Dynamic tiller

It would be great to get your views on setting dynamic tiller. By that I mean that the limbs should come to zero at the same time as the bow is fired but how can you account for that without a high speed camera? I've but the bow on my compound draw board and measured the tiller at full draw and then as the string returned to zero - in other words simulating the arrow launch. By doing so I changed the tiller on my barebow from zero to positive tiller. The bow shoots pretty good but I'd love to hear your opinions on this as a good method or perhaps flawed on some way
 


Also I set the pivot point on the string as a 30m crawl, so below the nocking point by 8 notches on my tab to simulate a real world situation
 


geoffretired

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I am not sure( could be wrong) that putting the bow on a draw board will tell you anything. For example, when you measured the tiller at full draw, what did that tell you? When the bow shoots the arrow, the path back to rest is not necessarily the same as the draw in reverse. On the power stroke, the string is held back, to some extent, by the mass of the arrow. That resistance on the string is not central so will change the way the limbs react as they unbend back to the start. Also, the way the string is held during the draw, with the fingers, will bend each limb slightly differently from the way they are drawn by the draw board.
. If the goal is to get both limbs coming to rest "nicely" so they don't end up flapping back and forth for some time afterwards, you could try adjusting the tiller bolts so they start from a different position, in the hopes that one starting set up will give the end result you are looking for.
If you go that route, I would make sure you count the turns on each limb bolt as you go so they can be put back if you need to. As you change the limb bolts, you will need to have some way of deciding if things are getting better or worse. It is not easy to see the difference and often the sound is much the same.
Changing the brace height can often change the way the limbs return to rest; so that is another option.
 


I found this on the Internet so I might get a stabiliser to test

This procedure adjusts tiller to give visually balanced bow behaviour on the shot.
i) Set up the bow with a light long rod. Shoot the bow at any comfortable distance, and observe the behaviour of the tip of the rod and subsequent behaviour of the limbs.
ii) If the rod kicks up instantly, increase tiller; if downwards, decrease the tiller. Repeat until the rod moves essentially straight forward. Take care to distinguish the natural bow movement from anything the archer does following the shot, and from natural forward or backward roll; look for the instant reaction to the shot.
iii) During the exercise, monitor the limb behaviour. Vertical oscillation after the shot, which may show as the nocking point vibrating rapidly up and down, suggests tiller imbalance. This should be minimised by adjusting tiller as necessary
 


geoffretired

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I would guess that a long rod with little or no end weight, will kick up instantly, as the bare bow tends to do that naturally. Many archers add weights to the long rod until they have enough weight to counter that kick. The kicking of the bow is not the same thing as the limbs flapping at the end of the power stroke.
 


Stretch

Member
I don’t see how a light longrod will help as that is not there when you will shoot your bow so you have changed the test system. Even a light longrod is heavy enough to compromise the test.

I think I have only ever shot one bow that the limbs didn’t close well over a range of tiller settings. So you’re probably worrying about something that doesn’t really affect your shot.

You don’t say if you are string walking - that will make a huge difference as you will need your tiller in a compromise setting to work for longest and shortest walks.

The best method is time consuming but fairly simple. Pick a tiller, tune it, shoot it and record the result as best you can. (Audio, video and how it feels). Then go up 1/4” and repeat. Usually one or two steps will give you a better/worse picture and then you iterate towards your optimal setting (remembering it could be less that your start point). You do have to retune at every setting or your comparing apples and bricks. Usually you’ll find something that says this is wrong - usually vibration.

Or if your bow sounds OK and is not vibrating too much just forget about it and shoot.

Stretch
 


Timid Toad

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Test your bow in as close to real world settings as you can get.
Your limbs need to close at the same time for the way you shoot it, and that's all you are trying to acheive? You can do that with a friend with an iPad or an iPhone set to high speed. It doesn't need to be really fancy.
Whatever tiller you end up with needs to be tested with a good retune and then shoot for good groups at the distances you need. If that all works, and it happens to be different to the perceived correct set up, so be it. Don't worry!
 


Hawkmoon

Member
Barebow so no stabilisers, sights etc
If you are shooting bare bow and string walking then the best thing to do is usually to make the tiller neutral, as you crawl down the string you are going to change the distance the limbs move and so you cannot really tune the bow. You are looking to the tiller setting that gives you a bow that settles down as fast as possible after the shot, and for most bare bow archers that will be either neutral or slightly negative.
 


Kerf

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There’s an interesting article on this very issue in the current Archery GB magazine. Mine arrived today.
 


KidCurry

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There’s an interesting article on this very issue in the current Archery GB magazine. Mine arrived today.
Yes, I read that too. I have found setting tiller on barebow to be quite problematic due to the amount of string walking I do. However I now have a dedicated indoor bow so I will test this procedure today :)
 


Kerf

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Yes, I read that too. I have found setting tiller on barebow to be quite problematic due to the amount of string walking I do. However I now have a dedicated indoor bow so I will test this procedure today :)
I’m waiting for some new limbs to arrive and was planning on trying this method. I’d be interested to know how you got on and if it works. Good luck.
 


albatross

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Is that the article that shows a protractor placed over the image? Why use a printed image and a plastic protractor (that can interfere with the view under it). If it is a digital picture. Put it in some graphic/paint application and use the software's line drawing facility to check the angles etc. You can also zoom-in for a clearer view. I did make this suggestion to the magazine when this idea was printed previously - to no avail.
 


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geoffretired

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I would guess that the plastic protractor on the screen of the mobile phone would be good enough. Even on the picture in the magazine, it is clear that the top limb is not on the same line as the bottom one. I wonder how accurately the limb tips need to match one another in order to reach the objective. Does a spot on match ensure the best results?
 


Kerf

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I would guess that the plastic protractor on the screen of the mobile phone would be good enough. Even on the picture in the magazine, it is clear that the top limb is not on the same line as the bottom one. I wonder how accurately the limb tips need to match one another in order to reach the objective. Does a spot on match ensure the best results?
That is a very interesting point. I shoot with a zero (neutral) static tiller, three under on Border limbs which have an inbuilt 3-4 mm positive tiller. I haven’t done the dynamic tiller test yet but if it shows the limbs are out of timing I’ll try a tweak to see if it makes any difference. I’m happy with quietness and performance thus far however.
 


KidCurry

Active member
I've just done three photos and taken them in to photoshop. Pasted a protractor over the alignment for a 3 under for 50m, a 1" crawl for 30m and a 1.5" crawl for 20m. At 20m crawl it shows the bottom limb is about 1" late, at 30m crawl the bottom limb is about 1.5" late and at 50m crawl the bottom limb is about 2" late. When I say late I mean too stiff. It was set up for 20y indoors with 4mm negative tiller. I will try to p[ost images tomorrow.
 


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Kerf

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KidCurry, very interesting pix. Thanks for posting. I’m guessing the benefit of using this method to “balance” the bow would be best seen indoors, as the range is always the same. I tend not to shoot less than 50 yards outdoors, which is almost point in for me with a tiny gap. Have you noticed any issues with the “lateness” your rig at these longer distances?
 


KidCurry

Active member
Yes, the arrows definitely fly better with zero tiller at zero crawl. I suspected this would be the case from my tuning over the last 6 months so the riser in the pictures is now tillered for 18m and my second riser is tillered for 90m. The reason the outdoor riser is not tillered for mid distance is outdoors I only have a 1" crawl at 70m and 30m as I change anchor at 50m and most points, that make a difference, are at 90m and 50m with zero crawl (WA1440 of course)
 


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