Brace height changes affecting EFOC flight?

[Doc Nock]

#2473

Ed thought this might be a good question to throw to the board.

My bowyer recommends leaving the bow strung. Unless going out in the heat in the car, etc…says more damage done to limbs unstringing and re-stringing than leaving strung.

Ok…so I get some “creep” when I leave it strung in the house for a week… went to a shoot Sat and leaving early in the AM, left bow strung in front seat till I got there with windows open and cooler air blowing.

Here’s the deal. I bareshaft tuned EACH of my arrows using Troy’s guide and several interactions with him via computer. They all were dialed in.

When I start to see a tail kick (usually weak) in flight around 15-18 yards, but it comes back on target, and I check brace, it dropped.

My arrows were tailing Saturday… by afternoon when the sun came out and the temp climbed high and sweat rolled, it really tailed… I was so wilted by the heat, I didn’t check brace and twist it up before the afternoon round. Doh! 🙄

Anyone ever have a brace that drop and then impact arrow FLIGHT and tail weak?

Thanks!

[Stephen Graf]

#10220

I don’t have an answer to your mystery, but I have seen the same thing.

I have had some strings that just keep creeping. Don’t know why. Replace the string, everything is fine.

I have had some bows that relax a bit after being strung. I would check the brace height when stringing the bow, and it would be up to 1/4 inch higher than what it would be after shooting the bow 10 times. The measurements were repeatable, so I just didn’t worry about it. Seems to me most bows do this at least a little bit.

But none of it has really been enough to mess up arrow flight. Maybe something needs to be tweaked on your bow to make it more forgiving. Like move the string nock set up a bit? Or increase the brace height a bit?

Or maybe the bow weight is too much. I find that if I am shooting a heavy bow, things go well for a while, but then fall apart as I get fatigued.

[Doc Nock]

#10268

Thank you for that thoughtful response.

I’ve shot these arrows for a year, tuned them individually bare out to 25 yards…

The only time I’ve seen this behavior is when the brace drops.

I’ve got new strings on order that are advertised to NOT creep… after initial stretch…we’ll see.

I’ve read over the years that lower brace means the arrow is on the string longer, thus storing MORE energy over a longer period. That COULD explain them showing ‘weak’ out at 15-18 yards.

I also know if the arrow is on the string LONGER then one’s “follow thru” has to be more consistent to not impart bad ju-ju to the arrow on release or dropping the bow slightly, etc.

I twist up the string and all is well. I have committed to only using a stringer on my new bow, so I just endured the insult of poor arrow flight… while out on the course this past weekend.

In the past, here at home, when it happened, I’d check brace, twist it up and all was right in the world of arrow flight again.

Just curious. A “non-believer” of EFOC is purporting that EFOC arrows are more “finicky” and “less forgiving”.

Just thought perhaps someone here had insights to any/all the issues I encountered.

Don’t want to make this about string creep and this or that material…just if anyone has seen well tuned EFOC arrows behave badly IF or WHEN a brace dropped due to heat, creep, etc.

Thanks!

[Bruce Smithhammer]

#10393

Doc Nock wrote:

Just curious. A “non-believer” of EFOC is purporting that EFOC arrows are more “finicky” and “less forgiving”.

Personally Doc, I’ve found just the opposite to be true. But then of course there are other variables to consider, such as shelf cut, etc.

I’m not sure if I fully understand your dilemma, but it seems to me that if your brace height drops, then your nock point will move as well. If brace height and nock height both change, it doesn’t seem too surprising that those changes are going to be reflected in arrow flight, but maybe I’m missing something here…

[Doc Nock]

#10399

Thanks, Smithhammer,

I would agree that normally, well-tuned EFOC are reported more forgiving .. but this gent is not to be swayed so I leave it alone, but it did make me stop and think…so I came here to ask.

You make good points on the nock point shift as well… but the only problem I saw was “in flight” tailing weak, which according to Troy’s guide on tuning EFOC/UEFOC has been addressed and eliminated a year ago.

I hit ok… unless I did something else wrong, but flight was squirrely. In the past, I fix the brace and all the flight variance disappears. But anecdotal evidence didn’t sway me so I came here to see what those smarter than I might say…

Thanks for the thoughts!

[Bruce Smithhammer]

#10413

Doc Nock wrote: Thanks, Smithhammer,

I would agree that normally, well-tuned EFOC are reported more forgiving .. but this gent is not to be swayed so I leave it alone, but it did make me stop and think…so I came here to ask.

I’m continually amazed at the number of people who are “not to be swayed” in this or that opinion about EFOC arrows. Especially since, almost without exception, they come from people with little to no experience actually using such setups…

Anyway, it sounds to me like you just need to keep on top of checking brace height, since for whatever reason, your setup is particular about the brace height that it wants. Out of curiosity – what type of string material are you using?

