a very enjoyable 2005, i have learned an awful lot this year and had great times. Many more to come, must also thank my camera lady and the ground crew for their assistace in launching the beast. Thankyou!!

Also must wish everyone on the forum a very happy new year, cheers to you Admins/Mods for making this forum a well kept and info packed friendly place.

HAPPY NEW YEAR - NOW LETS GET DRUNK

Edited by karlfoxman, 01 January 2006 - 04:29 PM.

[sizzle]

Indeed! (People who are firing wait till after your display )

[completebeginner]

so I finaly got my 3 inch shells working here is a 3 inch with my crap tts with 8 stars and bp coated rice puffs a tennis ball was used for the casing I would put the video on the net but cant find a good host