Going round so far you end up back where you started

[LineCutter]

Originally Posted by Jerry Tee

Sorry I thought you meant a literal harmonic.( Gone away to think (ouch))

That's the effect, which is what I was aiming at... but not as nodes on the shaft. My idea is that there are coinciding position/pressure effects that affect the arrow flight (which is the point of tuning, is it not). These do not have a single "U" shaped graph of pressure vs arrow flight, but represent a series of "U"s, with the series looking like "uUu" or ".uUu.".

The archer's loose affects the lateral pressure on the button & so the size of the error is either minimised or maximised depending on the size of the "U" that the bow is tuned to.

I think we need to PM Joe...

[joetapley]

Walk back tuning is awkward for two reasons. Firstly its complex technically so you need to know what you're doing to get a sensible result. Many "how to walk back" tuning write ups range from hopeless to daft. Secondly the old how to walk back write ups were written for fat slow aluminium arrows. The old methodology works very poorly with modern carbon arrows.

For basic bow set up it's much more sensible to use a 30m bareshaft approach for iniital setup as you have the bareshafts available anyway. You can use a modified walk back type approach for verification purposes and IMO anyway for minor button spring adjustment (Vittorio Frangilli regards walk back tuning aproach for carbons as useless - period).

As far as I know no one has written a how to walk back tune carbon arrows guide. Good idea. If you need a "how to" guide then you should leave walk back well alone.

[Jerry Tee]

There are only two things that I can think of that might help you. First is that you may have some thing mechanically wrong with the button. Second you might try short range tuning as described in the Easton tuning guide.

[WhitehartFB]

Originally Posted by joetapley

Walk back tuning is awkward for two reasons. Firstly its complex technically so you need to know what you're doing to get a sensible result. Many "how to walk back" tuning write ups range from hopeless to daft. Secondly the old how to walk back write ups were written for fat slow aluminium arrows. The old methodology works very poorly with modern carbon arrows.
.

Spot on Joe, carbon arrows and Aluminium/Carbon do not behave the same as aluminium when doing the walk back test. Agreed set the centre shot and30M bare shaft test which should give good enough results for most of us and then plenty of practice. It was proved to me (30 h'cap) that I will gain many more points practicing rather than messing around with a little spring.

[geoffretired]

Even more interesting! The problem is, I now know less about tuning than I did before;or so it seems.
I do appreciate Joe's explanations and there have been many times when I have relied on his expertise to help me out of my problems. With this one, I feel I need to step back and come up with a simple version of the truth. When the science/physics/maths is beyond me I cannot just give up. I need to use a simpler analogy that fits the truth and gets the results, if that makes sense.
Linecutter, I hope I am not hi-jacking your thread. As my problem is related, perhaps this is the best thread to reach a solution. If there is a better way, a moderator will probably move it.Sorry in advance if I am being a nuisance.
My simple outlook is this. An archer(who can shoot well enough to produce good arrow flight) has new arrows that do match the bow, according to the charts, but as the bow is wrongly set up for them, the best is not being achieved. We set up the nocking point using bare shafts;first.
We adjust the centre shot and button pressure to give good flight.( no wild swinging and no contact with anything) The bare shafts are landing just below the fletched group at distances that are comfortable for this archer.
We may stop there but could go on to walk back. The reason for the walk back is to check that the arrows are flying on a straight and in line with the line of sight so the windage does not need to be adjusted everytime the range is changed.
The walk back will require minor adjustments, I assume, so the bare shaft set up is not totally replaced.
The set up can be recorded/should be recorded. The archer may want to go to the next stage. They may shoot groups at longer range and try small adjustments to the variables( one at a time) to see if any improvements can be brought about.This will be a long process as many arrows will have to be shot in order to rely on the results.
That is simple enough for me to understand. If it contains elements that are untrue, please set me right.

[joetapley]

For a basic bow setup we, as Geoff said, we want the arrow to fly in a straight line in the vertical plane from archer to target. "Good visually perceived arrow flight" has little to do with this. The only thing we can easily see is a large angle of arrow fishtailing but fishtailing has nothing to do with the arrow flying in our desired straight line. see as an example http://homepage.ntlworld.com/joetapl...ersparadox.wmv

What causes fishtailing is the arrow not pointing in the direction its going. As per above arrow alignment (nodal alignment if you want to call it that) at launch or generated during the flight for basic bow setup is irrelevent (It's not irrelevant for fine tuning).

Both "button tuning" bareshaft and walk back methods directly look at "is my arrow travelling in a straight line or not". With the bareshaft method if the arrow initially flies in a curve the bare shaft deviates more than the fletched shaft so you can see the deviation. With walk back if the arrow is hitting the X at 20m but hitting left in the blue at 70m the arrow is clearly deviating from a straight line.

[geoffretired]

Thanks again, Joe. I was beginning to think I'd lost the plot?!
I feel better now. I hadn't connected the bare shaft and walk back so directly as your explanation does. That is very interesting and helpful. If the bare shafts and fletched ones land together, there will be straight line flight, but not necessarily good arrow flight? If they can't be brought reasonable close, they won't fly on a straight line and I assume that is an indication of spine mismatch too. I hope I've got that right!

[joetapley]

I will gain many more points practicing rather than messing around with a little spring.

Whitehart's point is worth emphasising. Any chart selected arrow will be close. If available adjustment of button or draw weight doesn't achieve "perfection" then don't panic and start sawing arrows in half or buying new ones. Do as best as possible. As long as you adjust for clearance the average archer's focus should be on technique not equipment.

[Rik]

Originally Posted by geoffretired

If the bare shafts and fletched ones land together, there will be straight line flight, but not necessarily good arrow flight?

Not necessarily... The shafts fly in curves (different ones, for bare and fletched shafts), generally, so you could get the bare and fletched shafts to group at a particular distance, and still find that the setup is poor. It just happens that you selected a distance for testing, where the paths of the bare and fletched shafts cross...

That's why it's normally recommended to do bare shaft tests at more than one distance (in the same way it's normally recommended to do paper tuning at more than one distance).

'Good arrow flight' is slightly irrelevant in any case. It's possible to get good flight and poor groups, bad flight and good groups. Which would you prefer?

[geoffretired]

Thanks Rik for your comments. I did say "distances" for bare shaft so we are in agreement. I was really trying to get my head round the complex issues in a way that I can use with other people who are tuning/setting up for their first time possibly. I agree with you also on the good flight/poor groups and good groups/ poor flight aspect. I think I would aim for good in both respects. If I had to sacrifice one for the other I would settle for good groups initially; but then I'd be asking questions again and thinking of changing arrows to get both.
I assume it is possible to get both. I think Joe will say good arrow flight is not really that good; we just can't catch the wiggles with the naked eye. But there has to be a definition of "good" where we can say it is acceptable and doing no damage to the scores or the arrows or even to the riser/rest. Put another way, poor arrow flight is fairly clear to the naked eye, where the first swings are clear for all to see.(apart from the archer launching them perhaps)