kilnbux

I am currently trying to tune my new Bowtech Allegiance ( 2005 ) bow and have ran into a brick wall. My goal ,as unrealistic as it may seem to some, is to have my bareshafts, fieldpoints, and broadheads all hitting the same general area. I did acheive this with my last bow and it shot very well.
Current equipment
-Bowtech Allegiance 05
/ binary cams
/ 80# draw weight
/ 29 inch draw
/ 28 inch Beman ICS 340 Hunter arrows
/ 100 grain tips
/ Drop Away rest
First thing I did was make the proper adjustments to get successful bullet holes on the paper test. I had the bow shooting nice bullet holes at various distances. I then reset my sites and found that my broadheads and field points were hitting the same general area at 20 yards.
Next I moved to bareshaft tuning. I removed my fletchings and then added the fletching weight back to the arrow by adding a cut down insert to the rear of the arrow. Got it within two grains.
I began shooting. Shot after shot, adjustment after adjustment, the arrow is consistently hitting with nock up ( downward angle ). Cant figure it out.
My questions are: Is this an arrow spine issue ( Beman ICS issue )? Is this a drop away rest issue ( Dropping too fast )? Is this a Bowtech / Binary Cam issue ( Out of timing )? or Is this an FOC issue ( use lighter fieldpoints > 85 gr)?

Thanks

akaSharkey

There is a possibility that if you split the downward cable to install your cord for the dropaway rest then served around it, the downward cable is now slightly shorter than the upward cable. Here is a link that has to do with that http://www.archerytalk.com/vb/showthread.php?t=218697 Just a thought. There is a lot more people who know about morethe binary cams thanI do.

kilnbux

This happened when i had my drop away 4000 on it too so i think we can exclude that problem.

Straightarrow

I wouldn't bother trying to get bareshaft arrows grouping with the others. Flight dynamics are too different without fletching. Use the bareshaft to determine correct spine, or shoot everything on the slightly stiff side. Getting broadheads grouping with field tips can be very difficult on some set-ups. Spine is very important and most people do not test spine at many different settings.

Important to check: Broadhead alignment must be perfect. Spine variance in the arrows should be very close. If not, the arrows should have been spine tuned. High FOCs can help keep broadheads from planing as much. You need to experiment with different arrow lengths, different draw weights and tip weights.

Your problem could be the drop-a-way rest, but I don't use them, so I can't help there.

gibblet

weird as this may sound, i'm hearing that bow likes a little bit of a weak spine. also, any pressure on that downward cable from a drop cord really effects that bow. the latest i'm hearing is the sims slide with the cord hole on the opp side of the slide is better to use. anyway, that's the latest i'm hearing.

Paul L Mohr

Ok for starters if your goal is to hunt with fixed blades and you want them to impact with your field points it sounds like you are already there. If they impact where you want them, group well and fly good I would quit messing with it. Or maybe try to broad head tune at a farther distance. Often times broad head tuning and bare shaft tuning will yeild different impact points.

And what you didn't tell us is where the bare shaft arrows impact, just how they were sitting in the target. Which is really of no concern unless the are very skewed in one direction. Slightly nock high with bare shafts is actually pretty good and I would be happy with that. That shows that you have good FOC and the fletchings are doing thier job.

When I bare shaft tune I cut the fletchings off leaving the base of the fletching. This is where most of the weight is so your arrows are almost exactly as they would be normally but without the steering control of the fletchings.

Then I start up close like 10 yards or so. And you need to use a soft target so you don't ruin your arrows. I use bag targets for almost everthing. Don't bare shaft tune in a broad head target! When I bare shaft tune I worry only about the impact points in regards to my fletched arrows and how well they group. I do not concern myself with how they look in the target. The arrows will fly different in the air, that is what the fletchings do after all, stabilize arrow flight. My concern is that the bow is throwing the arrows in the same spot shot after shot. I gradually move back as I'm tuning and fine tune as I go. I normally stop at 30 or 40 yards. However if you can get good bare shaft flight at 20 yards you are probably tuned pretty well.

