36 replies to this topic

[pyrotechnist]

Ok now that the title hopefully has caught your attention I am wanting to know if anyone knows or has a technique of getting a cable type product within a plastic tube? I am wanting to know this as I am currently trying to develop a method of creating plastic fuse without having to use an extrusion machine to apply the plastic sheef. Now I have thought about using liquid comp and injecting it into the tube at high pressure though I would suspect drying times would be very long. Another method may be forcing dry powder into the tube though again it would be tricky to do. I can currently wrap plastic around a powder core but it just doesn't feel like a good enough method to me. Now the last alternative is heat shrink tube but I cannot think of a method to get a semi-finished fuse into a 100 metre roll of heat shrink without having to do it manually. Hope someone can help!

[cooperman435]

would latex be suitable as it can be applies as a liquid?

I'm sure some of our chemical engineering peeps out there could suggest suitably flexible plastics that could maybe be dissolved in a solvent for applying in a similar fashion to NC on visco?

[a_bab]

The extrusion machine is really simple actually. It's nothing then a bath of melted plastic with a die where the cable (fuse in your case) exits covered in plastic. There are many plastics that would melt in the range of 120-140 degrees C, none enough to set off the BP type of compo. "How it's made: electric wire":

This docu gives some ideas of what the ultimate visco machine should do, including the plastic extrusion process.

What you didn't clearly stated is if you already have a fuse (visco maybe) that you want covered in plastic or if you want to somehow get a powdery or even liquid compo in a plastic tube? I guess it's rather the second option, in which case you are pretty well stuck. There is now way to get a "100 m roll of continuous fuse". The best bet would be to inject the compo as a paste in let's say 1 m lengths of tube which should be able to absorbe the solvent so it evaporates at the surface. An acetone paste with some soft PVC tubing may work, although I guess it'll take probably weeks to dry thoroughly (acetone only softens the PVC). While at it, wy not use some parlon/acetone/KP kind of compo? The fuse will be very elastic, could be made to burn different colors/effects and it could most certainly made to behave like flying fish if not like go-getters with the appropiate compos.

I personally hate the idea of using plastic and generally non biodegradable stuff in my fireworks, but to each it's own.

Edited by a_bab, 29 November 2010 - 07:08 AM.

[pyrotechnist]

Latex mite be a good option and it doesn't seem so expensive though would it burn away with the comp? I guess like A_Bab said the machine could be made similar to an extrusion machine with the semi-finished visco being coated in plastic. Plastic may not be so degradable but I do see its uses as a modern alternative due to its more giving and bendy nature plus structural strength compared to visco which can be over bent and damaged. The fuse once finished should not be much different to the old PIC fuse. Another idea could be visco wrapped in copper wire instead of thread with a copper core and then plasticated to create a time like fuse with a wall that doesnt burn away as well as being waterproof.

[Creepin_pyro]

Have you seen the fuse from these guys?

http://www.rastilhos...h/prodFuse.php#

[pyrotechnist]

Looks good though I want to produce my own for the fun of it . It seems that polyethylene can be dissolved in Acetone in which case surely a solution of polyethylene and acetone can be used to coat coat the visco fuse much like the fuses from the link above by rolling it through a thick bath of the solution and allowing the solvent to evaporate to dry the plastic on to the fuse.

[BrightStar]

The Monetti time fuse isn't plastic as such. It's essentially very high quality Bickford manufactured to a tight specs with a fairly thick polythene outer jacket.

Re the idea of a plastic tube filled with composition, I think the difficulty you might have is in stabilising the burn rate. Mantitor igniter cord has two wires running through it - steel for mechanical strength (plastic's stretchy after all) and copper for thermal transfer to regulate the timing. Even then, it's reputedly not as consistent as the old PIC in shell chains.

IIRC, Pyrotrev experimented with silver flying fish fuse dipped in silicone for waterproofing when PIC became scarce. There's probably a post on it somewhere here.

Edited by BrightStar, 29 November 2010 - 12:29 PM.

[a_bab]

Few points:

- polyethylene DOES NOT dissolves in acetone. I fact, pretty much nothing disolves it. You need to melt the stuff. This is how it's glued. While at it, hotglue could be another option (sometimes hotglue sticks are polyethylene)
- you may already have the plastic jacket components you're after under your nose: it's parlon. Elastic and fireproof.
- other plastics you may consider are PVB (polyvinyl butyral) - it's the stuff laminated between the reiforced glass panels such in windshield screens - it dissolves in alcohols, acetone, and other (common) solvents. It burns with a clear clean flame.
- yet another route would be neoprene based glues (lightly chlorinated rubber (NOT to be confused with parlon aka pergut) - again elastic and cheapish
- PVC + plasticizers (just add some plasticizer to PVC cement and you're set)

There are many other options I can't think about now; the bottom line is that you either go for the melted route (instant fuse) or the "plastic and solvent" route. Don't forget this page; it may give you an idea: http://fogoforum.us/thermalite.php

Imagine a system of continuous thermalite making (much easier IMO then visco) folowed by a plastic dipping bath and your rolls of fuse will soon start to coil up. Doable, but is it worthy?

If what you are after is a timefuse replacement then I doubt you can do it.
BTW, why do I have the impression you don't have access to visco and you're mumbling and muttering "gotta find a way to make my own fuse...a lifetime supply of it..."

[BrightStar]

pyrotechnist - apologies seem to have lost one of your posts (clicked the wrong button...)

I'll take some pictures of the PL10 when I have a moment. From memory it has what looks like a plain cotton central core wrapped with BP soaked cotton strands (25g / meter of BP). Around this there is a counter wound cotton jacket followed by approx 1mm thickness of polythene. Overall diameter is 10mm.

The polythene coating is solid so probably extruded molten around the core - it's much like thick electrical cable insulation.

[pyrotechnist]

BTW, why do I have the impression you don't have access to visco and you're mumbling and muttering "gotta find a way to make my own fuse...a lifetime supply of it..."

Thanks for the information but on the note of your 'impression' you are wrong it is not a bad idea to produce your own devices to create something in pyro just because you can buy it. When you say buy it most fuse is extremely expensive for the average joe in pyrotechnics compared to anyone who may be in the industry so that doesn't cut with me! I have a visco rig set up and works beautifully with pictures to follow shortly in another topic and to be fair do not see why anyone would want to buy the stuff when you can make it cheap as chips with a small investment in materials. One last argument and I am done lol, why should we make black match if we can buy it? pointless huh but we do!

BrightStar no problem about the post forgot what was in it anyway.

[BrightStar]

OK, Monetti PL5 and PL10 samples:

[pyrotechnist]

Looks like a very nicely made fuse! how quickly does hot polyethylene dry once out of the molten solution? Them fuses sure do have a thick coating, by the way does the entire fuse burn away?

[phildunford]

Thanks for the information but on the note of your 'impression' you are wrong it is not a bad idea to produce your own devices to create something in pyro just because you can buy it. ... One last argument and I am done lol, why should we make black match if we can buy it? pointless huh but we do!

Exactly - all hobbyists spend ridiculous amounts of time making things that we could probably buy more quickly & cheaply. You learn much more & it's more fun!

[pyrotechnist]

Ahh is this fuse used for timing?