Compound Bow 'Super Tuning'

 

This section covers the sort of tweaks and adjustments that are only worth considering after you have got to grips with standard tuning and are shooting good consistent scores, but just want that little bit extra.  It is impossible to say how much you should be scoring, or what size your groups should be before you consider these 'super' techniques and, frankly, you can try them whenever you like - they won't do any harm.  But none of the tweaks are going to convert a mediocre score into a cracking good one, and unless you are shooting pretty well you probably won't notice the difference.  What is more, unless you are shooting well, you won't be able to judge when you have achieved the best tune, or at least, not without some heavy-duty statistics.  

So, shoot carefully, take lots of notes and be prepared to spend a lot of time going over and over the same ground in order to work out what really works best.  But, on the bright side, if you are shooting well, some of the adjustments dealt with here just might make the difference you have been looking for.

The Golden Rules

RULE 1 – Concentrate on one thing at a time.  If you are clocking your arrows, don't change anything else or try anything new. This is not the time to try that interesting hand position you have just read about, and leave the new arrow rest at home!

RULE 2 – Don’t try to super-tune on slopes or in bad weather, especially not in wind. On the other hand, don't try it indoors either, not only are the distances too short for most purposes, but indoors is one thing, and outdoors quite another.

RULE 3 – Ignore badly shot arrows, but be honest about it.

RULE 4 – Write it down! Make notes of everything you can think of that might be relevant, because you won’t remember later.  In particular, use some form of plotting chart. 

You can print one by clicking this link: PlottingChart.pdf (close the page to return).  

If you don't have Acrobat Reader, download it from here: http://www.adobe.com/products/acrobat/readstep2.html

 

‘Clocking’ Your Arrows

It is obvious but often forgotten that, if your arrows are not identical in every significant respect, they will not go where you want them to, however well you shoot them. And, like the static and dynamic properties of the bow itself, just ensuring that all the arrows weigh the same, are of the same length and are identically made is not always enough. What matters is that, all other things being equal, they all land in the same place in the target. Consequently, most experienced archers carry out some form of ‘clocking’. That is, they shoot all the arrows in a new set a few times and look for rogues – the odd arrow that won’t group with the rest. What I am suggesting here is that you should take a more systematic approach, known for historical reasons as ‘clocking’.

The process

Assuming you have a dozen new arrows and have gone through the basic tuning process:

  1. Get hold of 24 plotting charts. 

  2. Check that all the arrows are the same in every physical way especially the same length and weight (plus-or-minus 0.5 grains). This is not the be-all and end-all, but it is a good starting point.

  3. Number each arrow where you can’t see it 'accidentally' as you shoot. The underside of one of the fletches is usually the best place. If you put the number where you can see it, it will inevitably affect your shooting and you won't get the outcome you're looking for.

  4. Shoot your arrows in the usual way (ie in fours if you usually shoot Field, in sixes for Target etc) at a middle to long distance target – I regard 60 yards as a minimum. Do not shoot the arrows in any particular order, even if that is your normal habit.  Unless you are shooting so well that you are damaging shafts, you can leave the arrows in the face until you have shot all twelve, as it makes interpretation easier, but still shoot them in distinct ends, with a rest between each end.

  5. Record your hits on the chart. The best way I have found is to record all the arrows for an end on one chart, marking in the number of the arrow in the place it hit, then - and this is the part that will really pay dividends – record all the No 1 arrows on one chart, all the No 2 arrows on another chart, and so on. So for example, for a set of a dozen arrows you will have 13 charts after the first end, 14 after the second etc.

  6. Repeat the process until you feel terminal boredom setting in, or for really good results, about a dozen cycles of the set (144 shots). Theoretically, it is best to do the whole thing in one go, but in practice, provided you can repeat the conditions, there is no reason why you shouldn’t partially complete the test and come back to it later.

