[whitetail101]

I am not sure about how TAP operates, but I would go with what the OT2 program suggests.

I have been using and recommending OT2 since it appeared on the market. I have found its recommendations and calculations to be spot on if you select and enter the information correctly.

OT2 is worth the money for what it provides the archer. If you ever get into trouble with the program, Larry is just an email away to get you back on track

 

[TundraWookie]

Cool, thanks whitetail... Anybody else have any input??

 

[[email protected]]

Eugene,

>>I downloaded the OT2 trail and I'm finding the spine chart is different compared to the TAP program.
Yep. Different results because both programs use different methods to calculate spine. Each also gives different consideration to the effect nock end weight has on spine.

If you haven't done this already, try switching to the "Both" filter (instead of Hunting) and enabling the Weight and FOC filters for OT2. If you have a target FOC of 15%, set the FOC filter to 13 to 17. For the weight filter set it at 450 to 550. You might not get a lot of options for shafts if you stick to just the GT brand.

Typically it's easier to achieve a high FOC if you go with a lighter gpi shaft..but if you do that, you won't reach your total arrow weight goal of 500gr. There's a lot of 300 spine shafts that might work if you kept insert and point weight around 135-150gr. The GT UL22 series comes to mind..problem is the total arrow weight for the UL22 would be closer to 400grs. There does appear to be a lot options in the 400-450gr range...with a lighter point.

 

[DocMort]

Gold tip Kinetic 200's
Big Game 100


They both would work for your set up. If you cut your arrow to 27.5 and use a 100-125 grain broadhead you might and I say might be able to get away with the HT2 300's they are a great arrow and will weight in at or around 425 or so for that set up,

 

[TundraWookie]

Why are they so different? Shouldn't they be the same? One of you guys have to be wrong. (not to be abrasive but it's true...)

I tried all that you said with the filters and with a 150 gr point I can't find any shaft that'll work for some reason... Not even the .250 and .200 spined arrows are coming up. Maybe I'm doing something wrong.

I input some numbers for the GT velocity arrows and I came out with a 150gr point with a 14.6gr insert with a 8.3gr nock at 26.25" arrow (I'm guessing that measurement isn't including the nock.) with the bow set at 72#'s and it came out really well. The FOC on this set-up is 17.24%!! Do you think that set-up would work?? Thanks.

 

[TundraWookie]

Gold tip Kinetic 200's
Big Game 100


They both would work for your set up. If you cut your arrow to 27.5 and use a 100-125 grain broadhead you might and I say might be able to get away with the HT2 300's they are a great arrow and will weight in at or around 425 or so for that set up,

The FOC on that set-up would be terrible, especially with the Kinetics at 11.6 GPI. Plus I'm sure I'd be waaaaay over spined at around 72#'s and a 100 or 125 point.

 

[TundraWookie]

Can anyone else shed some light???

 

[Fowtyfour]

Do yourself a favor and ditch the GT acculite nocks. At least with my setup they were breaking left and right. I don't know if this can cause a dry fire but I am not taking any chances. I am replacing them with UNI bushings and easton g nocks.

 

[TundraWookie]

Sweet... noted. Do you know what easton nocks will fit without the bushings?

 

[Fowtyfour]

I believe the easton microlite and the super nocks will work.

 

[Demp223]

Do yourself a favor and ditch the GT acculite nocks. At least with my setup they were breaking left and right. I don't know if this can cause a dry fire but I am not taking any chances. I am replacing them with UNI bushings and easton g nocks.

Curious which acculite you were using.I've heard of some issues with the clear colored ones. Several of us have been using solid white ones with thousands of shots and no problems at all.

 

[TundraWookie]

I think I figured out what I want as far as an arrow... I ended up with the 0.280 GT Big Game 100's at 26.75" with 150 gr tip with 15 gr insert with 8.3 gr nock with one FOB at 23 gr. It's just about where I wanted it at 480 gr and about 292 FPS and 91 KE and 14.53% FOC. This is at 74#'s and it's still good at 72 and 76#'s. It looks good on paper... I'll let you know how it flies with broad heads when I pick those out. Thanks for all your help.

