How to roll pyro-tubes

[VikingPyrotechnics]

Here you can see how i roll my tubes :-)

 

https://www.youtube.com/watch?v=T3s2rqp8wgo

 

Greets

VP

[leedrill]

what do you use for paste vp and do you roll your own 1lb tubes aswell

 

very neat and quick im goung to have to start rolling my own passfire tubes and stuff soon

 

and would love to be able to roll 3lb tubes that stand up to nept but will need some high quality paper for that

[VikingPyrotechnics]

I use white glue and water ( 40/60 )

Sometimes i also roll some tubes for my 1lb rockets.

Here you can see one of it......

 

https://www.youtube.com/watch?v=UoumAsEit5I

 

Greets

VP

[leedrill]

dude they sound harder than nept id love to see some controlled tests between the two {one of yours rolled to the same wall thickness and pressed unsupported untill the first drop in pressure }

 

pressed in 100psi increments and measured at start and finish of time intervals

 

held for 5 min intervals

 

press displacement measured from top of tube to top of rammer at start and finish of time intervals

 

same batch of fuel used {bentonite might make the test quicker but anything used must be finely powdered to get and even density and friction

between particles } and weight of fuel measured to 0.001 of a gram

 

every test ive seen so far on tube strength has been very basic from what i have seen {the tube broke at a specific psi }

 

if these guidelines where met a chart of the measurements, time intervals, and pressure will be very easy to see which is best

 

im not asking you to do these test vp but thought id just post this in hope someone feels the urge too oneday including me

[VikingPyrotechnics]

My press read in tons & kg.

My little tubes have a wall thickness of 2mm.

I have bentonite pressed in (without support tube).

At 800kg, the small tube is broken.

With the large tubes I have not done it yet. But they are very hard.

[leedrill]

that is a really good result vp i am impressed but

what i mean when i say that what you just gave me is pretty much the only results i ever see

the tube splitting obviously means it has failed but i would like to know the point where the tube integrity is compromised rather than fail point it is not necessary to know by any means

 

other than to tell how good your style of rolling tubes is compared to nept and wether we are wasting all that money when we could be rolling tubes as quick as you do with some practice

[Shizznt]

Nice tutorial VP. I was going to watch your old pyro tubes video, but it said that it was taken down. I was looking forward to watching the new video, so I could start making some tubes. Good Job!

[Col]

Nice vid VP,

Its worth consolidating the tube with a board after you`ve rolled it to illiminate any voids and increase the density of the wall

The split test is a good way to compare tube strength, the standard procedure is use 20g of bentonite in a 2" section of 3/4" id tube.

http://www.skylighter.com/fireworks/how-to-make/Fireworks-tubes.asp

The strongest tubes like nept use multiple sheets of virgin kraft calendered together and rolled with the grain parallel to the mandrel. They dont use pva as it softens at modest temperatures, you`ll be surprised at the difference in strength between a hot pva bound tube and a cold one

Edited November 22, 2013 by Col

[mabuse00]

Thank you wiking


Just curious: what and specific product of white glue are you using? As far as I know they all react differently to water addition, some loose strenght and some not so much.


Another thought concerning comparisons:
Try comparing tubes by processing them and check how much they shrink. Tubes are often significantly damaged from pressing without being visibly split.

Do you still have your 19,7mm tool? Have you ever compared your homemade tubes with those Rene had?

[AdmiralDonSnider]

Very nice tutorial. Clean work.

[leedrill]

i can imagine how much glue and other factors would affect the strength but ive never seen a comprehensive test before one that indicates stretching of the tube tearing of the inner wall and so on

 

a lot can go on in side of the tube without you knowing but the inner workings will all be affected by pressure

when stressing anchors the guidelines i sort of outlined must be adhered to to get a pass on the anchor and after stressing countless no.s

i just know a test like this would be very definitive im in aus so getting good virgin kraft is hard to say the least and i dont have the right jack setup or gauges to be able to do the test properly if any one reads this and does have the time and tools would be really great to see what needs to be done to match the results to an nept tube or better them with as thin of a wall as possible

[Col]

There is test equipment in the core winding industry that can measure minute amounts of tube deformation, stress etc but its too expensive for us hobbyists You can get some idea using Pi (3.141), if a 1" od tube increases by 1mm, the rigidly glued paper is likely to be damaged as it has to stretch by 1/8".

Edited November 23, 2013 by Col

[Bobosan]

Nice tut, VP. I can see you have been at this tube rolling business awhile.

 

What material is your mandrel made of?

