Shell and mortar sizes

[jukka]

Hi!

 

I have been playing and learning with cylinder shell for a year as on those I can use what ever size formers I would like to. Just put my lathe rolling and do my magic.

Or just shoot plastic ball shell, no problem on those neither (well 3" does have only 1mm spare room:)) but..

 

My problem is to harvest mortars that have correct sizes to fit the paper ball shells.

Now I have paper shell covers that should be for 2", 2,5" and 3" shells.

They have OD 2"=1,81", 2,5"=2,28" and 3"=2,8"

 

And my mortars IDs are 73mm (2,87"), 62mm (2,44") and 51mm (2,01")

 

The paper shell have exactly same OD than plastic shells (why?) and I havent have any problems to shoot those from my mortars.

But here lays my problem, if I start to use paper ones with all the pasting + QM or even add the cover for whole finalized shell in kraft paper, I'm quite sure they wont fit in my pipes.

 

I haven't found information on what are the exact IDs for mortars on these 3 different shell sizes (2",2,5" and 3"). On cylinder shell in F.A.S.T is told that use formers that are 1/2" smaller than the shell (3" => 2,5" etc.) but how this should be on paper ball shells?

 

 

So..

 

I would appreciate a lot if some1 could measure or tell me those IDs.

For purchasing mortars (HPED pipes with sufficient pressure class) that are at least near the correct sizes, would some1 know the final sizes of paper shell in these 3 different size groups?

Edited September 16, 2010 by jukka

[Arthur]

Many HDPE tubes are specified by outside diameter, mortars need to be specified by bore. Get some proper firework mortars.

[jukka]

Many HDPE tubes are specified by outside diameter, mortars need to be specified by bore. Get some proper firework mortars.

 

If I would have massive bank account, I surely would and much more . But for now, I would like to see if my pipe shop would sell close enough (couple millimeters wont hurt) ID pipes for this purpose.

 

BTW, getting 20 2,5" mortars to EU that are made form glass fiber (e.g. from http://www.pyro-stuff.com) + shipping would cost me 220€ = 286 US$.

With that money I could get 60meters of straight HDPE pipes and with length of 60cm each, that makes near 100 mortars.

Edited September 16, 2010 by jukka

[NightHawkInLight]

It sounds like you need to build one of each of your shells with just the amount of pasting you like on them (and write down how many layers you used). Once dried, see which of your guns will be needed to fire them. If you don't have a good fit, use a caliper on them to get the measurements and head to the hardware store with a measuring tape to find the pipe you need. Buy your guns about 4-6mm larger than your shells after pasting.

 

By the way, your plastic shells will do better to be pasted also.

[jukka]

It sounds like you need to build one of each of your shells with just the amount of pasting you like on them (and write down how many layers you used). Once dried, see which of your guns will be needed to fire them. If you don't have a good fit, use a caliper on them to get the measurements and head to the hardware store with a measuring tape to find the pipe you need. Buy your guns about 4-6mm larger than your shells after pasting.

 

By the way, your plastic shells will do better to be pasted also.

 

Yeah, I guess that would be the best way to proceed. At least I would end up on correct values.

 

This still doesn't kill my interest on this topic. As I haven't found any information on the exact IDs of commercial mortars for any sizes.

Would any of You have this kind of information? They cant be just 3", 2,5" and 2" as the commercial hemispheres are just around 0.2" smaller than those mortars (3" => 2.8"). Wheres the room for pasting etc? If they are, I have understood something totally wrong, but thats nothing new..

 

 

I would love to go and measure those by myself than bother you guys on this kind of trivia questions, but sadly thats just not possible in my country.

Edited September 17, 2010 by jukka

[jukka]

Found it!

 

3" mortar actual ID is 3.05" so they are little over sized. Now it makes sense to me.

I'm still going to use NightHawkInLight recommendation just to be on the safe side.

 

Thank You!