Interpreting the Results

If any of your arrows are real rogues, it will quickly become obvious and these arrows should be removed from the set - in fact, they should have been dealt with already. The next step is to look at the charts you have so laboriously drawn up, and see if any arrows are off-centre in a consistent, but less obvious way. You will have to use your experience and common sense here, and you must know your own limitations, but if a particular arrow is always, say, low and right then that tells you something important about that arrow, and you will want to do something about it. This is where the individual charts are invaluable, as each is dedicated to a single arrow, and any unwanted tendencies very quickly show up.  However, it is still useful to compare to the 'full-set' charts, to see if there was a tendency for all to go in the same direction because of a slight down-range wind, for instance.  This is another case where doing it is easier than explaining it.....

Correcting Problems

In general, corrective measures are fairly obvious and, in practice, they are the same whether the arrow is high or low, left or right.  

  • Check that the shaft is straight.  If not straighten it or junk it, as appropriate.

  • Check that the all-up weight is as it should be and adjust if necessary.

  • Check the fletchings - are they firmly stuck? at the correct angle? undamaged etc?  If in any doubt, refletch with three new vanes.

  • Check nocks and inserts - damaged? bent? properly indexed? correct string fit?.  I usually replace the nock on any suspect shaft as a matter of course.

  • Check points - firmly glued in?  undamaged?.  Again, routine replacement is often the best thing, provided you can get the point out.

As usual in archery, life is not always that simple and it is not uncommon to find that even quite serious rogues have no detectable faults. In these cases, I take a 3 step approach:

  1. Completely dismantle the arrow and carefully rebuild it, using a new nock, insert and fletchings and probably a new point as well. This often solves the problem, although I usually have no idea why. 

  2. If the arrow is still consistently high or low, add or subtract a little weight even if this makes the arrow significantly heavier or lighter than the rest. Unfortunately there is not much you can do about an arrow that is flying left or right and you must pass directly to the last step and ...

  3. Junk it! This is quite rare, but you do sometimes find a shaft that just will not group consistently, and it has to go.

Tiller Tuning

Tiller tuning is probably the next advanced tuning technique to try.  In certain cases, especially where the archer has an unusually high, or low grip, it can make a really significant difference to your results.

The full process, assuming your tiller is currently equal top and bottom as described in Standard Tuning is as follows.....

  1. Settle down by shooting a dozen or so arrows at about 60 yards.  Note the size of the groups preferably using a plotting chart. Another useful trick is to use paper plates as an aiming mark.  If you use one for each adjustment, they can be compared - provided you can guarantee being able to hit the plate every time, that is!

  2. Put a quarter of a turn on to the bottom limb bolt and take a quarter turn off the top bolt (this keeps your draw weight approximately constant).  Reset your nocking point and peep sight and shoot again.  Note the size of the groups.

  3. Repeat in quarter turns until you have a full turn on the bottom and a full turn off the top.  Stop if at any time things are obviously getting worse.

  4. Come back to equal tiller and repeat the whole process, this time putting turns on the bottom bolt and taking them off the top bolt.

The chances are that one of the settings not only produced better groups than the others, but felt steadier and more comfortable.  If so, experiment a bit further and try to refine the adjustment to the best possible position and you have your best setting.

It is worth checking things out at shorter and longer distances, but it is probable that the same setting will be best wherever you shoot from.  If you do find that it is not so good at different distances, then you must work out a compromise.

So what is happening here?  First, you are balancing the pressures in your bow hand and arm.  If you add turns to the bottom limb, you are pulling the bottom of the grip more tightly into your hand, and vice versa.  Neither is right or wrong, but some particular balance may suit you better than any other, and that balance may differ from bow to bow, or even set-up to set-up.  For example, with my current set-up, I like the pressure point to be high, so I put about half a turn on the top limb and take half a turn off the bottom.  With my previous bow, it was exactly the opposite - so don't assume that the ideal setting, once found will always apply, no matter what or how you shoot.

The second thing that is happening is that you are reducing the change of pressure as you loose to a minimum.  You will almost certainly find that the your stabiliser will kick up or down significantly less at your optimum tiller setting that anywhere else, in fact some experienced archers use this as the main way to judge their tiller settings.

Finally, you are balancing out the speed of recovery of the two bow limbs.  It may be that one limb is just naturally faster than the other, or that one cam is a little stiffer.  By putting a little more weight on one limb or the other this can be corrected.

