Oct 12, 2012 at 8:58 pm #1294964
I suggest that you buy a few of the following:
(1) SkyShark P$X Camo (.244 id)-Great deal on a very strong but flexible wrapped carbon tube
(2) Pultruded carbon tube (.240 inch od) that fits nicely inside the SkyShark tube shown above.
The small tube fits inside the larger tube and can be used like a telescope or as a ferrel.
You can have a lot of fun for very little money.Oct 18, 2012 at 6:41 pm #1922681
The two carbon fiber poles shown below match up well. I've tried them at home. Makes for a nice stiff tent pole, using the narrower one for ferrels. The narrower (pultruded) one has an OD of .344 inches and the wider (wrapped) one has an id of .346 inches.
Edited. Had link titles mixed up.Oct 18, 2012 at 6:50 pm #1922684
drowning in spamMember
I'm wary of those thin poles for larger tarp shelters. I might build a thicker carbon pole using parts from these guys.
I did the math for a thicker pole in Evan's thread.
Carbon Fiber or Aluminum Tarp Poles
My plan is to modify my Appy Trails Mark V with a stiffer pole as part of the modifications. Other modifications would be grommets on webbing, a sturdy door zipper and higher quality reflective lines with clam cleat line locks. I love the space inside this shelter, and the weight isn't bad, but I can't trust it on a long trip without modifications.Oct 18, 2012 at 7:21 pm #1922693
I checked out the link you posted. You did a lot of good number crunching in that post.
DarylOct 18, 2012 at 8:13 pm #1922701
drowning in spamMember
Thanks Daryl. Eventually I may brush up on my physics and try to get some estimates of deflection given a certain wind load. Oh hell, it wouldn't be brushing up on my physics. I sucked at it. It'd be applying it at a higher level than I could in school.
EugeneOct 19, 2012 at 5:21 pm #1922993
Thanks for sharing your experiences with these tubes. It saves the rest of us a lot of time and expense ordering materials to see how they work.
I would add a note of warning. After plowing ahead despite Roger Caffin's warnings, I've had a number of issues develop with pultruded tube and even solid rods. They have a nasty tendency to split, and sometimes even fracture across the grain. My purchases were from Goodwinds kites; however they sell Avia Sport, which I believe is sold on many of the sites.
I don't know if the pultruded carbon on the Kites and Fun Things site is any better or not, and know nothing about how much the quality of the resin bonding materials may vary. Kind of a repeat of where I was at a number of years ago with the quality of silicone coatings on silnylon. Ugh! Also note that a number of pultruded tubes sold as .240 O.D. are actually .236 to 238" O.D. and too small in diameter for a .244" I.D. tube. For purposes of comparison, Easton poles generally use ferrules that are 2/1000 of an inch smaller in O.D. than the I.D. of the main tube. I believe looser ferrules greatly increase incidence of breakage.
In any event, there are some alternatives to ferrules made from the stock pultruded tubing. For the larger diameter tube you mentioned first, there is Easton .344 ALU tube, available from Quest Outfitters and others, that can be cut into ferrule lengths. Last winter/spring we posted on a long thread from an OP about the larger carbon tubing. At that time, Roger posted some reservations about how strong it could possibly be given its weight. I ordered a few pieces from K&FT to look at, and they indeed are very thin-walled.
For the smaller diameter tubing you mentioned, Easton makes its Injexion arrow shafts in a .240" O.D. that might be sturdier than stock pultruded tubing. (An earlier post from me was about using the heavier .244" O.D. Injexion shafts to make ferrules for .245" I.D. tubes.) Easton claims that although the Injexion shafts are pultruded, they use a proprietary process. I don't think that Easton would manufacture arrow shafts as fragile as stock pultruded ones, and so am willing to bet on their shafts being superior.
There is one more thorny issue with this ferrule business. The ferrule must be at least as stiff as the main tube, or else when the tube is bowed, there will be an angle created where the outer tubes meet over the ferrule, and greater pressure on the lips of the outer tubes that invites breakage. More often though, the ferrule can be significanly stiffer than the main tube, unable to flex as much as the main tube, and thus placing greater pressure on the main tube at the lip of the ferrule inside it. So not only do we have to be thinking about the fit of the ferrules, we also have to look at their flexibility compared to the main tube. Fortunately, most of the arrow shafts are rated in terms of "spine," indicating their flexibility in terms of fractions of an inch deflection with a standard weight and span. So, it is possible to know if and how much stiffer the ferrule is than the main tube.
