RE: How important is shaft straighness for hunting??
 

Bowfanatic, I have to agree with this statement. Ever since I've built my spine tester, I've been a bit amazed at the variation in spine among a dozen carbons. Most dozens will show at least a .030 difference between the stiffest and weakest arrow in a group (that's a lot). I've measured some dozens where the vaiation was .065. That's incredibly huge variation, that can't possibly result in a consistant shooting dozen. If you're shooting borderline spined arrows, you are not likely to get the same point of impact from such variation, when shooting broadheads. I have found certain brands to be less consistent than others and have found the lower tolerance for-straightness arrrows to be less consistant than the higher end ones in most cases. This makes sense that a straighter arrow is also likely to test more consistant with spine. Aluminums shoot so good, because they are not only very straight, they are very consistant with spine. Seldom can I measure more than a .005 difference in a dozen.

I have managed to get great broadhead flight from my arrow building. My procedure to build an arrow is the following: Select a shaft that is slightly too stiff for the cam and poundage I'm shooting. I then cut from both ends at 90 degrees. I spine test, marking the stiffest side with a marker. I cull any arrows falling below a particular spine (too weak). I then align the cock feather with my mark. This way, each arrow has the stiffest side flexing the same way. Then, I attach feathers with a strong helical to get the arrows spinning and attach a broadhead heavy enough that I get an F.O.C. of at leat 10%. With this method I've gotten great flight from even cheap arrows. The difference is the number of arrows I keep out of a dozen. I've increased my percentage of "keepers" from all dozens, but the more expensive arrows (at least from some brands), have yeilded higher numbers of "keepers". This is the reason I have found them to be worth the price to me.

RE: How important is shaft straighness for hunting??
 

My thoughts exactly !! ;)

RE: How important is shaft straighness for hunting??
 

making your arrows is the way to go.

RE: How important is shaft straighness for hunting??
 

yea, i think we have beat this topic up enough.

RE: How important is shaft straighness for hunting??
 

Straightarrow,
It would be very helpful and informative to know just what the measured difference in point of impact was that you have found with these variations in spine deflection. Also did you find a pattern in point of impact differences to spine difference (weaker spine high, low, left or right)?
Also one thing that I don't believe I have seen mentioned in this discussion that has been the biggest determining factor for me in broadhead grouping is alignment of insert to shaft. I have my own system of installing inserts that works for me and I hate to let anyone else install inserts on arrows for me to shoot. I have shot arrows with fixed broads only to have them fly all over the place, then remove the insert and install straight and have the same arrow fly perfectly. This has occured with some of the best and worst straightness tolerance and and highest and lowest priced arrows.

RE: How important is shaft straighness for hunting??
 

Can you describe the way that you install your inserts? I would like to know how to get them perfectly square.

RE: How important is shaft straighness for hunting??
 

Unfortunately, I wasn't detailing any of that. If I had a confirmed flyer, I culled it. I number my arrows as i build them, and note what the spine variation is, but I don't record the actual numbers, or where they hit. That would take more work then I really want to do. I have also planned on building a few dozen where I align the cock feather with identically spined sides (not necessarily the stiffest side), and see how they fly. I haven't done it yet, because what I'm doing is working so well, I don't want to have to refletch a dozen. I'll have to get overcome that laziness and give it a try. If I have a spine of .340 on a dozen and I find one that is .370 on the stiff side, I cull it without shooting it. Once they get to the weak side, they just don't fly the same with broadheads. I'll save them up for someone shooting 55-60 lbs and give it to them.

RE: How important is shaft straighness for hunting??
 

This says it all. Great post SA. (I added the bold face). I think most folks would be appauled at the crap many manufacturers sell us under the guise of "quality" gear.

I'm curious how many people who are not worried about cheap carbons would tune your bow up for XX78 2314's, and then shoot a mix of 2314's, 2315s, 2413s, and 2219s out of it?

That's essentially what you are doing if you shoot a dozen carbons shafts which vary up to .065 in spine...

RE: How important is shaft straighness for hunting??
 

My personal limit is a difference of +/- .015 , though I think you could get away with a little more vairation than that. However, if your broadheads are large, FOC is small or you're using straight fletched vanes, I wouldn't.

RE: How important is shaft straighness for hunting??
 

I used to be a machinist years ago and some of the parts that we inspected we did a concentricity test on a metal shaft just 4" long.If the shaft was even .003"of an inch it was rejected.Now just think;three thousands of an inch of a four inch span compared to an arrow shaft that is at least 25"thats an awfull large error.Spin test any arrow with a broadhead at the end ,on a streight arrow with an "even" glue line, and you can even see some wobble wich could be from other factors other than the shaft .I would get the straightest arrows possible or that I could afford,You do get what you pay for most of the time.Hey and in archery or any target sport isn't accuracy paramount?Hunting too!