And if I am broad head tuning I do the same thing, but with broad heads instead of bare shafts. DO NOT SHOOT unfletched arrows with broad heads!!

Paul

kilnbux

Thanks Paul for the input. I have concluded that I am shooting an improper arrow. The Bemans I should be shooting are the ICS 300s and not the 340s. Proshop guy sold me the wrong ones according to the chart.

Today I tuned until my broadheads were consistant with my fieldpoints. I then shot gold tip 7595s and the beman 340s. It was obvious that the bemans were not grouping as wellas the gold tips. I also bareshafted both of those arrows and the bemans hit with a greater downward angle.

As far as where the tips of the bareshafts hit, they were pretty much in thelower nine spot.

Is it a good idea to shoot lets say 3 or more different arrows and go with the most consistant one? I really dont know any other way to determine if I'm shooting a properly spined arrow. Is there any other ways to checkand see if the spine is right? Also, how much of a downward angle should bareshafts hit with on a properly spined arrow with a tuned bow? My mathews safari was producing bareshafts that hit exactly the way they left the bow, but I was also shooting 98#s.

This microtuning is creating headaches, but I want to be at maximum performance; just think it'll will helpme be more consistant at greater yardages.

thanks

Straightarrow

That's one way of doing it, but not a very good one. Choose an arrow based on the quality you want to start with. Choose the arrow spine from the charts, but do not choose one that is anywhere near weak on the charts. To tune for exact spine, you have a couple choices. You can adjust shaft length. Or you can adjust bow draw weight. Choose a tip weight that gives you a high FOC. I'd strive for at least 10% and do not be shy about shooting an even higher FOC.

Shoot your bare shaft by wrapping masking tape where the fletching should be, until it equals the weight of the fletched arrows. If you want to shoot a particular draw weight, start with a very long arrow and shoot from about 15 yards into the target (use a target that will not redirect flight of arrow, like a foam one). If the arrow hits tail left (it should), it is showing a weak spine. At this point, you can start cutting the arrow down, and/or reduce draw weight until you get the arrow hitting with the tail centered. At this point, spine will be exact. Be careful not to cut the arrow shorter than your bow/rest combination can handle. If you start out with a lower quality carbon, I suggest tuning until you get them all shooting a little stiff. Low quality arrows with a wide spine variance, will leave you with some shooting weak and some shooting stiff - not a good formula for success. It is better that they all shoot slightly stiff when using broadheads.

If the tail is hitting very high or low, you need to adjust your nocking point. You can test this more accurately by paper tuning from about 6-8 feet.

kilnbux

I appreciate the advice. But what is the best way to make sure I have perfect centershot before doing this test? And why would a weak spine hit to the left with a compound and a release?? If I start shooting to adjust the length / spine of the arrow, how long past the rest should I start? If the arrow keeps hitting with a downward angle no matter what kind of adjustment, what is this showing....... too heavy tip, too forward foc.......... or is this an indication of improper spine?

ewolf

The way that I test centershot is the step back method. Shoot an arrow @ 5,10,15...35. If they make a C shape then the rest needs to move to in. If they make a backwards c shape the rest needs to be moved out. If they make a diagonal on the target, your spine is too far off to test for centershot.

I can tell you a very easy way to get the centershot really close. Put an arrow on your bow and look at your bow from about 5 feet behind it. Put the string in the middle of the grip, and make your arrow fall in line with the string. On longer bows (38" +), I haven't had to move one in 5 years after setting it up this way.

The left/right weak/stiff thing is only a "generally" statement. Sometimes it is reversed, and nobody knows why. If the bareshafthits to the right it should be too weak, but then again they might be to strong. Adjust the spine of the arrow/bow to see which it is.

Every, yes I said EVERY bow that I set up the broadheads, field points, and bareshaft fly to the same spot at 40 yards. I set up the centershot, then bareshaft tune to 40 yards. Put a broadhead on spin test it, and it will hit at 40 yards.