Tuning issue?

[pastorfarley]

I shot each model of broadhead I own last night to ensure they are hitting with the field points and I got interesting results, and maybe a tuning issue.

The Bow - "Buckmasters Pro" set about 45# with 27" draw

At ten yards:
Three heads shot to 100 gr field point impact point: 100gr Gladiator, 125gr Thunderhead and 125gr Vortex minimax 3 (The 85 gr minimax 3 also hits well in prior testing).

Three heads hit low and left - 4" - the group was tight, overlapping cuts in the paper for: 100 gr Premier, 125gr Bear Razorhead (circa 1977), 125gr Bodkin

Two heads hit low and right - 3" - also a tight group with each blade cut within the diameter of another: 100gr Viper, 125gr Aftershock

One head hit about 1" left - 125gr Vortex 2 blade

I do not see any real pattern here, but some of you more experienced tuners may know what is going on.

The Vipers have never hit to field point point of aim for anything I have done

This is the first time the Premiers or Razorheads have not hit point of aim.

[SPIKER]

Hmmm, at 10 yds there shouldn't be any problems at all.

I would say that I would not expect a 125gr head to tune well with a 100 gr fp at any distance past 10 yds.

Also, I'm not familiar with any of the heads you are using, so it's a good possibility that some are not passing heads. (I'd have to look that up in the testing section).

Do they all spin test properly?

If your Premier, and Razorheads previously hit on with your fps, and are now hitting low, left, there could be a few problems.

If you have changed shafts, or changed the draw # on your bow to a lower poundage, it could be that you have created a stiff spine.

If not, then your string might have stretched, in which case you need to re measure your ATA, tiller, brace, and nock point. If you have the original specs, you will be able to match these measurements.

Lastly, you might have to move your rest up, and right, just a tad...or...lower your nock point, depending on where the arrow is in relation to the berger button, and move the rest a tad right .

I hope this helps, I'm sure BT, and some of the others can fine tune the problem a bit more for you with some more info.


Ok...I just saw your other thread, and realize that this is a new bow for you, with a different draw length, so...we will need all the info to help you get this bow tuned to the arrow, and broadhead of your choice...

This is the info that you can start with:

Bow...Drawlength...LB.

Arrow...Length...gpi...Fletch...Head.

[pastorfarley]

This is my first time trying to tune a more modern bow.

I shot another round of field points and moved back to 17 yds and they shot a bit to the right. I am sure the moleskin on my prongs was wearing and it shifted the shaft just slightly down and left (one side was more worn than the other).

I fixed that and my next round showed the same vertical impact at 10 and 17 yds.

Right now I have 29" arrows with a spine in the 400 range, or the 45-60 on shafts so marked. I have a lot of arrow hanging off the end, I think this bow will allow clearance for all broadheads with a 28" shaft so I will be getting some shorter arrows.

You are right about the tiller, I need to work on that.

I am trying to accelerate my learning curve by asking for help.

[SPIKER]

Ok, you have the first part. So now you need to back up tune, then broadhead tune.

Start by shooting at the verticle from 10, 15, then 20 yds. Take some shots from 30 to fine tune.

Then place a piece of electrical tape horizontally across your target, and shoot 10, 15, 20. If the 15 yd arrow hits higher than the 10 you need to lower the rest a small amount until they hit together. If it hits lower, raise the rest a small amount. I'm not sure if your bow will shoot flat to 20, but find the yardage that the arrow starts to drop...I'm guessing 17 - 18 yds.

Once you have that straightened out, you need to broadhead tune. Check out this chart, it's a keeper:



Now, those 45-60s are spined for 28" @ your lb draw.

I would look into a lighter arrow that would be better spined for your setup like PSE Radial X Weave 100s.

www.pse-archery.com/cat.php?k=56063

Hope this helps..

[pastorfarley]

Thanks Spiker, I worked on the tiller and got two more heads to pass, and two more much closer. When I saw tiller I said Duh! I checked it earlier and thought it might be out but had not figured out for sure, then when I read "tiller" the whole thing became clear and I went right down and dealt with it.

I am working in the basement now so 10 and 17 are the only yardages I have available. I appreciate the chart, I remember seeing it before.

[Doegirl]

I second Spiker's suggestion of Radial X-Weaves in the 100 spine.
Those 45-60's are pretty heavy for your setup. Another thing I would like to suggest is to focus on working with one or possibly two selections of broadheads that you intend to hunt with. At least that'll drive you less crazy

[pastorfarley]

Doegirl - I agree on the X-weaves, and they are the 400 spines I was talking about. The point of impact difference is relatively consistent across three different shafts, and two fletch sizes. The X-weaves are the most reliable however. I will be adding draw weight through the summer so I may get to a place where I need the heavier spines.

I have a collection of sample quantities of heads and am, like many, searching for the "perfect" head. Whenever I get a chance to buy something I like the design of at a price that I like I give it the accuracy test. The passing heads get a function test if mechanical. Eventually I will settle on one, but the process is enjoyable and informative, when it is not baffling

[BT]

Mar 26, 2009 13:41:54 GMT -5 pastorfarley said:

I shot each model of broadhead I own last night to ensure they are hitting with the field points and I got interesting results, and maybe a tuning issue.

The Bow - "Buckmasters Pro" set about 45# with 27" draw

At ten yards:
Three heads shot to 100 gr field point impact point: 100gr Gladiator, 125gr Thunderhead and 125gr Vortex minimax 3 (The 85 gr minimax 3 also hits well in prior testing).

Three heads hit low and left - 4" - the group was tight, overlapping cuts in the paper for: 100 gr Premier, 125gr Bear Razorhead (circa 1977), 125gr Bodkin

Two heads hit low and right - 3" - also a tight group with each blade cut within the diameter of another: 100gr Viper, 125gr Aftershock

One head hit about 1" left - 125gr Vortex 2 blade

I do not see any real pattern here, but some of you more experienced tuners may know what is going on.

The Vipers have never hit to field point point of aim for anything I have done

This is the first time the Premiers or Razorheads have not hit point of aim.

When you see things like this happening, you have to assume that it is all of the above.
The fact that you have broadheads here that are a mixed bag of passing and failing heads of varying weight is going to drive you nuts.
You need to start with a head that has zero defects for flight.

Next is the fact that you need an arrow that is matched to the bow.
Carbon may have a wide spine range but it is a deceptive measure of performance when looking at the listed specs.
The further past 28" or under 28"....the less the listing applies to that bow.
Also, the arrow length is important. Shooting an arrow that is overly long will hamper tuning ability and performance.

With a bow that is set to factory specs at the beginning, the order of importance as to head or arrow is not an if/or question.
The arrow&head combination must be correct or perfection will not be achievable.

I would suggest a 35/55 shaft @ 28" (max. length) and a 100 grain head such as the Blitz which is a perfected head (in aerodynamic terms) with enough blade mass to pick up tune imperfections.
Head weight for this set up must not exceed 100 grains and will be best @ 85grns.

[pastorfarley]

Thanks BT, I was waiting for you to weigh in.

I have continued to improve the tune with Spikers advice and am working on it step by step. I have it shooting within 1.5" of flat at 10 and 15 yds and will continue to work on that, once I get as flat as I can I will work on the azimuth issue. Part of my problem is this bow was bought in a pawn shop by my friend and the draw module was replaced by an outdoor shop that works on bows, but I am not sure of their expertise level. Then there is my friend who fiddled with it some more.

I plan to take it to the Pro shop in Old Town that I trust and get the draw where it belongs, then I will get the arrows the right length, then I will go through this whole thing again ;D, but I will be more educated thanks to you all

[SPIKER]