Arrow spine help

[S.Clancy]

Where did you find a used arrow saw? And what kind of glue are you using to be able to quickly and easily remove and replace inserts during the cut down process?

Craigslist.

I do not remove the inserts. I glue the HIT inserts as the manufacturer describes how and leave them. When I need to cut down an arrow, I take the nock off, and cut it down, square, then put the nock back on.

 

[S.Clancy]

Reason I asked is because I often hear guys say "nock left = weak/nock right = stiff for a righty, vice versa for a lefty." This makes sense for traditional bows shot with fingers where the arrow typically starts away from centershot, but I don't think it has much relevance to a compound bow not influenced by fingers on the string with a cut-out riser that allows the arrow to remain in line with the string path throughout the shot. I can't conceive of why an overly weak arrow would leave a compound bow nock left and an overly stiff arrow would leave nock right. If you have a theory on that, I'd be interested to hear it.

I've played around with intentionally shooting significantly over and under-spined arrows (relative to what charts/calculators recommend) out of various compound bows and haven't witnessed the purported weak-left/stiff-right tear patterns. Arrow spine certainly can affect how a compound bow tunes (FWIW I believe the range of appropriate/acceptable spines is significantly wider than most people think), but I don't think the left tear = weak/right tear = stiff advice necessarily holds true.

If your method works for you, go with it, but when I see a horizontal tear, I don't immediately start adjusting arrow spine. I adjust cam lean/lateral position first then rest windage if necessary. Some combination of those two adjustments has always corrected my left/right tears.

I've just used traditional lore. It makes sense that a weak arrow would show more variance, whether left/right or both. You would expect a weaker arrow to flex more, which would cause that high variance. We should ask what a materials engineer/scientist thinks about it....know any?

I agree, the spine range that can be shot at is wider than most people believe. I've got a number of setups and weights to shoot well out of the same bow. All at 300 spine.

And I am just speaking to how I choose arrow length for a particular setup. I have never had to address cam lean or anything other than very minor adjustments to the rest Left/Right when bareshaft tuning at distance on the range.

I think alot of this comes down to the bow you shoot. Bow "tunability" varies widely from what I have seen. I shoot an incredibly consistent and easy to tune bow (Elite Impulse 34). I have never shimmed cams, twisted cables, etc to shoot bare shafts to 30-40 yards with fletched. Every fixed blade broadhead I have used groups with field points until the extra air resistance starts showing up at longer ranges and the groups shoot low. People buying notoriously difficult bows to tune (looking at you Matthews newer bows) doesn't make any sense to me. I've yet to have a major tuning issue with my current bow, they same can not be said about previous bows I've used cough **HOYT*** cough.

 

[Mighty Mouse]

And what kind of glue are you using to be able to quickly and easily remove and replace inserts during the cut down process?

You’ll have to use some form of heat reversible glue ("hot melt") if you want to be able to easily remove inserts. I've used Kimsha and Bohning Cool Flex with good results. FYI every carbon arrow manufacturer warns against using hot melt because excessive heat will damage the carbon. However, hot melt can be used safely with carbon arrows if used carefully. I've used it hundreds of times with no issues.

If you're using the Black Eagle FOCOS system, getting a hot melted "retention post" out could be tricky because there's not much exposed metal to grab on to or apply heat to. To remove a typical hot melted insert, I screw in a field point, use a heat gun to warm up the FP, then grab the FP with a pair of locking pliers and pull it out along with the insert. You might be able to do something similar to remove a FOCOS retention post using the tiny 3-32 retention screw instead of a FP. Or you could try dunking the front end of the arrow in boiling water to loosen the glue.

 

[RockyMountainWest]

Craigslist.

I do not remove the inserts. I glue the HIT inserts as the manufacturer describes how and leave them. When I need to cut down an arrow, I take the nock off, and cut it down, square, then put the nock back on.

Gotcha. That makes a lot of sense. Thank you again for all the information.

 

[TheViking]

I'll go through I how tune my arrow to my bow if I go with new arrows (if you don't change your setup, you obviously don't have to do this).

