41 replies to this topic

[bernie]

In many cases dextrin can be substituted for SGRS. I have no experience with SGRS but I understand it is a superior binder. I have found that wheat paste is far more effective with some flitter stars that use rather large flake alum.

Dextin is just about useless for rolling tubes. Matt has good success w/ pva.

[dfk]

thanks bernie
guess I wont be trying to roll my own tubes any time soon.
I was wondering about the binder because alot of fire dust stars call for SGRS.

[RegimentalPyro]

Dextrin/ricestarch are used as binders rather than as glue. I don't think either of them could be used in rolling tubes.

According to Mr Lancaster [God - also wrote the bible] Dextrin bound comps have a tendency to absorb atmosperic moisture and to "go soft". this is why rice starch was more prevalent in rather waterlogged blighty.

That being said - I use it "no worries"

Edited by RegimentalPyro, 06 January 2004 - 10:20 AM.

[Yugen-biki]

Just adding to the thred...

I use PVA (PVAc wood glue) glue mixed with 1 part water and 10parts glue. Then I apply the glue using a brush and soak the paper in a layer of glue. If I?m making tubes i roll the paper on ta a rod and press the air out using a wooden brick. This makes the glue penetrate the paper fibers (with help fron the water) and makes it really hard.
I have tried wall paper glue, potatoe starch, weet starch... but I find the wood glue to be the strongest but not the most flexible. The important thing is to let the paper absorb the glue.

[BigG]

This is bound to get some people giggling, as I am usually quite traditional, but an excellent glue to roll tube in a hurry is…. Glue stick.

Really – few years back I was clearing a couple of hours to roll a 100 ? inch tubes or so for fountains. Sitting at the workshop I discovered to my horror that I’m out of paste!!! It was either go home and make some, or find an alternative. Shockingly enough – I was out of PVA as well!!! How could I become so careless? Then I found in the drawer three sticks of glue sticks. It was slow, and I finished only about 30 tubes or so, but the results were very reasonable. There are a few pros to this:

1) Not messy.
2) The paper does not shrink. One problem with PVA/Water mixes is that the paper shrink when dries, and if you need the tube for rocket or fountains, you find it hard to push the rammer back in.
3) No special preparation needed if you need few tubes in a hurry.

The cons? Well:
1) Expensive. This glue is gone real fast. You need MANY sticks.
2) Slow.
3) Does not harden. Pva/water and paste glue make the glued paper shrinks and become quite hard. This is extra good when you want a close fitting paste paper around a shell. Glue stick seems to keep its properties. It actually seem to melt and lose it adhesive power if the weather is very hot – even few good month after you used the glue…

[lord_dranack]

Here's a tip I find quite useful when rolling tubes:
I normaly use wooden dowel as formers, and so the tubes can stick to the former. Also as prevously noted PVA can cause the tubes to shrink.
If you put a few layers of sticky tape or sticky backed plastic on the wooden former, then the diametre will be slightly increased to alow for shrinkage, andit is easier to remove the tubes!

[The_Djinn]

Sticking to paper, excuse the pun.. but I see Shimizu tends to favour news paper for shell casings. Has anyone tried news paper for their shells ? (didnt spot anything on the forum search).

And one for the more technicly inclined, they used to use chlorates to bleach pulped paper during the recycle process. Is this still the case and if so what are the chances of residues still being present or is there little or no chance of there being any sulphur / chlorate reaction ?

Mark

[lord_dranack]

I have a giant roll of newsprint paper- an offcut from industry. I have made cases for rocket payloads with them, using flour paste so they are very brittle. My first batch of shells have been made using cartridge paper (I have mostly done ground based pieces up to now)
Another bonus of newsprint paper is that the roll it comes in is a spiral wound cardboard tube about 3' long with an internal diameter of 3" and 3/4" walls!

