Samuel,

Are these the Victory 300s you referred to?

here



Daryl

The ones I recommend are the VForce 300:
http://www.victoryarchery.com/carbon-arrows/hunting/vforce/

The 0.245" ID is the key factor.

Cheers

Roger,

Thanks for the Victory 300 link.

I see that they have slightly thicker walls and are slightly heavier than the Skyshark 400s. This might partially explain the better performance in Samuel's strength testing.

Daryl

Daryl,
No. The ones I've been using are the V6's. On the Eagle website, I think they are these:

http://shop.eaglearchery.com/browse.cfm/victory-v-force-v6-series-shafts-300/4,11271.html

It's odd that Eagle Archery has so many more types of Victory arrow shafts than appear on Victory's own website.

The ones I use are just a tad too large inside to use .240" pultruded carbon tubing as internal ferrules. But a 3" section of Easton .344" "nano"tube weighs no more than 4" of the .240" pultruded carbon, and is a stronger ferrule that also protects the ends of the carbon tube from separating under stress, IMO.

Yes, I also found some plastic hose T's that fit well over the .385", but as you note, T's aren't elbows.

Have not given up totally on bending the Easton .344. Will have to try the sand, but I imagine Roger is right about the futility of it. 7/16" 6060T6 ALU tubing is more probably the answer.

Edited by scfhome on 02/05/2012 23:35:21 MST.

Roger,
Carbon Express makes a product called "Bull Dog Nock Collars," just small alloy bushings that go tightly over the end of the carbon tube where the nock is inserted.

The I.D. of them is not large enough for the Victory V6 300s, but since the Carbon Express Maxima is the same tubing as a new SkyShark product introduced last year, I thought I would mention it. This tube is identified in part by the carbon weave pattern on the outside that is really just a thin plastic cover - further confirmation of your opinion about Carbon Express - wasting pretty pics on plastic where another layer or two of wrapped carbon would make the tube much stronger.

Folks using internal ferrules on the SkyShark or other carbon tubing of the same O.D., might do well do look into the nock collars.

However, where the V6's will go over a Ti internal elbow, I will also add a short external collar cut from the Easton .344" tubing. It should probably be no more than half as long as the length of Ti elbow that goes into the insert in the carbon tube, the thought being to spread the force a bit when a typhoon hits. The inserts are plastic from Goodwinds that are bored out to a nice press fit over the 3/16" O.D. Ti elbows, and then glued into the V6 tubing with urethane glue - nothing fancy like Hysol, just Elmer's or LePage's. It expands as it dries, making it great for holding inserts and outserts. I had trouble with the hardeners in some epoxy glues weakening the bonding agent that holds carbon fibers together, so stopped using epoxy.

Sorry to hear of your difficulty with shipping from McMaster-Carr. I've been having trouble bringing up pages on their site lately. They do have a lot of stuff that is hard to find, and at lesser prices than some others.

Edited by scfhome on 02/05/2012 23:30:03 MST.

Hi Sam

The best I could do was a 4" radius. Even with a proper rolling jenny, the tube was starting to flatten at that point. A 6" radius would be a wise limit.

> It's odd that Eagle Archery has so many more types of Victory arrow shafts than appear
> on Victory's own website.
A lot of the shafts are a bit 'hidden' on the Victory web site. You have to burrow right into the pages and roll down a bit.

Cheers

I've posted this before but it fits the current discussion so here it is again.

A kitebuilder forum member did some destructive testing of spars here:

here

This is a test of spars, not ferrules.

He concluded, among other things:

(1) That a ferrule length of 4 times the diameter of the spar was adequate, with little strength being added after that.

(2) That internal ferrules resulted in a higher breaking strength than external ferrules for the Skyshark 400s. The challenge, of course, is to then find an internal ferrule strong enough to match the Skyshark 400 shaft strength.

(3) That wrapping the spar tip with string, tape or a tubing piece (as suggested by Samuel) would reduce shaft failure from an internal spar.

Seems like the first thing to determine is where the weak point is. Wrapping the ends of my Skyshark 400s, for example, wouldn't help if the weak point is the ferrule. When my Fibraplex pole broke, for example, it was at the ferrule.

