Questions about making my own tubes

[les]

I am thinking of a project where I need some non-circular tubes. such as triangle or square shape.
This is all for low power rockets.

I was thinking of getting some bar stock as a mandrel, wrap it with wax paper, then wrap it with card stock.

I was NOT going to do a spiral wrap, just wrap the length of card stock over the mandrel with an extra "tab" to glue back on itself sized to end at a corner. Basically for a square tube, the cardstock would have 5 sides, where sides 1 & 5 overlap and glue together.

So, bedsides the wax paper, should I apply anything else to the mandrel to help remove the tube when dry?

What glue should I use? Simple white glue, carpenters yellow glue, or should I use epoxy to strengthen the tube?

Should I even use card stock or use multiple layers of thinner printer paper?
And should I actually do a spiral wrap???

What else haven't I considered???????

 

[David Schwantz]

I would use some mold release on the tube just in case.

 

[tsmith1315]

Perhaps get a roll of kraft paper, some card stock and experiment! I bet spirals are done for good reason.

 

[KenECoyote]

Unless I'm missing something... why use a mandrel when you can simply mark and fold the cardstock into a triangle or square?

 

[Bill S]

I thought a hexagonal tube with an appropriate nosecone would have been awesome.

 

[techrat]

Spirals are done (I think) for the same reason that when you're laying fiberglass or carbon fiber, they say to lay the second layer in a direction 90 degrees opposite the first -- to get the fibers to criss-cross one another to enhance strength, reduce the tendency to bend in one direction, and make the resulting shape as rigid as possible with the fewest layers.

 

[Raythain]

Spirals are done so that you can get a longer tube than your paper stock. If I’m wrapping a tube from standard 8 1/2” x 11” paper, it can’t be taller than 11”. If I strip a couple of pieces, I can spiral wrap one longer.

Convolute wrapping is actually stronger, but it’s a lot easier to manufacture long spiral tubes and cut to length. If you delaminate a spent engine casing, they’re actually convolute wrapped.

I second the recommendation to get a roll of Kraft paper and test. At minimum I’d aim for two full wraps (so at least 6 sections for a triangular tube). Experiment with different amounts of wrapping, and different glues. My first attempt would be a glue stick or spray adhesive so I could coat the whole paper evenly.

I know there are a couple of Apogee Peak of Flight articles about making tubes, but I don’t have them handy.

 

[GlenP]

Length, width or equivalent diameter, drawing or pictures?

non-circular bodies from cardstock examples:
https://www.spacemodeling.org/jimz/ka-10.htmhttps://www.spacemodeling.org/jimz/ka-12.htm

a regular Glue stick works great for LPR cardstock rockets, easy to smooth a thin layer where you want it, it dries clear. You might not even need a mandrel, if you can use a small dowel or ruler to help press down the glue tabs when forming the shape.

 

[kuririn]

This is all for low power rockets.

What else haven't I considered???????

If you don't want to spend a lot of time experimenting on this:
Take a look at how Toblerone makes their triangular candy containers.
Three sides with a 1/4" glue strip.

Jim Flis did the same with a couple of his cardstock rockets.

For bigger, more durable rockets use corrugated cardboard like the Priority Mail triangular mailing container. Note that corrugated cardboard has a grain, keep that in mind when making the folds. You may want to lightly score the fold line first. It's a good idea to use some kind of metal straight edge to do the fold too.

Art Applewhite has some good designs using the corrugated cardboard from mailing containers.


Easy to extend the concept from three or five sided saucers to multi sided cardboard tubes.
And the Applewhite Hex Six, six sided cardstock rocket.

In any case, if more rigidity is needed the option of adding balsa or fiber rings (like in balsa airplanes) is always there.

Have fun!

 

[prfesser]

Commercially, spiral-wound tubing is easier and faster to make than convolute and is easily automated. The number of strips of paper to be wound are coated with adhesive---usually dextrin-based as it's cheap---and wound around a mandrel. A moving blade cuts the tube into the desired lengths. Here is a two-minute video showing one in action.

I've made hundreds of spiral wound tubes by hand, using gummed paper tape. Much easier than kraft paper and glue, which tends to wrinkle. One of these days I'll put up a few images and a video or two.

Suggestion: wrap two layers of wax paper or of silicone-coated backing paper (from Con-Tact paper or similar). Remove the tube from the mandrel while it's still damp, remove the wax paper, dust the mandrel with talcum powder, slide tube back on. It will shrink some. If done right it should shrink to the size of the mandrel, but is still removable.

[Dextrin adhesive is the stuff on lick-and-stick envelopes and such. It's easily made at home. A pound of cornstarch spread onto a large cookie sheet and baked at 400 F for an hour or so, stirring well every 15 minutes or so. It should turn a pale cream/yellow. Dissolve in water. May take a lot of stirring. Commercially, borax is added, I think as a thickening agent, but I've never done that.]

Terry

 

[G_T]

The borax is probably added to prevent things like fungus from growing on it and bugs from eating it. Just guessing though.

Gerald

 

[neil_w]

I thought a hexagonal tube with an appropriate nosecone would have been awesome.

It is cool!

 

[SolarYellow]

The borax is probably added to prevent things like fungus from growing on it and bugs from eating it. Just guessing though.

Gerald

Worth doing for anyone south of the Maxon-Dixon line and east of I-35.

 

[waltr]

It is cool!
View attachment 561302

Like this:
http://www.artapplewhite.com/free/13mmsixinstructions.pdf