How to roll pyro-tubes

[Extrarius]

Adding a former to the newspaper roller wont do the trick as the former/mandrel needs to be the driven shaft

Why? If you simply inserted a dowel into the 'newspaper' before putting it into the machine, the rest of the machine could still function as it does (turning a very loose tube into a very tight one), except that it couldn't roll the newspaper smaller than the dowel. Or am I wrong that the machine would still function?

[MWJ]

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 ?

Watch his video again and you'll see that he doesn't apply the glue to the first 1 inch or so. The dowel doesn't have contact with glue and that makes the tubes slide right off. I made the same mistakes and it stuck to my dowel too. Now I can make tubes any size I need as long as I have a dowel or rod the size I need. It works great! Thanks for the tutorial!

[Col]

Why? If you simply inserted a dowel into the 'newspaper' before putting it into the machine, the rest of the machine could still function as it does (turning a very loose tube into a very tight one), except that it couldn't roll the newspaper smaller than the dowel. Or am I wrong that the machine would still function?

 

You`ll need a lot of compression from the top roller to provide enough friction on the dry side of the paper to wind the paper onto a floating former. Wet paper isnt very resistant to crush damage which will cause it stretch. The wrinkling issues from stretching will soon render a tube useless.

A driven mandrel pulls the paper directly like a winch, it cant slip or slide as long as theres some tension on the paper. The tensile strength of wet paper can handle a lot of "pull" before it fails. I cant see how he can justify asking £500 ($837) for a few sprocketed conveyor rollers and a bit of chain

[DasKapital]

Great idea but I also scoffed at the price when I saw it Col. It's obscene.

[markx]

I would love to build a tube rolling machine, but I would opt for a compact desing for short tubes (motor lenghts). I've always used a sort of construction cardboard for rolling of tubes instead the kraft paper. The cardboard is cheap, thick (around 0,5mm or more) and rather strong. It is nice to only need a few layers for a decent tube. But all the obstacles in my way just keep putting out the light in my eyes: I need a lathe to make decent machinery.....but the damn things are so expensive. Even the chitty little ones with plastic gears. Come to think of it I also need a decent workshop to put the lathe in....to build that I need time. Which I do not have cause I must waste it to make money. If I take the time then I have no money to get things done. It really drives me to drink....tell me that I'm not the only one plagued by such problems

[Mike]

Well no, there's just one way to go around that problem, and thats to buy your tools.

For a rolling machine you even don't need a lathe, you can make one by just using a power drill and some Hand tools.

 

But your right a proper lathe would be amazing for most people (Well than you would lack all time as you propably won't be able to leave your shop for a long long time)

[markx]

Well no, there's just one way to go around that problem, and thats to buy your tools. For a rolling machine you even don't need a lathe, you can make one by just using a power drill and some Hand tools. But your right a proper lathe would be amazing for most people (Well than you would lack all time as you propably won't be able to leave your shop for a long long time)

Heck....I could live with that ! And I'm gonna make it happen, I know that I would hate myself for not doing so.

[ianagos]

I got a large lathe but I don't use it that often. I always want to help as when I was starting out in pyro some people helped me and that was enough. I offer my services for material cost and I have most of a machine shop but my mill is being converted to cnc at the moment. So let me know if anybody ever needs anything made. I'm willing to help and I like making parts as it teaches me something and a tube rolling machine is something I really want but haven't got the money to spend on. Btw if anybody lives around georgia and wants to help me with my failing rockets I would love the help.

[dagabu]

ARISE DEAD POST!!!

 

I am going to resurrect this post so that I can add to it and show you all how I am rolling tubes for rockets. What am I doing differently? What paper am I using and where can you get it? What glue and I using and where can you get it?

 

Before we get going, my primary intent is to create parallel wound paper tubes from kraft paper that mimic the same wall thickness as NEPT tubes. Secondary is to find out if the burst pressure is the same and if not, what is it and is it consistent?

[Col]

Hey Dag,

Cant wait to see the results

As you`ve resurrected the thread i`ll throw in a novel paper prep method i came up with. It may or may not be useful depending on the rolling method but it can be a real time saver and much easier than wrestling with yards of sticky paper.

Its pretty basic, all you need is a chunk of large (ish) diameter tube, (preferably erw steel but heavy wall pvc tube would work), 4x 12mm/1/2" bearings (32mm od), 4x 12mm /1/2" bolts and some angle iron to mount them on. I use 6" od x 1300mm and 225mm od x 1300mm steel tubes to produce kraft sheets 480mm or 710mm wide x 600mm to 1150mm long (depending on the kraft roll width used). The benefit of using steel tube is you can warm up the inside using a hot air gun.

It can also be used to cut sheets straight from the roll10 at a time, as long as you dont mind a little difference in each sheet length

 

Attached basic pic with the details.

 

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Edited November 21, 2018 by Col

[dagabu]

Col, I like that idea, calendering the paper would save time, for sure! I have pre cut sheets of white virgin Kraft paper 36" x 24" with the grain running the long way.

 

I am making strips 8" wide the long way and rolling them up one sheet at a time, letting them fully dry between sheets.

 

This is giving me a true 1/8" wall thickness that hopefully fits my supports as well as the NEPT tubes do.

 

I will post pictures this weekend of the materials and the process. No machines, nothing special.