[jessoman]

Thats brilliant, I've been doing a few of my own lately for rockets and had a few fail. The paper i use isn't as thick as that, that's notable thicker. I will have to keep searching hard for that sort of paper! We need better suppliers here in AUS.

[VikingPyrotechnics]

Hi Mabuse,

 

i used UHU white glue and it works just fine. Ponal works also, but a bit expensive

 

@ Bobosan,

 

it´s a fiberglass / plastic rod. But it works also with pvc etc.

 

Greets

VP

[dan999ification]

Nice tubes and tut vp, I also roll the tube with a board after

 

Dan.

[LambentPyro]

Thanks Vking, much appreciated.

[Col]

Thats brilliant, I've been doing a few of my own lately for rockets and had a few fail. The paper i use isn't as thick as that, that's notable thicker. I will have to keep searching hard for that sort of paper! We need better suppliers here in AUS.

Looks like virgin pulp kraft is available in Aus, (Rozelle NSW) it`s bit pricey but a roll will make a lot of tubes. I`d contact them to ask about the weight (gsm) as the roll lengths suggest it may not be a heavy grade. Heavy grades generally come in shorter roll lengths as paper is typically sold by weight. The general purpose is the one you want, not the masking stuff.

http://kraftpaper.com.au/collections/all/general-purpose

[leedrill]

thanks col looks like they opened up recently in 2013 i just gave up on looking pity they dont have a contact no. or email i guess ill try to contact them some how but either way what they have looks better than what i can get now would be a game changer for me to have a source of good kraft

[pyroman2498]

If I may as ,

How do you get your tubes to come off so easily , mine uslay stick to the dowel.

I've tried plastic around the dowel but that failed

 

Any tips ?

[a_bab]

Nice, simple yet effective technique !

What is the ID of your small tube?

[dan999ification]

There is a few things that cause it to grip, too wet, too tight, rough mandrel, rough paper.

I'm rolling my rocket tubes ( 10mm and 1lb ) on aluminium the only problem I have is with thin rough papers wound too tightly.

Clean the mandrel after every tube.

 

I roll 1/4" tubes on a wooden dowel covered in foil tape

 

Rolling the finished tube with a board can sometimes help seperate the tube from the mandrel if the winding is not too tight.

 

Dan.

[Col]

The easiest option is not to put glue on the first turn

If the glue has a lot of water in it you may need to pack the mandrel out to account for the tube shrinkage, silicon baking parchment is the best bet for that job as it doesnt stick to anything and its reusable. It adds around 0.08mm to the mandrel diameter per turn, great for fine adjustments.

 

Prolly only useful to Dan and other uk pyro`s but wilko`s sells a 380mm wide x 5m roll for a quid.

Edited November 24, 2013 by Col

[FlaMtnBkr]

I also use a board to roll the finished tube on the mandrel as mentioned in various texts. It tightens the paper and helps get rid of excess glue. I had trouble not getting glue on the first turn and found excess glue helped get the tube off the former. I'm sure the short sections also come off easier than a longer tube with more surface area contacting the mandrel.

 

Viking, does the knife score the mandrel and eventually cause it to need replacing?

 

I would also be curious what others find the best glue to be. I have tried watered down white glue and a dextrin glue. They worked ok but I imagine there might be something better such as wheat paste or even sodium silicate for certain applications where tube burn thru can be a problem.

 

I used to make many of my tubes before I had good kraft which might be why they were good but not great. Guess I need to try rolling them again now that I have a couple different weights of virgin kraft. Regardless, those were some great looking tubes in the video.

[Col]

Here`s how you get a long tube off a mandrel, drill a hole the same size as the mandrel in a piece of 1/2" thick nylon chopping board. Hang on to the mandrel (not the tube) and push the tube off with the tool. If its especially stubborn, set the end of mandrel on the floor so you have something to push against, once it starts moving it`ll be very easy to push it off.

 

A high solids glue is the best type for tube rolling, less water means little to no shrinkage and faster drying times. Wheat starch is good, gives about the same bond strength as pva but doesnt soften with heat. Downside is a low solids content, typically around 30%.

Sodium silicate can take the heat but it doesnt have the green tack of pva or wheat starch. It can make solid tubes but the glue line tends to be brittle. If you roll a thin wall tube and squash it when its dry, you`ll hear the glue cracking and probably notice delamination in the paper layers at the end of the tube. To tick all the boxes (green tack, heat resistance, strength and flexibility) you need a blend of different types .I use a homemade glue concoction that resembles beef gravy.