1. Set your bow to poundage/draw length you will shoot and set the rest to the factory centershot (you'll have to look up the bow specs for this, most are around 3/4" from the riser)
2. I use a spine calculator to make sure my spine is at least close. There are several apps you can use, I use the Victory Arrows spine calculator (https://www.victoryarchery.com/arrow-guide/)
3. I cut my arrows long (by the spine calculator, weak). So, for my 28" draw length I would cut them ~29"
4. Put insert and point you are going to use in 1 arrow, cut it to the length above. I will cut off both sides of an arrow.
5. Insert nock and shoot through paper. Shoot a couple times to make sure it is consistent. You are looking for whether it is a weak or stiff tear. Because you cut the arrows really long, it should be weak. Weak should show left (nock left) tear. If it is stiff, you screwed up, you need to start over with a longer arrow.
6. Take the nock off, cut 1/4" off the back of the arrow. Square and put nock pack on.
7. Shoot arrow through paper a couple times to get a consistent tear.
8. If tear is still weak (the tear should decrease in amplitude tho), complete steps 5&6 until you get ~ a bullet hole (you are shooting bare shafts, so you should get close, maybe not exact bullet hole as this depends on form alot). If you get a bullet hole, congratulations, you are done. You can now cut the rest of your arrows to that length.

After this I will fletch the arrows, leaving the original bareshaft. I then go out and bareshaft tune at the range out to 30-40 yards. If you do the above steps, your bow is really well tuned and will shoot any broadhead excellently.

***If you are seeing inconsistent results in the paper tune part, you need to work on your form and hand pressure. No amount of good tuning is going to make up for shit form***

This is great information and I follow very similar steps.

As far as setting your bow to factory specs and still getting a tear - at what point is it arrow spine, or do you need to shim the cams?

I guess this goes back to - do you tune your bow to the arrow? or do you tune your arrow to the bow?

 

[S.Clancy]

This is great information and I follow very similar steps.

As far as setting your bow to factory specs and still getting a tear - at what point is it arrow spine, or do you need to shim the cams?

I guess this goes back to - do you tune your bow to the arrow? or do you tune your arrow to the bow?

I think it is very bow dependent. Theoretically, your bow is going to operate best at factory specs. Thus, I prefer to tune an arrow to the bow at factory specs. I know some people have to start shimming etc with poorly designed bows or trying to shoot an arrow setup that is unreasonable. To me it is easier to tune the arrow to the bow.

Lots of people make a big deal out of stuff that doesn't matter (FOC!, or 500 gr vs 530 gr arrows, whatever). A well tuned arrow and good form is prob 95% of the equation, but those things take work, it's easier to believe that buying something new is going to be the "answer"....

 

[Mighty Mouse]

I guess this goes back to - do you tune your bow to the arrow? or do you tune your arrow to the bow?

Given those two choices, I would say with a compound you tune the bow to the arrow and with a traditional bow you tune the arrow to the bow. In both cases you're really tuning the bow/arrow combo to the shooter, but with a traditional bow the arrow plays a larger role.

 

[Billy Goat]

Factory specs doesn't mean a bow is set correctly. There's too many variables. Cams need to be shimmed/adjusted to balance the load of the limbs. Deflections aren't all the same. They get balanced by adjusting the yokes, shimming the cams, adjusting the cable guard, or adjusting the whole limb pocket.

A compound needs enough spine, but too much in most applications isn't detrimental. Infact, it creates a more consistent reaction out of the bow, why a lot of indoor shooters have gone to crazy stiff arrows. See it frequently with 3d too, hasn't carried over to field as much. Less flex coming out of the bow definitely helps when you have wings on the front of the arrow (fixed broadheads).


Just saying worrying about having perfect spine in a compound is a waste of time in my opinion. Make sure you have enough, after that it doesn't matter. Same with fletching, have enough drag on the back, more generally won't help. Both areas tho when you are only marginal it can be fine most of the time until it isn't, so I choose not to push the boundaries much on too little.


The only thing that might make a weak/stiff spine reaction true with a compound in regard to right or left handed shooters is riser flex. Tho with most using drop away rests I think it probably isn't noticeable. I think its simply a function of if the powerstroke of the bow is centered and the rest is aligned properly, independent of weak or stiff arrows.