Congrats Daryl, you win my bet. As best I can determine, the SkySharks I break-tested were the P300 and the P3X, both of which were no better than average. The P400 you mention, I did not test, probably because it was not on Goodwind's or Kitebuilder's site at the time. I see that it is a thicker walled tube, weighing around 8.97 gsi, or .58 gm/in, compared to the 8.2 gsi, or .53 gm/in, for the P300. So, it might well be above the average strength for the tubes I tested. The P3X are no longer listed on the Goodwinds site, because they quickly sold out of them and did not restock; however, IMO they are the same tube as the Carbon Express Maxima shafts that are readily available (They appear the same, have the same O.D, and weigh the same to a thousandth of an ounce). By comparison to the P400s, the Victory V-Force V6 300s are around 9.8 gsi, due to even more thickly walled tubing.

I cannot concur with the conclusions from the post by the kitebuilder forum member you linked to. Specifically:

1. I don't think he was referring to ferrule length as being 4 times the shaft diameter, but to the length of insertion or "engagement" of the ferrules into each tube. Carbon arrow shafts generally run below .3" O.D. Four times that is 1.2". A 1.2" ferrule would be woefully short, and would not distribute the stress of a bend over a wide enough arc, an invitation to breakage. Both Fibraplex and its predecessors have used 4" tubes for internal ferrules for carbon poles. Makers of alloy poles, like Easton and DAC, typically use 3" ferrules.

There must be some amount of looseness between the main tube and the ferrule; otherwise the tube could not readily slip into or over the ferrule. Even when that looseness is minimized, there will be some slight amount of cant between the tube and the ferrule, resulting in more pressure on the main tube at its lip, and at the point where it passes over or out of the lip or end of the ferrule. The longer the ferrule, the more this pressure is distributed when the entire pole is flexed, I believe.

The kite forum tests seem to contradict this; however, as I discovered, the degree of snugness between the ferrule and the main tube markedly effects the resistance to breakage, and differences here will totally skew break test results. I did not see anything in the kitebuilder forum test methodology to assure equal snugness, the same mistake I made when I began break testing, and the reason why I have not published my earlier results.

2. What I would like to see in support of the kite forum test conclusion about internal vs external ferrules is some reason to believe that internal ferrules are more reliable than external ones. Without that, I would not accept the kite forum test results without evidence of some control for snugness. Morevoer, an external ferrule offers more of the same protection from breakage that a collar over a carbon tube does, a proposition you accept. Even with the transverse wraps, carbon poles are prone to damage or separation at their ends, and the external ferrules also prevent that when in place. Internal ferrules do not.

However, I can see how internal ferrules of equal snugness might arguably be less likely to break a stressed tube than external ferrules would. With an external ferrule, all other factors being equal, when the pole is arced and stressed, more of its surface is exposed and forced against the lip of the ferrule than is the case with an internal ferrule. Indeed, this may have something to do with the reason why Easton chose internal alloy ferrules for its carbon FX tube poles. But even if the kitebilder forum tests are correct about internal ferrules being less likely to occasion breaks in the main tube, there remain some practical considerations.

3. .240" O.D. pultruded carbon tube should be as strong as the SkyShark 400s, and is available at many of the kite sites. The ends can be reinforced by soaking with Cyanocrylic glue (Krazy glue) - best I've found for this purpose is Bondini - but since the ends of internal ferrules are protected and reinforced by the outer tube, that helps to protect against wear and tear. Nevertheless, during the period of over ten years I used internal carbon ferrules on carbon poles, I had problems with pultruded ferrules eventually splitting. This could be corrected before breakage by keeping an eye on them, but was still a problem. But the more serious problem was that the ferrules were either too loose or too strong, causing the main tube to break. Carrying an extra pole section always sufficed, and the alloy sleeves in the pole repair kit never had to be used, but still ...

If you break a stick over your knee, it will break where it contacts your knee. Similarly, if a ferrule is stronger and has less flex than the main tube, the tube will break at the lip of the ferrule. So you don't want it to be stonger, or have a higher "modulus of elasticity," than the main tube.

