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Pete_001 - 5/18/2018 2:47:28 PM

Hi,

I'm new to carbon fibre but looking to use it for a new project(s).
1) I am aiming to use 25mmOD tube (either 1mm or 1.5mm wall thickness) and end up with a pole just short of 2.5m long
2) The pole will be carried horizontally at thigh height
3) A shoulder strap will be attached to the pole at one quarter and three quarters of the way along the length
4) On each end of the pole will be a 2kg weight

What are your thoughts about flexibility?
Is the proposed 25mmOD tube a sensible size for the length and weights attached?
Given the above, what about wall thickness?
I'm not looking exact engineering figures - just want to know if this will be fairly rigid or would I need to increase the diameter?

My next problem is that I need the pole to be able to break down into 0.5m lengths
Thoughts are along the lines of gluing a protruding insert into one end of each pole - so you end up with male and female ends that can push into each other and butt up
Now I need a quick release type connector (permanently attached at one end of each pole) to stop the tubes moving apart while in use. I can find lots on-line but they are all for telescopic tubes so mate with two different diameter tubes. They also need to be plastic or aluminium (I can replace steel bolts and pins with brass). Anybody come across such a thing? Or indeed have any ideas about quickly, securely and temporarily joining tubes of the same diameter?
(it was my intension to a key-way lug at each joint to avoid rotation)

Pete

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Dean C - 5/21/2018 3:09:09 PM

Good Afternoon,

I first want to say that I am an employee with DragonPlate and I am only on these forums to answer questions and offer tips or assistance. I only offer the links below for ideas and do not expect you to choose DragonPlate for your solution.

Typically, a tube for this application would be a roll wrapped twill finish tube. Specifically for your application, a 0.875”ID tube from dragonplate has a 25.4mm OD (http://www.dragonplate.com/ecart/product.asp?pID=6140&cID=135). With 2kg on each end and being fixed in the center, it would deflect around 1.5” on each side. If you want to less deflection and don’t have constraints on the OD, I would suggest going up in size.

With regards to your connections, we at dragonplate have two different solutions:

The first option is to use our carbon fiber tube ferrules: http://www.dragonplate.com/ecart/categories.asp?cID=165. One could bond one end into a tube and drill a hole for a push button system. We don’t offer the push buttons because drilling holes in carbon introduces stress concentrations into the epoxy matrix that could cause cracking and breakage. You can use tubes from 0.875”ID (which has the 25mm OD), up to a 1.75”ID tube.

The second option would be our threaded end connectors: https://dragonplate.com/ecart/categories.asp?cID=308. These are bonded into the ends of the tube and allow the assembly to thread together like a pool cue. The connectors are aluminum and the threads are steel. This assembly would be a bit heavier, but the joints would be more rigid and you would see less deflection. The pullout strength of the epoxy with our proprietary design is higher than the max failure stress of the tubes. We offer these connectors in the tube size you need and the connectors should be flush on the OD.

My last piece of information is about cutting. Tube can be cut with a band saw and a very fine tooth blade, a diamond blade on a saw, or a grinding wheel surface as with a Dremel tool. Be sure to wear eye protection, a tightly fitting face mask, and gloves as the fibers/dust is extremely irritating to the skin.

I hope this information was helpful for you to make a decision on how to move forward. Have fun working on your project!