efoc vs arrow integrity

[stalkin4elk]

#6892

Thanks to Dr Ashby for another informative update. I’m concerned of shaft breakage/failure approx. 4-6 inches behind the point on angled impacts(refer to 2008 update force graphs)with efoc arrows initially built from 7-9 gr/inch lightweight shafts. At some place weight reduction will have the unintended problem of weakness resulting in arrow failure and thus violate the entire principle of shaft integrity. I’ve broken my share of arrows behind the inserts with only approx 20% foc — the force has to go somewhere. It seems that internal footings are almost mandatory (previously discussed designs)to avoid failure with efoc 30% range.
Perhaps the Alaskan Grizzly Stiks and Arrow Dynamic Hammerhead arrows would be reasonable compromise, “turn key”, strong shafts with respectable foc ??
I hope some of you experimenters have found the above not to be the case.
Thanks

[David Petersen]

#57608

At this point there’s no getting around the fact that carbon shafts offer all the best stuff for EFoC arrows, including integrity with light shafts. But my experience there is limited, having tested and hunted with only ABS GrizzlyStiks and el cheapo Walmart Carbon Express 45-60s. My only “internal footings” are 100 and 125-grain brass inserts. While I’ve never had a shaft break completely, I’ve had a few of the CE shafts split from the insert back an inch or more. And on last year’s elk, the head came out of the shaft at some point after impact (not that it helped the elk any!). I’m currently playing with footed wood shafts, but disappointed with low FoC and while footings strengthen the shafts behind the head, then tend to break farther back so nothing at all gained. Some look at all this “messing around” with arrow system possibilities as unnecessary confusion, expense and hassle. So far, I find it fun. My 2 cents, dave

[Ed Ashby]

#58119

There will be a section dealing with this in an upcoming Update. The shaft-damage results with the very thin shafts used on the Ultra-EFOC arrows was not what I had expected it to be. However, all the test data to date with these Ultra-EFOC arrows has been on shots fired from a broadside shooting angle, giving a bone-impact angle closer to perpendicular. I haven’t yet done any oblique angle impact testing for shaft durability but suspect that some problems will be encounterted on these, making the use of a IF of greater importance. But, as with the direct impact testing, what I expect doesn’t always end up being the same as what the actual results show. Only time and actual testing results will tell the true story.

Ed

[kingwouldbe]

#58814

I have been working on making a tank killer arrow, ( it has so far eluded me )

These arrows are triple footed, what I have found is it only moves the weak spot back on the shaft.

#2-#3 is missing a section still in the hogs chest, the arrow went in and stopped with the for end sticking out the other side and as it rolled it broke off both sides of the arrow.

#1 exited right through the scapula and broke as the hog ran through the brush.

[stalkin4elk]

#58853

I believe most carbon arrows are engineered for light, fast compound set ups. Researching “tough arrows” gives Grizz stiks, AD hammerheads, CE heritage ,and Easton fmj contenter status. Here are some observations from stump/field type of shooting with a 63#recurve and a 70# Mathews(easy now).
I used 300 fmjs (skinny,expensive,h.i.t.insert) and Easton epic shafts(standard dia.,inexpensive,standard insert) because I already had them. Keep in mind the 2008 force graph of the bending shafts.
1) Approx 40 gr. Alum. Insert and 100gr. F.p. Both shafts hold up quite well to a variety of impacts such as oblique boards, frozen ground, trees, etc. Some blown nocks or cracked shafts on only the most severe impacts. These are low weight and low foc set ups like the compound pro shop recommends.
2) Add 100 gr. brass insert and 100 gr.f.p. Things get more interesting with more nocks blown,cracks and complete shaft fractures,some flowered insert junction fractures. Now the fmjs are definitely better survivors. Really, somewhere in the 75% survival rate when trying to damage the shafts.
3) Add 100 gr. brass insert and a 250-300 gr.f.p. Now let the carnage begin! All the above at an alarming rate. Plus the fmjs are quite easy to bend(internal fracture) behind the insert when ricocheting a shot off frozen ground. Direct hits bulge the point eng of the fmjs as the insert is driven into the shaft. I would not feel safe shooting the epics twice into anything other than a quality target at this weight/foc !
4) Aside note is the epics are easy to break when a standard bag target falls forward onto them. The fmjs are not damaged in this case.

These are just observations and this is not quality research but one gets the idea of momentum and bending forces in action.High K.E. does not seem to ruin much stuff.Internal footings!? Heck, maybe I’ll try some Hammerheads next. Come on guys, volunteers vs. Grizz Stiks vs. C.E. Heritage would be great fun and save the rest of us some cash!

[Ed Ashby]

#59216

David, are those impact breaks or breaks created by the animal moving with the arrow still in him?