Please note that Carbon Express has a product named "Bull Dog Nock Collars." They are small red anodized aluminum rings, intended for the nock end of arrows, that fit over the end of carbon tubes to resist breakage and split ends. They are much cleaner and lighter than rings made from cut tubing, and come in two sizes, 250 and 350; and as best I recall, the 350 fits the end of SkyShark P3X tubing, and may fit Victory VF V6 400 shafts with some lubrication.
Hope all that is of some interest to the carbonites amongst us.Oct 30, 2012 at 6:45 pm #1925488
Looked at the specs for the Easton Injexion all carbon 400 arrow shaft, and it is .236" O.D., not .240", as was suggested. However, the Fibraplex ferrules are a full .240" O.D.
They are quite a bit beefier now than the ones sold originally, and are nicely bevelled at the ends.Oct 31, 2012 at 2:33 am #1925546
> a number of issues develop with pultruded tube and even solid rods. They have a nasty tendency to split,
Oh they do!!! NO circumferential strength at all. Great for kites, but not for bent tent poles.
CheersOct 31, 2012 at 9:53 am #1925614
"However, the Fibraplex ferrules are a full .240" O.D.
They are quite a bit beefier now than the ones sold originally, and are nicely bevelled at the ends."
Good to hear about the ferrules being beefier. The one Fibraplex pole that broke on me broke at the ferrule.
Do you know if the new Fibraplex ferrules are made from wrapped or pultruded?Oct 31, 2012 at 3:39 pm #1925721
"Do you know if the new Fibraplex ferrules are made from wrapped or pultruded?"
No idea, Daryl. You could call or email Linas at FP and ask, though.
As I mentioned, I've had small diameter (5-7mm) pultruded tubes and rods break not just by splitting, but across the grain as well. I would bet that your FP ferrule broke across the grain. The old ones had a little squeezed lip on the end, while the ends of the new ones are thicker walled and bevelled at an angle. I also had the old ones break, across the grain at the ferrule when the main carbon pole was bent to too tight a radius. I even had a .21" OD solid carbon rod from Goodwinds break across the grain where it entered a Fibraplex hub (was making a hubbed pack frame).
Not sure what to make of all this. If the resin bonder is poor, it is easy to see how the rod or tube would split lengthwise; but when this supposedly super strong material breaks perpendicular to the direction of the fibers, one has to wonder if the material is simply dreck. There have been a number of posts about a specialty carbon supplier, but the prices are astronomical, so I've not tried that.
As a solution for the pack frame, I've tried ordering carbon rods from Goodwinds that telescope tightly inside wrapped fiberglass tubes that they also sell. The end product is .248" inches in diameter, and twice as stiff as the FG tube alone. (Stiffness was needed to properly tension a mesh backband.) I did not glue the rod into the tube due to concerns about different coefficients of expansion, and allowing the carbon rod to move freely inside the tube when both are bent. I had tried gluing with a similar combination with smaller diameters, and when the end product was bent to a certain point, there was an audible crack when the urethane glue between the outer FG tube and inner carbon rod let go.
None of which addresses your concern about the ferrules, of course. I suppose some break tests would help to see if the ferrules from Fibraplex, or those made from Easton Injexion shafts, are better than stock pultruded carbon tubing. You could just bend a couple lengths of main tube ferruled together to see what fails first, the main tube or the ferrule. Will probably do this expensive exercise before deciding on ferrules for the next tent, and will post the results.Oct 31, 2012 at 4:34 pm #1925727
Thanks for the info.Nov 1, 2012 at 12:12 pm #1925865
I e-mailed Linas at Fibraplex and asked him if the 292s and the ferrules are wrapped. Here's the reply:
"Yes, the 292’s are wrapped. The ferrules are made by a filament winding process. Both are designed for similar strength and stiffness."Nov 1, 2012 at 1:35 pm #1925883
I don't know if this will help but I was going to use Easton Flatline 500 arrows with a short aluminum ferrule on the outside. They are 6.5 grains per inch and come in 30 inch lengths. If not cut properly they will splinter. The bow shop will cut them to length. They are .2813 o.d. If you just need carbon ferrules the bow shop will have cut offs that they will probably give you. They might look at you strange when you ask but who cares.Nov 1, 2012 at 5:59 pm #1925932
"They are 6.5 grains per inch …"
That is not much strength for resisting the elements.
You may have missed the long thread last winter/spring about elbows and ferrules.
