Ways to adhere a non-flush metal rod inside a carbon fiber tube?

[fuzzybabybunny]

I've got one leg of a carbon fiber tripod and I want to mount a 1/4" threaded tripod screw onto the tip.

The section of tripod leg is basically a hollow carbon fiber tube:

10mm OD
7mm ID
Smooth on the inside
1 foot long

I need one end of the tube to have a solidly-attached 1/4"-20 threaded screw so I can screw on a small ballhead, GoPro mount, or other attachments.

1/4" is 6mm diameter, so it doesn't fit flush or tight with the inside of the tube which is 7mm.

Any ideas for ways to do this?

I was thinking of buying a long 3" screw with 1/4"-20 thread and cutting off the head. Then coat it in some kind of glue that expands when it sets (perhaps Gorilla Glue?) and hope that that's enough to withstand the resulting rotational forces from screwing and unscrewing various attachments to the exposed screw thread. I doubt Gorilla Glue would be good for this though as Gorilla Glue is pretty foamy and soft.

Ideally I would like a metal part where one end is a smooth 7mm cylinder while the other end is threaded in 1/4"-20, but that's probably not going to happen.

 

[John Connor]

Instead of messing with all of that, why don't you just buy a mono-pod? I got mine at Walmart for like $20.

But if you insist there are some great adhesives out there. Go to Ace Hardware with the helpful hardware folks and ask what they recommend. I knows there's this one epoxy that once cured is like cement, and it bonds to most everything. Although, carbon fiber is an interesting one.

Edit-

Come to think of it, I'm sure there are epoxies out there meant for boats that might work well.

 

[fuzzybabybunny]

Instead of messing with all of that, why don't you just buy a mono-pod? I got mine at Walmart for like $20.

But if you insist there are some great adhesives out there. Go to Ace Hardware with the helpful hardware folks and ask what they recommend. I knows there's this one epoxy that once cured is like cement, and it bonds to most everything. Although, carbon fiber is an interesting one.

I have a selfie-stick and monopod already, but I don't want to carry it. The tripod I have has a leg that's removable and turns into a monopod, which is what I'm trying to thread here.

The fat end of the monopod / leg has the 1/4" screw for mounting a ball head, but the thin end (the foot) does not. I could mount a GoPro to the fat end no problem, but it is really really cumbersome to use as a selfie-stick when you're holding the thin end of the stick in your hand with the heavy fat end at the other end - it needs to be the other way around.

 

[John Connor]

1/4" is 6mm diameter, so it doesn't fit flush or tight with the inside of the tube which is 7mm.

I'm thinking with the right epoxy meant for both materials, all you have to do is build up the epoxy to only the 1mm needed inside the tube. Otherwise you're gonna have to come up with a taper idea and I think that just complicates things. But that's just me being a simple man. LOL 1mm isn't much space though. That's 0.039 of an inch.

 

[John Connor]

Full disclosure, I'm no engineer. Someone might have a better idea.

 

[John Connor]

Is the screw just steel? If needed you could go copper or brass if necessary to bond to the epoxy and carbon.

 

[fuzzybabybunny]

The screw will likely be steel. Depends on what the hardware store has. Does brass or copper bond better to epoxy or something?

I'm also thinking that some sort of epoxy is the best bet. Epoxy has good shear strength so it should withstand twisting motions, and epoxy can fill gaps as well as be removed by heating the parts up.

Gorilla Glue does not have good shear strength and while it expands, it rapidly loses strength after about 1mm of expansion. It's also not very rigid.

I also looked into threadlockers but those seem to require a metal-on-metal surface and an anaerobic environment to set. A gap between a steel screw and a carbon fiber tube would likely not be the best for threadlocker.

Cyanoacrylates like instant super glue are brittle and probably wouldn't be good in this scenario.

 

[lxskllr]

Teflon tape. Wrap the threads, and screw it into the tube.

 

[JulesMaximus]

You could use a two part fiberglass resin.

 

[JulesMaximus]

Teflon tape. Wrap the threads, and screw it into the tube.

That would split the tube. Carbon fiber is extremely brittle.

 

[lxskllr]

That would split the tube. Carbon fiber is extremely brittle.

Wrap the outside with cord using a temporary whipping.