Simply moving the weak point of the shaft farther back was also what I observed when using the all-parallel internal Footings too, on oblique angle impacts. It was only after going to the tapering back section Intertnal Footing that the shaft fractures ceased to be a major, major problem.

Ed

[tom-wisconsin]

#59430

Dr. Ed Ashby wrote: David, are those impact breaks or breaks created by the animal moving with the arrow still in him?

Simply moving the weak point of the shaft farther back was also what I observed when using the all-parallel internal Footings too, on oblique angle impacts. It was only after going to the tapering back section Intertnal Footing that the shaft fractures ceased to be a major, major problem.

Ed

Dr. Ed

Do you know what the internal footing of the Hamerhead arrows of Arrow Dynamics consists of?

Tom

[kingwouldbe]

#59902

Dr. Ed Ashby wrote: David, are those impact breaks or breaks created by the animal moving with the arrow still in him?

Simply moving the weak point of the shaft farther back was also what I observed when using the all-parallel internal Footings too, on oblique angle impacts. It was only after going to the tapering back section Intertnal Footing that the shaft fractures ceased to be a major, major problem.

Ed

Yes, Both broke from the animal after the shot, I have not had one break on the shot just the animal running or rolling on the arrow.

I don’t know if there is anything that can stand up to a rolling boar or elk.

My goal is to jump through everything, thus saving my arrows 😆

[stalkin4elk]

#60284

Interesting new insert/outsert at http://www.trophyridge.com
Thoughts?

[Ed Ashby]

#61073

No idea Tom. I’ve not even seen one.

David, I doubt that there’s any shaft that’s going to routinely stand up to breakage by an animal rolling on it. Not even the best hardwood shafts stand up to that, and they are the most damage resistant shafts tested. Best cure for that is to have pass-throughs as often as possible! The big concern is breakage on hard impacts, especially at oblique angles.

Ed

[Ed Ashby]

#61076

One never knows for certain until it’s tested, but my impression of the outsert/insert design is that it should definitely provide extra strength on direct hard-impact hits, but won’t add much (if any) extra strength on the angular impacts. On those angular impacts it will still not add support to the shsft at the point where the insert terminates inside the shaft; and that’s precisely where the weak point is on angular impacts. It’s at this point where the gradually tapering portion of the Internal Footing adds additional support, spreading the force across a 5″ long section of the shaft; rather than having it concentrated immediately back of the insert – or the forward, parallel section of the Internal footing.

Ed

Ed

[Patrick]

#61102

Dr. Ed Ashby wrote: It’s at this point where the gradually tapering portion of the Internal Footing adds additional support, spreading the force across a 5″ long section of the shaft; rather than having it concentrated immediately back of the insert – or the forward, parallel section of the Internal footing.

From this, I gather that a 5″ gradually tapering insert would be absolutely ideal. Not that I could make something like that anyway, but hypothetically speaking, if that would be ideal, what should it be made of?

[stalkin4elk]

#61501

The insert/outsert tells me that at least mfgs. might be listening to a product need. In conjunction with the internal footing a person might really be getting somewhere.

[Ed Ashby]

#61508

Patrick. I generally make my IF’s either 7″ or 9″ OAL. The first 2″ of the 7″ IF (or 4″ on the 9″ IF) is parallel, with a diameter matching the shaft’s internal diameter. The rear 5″ on each is tapered in a parabolic curve.

I’ve tried several materials. Whatever material is used for the IF it needs to be something with some degree of flex. From among all the materials I’ve tried the ones which have worked best so far are hardwood, hard nylon and carbon. I use oak the most. On the hard nylon you need to add glue groves in the parallel portion in order for it to hold securely on direct impact. I found 4 glue groves, each 5mm wide and 1mm deep was the minimum number for a secure grip of the nylon IF to the shaft’s wall.

Ed

[Ed Ashby]

#61513

Patrick, I brought the IF thread back to the top. It has photos and some of the construction and assembly details.

Ed

[Patrick]

#62465

Thanks Dr Ashby! You know, I actually read through that entire thread during its making. I just re-read it, and it got me thinking some more. BUT, I was really just thinking of inserts, in and of themselves…for lazy people (like me:oops::D).

Inserts are relatively short, and none of them have tapered ends, to my knowledge. So the idea of a long, tapered insert just popped in my head. Similar to what happened when Isaac Newton discovered gravity, Galileo invented the telescope, Einstein came up with the Theory of Relativity…and Al Gore invented the Internet. :D:wink:

[Ed Ashby]

#62522

Patrick, we’ve tried several different long, one piece insert/IF’s. So far none have worked. None of the flexable materials we’ve tried were strong enough to withstand hard, direct impacts and the harder materials didn’t have enough flex to prevent breakage on the hard impact angling shots.

Ed

[Patrick]

#62533

Yeah, but have you done any REAL research on it or are you just guessing? 😆

[Ed Ashby]

#62729

🙂

Ed

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