What it seems to come down to is whether carbon tube is stronger when subject to pressure from the inside or from the outside.
If weaker on the outside, or more susceptible to crushing, then external ferrules will more likely crush the tube under stress. Even though external ferrules do protect the tube ends.
If weaker on the inside, then external ferrules are better.
But the thought is that the alternating layers of wrapped carbon in the tube make it stronger resisting pressure from the inside. That's the argument, anyway, as I best understand it from Roger Caffin's posts on that thread. Granted, it is counterintuitive to 6th grade science about what makes eggs resist breakage from outside forces, but allows the chicks to break out when ready to be born. Daryl posted a link to some tests on the Kitebuilder forum that also favored the internal ferrules. I guess until we get some engineering guidance, we pick our poison.
But one approach is to use internal ferrules, and put ALU collars over the ends of the pole sections that are naked, or do not have the ferrule glued in and protecting the end of the pole section tube. Roger used something like that with collars at the elbows used on the poles for his tunnel tents.Nov 1, 2012 at 11:50 pm #1925972
I really doubt any tent maker would ever use pultruded CF tubing for bent poles. I done some testing myself. Sigh.
> alternating layers of wrapped carbon in the tube make it stronger resisting pressure from the inside.
> makes eggs resist breakage from outside forces, but allows the chicks to break out
> when ready to be born.
A chick in the egg has a smal spike on the tip of its beak, and this allows it to chip a hole from the inside. The pressure at the tip of the spike gets rather high.
'But I have never seen such a thing on the beak of any bird.'
No, you won't. It is lost very shortly after hatching – within a day I think.
> ALU collars over the ends of the pole sections that are naked, or do not have the
> ferrule glued in and protecting the end of the pole section tube.
Yes, but not to withstand any forces from bending. I did it to protect the ends of the CF tube from dings and impacts when pitching the tent. After all, the little bit of Al tubing has much less strength than the CF tubing.
CheersNov 2, 2012 at 6:37 pm #1926077
"I really doubt any tent maker would ever use pultruded CF tubing for bent poles."
No argument there, Roger. Hope no contrary impression was given.
Sounds like I got it mostly right. There remains the question of ferrules, as distinguished from the main pole sections. Not sure I buy from Daryl's inquiry of Fibraplex that the ferrules are filament wound. One would expect to see some sign of that on the bevelled surfaces on the ferrule ends. And the Easton Injexion shafts seem very sturdy to me for use as ferrules, even though Easton says they are pultruded, albeit with their own proprietary process. Can't imagine they would sell arrow shafts with the characteristics of stock pultruded. Only their legal department would benefit.
To break test or not to break test, that is the question.
P.S. For cutting, one can use the small abrasive wheels on arrow saws, but i use the Harbor Freight mini cut-off saw with a thin steel bladed wheel. But I always put on a fresh cutting blade before cutting carbon, and buff the cut ends with a heavy rotary pad. Used to also seal with thin Bondini CA glue, but that no longer seems necessary with materials that are better than stock pultruded, which was prone to splitting anyway.Nov 3, 2012 at 2:10 pm #1926179
> Can't imagine they would sell arrow shafts with the characteristics of stock pultruded.
Ah, pultruded may be OK for an arrow. The arrow stays (mostly) dead straight, and glass is pretty good in compression. If an arrow hits a rock then there are going to be little bits everywhere, either glass or CF I imagine.
Same goes for kite spars. They get a tiny bit of a bend to hold the kite shape, and that is all. Not the same as a flexed tent pole in a storm!
CheersNov 3, 2012 at 7:27 pm #1926233
Am not a hunter, but my understanding is that having a carbon arrow break when being removed from the animal is a big no-no. Some Gold Tips I bought some years ago were actually perforated so they would break outside the animal. (So they were worthless for my purposes.)
With all the breakage issues I've had with pultruded carbon tube and rod, I can't see how any company would use on a hunting arrow pultruded carbon of a quality much more likely than wrapped to break inside the animal. That's why I'm inclined to think that the Easton Injexion arrows, while said to be pultruded by the manufacturer, will be substantially less likely to break than the pultruded stuff I'm used to. And of course, I only intend to use it for internal ferrules that will be inside wrapped tubing when stressed. If I'm wrong about this, you and MYOG will be the first to hear about it.
In the meantime, I'll bring along a few Easton .344" OD external ferrules in case of failure of the internal ferrules. I would bring them anyway for temporary repair of the wrapped carbon pole tubes if they break.
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