[David Petersen]

#10445

Doc, your thread title is a bit misleading insofar as a change in brace height due to string stretch will of course affect arrow flight … but EFOC or lack thereof has no bearing on it. Does your friend think that arrows with low FOC would not be affected by string stretch and consequent relocation of nocking point and arrow angle on the shelf? I see no EFOC cause-effect relation, as friend is attempting to imply. All critics of EFOC, at least in my experience, lack extensive experience and a real working familiarity with EFOC. In general, I agree with others that EFOC, or even degrees of increased FOC, deliver superior arrow flight under all circumstances. Any negatives such as increased trajectory don’t much seem to come into play at ethical trad shot distances. Does your friend shoot trad or wheels? In any event, never leave a strung bow in a car under any conditions. :P:D

[Ed Ashby]

#11373

Here’s the pertinent part of the reply I sent Dave to his question.

“I use endless-loop strings, made with low-stretch materials (never B50; changed from it to Kevlar in the mid 70’s), and don’t have any problem with string stretch (after the initial stretch), so my brace height stays where I set it [which is precisely why they use endless loop strings on compounds ]. I, too, leave my bows strung for long periods of time, only unstringing when I’ll not be using that bow for a good while, or when traveling. I’ve never encountered a tuning problem due to string stretch.

… because of the greater inherent flight stability as FOC increases, you SHOULD have LESS change in arrow flight with an EFOC/UEFOC arrow than with a normal FOC arrow, as brace height changes. …

I never liked Flemish splice strings because of the string-stretch problems I encountered, especially with the high draw weight bows, so quit using them almost 40 years ago!”

Ed

[Doc Nock]

#12708

Sorry, David, that you feel my title was misleading, but that is my question…totally related to EFOC cause that is what I shoot & have for some time… never saw that and thought being more stable, it would show less as Smithy suggested. Nock height usually affects up and down flight wobble (for me) or changes vertical impact, not causes tailing sideways showing weak in flight…??

Smith,

It’s D10…6 strand…been shooting it a year with a lay off due to some health over winter. Bowyer wants me to leave it strung in the house… says more damage string/un-stringing than leaving strung in house.

Restrung today first time since last Sat… Wow… every arrow, out to 30 yards flew beautifully… then I started to notice some “tailing” (weak side “kick”) after 20+ arrows and sure enough, checked brace…bingo… dropped 1/4″ again while shooting.

New Rick Barbee string is due this coming week. Hydraulic pre-stretch, vibrated heavily… etc. See how that fares.

BTW, disbeliever in EFOC is a Westerner like you, David, and shoots sticks, but BELIEVES there is a parabolic increase in arc due to EFOC.

I’ve tried to explain to him/others, it’s NOT the EFOC…but the difference in total arrow weight that causes EFOC to appear to be more parabolic in flight. Like Ed and I have discussed repeatedly over the years, we asked for– an GOT higher GPI carbon shafting…and once we add the point weight to produce EFOC, it’s a heavier arrow. Ergo, EFOC arrow being heavier than theirs w/ lower EFOC there’s is flatter shooting. Due to weight, not the EFOC!

I understand that Ed did demos at PBS and elsewhere showing ‘arrows’ of the same weight, but different FOC shot from the same machine resulted in longer cast of the EFOC ‘arrow’.

Alas, some people, like with religion or other hot topics, are best left to their own ideas than to try to change their mind.

Trying to educate one who doesn’t want to learn, is like the ditty about putting lipstick on a pig to make it more appealing…does nothing for the pig’s looks only ticks off the pig!

[Timbow]

#14304

Ed,

I never realized that you used an endless loop string. Do you use a skinny string like O.L. Adcock used to recommend? How many strands do you use?

Tim

[Ed Ashby]

#14792

Tim,

For years I used heavy, “over built’ strings. I used them mainly because I was usually hunting in remote areas, for extended periods of time, and wanted a string that was still usable should a strand or two get clipped. That was so I didn’t have to carry an excessive number of spare strings to cover those ‘just in case’ situations. And, yes, those ‘overbuilt’, endless loop strings would hold without slipping after a few strands were cut, even on my heaviest bows. That I tested thoroughly prior to trusting the concept. Those strings were 18 to 22 strands, depending on the bow.

I’m now using skinnier strings, with the strand count dependent on the bow poundage and particular string material used. I’m still experimenting and have not settled on a ‘best material’ or best strand count yet. Most of the strings are running 8 to 12 strands. I’ve experimented down to four strands, but remember that none of my bows are below 70#. One thing I found is that the extremely thin strings, the 4 and 6 count, are too just too hard on my fingers, even when double-served. I think they would be okay on a lighter draw bow, but not at heavy poundage!

