22 replies to this topic

[vaslop2005]

I'm just about to put in a large order to stell, if anyone wants any large bore (or standard) paper tubes please PM me.

I know they are getting hard to find, especially for us in the UK.

The more that are bought, the cheaper they'll be. that's the idea of this 'community' order.

I'm buying, 1/2" 3/4" (at 50cm) and 1", 1 1/4", 1 1/2" (at 1m) they are made to be strong, and are used in pyrotechnics industry already.

Thanks Vas

[digger]

So what prices are they?

[vaslop2005]

1/2"--60p
3/4"--75p
1"----£2.10
1 1/4-£2.60
1 1/2"-£3.20

Finally figured it all out, what do you think of the prices digger?

That's per tube excluding postage

[digger]

It all depends on a number of things. For example what is the wall thickness and what material are they being constructed from?

[a_bab]

The material is 100% chipboard (aka crap-board).

About the ONLY company that would use virgin craft is NEPT.

[vaslop2005]

Unfortuantely yes, it is chipboard, but that's all I've managed to use in the past and it's never been a problem in my opinion.

[cooperman435]

Stells will roll anything you ask them to and even use Sod Silicate as adhesive if your willing to pay.

Chip board unfortunately does make poor strength tubes unless made very well which machinery doesn't.

[portfire]

Apart fron the larger ones....ROLL your own!!!!!

[pyrotechnist]

Nothing like the old standard tubes which are rock hard made from craft paper. I wonder where these got obtained from?

[cooperman435]

Stells

[pyrotechnist]

So what is the price difference from using kraft to using chipboard?

[BrightStar]

I've been playing around a bit recently with different grades of paper and it's been quite enlightening.

The technical difference with Kraft is that it is made using a chemical pulping process (expensive) rather than a mechanical shredding process (cheaper). As such it is coarser, has a pronounced grain direction (although it's not always visible) but more importantly it's considerably stronger. Kraft comes in many grades from bleached white, calendered (smooth), raw (rough surfaced) and so on. It also varies in the percentage of recycled content - virgin Kraft is near 100%. The recycled stuff has shorter grains on average and so is weaker. Chipboard (mechanically processed) is usually weaker still.

IIRC, in Portfire's tube rolling tutorial he used 125gsm part recycled carpet underlay kraft. It looks like ordinary brown chipboard but if you test it by wetting or bending the sample there is a definate directional grain.

The grain usually lines up in the 'machine direction' (ie in parallel with the length of the roll). Home made tubes should be rolled 'grain short', so rather counter intuitively, you cut strips off the big roll and make them up with the mandrel at right angles to the direction of the original roll.

It seems there's a lot to learn about paper... Portfire's Spark article, Shimizu FAST 13.8 and printing industry web sites are all worth a good read...

I guess what we need here is a 'pressure on the clay' press test of a few sample tubes.

Edited by BrightStar, 11 December 2010 - 09:24 PM.

[vaslop2005]

I've requested kraft tubes from stell, and if they can make them, I will revise the order.

Also I'll see if they can do silicate glue also.

[vaslop2005]

The can do kraft paper tubes, but only up 4mm walls, what does everyone think?

[vaslop2005]

The can do kraft paper tubes, but only up 4mm walls, what does everyone think?