Reinforcing pultruded fibreglass poles

[Moondog55]

I have a large number of broken fibreglass poles here and while I was stripping them down to insert repair sections I had a thought. Is there a strong and reasonably priced permanent tape that could be used to make a wrap around the wand sections so that they will not split so easily?
Prewrapping should be effective if I can find a strong enough tape and wrap tightly enough
Just another mad thought but maybe somebody here has tried it or heard of some-one else doing it

[Scottyk]

You could try this stuff http://www.blackwoods.com.au/part/00472 ... 12mm-x-55m
It has an incredible tensile strength and wrapped very tightly I would think they would make a difference. It has unidirectional fibreglass running along it and it might stop the pole from splitting.
It would be interesting to wrap some old pole sections and do some destructive testing to see if there's a difference against an unwrapped pole.

[Moondog55]

Interesting that you should post that link.
I found something similar at a supplier here in Geelong and they have ordered me 2 rolls
1 roll linear and a roll of bidirectional for me to try out. The linear is only $4- a roll in 38mm * 45m and the bi-directional a reasonable $6- a roll
I agree the linear tape should work best in a spiral wrap
OK how do I get a real test going? Suspend a mass from the centre of the wand section and keep loading it until it snaps
What would be a reasonable test mass for a 460mm length that approximates a real world wind speed of 100kph+
I'll do this as i have lots of old pole sections here and see what the difference is
it will take a few weeks tho for me to get organised

[Zone-5]

Heat shrinkable tubing



I have used adhesive lined heat shrinkable tubing for donkeys years for my tent poles. Stops them from splitting and stringing and keeps the glass out of the tent and that blasted tent itch you get after a while! I had to burn my first tent because it was riddled with glass fibres but the new tent got to heat gun this shrink tube onto the rods and they stay as new for years. Try it you won't ever go back to factory raw fibreglass rods...

I got in a 20 meter roll, heat gun + head attachment and was worth spending the $$.

[Scottyk]

Interesting that you should post that link.
I found something similar at a supplier here in Geelong and they have ordered me 2 rolls
1 roll linear and a roll of bidirectional for me to try out. The linear is only $4- a roll in 38mm * 45m and the bi-directional a reasonable $6- a roll
I agree the linear tape should work best in a spiral wrap
OK how do I get a real test going? Suspend a mass from the centre of the wand section and keep loading it until it snaps
What would be a reasonable test mass for a 460mm length that approximates a real world wind speed of 100kph+
I'll do this as i have lots of old pole sections here and see what the difference is
it will take a few weeks tho for me to get organised

Get a spare pole with the pole joiner bit in it and put it in a vice at about 45 degrees above horizontal. The slip the taped pole to be tested in the open pole joiner, tape some rope on the end of it. Then hang weight onto the rope until it breaks the test pole, record weight it took to break it and then do a few more for some accuracy (average). Then repeat without any tape on the poles. Basic kind of destructive testing stuff

Interesting idea zone5, would help with the fibres entering the tent but I wouldn't think it would increase the strength. Unless it reduces damage from being dropped etc and therefore stops them breaking??

[Zone-5]

No amount of wrapping will increase the strength! What the shrink does, it holds the fibres in place with a hard plastic coating that shrinks down tightly onto the rod. This stops the fibres from splintering off thus keeping the rod together to use it maximum strength. You can bend these rods way past breaking point with no observable damage or failure. Also keeps you hands clean of glass needle stick injuries...

[Moondog55]

Interesting
What did the roll of shrink wrap cost and are there different grades?
Looking at the OZtrail poles I have here as spare parts I think those might actually be shrink-wrapped, but if so it is with a fibreglass reinforced tape
OZtrail say their poles are 30% stronger than a normal pultruded wand

[Scottyk]

Heat shrink is not a hard plastic, it is still quite flexible.
Wrapping uni-directional tape around the pole will work much better at stopping the splitting than a soft plastic wrap will.
Let us know the test results if you do some Moondog

[Moondog55]

Skottyk I will certainly try and be a little more disciplined in my testing this time
I found this when doing my Google search

http://www.google.com.au/patents/US5328743

So a product does appear to be around somewhere

[Scottyk]

Interesting product, looks like it is more aimed at product wrapping for shipping etc. If it came in long tubes ready to shrink it would be the perfect as it has filaments in the composite.

[Moondog55]

Found this

http://heatshrinkprinting.com/shrinkfle ... ink-tubing

I just send an email inquiry

[Mickl]

Moondog if you wanted to get a small amount of heat shrink tubing with the glue Jaycar sell it if you have them in Vic otherwise heaps on Ebay. The heat shrink with glue doesn't stay soft like the normal gear as the internal glue sets and goes hard...

[Moondog55]

For a small amount as a test I suppose I can afford Jaycars exorbitant prices and it's just 10 minutes down the road

[madmacca]

No amount of wrapping will increase the strength! What the shrink does, it holds the fibres in place with a hard plastic coating that shrinks down tightly onto the rod. This stops the fibres from splintering off thus keeping the rod together to use it maximum strength. You can bend these rods way past breaking point with no observable damage or failure. Also keeps you hands clean of glass needle stick injuries...

This is way past my knowledge of stress engineering. But wouldn't wrapping help transfer some of the stress from a narrow point on the inside of the bent pole to its full circumference?