Another more practical problem with the .240" tubing is that most of the carbon tubes used for arrows are manufactured on spindles of the same diameter, and therefore have an I.D. of around .245". Hence, the difference in diameters is .005", compared to the difference of .002" found between poles and ferrules on Easton tent pole tubing. Again, this much difference will markedly increase the likelihood of the main tube breaking at the lip or end of the ferrule.

I could not find carbon tubing of any kind with around a .243" O.D., and that is yet another reason I went to external ferrules, because the Easton .344" tubing fits over the Victory V6 300s as precisely as could be hoped without being too snug. I believe Roger also found Easton tubing that fit snugly over the carbon shafts that he uses.

If internal ferrules are inherently less likely to occasion breakage, it would make sense to use them, but only if a snug fit could be obtained between the ferrule and tube from materials available to MYOGers, and if outer collars were also used. But, so far I have not found materials that would provide such a snug fit, with close to the same elasticity. I did find a fiberglass tube that fit well as an internal ferrule, but it was so elastic, it bent at the spaces between the main tubes. I also found an alloy internal ferrule that fit well, but was only 2" long, not long enough IMO, as I'm not ready to discard the conclusions of the large pole manufacturers in favor of the kitebuilder poster's tests.

So it would be interesting to hear what Roger and others have to say about the argument for internal ferrules; but without availability of the right materials, the argument may have to remain academic.

4. When you state that your Fibraplex pole broke at the ferrule, I'm not sure if you mean the ferrule broke, or the main tube broke at the lip of the ferrule. Frankly, it could be either, because the ferrules Fibraplex was using, at least a few years ago, were much thinner walled than .240" pultruded carbon tube. I then spoke to Linus, and encouraged him to obtain stronger ferrules. With the pultruded tube as a ferrule, a break would probably occur where the tube passes over the lip or end of the ferrule, as noted above. Achieving exactly the same modulus of elasticity for both the ferrule and main tube, while possible for a large manufacturer, may be like looking for Godot for a MYOGer.

I admit that I don't know if the .344" O.D. Easton alloy tubing and the Victory V6 300s have the same modulus of elasticity; however, I did note in my break tests that they both broke at about the same pounds of force, while protruding from external ferrules of as close to equal snugness as possible. So I am optimistic, but accept that as a MYOGer, I can't expect to achieve precise scientific data on this without the benefit of laboratory facilities, and even if I could, where would I get the precise fitting materials with almost precisely equal elasticity.

That's my opinion, FWIW.

Edited by scfhome on 02/07/2012 02:03:55 MST.

Hi Sam

OK, comments.

> Carbon arrow shafts generally run below .3" O.D. Four times that is 1.2". A 1.2" ferrule
> would be woefully short, and would not distribute the stress of a bend over a wide enough
> arc, an invitation to breakage.
However, my internal ferrules are about that size - 1.2" long.
They work for me because I machine the SS tubing myself so it is a very good snug fit. When the fit is that close, a bit of force causes enough deflection of the CF tubing (or rather the plastic/epoxy used to matrix the fibres) that the area taking the load becomes large. For a more sloppy fit you would indeed need a longer engagement.

> some reason to believe that internal ferrules are more reliable than external ones.
Yes, definitely.
An external ferrule exerts compression on the tube from the outside, and almost all the force is taken by the plastic matrix. The wrapping fibres are in compression, and have very little strength like that. (Long ferrules needed.)
An internal ferrule forces expansion on the wrapping carbon fibres, and they just don't stretch that much! The amount of plastic around them is so small that the fibres are pretty close to touching, so the strength of the plastic is secondary.

> .240" O.D. pultruded carbon tube should be as strong as the SkyShark 400s,
I'll repeat what I said before: pultruded tubing splits catastrophically.

> If you break a stick over your knee, it will break where it contacts your knee.
Yes, if broken over your knee.
However, if broken by bending it will very often make two closely adjacent breaks. Pretty wierd when you see it for the first time, but the two simultaneous breaks are predicted by theory.

Cheers
PS: you need a lathe as well as a sewing machine ... :-)

Samuel,

"I don't think he was referring to ferrule length as being 4 times the shaft diameter, but to the length of insertion or "engagement" of the ferrules into each tube."

I agree.

