An experiment: building a larger ring out of smaller tubes

[neil_w]

Had this idea while PMing with @rklapp... You can make a coupler or smaller tube by slicing a piece of a larger tube... could you also go in the other direction and make a larger tube? I've been faced with this need before.

So, a quick experiment: starting with BT80 (2.6" OD), make a ring approximately 3.3" OD. The ring will be 1/2" wide. Going in I have no idea how well this will work.

The materials:

• 3 BT80 rings, 1/2" wide (two shown, I later realized I needed a third)
• "mandrel": a masking tape core covered with foil tape to prevent accidental gluing (foil tape not shown in this pic)

I snip each of the rings so they can expand, then wrap one around the mandrel. As expected it doesn't go all the way around.

Next I cut a piece of the spare third ring to fit the gap. Ideally, undersize it by a millimeter or two (I failed to do this, regardless of how it looks in the picture.)

I then glue that piece to the inside of the second ring:

Next three steps not photographed while I juggled gluey stuff:

• Apply glue to outside of ring on mandrel
• Place the second ring (with extra piece above) around it, lining up the extra piece with the gap in the inner ring
• Try like heck to get the two rings wrapped as tightly around the mandrel as possible. As I have learned while bending balsa, it is very very hard to do this perfectly. The resulting ring will end up being a millimeter or two oversized.

Then cut another piece of the spare ring to fill the gap in the outer ring, and glue:

Keeping the ring on the mandrel, I worked it around and kept squeezing it with my fingers to ensure that the glue bonded properly all the way around. Eventually when I was satisfied it was going to stay put, I wrapped a rubber band around it and let the glue dry the rest of the way.

And, finished:

Seems to be maintaining its roundness, looks pretty good to me. For proper finishing, I would use some filler to smooth out the seams, and then sand the edges.

I call this a success. Whole thing took me about 15 minutes, and was much easier than bending balsa. Finished ring is slightly heavier than a two-ply (1/32" per ply) balsa ring, but thinner.

In this experiment I expanded the ring by 27%, and it's fine. Don't know how much further I could go before it started to strain. Also I expect it would get challenging to do with a much longer piece of tubing.

 

[mbeels]

That came out well. From here, it looks like it would be quite strong.

 

[neil_w]

That came out well. From here, it looks like it would be quite strong.

It's not as strong as the one I made out of 2 x 1/32" balsa. So much quicker and easier to make, though.

 

[BABAR]

Looks great! Less filling,

I.e., what you have looks great (and requires less filling than balsa)

I’d look at Quaker Oats boxes and mixed nut “cans” (often metal top and bottom, but sides are actually cardboard). If the measurements don’t have to be exact, you may find something “off the shelf” that might work for you.

I cannot be held responsible for the effect of this technique on the diameter of your waistline.

 

[Ronz Rocketz]

Now that's what I call rocket science!

 

[Ronz Rocketz]

 

[jqavins]

Had this idea while PMing with @rklapp... You can make a coupler or smaller tube by slicing a piece of a larger tube... could you also go in the other direction and make a larger tube?... So, a quick experiment: starting with BT80 (2.6" OD), make a ring approximately 3.3" OD. The ring will be 1/2" wide. Going in I have no idea how well this will work...

Keeping the ring on the mandrel, I worked it around and kept squeezing it with my fingers to ensure that the glue bonded properly all the way around. Eventually when I was satisfied it was going to stay put, I wrapped a rubber band around it and let the glue dry the rest of the way.
View attachment 455881

Suggestion: a hose clamp would help with pulling everything tight on the mandrel and would be at least as good for the glue drying as the rubber band.

And, finished:
View attachment 455882

This is why you are known as a master modeler.

I’d look at Quaker Oats boxes and mixed nut “cans” (often metal top and bottom, but sides are actually cardboard).

The insides of the nut cans are foil lined cardboard, at least some of the time. So gluing might be an issue. The oat canisters is a great idea. There are also bread crumb canisters. And Pringles cans, for smaller rings, again with foil lining on the inside if you can deal with that.

 

[neil_w]

Suggestion: a hose clamp would help with pulling everything tight on the mandrel and would be at least as good for the glue drying as the rubber band.

Didn't have any handy and totally forgot about that option.

I tried hose clamps for my Alcubierre balsa rings and just couldn't wrangle them... also the clamps imprint on the balsa. For these rings made from BT, where a lot of clamping pressure isn't required, the hose clamps would probably work very well.

 

[BABAR]

Didn't have any handy and totally forgot about that option.

I tried hose clamps for my Alcubierre balsa rings and just couldn't wrangle them... also the clamps imprint on the balsa. For these rings made from BT, where a lot of clamping pressure isn't required, the hose clamps would probably work very well.

Put something smooth (?parchment or waxed paper?) Between clamp and ring?

Electrical tape also good, it stretches and can compress

 

[neil_w]

Put something smooth (?parchment or waxed paper?) Between clamp and ring?

When trying to wrangle balsa that wants to straighten out, it is very difficult. My most recent adventure making a balsa ring (not documented here I don't think) used a different approach that might have worked with the clamps, maybe I'll try it in the future.