I would have thought that there is very little risk of chlorate residues being a problem. I believe they often use gaseous chlorine or hydrogen peroxide in favour of chlorates for bleaching now, although I don't know what they use in the paper industry.

[dfk]

Another bonus of newsprint paper is that the roll it comes in is a spiral wound cardboard tube about 3' long with an internal diameter of 3" and 3/4" walls!

Ive used one of these, I took it from my art coruse, they are perfect for shooting three inch shells and mines. Normally spiral wound tubes arent recomended for mortars due to there weeker integrety but i think the thick 3/4" wall solves this.
the one I had was shot after just two fireings. after this I read that you can harden tubes with varish, just completely coat and hang up to dry. the varnish since it coats the whole tube will decrease the inner diameter a tiny bit, so thats something to take into acount. I have also read that Rockite® wood hardener makes tubes ...well .. rock hard. I know this was meant for small tubes were high pressure would be exerted like for instance in rocket tubes, but i am not sure if it is suited for mortars.
anyway back on point my teacher said that your local publisher will give you these rolls if you just go and ask. Is this what you did?, has anyone tried this? i figure if they even let me in the building they'd look at me wird when I ask for a roll of newsprint and a dozen tubes for a "school project"

[dfk]

My mistake, the memory is going
Rockite is an expanding cement that when mixed with hv/ac in a 50/50 ratio makes an erosion resitant nozzle.

the wood hardener that is used to harden tubes is Minwax®. This is probably perfect for those of you who roll your own tubes and want some strenght for those bp rocket caseings.
(I think this was read from skylighter.com)

[lord_dranack]

To harden my tubes, I follow a method I think I found on Tom Perigrin's page (I can't remember the web address). It involves washingthe tubes in CaCl2 solution and then in sodium silicate, to coat the tubes with calcium silicate. If anyone is interested I can post more details...

I don't know where I got the tube from- it was just knocking around the house, but one of these days I will ask at the Liverpool Echo I they have any old tubes.

[pyrotechnist]

Hi does any one know if fire-fox enterprise sells 3" shells to the UK or not? I need to get some in a I am sick of making my own shell casings it takes ages to make the pieces of paper and ages to make one half of the shell like a full day. So I want to get some shells and they sell them so I sent them email asking but just wondering if any of you have guy?s bout in the UK or not thanks.

[Yugen-biki]

About rocket tubes. I have had great success using VP-pipe. They are made for protection off electric cabels in houses. For 0,5 to 1 euro per meter, depending on size, the price is worth not having sour hand after days of rolling tubes . You might think the plasic may melt, but it doesn?t. One other thing: paper tubes may crack when ramming or pressing, but the plastic tubes are elastic. No more rockets thrown away because off the paper ruptureing!
I have some great pics of my rockets. Is it possible to post them here?

[BurlHorse]

whats the difference between dextrin and soluable glutinous rice starch in stars. can they be switched? and does dextrin work for rolling tubes or not even close?
thanks
marcus

Marcus,
Shimizu says and I will confirm and agree that it (SGRS) dries faster when used as a binder in stars, They dry harder and faster. I have used Dextrin, Starpol and SGRS, and N/C Laquer as Binders, I like the SGRS in any Color changing star Comps, as it doesn't tend to cause any "Driven in" problems, like Starpol and to a lesser degree Dextrin. As to Using Dextrin to roll tubes, I dunno, Hi-Ho Hi-HO, Out to the workshop I go....Will get back to ya!

Regards, Stay Green,

Bear

[Jerronimo]

Hi does any one know if fire-fox enterprise sells 3" shells to the UK or not? I need to get some in a I am sick of making my own shell casings it takes ages to make the pieces of paper and ages to make one half of the shell like a full day. So I want to get some shells and they sell them so I sent them email asking but just wondering if any of you have guy?s bout in the UK or not thanks.

Firefox is way to expensive!

If you want some high quality plastic shells you should go to pyroplastics.com
pyroplastics