Recommendations on rolling your own large body tube

[Rktman]

Suggestions on the best way to roll a 5" diameter tube using poster board? Largest boards I can easily get are 22" x 36" and one "layer" requires approx. 16.5" of paper. That means the thickest I can get is only 2 layers. Is it okay to join several pieces of poster board?

Is kraft paper thicker than poster board? I know they have those in rolls.

 

[Charles_McG]

I've been doing 3.4" ID tubing with 2" un-reinforced, water activated paper tape spiral wound around a PVC mandrel.

https://www.uline.com/BL_3062/Kraft-Paper-Tape

I do 5 ply, the base one glue up. It took a couple tries to get the hang of winding a smooth wrap with even gaps.

It took several more tries to figure out how to get the tube off the mandrel. My current approach is to pre-wrap the mandrel with baby-powder dusted wax paper. After wrapping the 5 layers, I put it in the freezer for a while. Pull it out, slide it off, let it finish drying.

The water-activated tape seems to shrink a bit as it dries. The ones I let dry on the mandrel, I had to cut off :-(

 

[Rktman]

I've been doing 3.4" ID tubing with 2" un-reinforced, water activated paper tape spiral wound around a PVC mandrel.

https://www.uline.com/BL_3062/Kraft-Paper-Tape

I do 5 ply, the base one glue up. It took a couple tries to get the hang of winding a smooth wrap with even gaps.

It took several more tries to figure out how to get the tube off the mandrel. My current approach is to pre-wrap the mandrel with baby-powder dusted wax paper. After wrapping the 5 layers, I put it in the freezer for a while. Pull it out, slide it off, let it finish drying.

The water-activated tape seems to shrink a bit as it dries. The ones I let dry on the mandrel, I had to cut off :-(

Thanks Charles, those are some great ideas, especially about the wax paper/baby powder and chilling it in the freezer. I'm guessing that it starts hardening the paper up while shrinking the pvc a bit. Appreciate the link too.

 

[dr wogz]

Why do you want to wrap your own tubes?
What kind of strength are you expecting?
I ask out of curiosity, and not to appear condescending.. Trying to get a grasp of what you're trying to achieve..

have you searched for videos on how paper tubes are made? that might also help you with ideas on how best to approach it. getting a decent mandrel might also make the endeavour unachievable..

Oh, and remember that paper (like many things!) also has a grain. it'll form / roll / tear easier in one direction than the other.

Papier mache? like you did in art class? strips of glue-soaked paper over a waxed / wax paper covered mandrel..

LOC has a 5.38" tube, mind you it is $40!
Uline (a shipping supply company) has 5" mailing tubes, but they might be a bit heavy.. https://www.uline.ca/CustomProduct/BrowseR_Listing?subgrp=3706&diameter=5
(I's us the US has a similar supplier..)
Lastly, you might want to look at 'Sono tubes', typically at the local home / hardware store.. Tubes used to hold concrete for decks, fence posts, etc..

 

[Rktman]

Why do you want to wrap your own tubes?
What kind of strength are you expecting?
I ask out of curiosity, and not to appear condescending.. Trying to get a grasp of what you're trying to achieve..

have you searched for videos on how paper tubes are made? that might also help you with ideas on how best to approach it. getting a decent mandrel might also make the endeavour unachievable..

Oh, and remember that paper (like many things!) also has a grain. it'll form / roll / tear easier in one direction than the other.

Papier mache? like you did in art class? strips of glue-soaked paper over a waxed / wax paper covered mandrel..

LOC has a 5.38" tube, mind you it is $40!
Uline (a shipping supply company) has 5" mailing tubes, but they might be a bit heavy.. https://www.uline.ca/CustomProduct/BrowseR_Listing?subgrp=3706&diameter=5
(I's us the US has a similar supplier..)
Lastly, you might want to look at 'Sono tubes', typically at the local home / hardware store.. Tubes used to hold concrete for decks, fence posts, etc..

This is related to the Ring Hawk project and bending balsa thread I started elsewhere. I just haven't been able to achieve perfectly symmetrical fin rings using balsa or even plywood. (I've tried different joint methods using the techniques/resources I have -- no power tools -- and over time the joint always ends up bowing outward no matter what I do. Call me a perfectionist or the result of the occupational hazards of being a former graphic designer, but it bugs me to no end to have sloppy or amateurish models.

So fast forward to my 2nd attempt at building the model, this time rolling my own fin ring because all the 5.0" (or close to) body tubes I could find are far too heavy, as they're thick-walled and designed for high power rocketry. (Appreciate the recommendations though. I bought an LOC bt but it ended up being far too heavy). I don't want to abandon this model because it's not only cool-looking and totally improbable as a glider, but it actually works--as a sport model. Maybe I'm addicted to the surprised looks when it unexpectedly transitions into a glider. However after only 4 flights (every one of which unfortunately ended in tree impacts) it's in sad shape.