I heard the acculite nocks were really sturdy as well. I'd be interested in hearing about which nocks are best. I DEFINITELY do NOT want to risk dry firing my bow!

 

[[email protected]]

TundraWookie,

>>Why are they so different? Shouldn't they be the same? One of you guys have to be wrong.

They would be the same if both programs were written by the same person and used the exact same method to calculate optimal spine..but they don't. <<Each also gives different consideration to the effect nock end weight has on spine.>>

OT2 uses "shaft material only" when it asks for "shaft length". The shaft length does not include nock length, nock bushing, or point insert. If the 28" length specified in your original post is "complete arrow length"..ie nock groove to point insert..and you used 28" where OT2 asks for shaft length, it would be recommending a stiffer optimal spine than if you'd entered, say, 27.25" or 27.5". Nock and bushing lengths can add between 3/8" to 3/4"..just something to be aware of.

Try this experiment in each program..note your FOC and suggested (optimal) spine.

1) add weight to the nock end of the "built arrow"..change the vane, wrap, or nock weight to something heavier or lighter.
2) click the recalculate button
3) notice any changes to FOC or suggested spine?

With OT2..
Adding weight to the nock end will stiffen dynamic spine, allowing use of a statically weaker shaft. Decreasing nock end weight will weaken dynamic spine, requiring you to use a statically stiffer shaft. Weight added to the nock end of your arrow has the opposite effect of adding weight to the point end.

Weight added to the string..ie heavy peep, brass nock sets, heavy silencers, etc...will also change the spine requirements.

The screen shots show results for shaft material length of 26.25"...and the filters and settings used...changing the FOC filter's low number from 14 to 15 causes most, if not all of the shafts, to dop out of the Find MAtch results. So if you come up "empty" on a search, widen the upper or lower range and try again.

 

[TundraWookie]

Nice... That makes the arrow a little shorter and is favorable for my set-up. I'll have to check it out and really tell you what I find with my paper tuning, walk back tuning, bare shaft tuning for both paper and walk back and broad head tuning (the real test...). Thanks!

One last question, Why is it that when switching to a hunting arrow the spine gets weaker?

 

[TundraWookie]

Also, if I add weight to the nock side of an arrow, it effectively adds or stiffens the spine of the arrow as opposed to when you add weight to the front of the arrow and weaken the spine?

 

[[email protected]]

TundraWookie,

>>hunting arrow the spine gets weaker?

Essentially it's a way for the program to emulate the way the Easton Charts do things. Easton has Hunting and Target charts. Given the exact same setup, the Easton hunting chart recommends a stiffer spine than the Easton target chart. Presumably, a broadhead tipped arrow is easier to tune when slightly stiff. OT2 follows the same principle of recommending a slightly stiffer shaft when the "Hunting" Filter is used. When searching for arrows I use the "Both" Filter..it splits the difference between the Hunting and Target Filter recommendations and opens the database to search all shafts. The DB is seperated by mfg recommendations for target or hunting..for whatever reason the mfgs have chosen straightness as the determining factor.


>>if I add weight to the nock side of an arrow, it effectively adds or stiffens the spine
Yes..correct. Think of adding weight to the nock end of the shaft as having the same effect as adding weight to the center of the string.

 

[Fowtyfour]

I have the white acculite nocks that came with my GT Velocity XT's. A bunch of those broke. I ordered a dozen in orange. They broke just the same. My nock point is served above and below the nock and I make sure to leave a little extra room so there is no nock pinch. I am going to give the PDP UNI bushings and G nocks a try.

I'd like to hear an answer to TundraWookie's question about adding weight to the nock. I always thought adding weight to the nock would weaken spine but now I'm not sure.

 

[TundraWookie]

Let me know how those g nocks work out...

 

[Fowtyfour]

Well I got the UNI's and G nocks installed. I decided to check it through paper. The extra few grains made the arrow act a bit stiff. I moved the rest out a tiny bit and it was right on.

I really like the G nocks and bushings. They look a bit funny to me but I think they are considerably tougher than the acculite nocks.