Roll your own?

[McKailas Dad]

Body tubes, that is... Yes, I could buy them, but I'm kinda diggin the scratch building. We've made a few of the FlisKit Midnight Express rockets (thanks Jim!), where the tube is 'verticaly' rolled, but what are some techniques for spiral rolling?

I tried a spiral roll with some posterboard around a Pringles can, just for kicks. I cut a 2 inch strip and spiraled it, and tried to 'tack' it together with CA 'spot welds'. Then went back and filled in where I hadn't glued, untill the full spiral was glued.

Needless to say, that 2 inch strip is permanently glued to the can...

Would wax paper have helped? PVC mandrel maybe?

Also, I looked at an empty paper towel tube and noticed it seems to be a double spiral; an interior and exterior? Are BT's usually more than one layer?

If 2 or more layers, would a spiral 'up' and a spiral 'down' as to make opposing 'grain', make it more stable/sturdy? Maybe a foil layer?

Just thinking out loud...

Thanks in advance!

 

[GregGleason]

A similar technique is used by composite airframe builders when using fiberglass or carbon fiber materials and laminating epoxy (not epoxy adhesive).

One method is to take a tube form (the mandrel) and coat it 10 times with release wax. Then wrap thin mil Mylar around the mandrel and tape the seam and coat that with about 5 or 6 coats of release wax. The idea is that the Mylar will release itself from the mandrel.

Then apply the 2 or 3 wraps of fiberglass or carbon fiber to the Mylar. Let cure for about 24 hours. You should be able to work the layup from the mandrel.

I suppose the same thing could be done with paper, but if you are going to all that trouble for a 2 inch OD airframe, why not make something that is fairly crush resistant?

:2:

ShadowAero's first instructional DVD (video 1) shows you how make fiberglass airframes (if you are interested) and do not have a rocket mentor close by.

Greg

 

[Rocketjunkie]

If 2 or more layers, would a spiral 'up' and a spiral 'down' as to make opposing 'grain', make it more stable/sturdy? Maybe a foil layer?

Just thinking out loud...

Thanks in advance!

I spiral roll many of my casting tubes when making motors, also for odd size 'one of' tubes. All are at least 2 layers, more if thicker tubes are needed. I use gummed paper tape like McMaster 7624A1 (thru 6). One roll will make a LOT of tubes. You meed a mandrel the size of the desired ID. I use a metal rod or tube. You can roll nesting tubes by rolling a tube on the mandrel, then rolling another shorter tube on top of the first. The width of the tape should not exceed about twice the diameter of the tube you intend to make.

Cut a piece of tape for each layer in the finished tube. One piece needs to be about 4 times the width longer than the rest. Take the long piece, and glue side out, wrap it around the mandrel so the edges touch. A small piece of masking tape will hold down the end. Continue spiraling the tape down the mandrel with the edges touching until all in wrapped. Use a second small piece of masking tape to hold down the second end. Do not wet this piece!! Wet the second piece of tape and align it over the seam in the first layer, glue side in. Roll it the same direction, covering the seam in the first layer. Repeat for any additional layers. Once done, remove the masking tape from the first step and slide the tube off the mandrel. Once dry, trim the ends. An alignment line may be drawn on the tape strips to help with aligning the later layers. Draw this line on the glue side of the long strip and the other side of the rest. Multi layer tubes will show a gap as the OD gets larger. For short tubes you can adjust the angle to keep this gap closed but longer tubes will expose the seam in lower layers.

It does take practice to make consistent good tubes but the supplies are cheap. Oopsies can be cut from the mandrel with an x-acto knife.

 

[texas-bill]

...coat it 10 times with release wax. Then ... coat that with about 5 or 6 coats of release wax.... Then apply the 2 or 3 wraps of fiberglass or carbon fiber to the Mylar.

...but if you are going to all that trouble for a 2 inch OD airframe...

If I'm going to that much trouble, I'm gonna drop 10 bucks on rocket tube to start with.

_

 

[gpoehlein]

OK - my technique for making my own spiral tubes is to get some thin paper - 20lb bond is good. Actually, my favorite is adding machine tape - it is about 20lb and you can cut strips as long as you need - the longer the strips the longer the tube.

Next, you need a mandrel. Take a length of brass tube or dowel rod a bit smaller in diameter than the inside diameter of your body tube. Wrap enough layers of computer or typing paper around it until it is just a bit smaller than you need. Finish off with wax paper until the inside diameter is just the right length. Glue the inside of the wax paper with CA to hold it in place.

Now cut strips of paper about 1/2" wide from the adding machine tape. Wrap the first layer spirally around the mandrel so that the edges just touch but don't overlap. Secure both ends with masking or Scotch tape. Start a second layer of 1/2" wide paper going the oposite direction around the mandrel, but only secure one end. Unroll it and apply white glue thinned with water to the inside of the paper strip with a brush. Smooth in place, taking care again not to overlap the spirals but to keep them as close as possible. Repeat with a third layer going in the same direction as the first. Let dry, remove the tape and remove from the mandrel. Square up the ends and you've got a nice light weight body tube. You can add a fourth layer if you really need a thick walled tube, or use heavier (24lb) paper.

 

[Micromeister]

Have a agree with Gregs methods (I love using adding machine tape also)... but Like Texas-bill:

For most "standard size" model to mid power body tubes they are so CHEAP it's just not worth the time to roll your own tubes.
and if you buy in bulk they get down to pennies per model

 

[TheAviator]

I think that rolling your own tubes is an excellent technique to learn, if only for the fact that you can make any size of tube you want. Need a tube for that scale model? Got it. Need something that slips over a particular tube? Got it. Need a HUGE but lightweight ring fin tube? Got it.

Not that I don't have my stock of standard tubes (nowhere NEAR what yours is, though, MM :jaw: ), it's just a really useful technique IMHO.