 

[Rocketjunkie]

The insides of the nut cans are foil lined cardboard, at least some of the time. So gluing might be an issue. The oat canisters is a great idea. There are also bread crumb canisters. And Pringles cans, for smaller rings, again with foil lining on the inside if you can deal with that.

The foil inside and outside of nut cans will peel off. I built a tube fin rocket with nut cans, peeling off the inside of the outer cans and using slit cans with the outside peeled off for couplers. Called it "You Gotta Be Nuts" LOC 4" nose cone Need to rebuild it after J99 cato

 

[jqavins]

If it dirt dives, you could say that it...





Wait for it...






Planted itself.

 

[Ronz Rocketz]

The outside ring is easy to glue into place so started with that. The inside is harder because the ends want to curl in so I tacked them with thin CA. The trick is to get it to the correct OD (66mm). I figure I'm +/- a mm. The real test is when I glue it to the insides of the fins. The genius of the design (yeah I said it) is the two part system. The grains are perpendicular to the airflow, and there's about 2mm of overlay to fit the ring.

 

[icyclops]

How about those wood rings they sell at Michaels or Hobby Lobby used for stitchery. They come in various diameters and you can remove the 2 end clamps. Maybe glue 2 0r 3 on top of each other to increase the height. Might work?

 

[Marc_G]

I made a largish ring fun once by using some large container as a form (think Quaker Oats), wrapping it in parchment paper to ensure release, then taking a long strip of craft paper and wrapping it around, using thin CA saturation to bond layers together. Worked fine. I used CA instead of white or yellow glue for some reason that made sense at the time but escapes me now.

 

[mjennings]

Good stuff! I may have to make a 3.5" ish diameter tube soon. Very helpful!

 

[jqavins]

I made a largish ring fun once by using some large container as a form (think Quaker Oats), wrapping it in parchment paper to ensure release, then taking a long strip of craft paper and wrapping it around, using thin CA saturation to bond layers together. Worked fine. I used CA instead of white or yellow glue for some reason that made sense at the time but escapes me now.

We've crossed over from upsizing existing rings to basic tube roling.

 

[BABAR]

We've crossed over from upsizing existing rings to basic tube roling.

As @neil_w has shown, upsizing rings from existing rings CAN be done.

what I personally find more satisfying is not, “Can it be done?” Is “Why are you doing it?”

In this case presumably the answer is, “Because I NEED a bigger ring than I currently have!” (Sometimes followed by, “obviously, you idjit!”)

the reason the “Why” is so important is that, if the goal is really “I need a bigger ring”, rather than just developing the art of MAKING big rings out of small ones (not that there is anything wrong with that), then the forum is a GREAT place to share ideas on the easiest and/or cheapest ways to obtain BIGGER RINGS.

I know, I need to get out more. On the plus side, weather is looking good next two days, and I have some new birds to launch. Fingers crossed!

 

[jqavins]

As @neil_w has shown, upsizing rings from existing rings CAN be done.

Well, yeah, that was kind of my point. If the thread is about Neil's successful experiment, and it's migrated into other sources of bigger rings, one could say "You could roll a tube of whatever size then cut the length of ring that you need" without giving a tutorial on tube rolling or the notion that it's a novel solution to the larger ring issue.

Marc_G, sorry if the above sounds dismissive of your earlier post. Sure, rolling ones own certainly is a valid way of getting big rings.

 

[neil_w]

Don't worry about me in any case, I had my say up top. Discuss whatever you'd like here.

 

[icyclops]

As @neil_w has shown, upsizing rings from existing rings CAN be done.

what I personally find more satisfying is not, “Can it be done?” Is “Why are you doing it?”

In this case presumably the answer is, “Because I NEED a bigger ring than I currently have!” (Sometimes followed by, “obviously, you idjit!”)

the reason the “Why” is so important is that, if the goal is really “I need a bigger ring”, rather than just developing the art of MAKING big rings out of small ones (not that there is anything wrong with that), then the forum is a GREAT place to share ideas on the easiest and/or cheapest ways to obtain BIGGER RINGS.

I know, I need to get out more. On the plus side, weather is looking good next two days, and I have some new birds to launch. Fingers crossed!

There are many reasons to use this technique....I am always on the lookout for large ring/tube diameters to use in my designs....everything from fins to tube mods....

 

[Jeff Lassahn]

Are there advantages to starting with cut bits of tube instead of flat cardstock?

 

[neil_w]

Are there advantages to starting with cut bits of tube instead of flat cardstock?

My thinking was that BT already is built up from many layers, so
a) it is pretty strong to start with, and
b) tends to want to hold its round shape.

I'm not sure how many layers of cardstock it would take to achieve the equivalent, or how hard it would be to get it perfectly round. I suspect it would be harder than what I did, but I'd welcome a demo from someone to see how it would go.

 

[tsmith1315]

It's another tool in the toolbox, Neil. There's always room for more.

Are there advantages to starting with cut bits of tube instead of flat cardstock?

It may be as simple as what you have on hand to work with. That can be a huge advantage for me, so all techniques are fair game.