[Moondog55]

Zone-5 I need you to explain this
My understanding from making a few Carbon fibre poles it that the strongest poles come from having the fibres oriented in different directions. Longitudinal fibres for flexural strength and radial fibres to provide resistance to the compressive and tensional stresses that would allow the longitudinal fibres to separate.
Wrapping a pultruded wand section with linear tape would provide this added resistance as would using the cross weave tape longitudinally.
I suppose then I could go the extra yard and add the flexible shrink wrap over the top in case the glue lets go but having used a similar tape in packaging before the tape is both very strong and tenacious.
When I first posted the question I had forgotten my previous experience with the tape

[Moondog55]

Jaycar however do sell this braided heat shrink tube which would seem to be a product I could use
It is however [ like most Jaycar products] very expensive for what it is

http://www.jaycar.com.au/Wire%2C-Cable- ... m/p/WH5620

But it may be cheaper than replacing whole poles

[Zone-5]

I have a large number of broken fibreglass poles here...

Zone-5 I need you to explain this
My understanding from making a few Carbon fibre...

I'm not talking about Carbon Fibre! That is a completely different animal as to fibreglass!

With fibreglass rods the fibres run longitudinally only...
Once a glass fibre peels or splinters off a rod/pole it reduces the strength of the fibreglass pole as a whole.
My solution simply stops the fibreglass fibres from splintering off a fibreglass rod when it is bent.

http://www.techflex.com.au/techflex-bra ... ink-tubing

[Moondog55]

Cheap pultruded FG wands may only run longitudinally but it isn't the only way to make an FG pole
A laid up pole in either material can use a combination of longitudinal and radial fabrics
Some FG fishing rods are amazingly flexible as well as super strong.
Pultruded sections use far more resin than fibre, this is of course to get the cost as low as possible.
I would like you to explain the engineering behind your statement in language simple enough for a non-engineer to follow.
Thanks for the link I have been waiting since last Thursday for a reply from them as Jaycars price is exorbitant even with my trade discount.
To my way of thinking it doesn't matter how you constrain the longitudinal fibres, either with shrink wrap or the much cheaper tape.
If I'm wrong I need to know so I do not spent too much money chasing the wrong rabbit and my curiosity means I also need to know why.

[Zone-5]

Yes you are right, you can use anything to hold the fibres together just as long as you do. I just find that the glued harder plastic reinforced shrink wrap hot gunned onto fibreglass rods is a cheap, strong and a very quick solution.

The main problem I find with bare fibre glass is that it is easily damaged while in storage. A scratch, nic and a drop can dislodge or weaken the fibres. Shrink wrap tubing adds that extra layer of bonded protection and adds resilience with an extra tough layer.

The shrink wrap does not add strength, it just help the rods maintain their 100% strength for much longer.

Hope you find what you can use and cheaply...


NOTE: here is a tip. Write to the manufacturer and explain what you are doing. They will gladly send you out free samples to test so you don't waste your money. If it works out OK then they will have got another happy customer with good recommendations...

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For those who are interested here is the pultruded fibreglass pole manufacturing process simplified...

[Moondog55]

So using it is simply a constraining layer; OK; your use makes sense even if it isn't the strongest way; it is strong enough I assume
I never thought about asking for a sample although I did explain what I was trying to do.
I'm conducting a thought experiment at the moment and wondering if using a combination of both products would work better than either on it's own
The tape has arrived; I could try wrapping a wand section in tape then shrink wrapping and quickly compare that to a section that has been done with each product on its own
Shame I do not know any trade teachers with access to a testing laboratory

[Zone-5]

The strength is 100% in the fibreglass rod not the tape. The tape does not add any strength!

[Moondog55]

I'm still asking you to prove that so I can understand it.
It goes against my understanding of how tent wands work
My understanding is that when a wand section splits it isn't the fibres breaking but the resin bond.
As the tensile strength of the fibre is much greater than that of the resin then wrapping the pultruded blank with a tape reinforced with FG must be part of the resistance to splitting as I see the problem
Spiral wrapping is how fishing rods used to be made before mandrel rolling was developed

[Zone-5]

...get some shrink tube and some wrap tape. Wrap 'em up and flex'em heaps of time until they break. Go with what works best...

[Moondog55]

So I got myself some of that FG wrapping tape, one roll of each type and some of the woven fibre shrink-wrap from Jaycar
The Jaycar shrink-wrap isn't really suitable but it works
I was able to bend a joined section of tubing double and it then cracked at the centre ferrule, that's way more flex than it wold see in a storm so it works and works well enough to persevere
Now to find a local supplier of that polyester fibre reinforced clear stuff
EDIT
Actually it wasn't the fibreglass wand that broke, it was the steel ferrule snapping in half. I have never seen a wand do that before
I just put a section over my knee and tried to break it
No way I could on muscle strength alone and I couldn't bend it double in such a short [660mm] length
Whoopee

[Zone-5]

Yep, what I found as well...

...and look no glass fibers sticking into your hands or messing up the tent interior either!

[Moondog55]

So now all we need to do is find a supplier of the fibre reinforced shrink-wrap tubing and we can make our own super strong FG wands at a reasonable cost

[Zone-5]

Email these guys and ask for a test sample before you make an order with them...

http://www.techflex.com.au/techflex-bra ... ink-tubing
&
http://www.heatshrinkprinting.com/shrin ... g-products

[Moondog55]

They are the company that supply Jaycar and they don't send out samples unfortunately

[Moondog55]

Update time soon
I've been spending the rainy morning wrapping the cheap FG poles of the new tent.
The 38mm cross weave tape just goes around an 11mm wand section
I tried spiral wrapping and it didn't seem to be much if any stronger
Tedious job but I think it will be worthwhile; I may shrink wrap the part where the steel ferrule joins the wand just to make them a little pretty and a bit smoother for feeding through the sleeves on the tent