5 replies to this topic

[pyrotrev]

Last year I was supplied some large (22" ID) convolute wound paper tubes for a non-pyro project. For extra strength the vendors made them using a silicate adhesive (waterglass??), and yea, verily they are strong. An interesting side effect of this adhesive is that they don't seem to char as quickly as fibreboard tubes made with the normal (PVA) adhesive - could have applications for gerbs, saxons etc.?

[Karl]

Last year I was supplied some large (22" ID) convolute wound paper tubes for a non-pyro project. For extra strength the vendors made them using a silicate adhesive (waterglass??), and yea, verily they are strong. An interesting side effect of this adhesive is that they don't seem to char as quickly as fibreboard tubes made with the normal (PVA) adhesive - could have applications for gerbs, saxons etc.?

I?m not too sure. The tube that you described sounds like Phenolic tubing. Which I don?t think would be suitable for Pyro. Phenolic is basically cardboard but soaked in Epoxy to give it extra strength. It depends how think the wall is really, the tub itself could hold the pressure but would the tube burn through?

Personally I have used 54mm, 3? and 4? tube and the wall thickness isn?t thick enough IMHO.

[pyrotrev]

These weren't phenolic, just rolled kraft paper with the silcate glue. Wall thickness on my samples was 10mm, but the company that made them could do any thickness over 6mm.

Edited by pyrotrev, 04 February 2006 - 03:48 PM.

[JamesH]

Last year I was supplied some large (22" ID) convolute wound paper tubes for a non-pyro project. For extra strength the vendors made them using a silicate adhesive (waterglass??), and yea, verily they are strong. An interesting side effect of this adhesive is that they don't seem to char as quickly as fibreboard tubes made with the normal (PVA) adhesive - could have applications for gerbs, saxons etc.?

According to David Sleeter, author of amateur rocket motor construction, convolute tubes rolled with silicate adhesive are superior for use as rocket motor cases.
They are indeed a lot more fire resistant and would be very suited to stinger missiles (spin-stabilized rockets), hummers, or high temperature, high metal content gerbs.

Do the vendors supply smaller diameter tubes?

Edited by JamesH, 04 February 2006 - 09:34 PM.

[pyrotrev]

Do the vendors supply smaller diameter tubes?

Err, slightly smaller - they do a 345mm ID! (think of the gerb you could make with that!). I enquired of Stell's whether they could do smaller ones, and the answer is yes, but only for a large quantity, since it means changing the adhesive on a machine which involves a lot of cleaning. Anyone know any other convolute tube manufacturers?? Alternatively if you wanted to roll your own for special purposes, sodim silicte solution seems to be quite widely available.

[JamesH]

Err, slightly smaller - they do a 345mm ID! (think of the gerb you could make with that!). I enquired of Stell's whether they could do smaller ones, and the answer is yes, but only for a large quantity, since it means changing the adhesive on a machine which involves a lot of cleaning. Anyone know any other convolute tube manufacturers?? Alternatively if you wanted to roll your own for special purposes, sodim silicte solution seems to be quite widely available.

Sounds like those large diameter tubes would be a possible candidate for the tumbling barrel in corning machine project on passfire!