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Rolling Bottom Shots


AirCowPeacock

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I have been having trouble rolling spiral wound bottom shots of the right size. I rolled two side by side the other day, one turned out too large and one too small; not by much, and I will still be using them. However, for a different shell I made another bottom shot, it turned out and 8th inch too large, which would make for a tight fit, and was ovoid, which mades for a weird shell, especially a multibreak shell (which it's for.) I think that variation I'm experiencing is due to the amound of wheat paste applied. I'm using 30 lb recylcled kraft. Do you have any advise on making better spiral cases for bottom shots?
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Roll the cases convolute (sp?) out of folded newsprint or chipboard per the instructions in Pyrotechnica XI.

 

There is a picture tutorial on both Passfire and Fireworking.com describing the process. It is easier than trying to roll spiral tubes and allows you to make any size of bottom shot you want,

Edited by nater
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I have not seen that video, but the diagrams in Pyrotechnica were much more clear to me after I saw photographs.

 

The idea is simple, you fold long strips of chipboard or newsprint so that their width is the height you want the bottom shot to be. You then roll a flash bag out of kraft a few turns around a former and roll the strips of folded newsprint around the flash bag until it is the OD you want. The OD is sized so that when the report is spiked and pasted, it is used to roll the casing for the last break.

 

I have left ALOT out in hopes you will turn to the real experts, texts, or video.

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Roll the cases convolute (sp?) out of folded newsprint or chipboard per the instructions in Pyrotechnica XI.

 

There is a picture tutorial on both Passfire and Fireworking.com describing the process. It is easier than trying to roll spiral tubes and allows you to make any size of bottom shot you want,

 

Sorry, I ment the process in pyrotechnica XI, I became confused. I've that process, except using 30lb kraft. Perhaps that itself is my mistake. For clarificicarion, I am not getting a lump in the side, I am getting an oval symetrical on x and y axis (if aligned with the oval.)

 

I think I didn't fully understand the description in pyrotechnica XI... I'm goinf to read it again.

Edited by AirCowPeacock
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When is it getting out of round? When the shot is spiked, the tension should even out any irregularities. Are your end discs round?
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It actually seemed to loose roundness after that pastewrap dried, but that have only been because I didn't realize it until I tried to roll my case with it. I'm going to use it as a lone salute, and try again later today. I didn't realize I was supossed to use several strips of folded newsprint to zone in on the exact size, and I didn't realize I wasn't suposed to paste the folded paper. I spike right before the paste wrap and after I pleat the case down. My discs are round.
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I don't paste the folded paper itself. Just a dab of paste on the end after it is rolled on the former so it does not unwind. But yes, use as many strips as necessary so it ends up the same size as your discs. It was recently suggested to me to roll the core slightly larger than the disc, because it will compress when you spike it.

 

If it is getting loose after the paste wrap dries, I wonder if you misjudged the grain direction. The paper should shrink up as it dries, making a nice and tight finish. I have a hard time pasting with recycled kraft, the grain is hard to judge and it falls apart or tears too easily when wet. It can work though, the nicest looking handpasted shell I have seen used recycled Kraft.

 

I took a bunch of pictures while making a dummy one recently. I will try to post a few when I get home on Saturday. I was trying to get exact notes on everything I need to make a 3" color and report shell.

Edited by nater
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I actually got a copy of Don's video before the pictorial was posted on passfire. I will agree that the passfire pictorial is extremely useful. I still feel that Don's video is a worthwhile purchase however. He discusses some trouble shooting and tips as he goes, as well as some special techniques for bottom shots for bigger shells.

 

By far the biggest jump in understanding and getting these to work right for me was the idea that you could use both chipboard and newspaper. This is what Don does, and what the passfire images show. Pyrotechnica make it sound like an either/or proposition. I had trouble getting chipboard to lay down straight and tight, and I couldn't ever get what I felt was a tight enough roll with newspaper. Combined though, they work like a champ.

 

I surprised an older gentleman at PGI a few years ago. I was looking through Tom Miller's supplies that he was trying to sell. This gentleman came up to me as I was looking through some things and pointed at something, and said "I bet you don't know what that is". It was very clearly a "book" as it's called for making hand rolled bottomshots. I think I probably took a little of the fun out of it for him, as I suspect he was planning on filling me in on this somewhat lost craft. In retrospect, I should have tried to find him and have a beer at the afterglow. Anyone who gets that excited about hand rolled bottomshots is almost certainly worth getting to know.

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That's too bad Mum. I'll post again in the morning (started early, it's my friend's birthday). But after some clarification from M. Swisher, once you go beyond 3" shells, chipboard should always be used in your "book".

 

 

WB

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I tried again with folded newsprint (several times.) No good, always crooked, and not the perfect size. It does get crooked after rolling the folded newsprint, not after spiking or pasting. I just used chipboard, it worked much better and faster. Its now spiked pasted and dried. I'll be filling my shell with it tonight. Its practicly perfect, only about 1/32" to large.
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What size bottom shot are you making? What size former? It sounds like you may not be rolling it up tight enough.

 

To make a "book" fold a "shingle pile" of chipboard strips into the newsprint. The white part at the top of the photo is the chipboard.

 

BS book

 

 

Part of the beauty of hand rolled bottom shots is that you can roll them to any diameter you want. This is very easily changed by varying the number of "books" used or the amount/length of chipboard in the books.

 

 

WB

Edited by WonderBoy
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Only 1.5" now (for 2" shell.) I want to perfect it before I move up to 2.5" (for 3" shell.) Ya figure the concept is broken in such a small example?
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I still feel that Don's video is a worthwhile purchase however.