Daryl

OK, you guys have sort of convinced me. Hope you're right.
But am not going to buy a machinist's lathe. Can't afford such things.

As Daryl said:

"The challenge, of course, is to then find an internal ferrule strong enough ..."

Yes, and one that fits as well.

So be it.

Cheers, I guess.

Hi Sam

Lathes - a little secret. There are lots of them around. Farmers have them, and so do retired men playing model railways, especially the steam freaks. Chase around, with a few cans.

Cheers

Roger,
There are a couple who have a big model railroad shop in Intervale NH, so I will go up there and see what I can find out. Of course, having one and knowing how to use it well are two different things.

Quarter inch diameter 6061 T6 tubing is available in three different wall thicknesses from onlinemetals.com, and could be turned down to just the right O.D. Was thinking of paying a local machinist to do it right. Any thoughts about wall thickness and suitability of 6061 T6 for a strong enough inner ferrule for CF wrapped tube with an inner diameter in the .243-.245" range? Material from onlinemetals might also be suitable for the elbows that Aaron started this thread about, way back when.

BTW, don't think the wrapped arrow tubes are all made on the same mandrel, as the inside diameters do vary a bit. There is a nice little discussion at skyburner.com about their manufacturing process that you may find interesting:
http://www.skyburner.com/skyshark/ssnews.html
Sorry, no photo of the machine, though.

Am thinking about doing some tests of both tubes and ferrules by bowing two 30-32" tubes connected by a ferrule at the center, pushing one end toward the other until failure; and measuring how far apart the ends were at the time of failure. Will just have a tape measure open on the mat as I push. Could try both internal and external ferrules of different materials and lengths, and try with Victory V6 300s, SkyShark P400s, and Fibraplex, a nice range to work with. Goggles and gloves, on ... push!

Could stuff pole tips in the tube ends just to hold onto for the tests. Or I could install a small fish weighing scale at the pole tip and pull on it to also register the pounds of force at the time of break, but that would make the process more difficult. Photos of the breaks would also be interesting, especially if at the ferrules, as I expect. What do you think?

P.S. "Chase around with a few cans" You lost me with the cans. Are you meaning to suggest that I get married?

Edited by scfhome on 02/08/2012 21:19:39 MST.

Hi Sam

OK, first off, what SkyShark call a wrapped tube is a bit of CF fabric wrapped around a mandrel - like the Fibraplex ones. That is very different from the '2D wrap' construction I use.. Yes, they make quite a few IDs in wrapped-fabric tubes - low capex.

> P.S. "Chase around with a few cans" You lost me with the cans.
Australianism? Cans of beer!

Aluminium tubes:
I know the 6061 can be bent with a proper bender. Not sure about the 2024 - that alloy you would need to test (and it's all too big anyhow). 6063 is definitely softer - I would prefer the 6061.
0.25" OD x 0.035" WALL x 0.18" ID - ooh, thin wall!
0.25" OD x 0.049" WALL x 0.152" ID - hum ...
0.25" OD x 0.058" WALL x 0.134" ID - possible
0.25" OD x 0.065" WALL x 0.12" ID - yeah, possible

They also do some nice SS tubing. Their prices are ... not cheap, although you don't need a lot.

> doing some tests of both tubes and ferrules by bowing two 30-32" tubes
Fun stuff. I did a lot of stiffness testing, but staying in the linear range!
Oh, I can see lots of fun with goggles and ear plugs. Yes, real live test data!!!!
(Use a small empty room for testing: the middle bits can go flying!)

Cheers

Hi Roger,
Not sure of your terms, but yes, I have noted your descriptions of the manufacture of multi-layer wrapped tubes on other threads, and see the clear difference. Did order a couple of SkyShark 400s for testing, though. Initially, will just use my old method of sticking it into a metal tube in a brick wall, attaching a hang scale to a connecter on the end of the CF tube at a precise distance from the brick wall, and pulling slowly until the break. But only if I can find a tube to go into the wall that will fit snugly over the P400 - expect so.

If it becomes necessary to turn down the 6061 T6, will use the thickest .065" wall as you suggest. Some must come off to get down to around .243" O.D. Goodwinds has an aluminum ferrule that is spec'd at .243" O.D., but is actually around .248". What a revoltin' development. After my most recent talk with them, I think they may change the spec listed on their site.