A Shortcut...

With a little bit of luck, you can shortcut much of the simple, but tedious process of tiller adjustment.  My experience is that if you find the tiller that feels best in your hand, and gives you the steadiest aim, the rest will follow automatically.  Add and subtract turns as above, but don't bother to shoot.  Just note what gives you the steadiest, most comfortable hold at full draw.  This can usually be done in a couple of minutes as it is obvious when you are going the wrong way, and certain settings do immediately feel right.  Check out the grouping and compare to the full procedure if you like (at least the first few times you do it), but unless there is something quite unusual about your set-up or style, I will be surprised if you can do any better.

Cam Tuning - Kudlacek Split Cables

It is both a strength and a weakness of the Kudlacek system that each side of the split cable can be of a different length.  Initially, it is good enough to ensure that the axle-to-axle distance is the same on each side, as described in the 'Shoot-through Cable Systems' section.  However, by this stage, you may want to super-tune.  The principal is much as described below for overall cable length, except that you place half-turns in each side of the cable for each limb, and look for the smallest groups.

 

Cam Tuning - General

So far, you have set up your cam timing by eye, and this has probably been good enough.  Some people recommend more accurate measurement usually using bracing height gauges and callipers.  Personally, I have not found that to be any better, when it comes to grouping, than eyeballing.  What I have found to make a small, but significant difference is (as usual) letting my groups determine the best timing...

The idea behind this is that when your cams are perfectly timed your groups will be much less affected by small variations in draw length -  a fault I am very prone to, as I use a static loose.  Frankly, I am not sure of the reason for this, but it seems to be true, although I stress again that this section is about 'super tuning' and I am talking about small improvements in grouping and small variations in draw length.  

NB - If you use a style that relies on heavy backward pressure of your release hand, you will not be able to carry out the 'front of valley' part of the test and you will not need tell-tales.  Breathe a sigh of relief - you only need shoot half the arrows, and the results will be much easier to interpret, as you just go for the smallest groups! 

  1. Make sure your cams are balanced by eye.  If you have Kudlacek cables, tune them before this procedure.

  2. Put a pair of tell-tales on your cables (I use insulating tape) so that, as one cable goes down and the other comes up the tell-tales come together to mark the very back of your valley, or where you are hard against the stops.  You can do this yourself by trial and error, but it is much easier if you have help to place the tell-tales.

  3. Shoot at least a dozen arrows at a middle to long distance target, being particularly careful to align the tell-tales for each shot.  As usual, record your group on a plotting chart.

  4. Place a half-twist in each of your upper cables and repeat, recording on a separate plotting chart.

  5. Repeat, a half-twist at a time, until you have obviously gone too far (you will know!).  This is usually something like 6 half-twists.

  6. Untwist the cables back to their original position and move the tell-tales so that they now mark the front of your valley.

  7. Shoot and twist, as above, but this time from the front of the valley - which is not so easy!  

  8. Untwist the cables back to their original position, move the tell-tales to mark the back position and repeat the whole exercise, back and front of valley, but this time twisting the lower cables.

It is unlikely that you will want to, or be able to carry out this procedure in one go, as it is extremely time consuming and requires a lot of concentration.  Provided you keep adequate records, and can duplicate the conditions, you should be able to break at any point - usually, in my case, when I start to get bored - and pick up where you left off.

Interpreting the results

With luck, you will have a plotting chart that shows quite clearly that a particular set of cable twists produced the smallest groups and the smallest difference between front and back of the valley.  In reality, you will probably be able to rule out some bad ideas immediately, and you will be left with a number of set-ups that represent a compromise between group size and front-to-back consistency.  In this case you might like to repeat the test, just for these settings, and if that doesn't produce a clear-cut result, choose your setting on the basis of your style and what you know to be your own personal tendencies.

So, is all this worthwhile?  I would say that it is as, just occasionally, it produces a large and unexpected result.  Even if it doesn't, it should give you more confidence in your set-up, and that must be good.  Like everything in archery, particularly at this level, you must make your own mind up.