 

[Charles_McG]

Back when I built my downscale, I also gave some thought to an upscale. Based on using a 5 gal plastic bucket as the ring mandrel.

While you could do about 3-4 ply spiral wound thin paper, about a foot long, and then cut 2 rings out of the center, I'd also give some though to doing something much like you did the first time - but with 2 layers of 1/64" plywood, with the joints pi radians out of phase. I might even do the inner layer with split ends, interdigitated. It would make a thick spot - but only a little.

 

[dr wogz]

Rktman,

Thanks for the update, knowing what you intent is helps a lot with trying to achieve said goal!

As Charles said, going with layers of 1/64" or 1/32" ply would be the way to go, in my opinion. "Vacuum bagging" the assembly while it cures would also help with strength, and help remove any gaps & such. (But that's a set-up in itself!!)

have you thought of getting it 3D printed?

 

[dr wogz]

What about styrene sheets? I know you can get it pretty thin, and you will likely be able to build it up to the thickness / strength you want. You might even be able to 'heat form it with a heat gun..

What about a 2l soda bottle? or even a Tupperware container.. cut it as needed..

 

[Marc_G]

I rolled my own fin ring once; learned a lot. I did a few sizes. Got good results using brown paper from a big roll (not waxed or plasticized), around a mandrel that had a wrap of parchment paper for release, and saturated the paper with CA. The resulting ring was strong and not too heavy as I recall. I made a couple... 2 wraps, 3, 4. The one with 4 was heavy...

 

[Rktman]

Back when I built my downscale, I also gave some thought to an upscale. Based on using a 5 gal plastic bucket as the ring mandrel.

While you could do about 3-4 ply spiral wound thin paper, about a foot long, and then cut 2 rings out of the center, I'd also give some though to doing something much like you did the first time - but with 2 layers of 1/64" plywood, with the joints pi radians out of phase. I might even do the inner layer with split ends, interdigitated. It would make a thick spot - but only a little.

I'm afraid terms such as pi radians and interdigitated are out of my vocabulary range, though I'm making an educated guess that you're referring to having the joined ends 180° opposite each other with the cut ends interlocked dovetail fashion? Unfortunately I don't have the tools necessary or the skill and experience working with such thin material.

Since I cut the material a bit longer for the overlap, I was considering a butt joint and gluing the excess that's cut off as a brace behind the joint to prevent bowing?

 

[Rktman]

Rktman,

Thanks for the update, knowing what you intent is helps a lot with trying to achieve said goal!

As Charles said, going with layers of 1/64" or 1/32" ply would be the way to go, in my opinion. "Vacuum bagging" the assembly while it cures would also help with strength, and help remove any gaps & such. (But that's a set-up in itself!!)

have you thought of getting it 3D printed?

I hadn't thought of 3D printing, great idea, and since I know a hobby shop owner who has a small 3D printer, I'd be willing to pay to have it output as long as his unit could handle a 5.0" ring. He did mention the material is made from an organic plastic derived from corn, so as long as it doesn't melt at summer temps (it can get to a high here of 103°F) and rain doesn't dissolve it, it sounds like a workable solution to try.

 

[Rktman]

What about styrene sheets? I know you can get it pretty thin, and you will likely be able to build it up to the thickness / strength you want. You might even be able to 'heat form it with a heat gun..

What about a 2l soda bottle? or even a Tupperware container.. cut it as needed..

Tried several large soda bottles but they weren't rigid enough and also sacrificed a plastic food container which ended up too heavy. It's been a tough balancing act between weight and strength. If I ever get this sorted out, I'm wondering if I'll just end up keeping it permanently on my display shelf to admire rather than risking having it rendezvous with yet another tree and trashing all that work...:wink:

 

[Rktman]

I rolled my own fin ring once; learned a lot. I did a few sizes. Got good results using brown paper from a big roll (not waxed or plasticized), around a mandrel that had a wrap of parchment paper for release, and saturated the paper with CA. The resulting ring was strong and not too heavy as I recall. I made a couple... 2 wraps, 3, 4. The one with 4 was heavy...

I was considering the dry roll technique; squeegee on a thin even layer of white glue onto kraft paper, let dry, roll, then apply heat (an iron will do). The heat temporarily liquefies the glue and bonds the layers together. I tried it on a small scale using calculator paper but it was too thin. It took 7 layers and was still not rigid enough. Poster board was better but the limited size of the sheet limited me to only 2 layers. Cutting more strips and adding it on got messy and the ends weren't square anymore, but I know kraft paper comes in rolls so I'll try that route as well as maybe going the 3D printed route as suggested by dr wogz.