Will look into the SS tubing if the 6061 T6 bends in use.

Re: Ear plugs. Have broken quite a few, including the Easton FX, and no big bangs so far. But the shock totally discombobolates the 50 lb. fish hanging scale, and often the pointer and cover plate come flying off, so the scale must be reassembled and recalibrated after each test. Good suggestion about the empty room - wish I had one.
But it is the basement workshop, and is a total mess already. Squalor. Very unscientific. Some of the gear made there has been good, though. (And some - not so good).

Hi Sam

Another way of applying force without too much disaster. Bucket 2" above ground. Slowly add water, 1 L at a time. 1 L = 1 kg.
If you use a wide bucket, it is unlikely to tip when it falls. Bit of a splash maybe, but you were counting the number of 1 L additions ... Outside.

Cheers

Hi Roger and Daryl,

Well, I now have two machine shop estimates for 8 6061 T6 ALU ferrules, with two different wall thicknesses, O.D. .244" to fit in a Victory VForce V6 300 carbon tube: $65 and $100. An that's with me supplying the metal.

Found a used Taig metal working micro lathe with all kinds of accessories for $300.

To paraphrase Laurel and Hardy - Now look at the pickle you've got me into!

Life was so much easier with the external ferrules cut from Easton .344 tent pole tube at less than 50 cents each.

Sure hope internal ferrules are really better.

P.S. Not going to even hint at what to do with that bucket.

Edited by scfhome on 02/16/2012 18:38:18 MST.

Found this thread last night as I was investigating possibilities for poles and angle connectors for making just such a tent (Roger, I think I emailed you some tent questions a year or more ago). I'm intrigued by the idea of using the arrow shafts, but not being a machinist am a bit confused by exactly how this would work. I get from this thread that the angles Roger uses are SS that fit inside the shaft, and that the best reinforcement for the ends of the shafts would be internal ferrules at least 1.2" long. But I am not certain about ferrules vs. connectors; do both ends of each shaft have internal ferrules, then the SS angles fit inside those, and the straight connectors fit outside the ends of the shaft? Or do the SS angles take the place of the ferrule where they occur? Or something else entirely? Please clarify (aka Poles for Dummies, said dummy being myself).

I have a colleague (in my orchestra) who is also a machinist; sent him a little about the elbows last night before I found this thread and he may be interested in helping me. I find the sewing end of tent-making far less intimidating, since I have plenty of experience with sewing. But the pole setup is not so straightforward for me.

Thanks,
Debbie

Hi Debbie

OK, lets start with a photo of my tent poles.


In this photo you can see a stack of carbon fibre poles folded up. Details:

The long green sleeves over the CF are Easton arrow shafting used as straight connectors - needed to get the section length down to fit in my pack.

The short green sections are the same arrow shaft used as reinforcing for the ends of the CF tubing. They won't really reinforce the CF tubing againmst splitting - the CF is stronger, but they do protect against bumps, abrasion, wear etc. For the tiny incremental increase in weight, I think they are justified.

The shiny things are the SS elbows which go inside the CF tubing. They are bent at about 30 degrees, and they have a short bit of heavy heat shrink tubing in the middle of the bend. The heat shrink stops the ferrule from penetrating in too far and jamming at the start of the bend. So each elbow really has two shiny ends and a black bit in the middle.

The elbows started life as 1/4" SS tube, cut to the required section length. Then I turned each end of the bit down to a really snug fit in the CF tube. This left a larger diameter region in the middle - under the heat shrink.

How are we going?

Cheers

Edited by rcaffin on 02/21/2012 13:56:18 MST.

Hi Sam

> two machine shop estimates for 8 6061 T6 ALU ferrules ... $65 and $100... with me
> supplying the metal.
Sounds fairly cheap as a commercial thing.
That's $10 for the machining, $50 for the set-up, and the rest for time talking to the customer.
Yes, seriously.

Ah, but with your own lathe ... welcome to the slippery slope into a complete machine shop. (Drill press, manual lathe, manual mill, CNC machining centre ..., CAD, ...)


Cheers