 

[PottedMeat]

find some <7mm OD rubber washers (like faucet washers maybe) and stack them on the 1/4-20 bolt. put the bolt head down into the carbon fiber tube until the rubber is under the carbon rim. use a 1/4-20 nut to crank down on the rubber until it expands to hold in the tube

 

[deadlyapp]

find some <7mm OD rubber washers (like faucet washers maybe) and stack them on the 1/4-20 bolt. put the bolt head down into the carbon fiber tube until the rubber is under the carbon rim. use a 1/4-20 nut to crank down on the rubber until it expands to hold in the tube

I actually really like this idea but may cause the CF to crack. Depending on how the CF was formed, it may have a weak point that will burst if any pressure is applied from the inside.

FBB, I think you're overthinking this. Most 2 part epoxies bond extremely well to nearly everything, and realistically you're not using tools to tighten the parts down, so you shouldn't worry about applying too much torque. If you're especially worried, then find or make a sleeve to go over the top of the CF rod as well, which will give you further contact and will prevent the bursting due to pressure on the inside.

 

[tynopik]

just drill baby

 

[John Connor]

Does brass or copper bond better to epoxy or something?

There are many, many different types of epoxies. And they all bond to different materials. Some will bond between plastic and steel, but it has to be a certain plastic or a certain steel. There are universal epoxies, but you want to find something more specific. So I mention that if you can't find an epoxy that says it bonds between carbon fiber and steel, but brass or copper, then that is an option.

Like I said, visit your local Ace or another good hardware store and describe are project. They're usually pretty helpful. More so than the big Home Depot type stores.

 

[John Connor]

just drill baby

SMH Intelligence level subatomic particle in absolute zero.

 

[dave_the_nerd]

Tap & Die kit and a sleeve.

Get another piece of pipe with an 8mmOD and 6mm ID. Thread it, and thread the inside of the plastic tube. Then loctite the whole thing together.

You'll probably have to reinforce the plastic tube, as noted above (by wrapping it in something.)

The "cheap" way with the screw floating inside and a bunch of epoxy to fill the gap would also probably work fine.

 

[John Connor]

Every damn time I've used a tap & die it never quite worked out. I was successful in one instance. I find myself using screw extractors more so then anything. Thank GOD! for that invention.

 

[dave_the_nerd]

Every damn time I've used a tap & die it never quite worked out. I was successful in one instance. I find myself using screw extractors more so then anything. Thank GOD! for that invention.

I've broken off a tap here and there, but mostly, it's not hard if you use lots of lube and go slowly and carefully. (No jokes, please.)

You know what's really fun? Tap and die kits for wood. You can make all sorts of cool retro kids toys, etc.

 

[John Connor]

You know what's really fun? Tap and die kits for wood. You can make all sorts of cool retro kids toys, etc.

Wow, that's cool. I never much thought of those, and I guess it makes sense given some things I've seen made in wood.

 

[herm0016]

some odd suggestions above for sure. I worked in a composites factory for a bit as an engineering tech.

The expanding stuff may work, but it will be a pain ever time you want to remove the camera, and it is likely to crack the CF tube.

CF tube is resin (glue) and the carbon fiber strands. I would rough up the inside of the tube with a little sand paper, a file, or similar and glue using either e-6000 or a 2 part epoxy like the lok-tite brand stuff in the tubes. .5 mill radially is not a big gap to fill. Rough up the metal insert with scratches that are along its length, not along the circumference. you want mechanical keying in the resin of the tube and in the metal. IF you are worried about the stress on the end of the tube, wrap the first half inch in braided fishing line, almost the same as CF, some of it is kevlar even. and use cyanoacerlate (super) glue or the epoxy to bond it. don't touch any of it until it's dry.

The only advantage of brass would be corrosion resistance.

this also has the advantage of being easy.

 

[WHAMPOM]

Why no one suggests a clamp on camera mount (one designed for car windows could work) I have no idea at all.

 

[IronWing]

Squirt hot glue into the tripod tube, heat the steel rod and push it into the glue. Let cool.

 

[Thebobo]

30 mix epoxy and filler such as fiberglass shavings or glass beads or even sawdust or the like. Mix epoxy with filler 50 50 and install tube.


Or you can strap it to the side of the leg with spider wire and wrap it a bunch of times and epoxy you be able to hammer with after. Like a splint.

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[fuzzybabybunny]

Why no one suggests a clamp on camera mount (one designed for car windows could work) I have no idea at all.

They're really bulky in comparison to a single screw and the bar mounts get caught on literally everything. Plus the diameter of the tube in question is too thin for a typical bar mount.