 

[Incongruent]

3D printed structures are generally rough and relatively weak.

 

[Charles_McG]

I was thinking of slitting it lengthwise for an inch or so, and having the overlap be on top on one side and on the bottom on the other. Makes a double thick spot, but the second layer would go over it.

When you ammonia shaped the balsa, how much overlap did you leave, to be cut back to the join later?

 

[Rktman]

I was thinking of slitting it lengthwise for an inch or so, and having the overlap be on top on one side and on the bottom on the other. Makes a double thick spot, but the second layer would go over it.

When you ammonia shaped the balsa, how much overlap did you leave, to be cut back to the join later?

Gotcha, makes a lot of sense.
Overlap was about an inch. But because of that overlap, the end of the overlapping balsa strip developed a rectangular lump that wouldn't go away.

 

[dr wogz]

"PLA" is the corn based plastic most often used. And yes, they can be rough (surface texture, depending on build level settings) and weak (I'll be one of the first to say it too!!). But in your case, with the right supports, should be too bad. ask if he can do ABS, much better. And, paper it for a smooth finish. Use the 3D printed part as the core; add lightening holes as needed..

 

[rharshberger]

In the last year or two a TRF'er was doing a scale SpaceX Falcon iirc and was rolling his tubes from paper drywall tape. Of corse the search function sucks and I cant currently locate the thread.

 

[Rktman]

"PLA" is the corn based plastic most often used. And yes, they can be rough (surface texture, depending on build level settings) and weak (I'll be one of the first to say it too!!). But in your case, with the right supports, should be too bad. ask if he can do ABS, much better. And, paper it for a smooth finish. Use the 3D printed part as the core; add lightening holes as needed..

Thanks for the advice. I tissued the original wood ones and still have a lot left over, so good suggestion.

 

[Rktman]

In the last year or two a TRF'er was doing a scale SpaceX Falcon iirc and was rolling his tubes from paper drywall tape. Of corse the search function sucks and I cant currently locate the thread.

Wow that's a new one. Worth checking out my local Lowes store down the street to get an idea of thickness/strength. But if he was using it for HPR it must be plenty durable.

 

[rocketguy101]

In the last year or two a TRF'er was doing a scale SpaceX Falcon iirc and was rolling his tubes from paper drywall tape. Of corse the search function sucks and I cant currently locate the thread.

several hits (about drywall tape tubes) came up on google using this search "drywall tape site:rocketryforum.com" (without the quotes)

 

[rocketguy101]

In the last year or two a TRF'er was doing a scale SpaceX Falcon iirc and was rolling his tubes from paper drywall tape. Of corse the search function sucks and I cant currently locate the thread.

several hits came up on google using this search "drywall tape site:rocketryforum.com" (without the quotes)

 

[rocketguy101]

Apogee published an article on figuring the wraps for spiral tubes in newsletter #304 https://www.apogeerockets.com/education/downloads/Newsletter304.pdf

 

[prfesser]

I've been doing 3.4" ID tubing with 2" un-reinforced, water activated paper tape spiral wound around a PVC mandrel. https://www.uline.com/BL_3062/Kraft-Paper-Tape I do 5 ply, the base one glue up. It took a couple tries to get the hang of winding a smooth wrap with even gaps. It took several more tries to figure out how to get the tube off the mandrel. My current approach is to pre-wrap the mandrel with baby-powder dusted wax paper. After wrapping the 5 layers, I put it in the freezer for a while. Pull it out, slide it off, let it finish drying. The water-activated tape seems to shrink a bit as it dries. The ones I let dry on the mandrel, I had to cut off :-(

About 20-odd years ago I wrote a pamphlet on making spiral-wound tubes, I think that Apogee still has it. Charles has the right of it. Gummed kraft paper tape is very strong and much easier to work with than paper-and-glue. Yes, the tubes shrink a bit as they dry. One solution is to apply two layers of wax paper to the mandrel, then remove the tube as soon as it's done, remove both layers of wax paper, and slide the tube back on so it will dry evenly. A little baby powder on the mandrel doesn't hurt. Most 3" wide gummed paper tape is 0.007" thick so seven layers gives 0.049" thickness, more or less. Winding alternating layers in opposite directions gives a stronger tube. Oh, and you handle a lot of paper with this method. Caution is advised. Paper cuts are not fun, especially when you get two or three in the same location. :-( I still make my own casting/liner tubes for making propellant, in some cases. It's also possible to make tubes from polyethylene-coated kraft paper, wound very tightly around a metal mandrel, and baked in an ordinary oven. Devil is in the details.... Best regards -- Terry

 

[Rktman]

Apogee published an article on figuring the wraps for spiral tubes in newsletter #304 https://www.apogeerockets.com/education/downloads/Newsletter304.pdf

Appreciate the urls David!