[Col]

Having the kraft in sheet form saves lugging a big heavy rolls about Sounds like your kraft is a similar thickness to mine, i use 2ft roll and 4 layers for 3/4 id x 1/8 wall tubes. 4ft roll and 2 layers give the same result but 4ft is more useful for the larger id`s. Its not easy to get a perfectly consistant tube od, its normally plus or minus a gnats wotsit which isnt an issue with DF`s brass shim support method. I dont have a clamshell support so i dont know how much wiggle room there is with those but a smidge undersize is easily fixed with a few tight turns of dry kraft. Oversize is trickier, maybe throw it on your lathe

[dagabu]

 

 

 

 

 

 

Edited November 22, 2018 by dagabu

[dagabu]

The tubes turned out just fine, they fit in the support just like the NEPT tubes after they are dried thoroughly.

 

UPDATE: My error, these are the calendar rolled tubes. As you can see, the sheets are coming apart as they shrink. I guess its back to single sheet rolling. They don't fit in the support either.

 

 

Edited November 22, 2018 by dagabu

[Col]

Nice looking tubes

i figured you were using 4 strips but it looks like 3 so your kraft must be a bit thicker than mine. Might be worth putting a caliper on a piece of kraft from an nept tube to get an idea of what they`re using. The fun part next, destroying them in the press to see what they can handle

 

Found a pic of the paper prepper in case anyone needs it. The big tube is forced against the conveyer roller by gravity, its own weight and the height difference of the rear support bearings.

 

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Edited November 22, 2018 by Col

[dagabu]

These tubes were rolled sheet by sheet and allowed to dry between, notice the lack of separation in the sheets.

 

Edited November 22, 2018 by dagabu

[Col]

Hi Dag, thats not so good. i guess its a water issue Allowing each sheet to dry before applying the next resets the moisture to zero. If you have a 2ft+ chunk of ~70mm od tube laying around you could roll a 3x2 sheet onto it (4 turns), let it dry and then cut it off lengthwise. Notching the sheet will provide feathered ends but the main purpose of the test is to take water out of the equation to see if the calendered result is any different

Logic says if you can get a nicely consolidated 3/4" tube from a single 8" x 2ft sheet, there`s no reason why you cant get a nicely consolidated 70mm id 4 turn tube from a 2ft x 3ft sheet My kraft paper thickness is 0.0825mm for a single dry sheet and 0.36mm for 4 sheets including the glue when fully dried.

[NeighborJ]

I've always found the key to rolling good thick tubes without shrinking is to not roll them wet. Here's a clip of mine rolled with tag board and the method i use. I've since found a source of longer higher quality sheets so they don't need spliced together.

[Col]

Nice, not sure what tagboard is but it looks like pretty thick stuff

Did a quick test to see if its possible to calender kraft on a 2" od tube and the answer is yes. I could only find enough kraft to make 3 turns (rolls are up the shed) but adding more turns would be no problem. The paper was 480mm x 280mm. After rolling it onto the 2" tube I let it sit for about 10 minutes and then cut it lengthwise with scissors and rolled a test tube.19.15mm id x 160mm long (2" tube circumference), wall thickness 1.18mm according to the digital caliper. Nice and round with no wrinkles or apparent delamination. I`ll cut the ends off for a closer inspection when its fully dry.

[NeighborJ]

Tag board is what file folders are made from.

[Col]

i know what it is now

Here`s the result of the test, i cant get a great pic of the tube end wall as its only a tad over 1mm thick. There`s no delamination which was surprising considering i cut it with a 24tpi saw. The 3 layer sheet took a shade over 4 turns on the mandrel, the tube wall has 12 layers of paper in it.

 

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Edited November 24, 2018 by Col

[dagabu]

Very nice, Col.

[Mixer]

The tubes turned out just fine, they fit in the support just like the NEPT tubes after they are dried thoroughly.

 

UPDATE: My error, these are the calendar rolled tubes. As you can see, the sheets are coming apart as they shrink. I guess its back to single sheet rolling. They don't fit in the support either.

 

 

Dag,

You don`t have to give up on that process - just modify it a little. There are many small hurdles to overcome in making good strong tubes.

I wrote a detailed tutorial on tube rolling which is in the `Members Tutorials` section headed HAND ROLLING STRONG TUBES.

 

Additionally, I now run a damp cloth over the tube between each additional length of Kraft to liven up the dry paste. Also to help in initial alignment of the paper I mark a centre line on each side.

Edited November 28, 2018 by Mixer

[Col]

If you calender on a large diameter tube you dont have to worry about alighnment The 1st turn is dry and the rest are glued so they automatically lock themselves into place as they are laid down and remain under tension so they`re not free to expand, wrinkle etc. Glueing and placing several large sheets together is stressful and time consuming. Any imperfections that appear in the lower sheets make it progressively harder to get a good finish

Going straight from the roll onto a large diameter former is so much quicker and easier. The tricky part is finding a big chunk of tube with the right od to use as the former.

Edited November 28, 2018 by Col

[Mixer]

If you calender on a large diameter tube you dont have to worry about alighnment The 1st turn is dry and the rest are glued so they automatically lock themselves into place as they are laid down and remain under tension so they`re not free to expand, wrinkle etc. Glueing and placing several large sheets together is stressful and time consuming. Any imperfections that appear in the lower sheets make it progressively harder to get a good finish

Going straight from the roll onto a large diameter former is so much quicker and easier. The tricky part is finding a big chunk of tube with the right od to use as the former.

 

Actually the Gluing and placing of the two strips is the best part for me. I simply lay them side by side, paste both sides sparingly, and when all dimples are gone - indicating that maximum expansion has taken place they are brought together and smoothed out with a spatula or hard roller.

Quick and simple.

 

The mark for alignment is there so that when the tube is finished there is no need to trim the ends of the finished tube - just a brief circular dress with a sanding block.