Ed

[handirifle]

#18314

I stopped using skinny strings when I sold my High Country double hatchet cam compound. I had to retune that bow once a month.

I use heavier, endless strings on all my trad bows, and never have an issue with string creep. I can see string stretch affecting the spine, due to a (slightly) increased power stroke. Your arrows may be tuned right on the brink of weak spine and this is enough to send them into a tailing flight when the stroke is increased.

I do not have the qualifications of many that have spoken here, but I personally, would take at least one arrow, and shorten it in small increments, like 1/8 or 1/4″ until I got too stiff of spine. Then I would cut the others to the mid point from the old length. This should give you more leeway for the brace height. Your setup seems awfully touchy to me.

I use B50 endless strings, and I have had the same string on for 2 years, and it hasn’t stretched enough to make a difference.

I would go to a heavier string (it will be quieter too) no matter what material you use. To me ANY small gain a lighter string gives, is not worth the hassles it causes.

[Doc Nock]

#22473

Wow! Thanks for all the interesting thoughts and comments. I tried clicking all sorts of things on my profile to get a note when someone replies, but I can’t get that figured out so haven’t kept up like I’d like.

Dave felt my title was misleading and apparently it was. this wasn’t meant to be about skinny strings or if/how skinny strings creep, as much as IF there is creep, are EFOC arrows more prone to show big flight changes toward weak or stiff in flight…?

I did get a good education on all sorts of related string issues and am grateful.

I contacted Rick Barbee in TX and got a couple strings coming in from him. He uses hydraulics to stretch strings, then uses intense vibration to settle even more… and the one I got so far, settled in at my brace in 24 hrs and hasn’t budged.

We’re still working thru nock fit. I’m a stickler on nock fit finding that even a slightly tight nock that doesn’t come off the string when pointed down, with a light “tap”, will cause arrow flight issues.

But that is a whole different thread. 😀

Thanks again for the varied thoughts!

[Robin Conrads]

#22651

Doc Nock, and anyone else who is interested, you can set it up to get emails when anyone posts in a thread by using the selections at the very bottom of the thread. Here is a picture to show what to click. Conversely, if you are getting emails about threads and you want them to stop, click the other link.

[handirifle]

#22825

Why Doc Nock, are you accusing us of getting off course, the nerve! 😀 yea it’s easy to see where we veered off course.

Sometimes the off course runs are educaring, sometime just frustrating. You have a good attitude. Honestly, personally, I had never paid much attention to that particular issue, probably because I had too many other things causing poor arrow flight (like the shooter maybe?).

While wemay not have completly answered your ORIGINAL question, maybe eliminating the creep alltogether, makes it a non issue. Yea yea thats how we solve your problem:D

Sound logic huh

[Doc Nock]

#22923

Webmom,

Yup. I got that “subscribe to thread” checked YES but never get nuttin… I hate computers often than not! 😛

[Doc Nock]

#22926

Handrifle… 😀

Now…dangnabbit…I thought I took responsibility for a bad title and question…!

I’d written to Troy with the same question, and after he got his new computer up, I got a reply.

As I had thought I read for a long time…a lower brace height creates a longer power stroke (if I said that right) and in effect, acts like a higher poundage bow increasing the horsepower to the arrow…ergo, I was showing “weak” in flight down range…hit ok…but I tuned my shafts following Troy’s good directions on Tuff Head website to eliminate that.

I would have thought, and Troy echoed, that usually EFOC arrows tend to respond LESS to such variables…but this bad boy string had “slipped/crept” a full 1/2″ till all was said and done!

Thanks for the other illuminating insights to strings, creep (some live near me) and other fine points of interest!

[Robin Conrads]

#23835

Doc Nock wrote: Webmom,

Yup. I got that “subscribe to thread” checked YES but never get nuttin… I hate computers often than not! 😛

Let me know if this works now.

[handirifle]

#25367

Doc Nock

Just curious. When the string stretched before, when the flight was affected, did it by chance have any effect on whether or not it kick the tail up or down?

I keep getting tail high from this bow, and wondering if brace height will change that.

[Doc Nock]

#25374

Handi,

Nope. Sorry. All I got was tail weak flight downrange from lower brace… hit ok…but flew snotty.

I’m far from an expert on any of this, but what I read about what I call porpoising, was nock adjustment.

Too high can hit the back of the riser and make it tail up and then porpoise up and down… as can too low.

If you shoot with a “canted bow” then all sorts of other dynamics come into play… perhaps one of the more sage readers can answer or you can post a special question on that issue…Good luck!

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