 

I second that it´s a great video, but I felt he unfortunately very quickly slides over one of the most essential parts of the whole process: making the "book". It´s explained so quickly I did not get how he "stacks" (or feathers) the chipboard strips after preparing them. I may be missing the passfire pictures though. Anyone willing to explain to me?

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I cut strips of thin chipboard that lines small cases of cat food 1.25" x 5". The dimensions really do not seem to be critical. Whatever width you cut these strips, will be the height of the bottom shot. The chipboard is 5" wide and my ruler is 1.25" wide, which just happens to work well for a report intended for a 3" shell.

 

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Crease a square of newspaper on a diagonal and open it back up. Lay out the strips along the crease. I overlap them by half, so I get 2 layers of this thin chipboard along the length of the crease in the paper.

 

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Fold the paper over the chipboard making a triangle. Make sure the chipboard strips lay flat and roll up the paper. Rolling / folding the newsprint like this helps even out irregularities in the chipboard strips and helps keep them in place.

 

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Once it is folded up, secure the newsprint with a piece of tape. Make as many of these as you need to roll up your cases.

 

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Stay tuned...

Edited by nater
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I've made single fire reports to be fired out of a class C sized mortar. I assure you the techniques remain the same for casings that small. Mine were 1 3/8" ID x 1 3/4" OD, and worked fine.
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Cut a rectangle of 30 lb kraft that is as wide as your newsprint strips + about 2/3. This will be the inner flash bag of the report and needs to be as tall as you want the bottom shot, plus enough paper to fold each end shut. It needs to be long enough to make the appropriate number of turns around the former as if you were rolling the case for a shell. ( 2 turns for 2" former, 3 turns for 3" and so on). In my case, the strips are 11.5" x 4.5". Roll dry around your former, tape shut. Close one end with a triangle fold and pierce a hole in the center of the closed end with a sharp awl.

 

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Next, roll the prepared strips of newsprint / chipboard around the inner bag on the former until it is built up to the diameter you are shooting for. Again, secure the strips with a dab of paste or a piece of tape so it does not unroll. Dry roll some 60 lb kraft around the newsprint core just like you would roll a shell casing. This will be the outside of the bottom shot. Place a fused end disc on top of the newsprint core with the fuse or spollette inserted in the hole you pierced in the inner bag. Secure the end disc by folding the edges of the outside case, just like making a standard break. You can use a rawhide mallet and tap the folds shut so it lays down flat.

 

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Remove the casing from the former. Fill with your report composition just a hair under the height of the news paper strips. Fold the inner bag closed with a triangle fold. Fill any voids with sawdust, so that a solid disc will lay flat. Place the disc on top and fold the outer casing as you would any other break.

 

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Another end disc with a hole and a solid one are placed on each end and the bottom shot is spiked and pasted in the same manner as a color break for its given size. Take extra care to fully seal the spollette with a "crown" of pasted paper. You don't want the report to break prematurely. One dried, the bottom shot is used as a former for the final color break in the shell. I don't have pictures of these steps yet, but I will get some as I work more on color and report shells this Spring.

 

I cannot take any credit for the steps I showed. They are outlined in Pyrotechnica XI and similar pictures have been posted by other users on various forums. I am very much still learning these techniques, and took these pictures for my use so I can make consistent shells. Because this was built and photos taken indoors, no live material was used. (Notice the salt used as report comp).

 

One thing to consider is the final size of the shell. You want to make sure you don't built it up too much so it won't fit in your mortar. Remember the bottom shot is serving as the former for the shell. You might be able to use the same discs for the bottom shot and color break on a 3" shell, but on larger ones you will want to use slightly smaller discs so the OD of the COMPLETED bottom shot matches the standard OD of a former for whatever size of shell you are making.

 

Pyrotechnica XI has a nice table with the former and end disc sizes to make the bottom shot the right size. For anyone interested in building cylinder shells, this text is a must have. PAY FOR IT and support the authors who provided this information to us in the first place.

Edited by nater
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Thank you very much for the detailed description. I proudly own the Pyrotechnica series and will give the suggested volume another close look. The thing I had no clue about so far is how much to overlap the strips of chipboard when making the book.
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Thank you very much for the detailed description. I proudly own the Pyrotechnica series and will give the suggested volume another close look. The thing I had no clue about so far is how much to overlap the strips of chipboard when making the book.

 

You're welcome, and I think the answer to that question is also subjective. The goal is simply to build up the walls of the core to the OD you want and give enough containment to the report. Overlap the book more than what I do and you end up with thicker strips. These will build up the core quicker, but maybe too much. My best suggestion will be trial and error, which is the phase I am in right now.

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This is great Nater, thanks for posting it! Aaron's pictorial on passfire is very similar but it's nice to see a slightly different variation, as well as being on a forum that doesn't require membership to view the content. I've recently started doing sort of the same thing...experimenting with hand rolled "reports" without live comps. When I think I have it down I plan to post pictures of my own, more for feedback than anything else.
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Thanks, yes the pictures are similar to the ones posted. I am working on another idea that I hope will allow the binary method to be used. Testing will have to wait until our regular shoots start up in April. They work okay with BP, which I like the tone of better than flash. The few I made recently with inert materials were just to get notes for paper dimensions, length of string for spiking and other supplies used for each shell. I also tried a few different spiking patterns to see which I liked the best.

 

I am trying harder to keep precise notes so I can improve consistency. I also want good lists of needed materials for each size when I pack for events. Between camping gear and tools, I need to make the most out of limited trunk space.

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I like the binary idea. Do you have a good way of adjusting components to remove the void?

 

I watched Don's video last night and found it very inspiring, as well as entertaining and enlightening. Plus it featured some sweet banjo tunes.

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