Tiller

[WhitehartFB]

Like Bowman I have never really given tiller a thought on my current bow.

I have now carried most of this philosophy over in setting up my new bow and limbs, I set the tiller at 4mm positive, put all the gear on the bow sight stabilisers etc and then found the nocking point based on the position of the bareshaft in relation to the fletched at 20 yards. Funnily enough it comes out at 1/8th inch above square. If it had come out rather high or low and or there were subsiquent issues with arrow clearance then perhaps I would have played around with the tiller by a mm or two.

The final check is that the bow sits comfortably at full draw, not wanting to tilt back or forwards.

The comments about limbs being wound in are interesting as when I chose the poundage I went for the correct weight for me at full draw with the limbs wound out, as the riser manufacturer told me this would be the most stable position. (I wish all manufacturers would divulge this information as it appears to be different from manufacturer to manufacturer and all ILF geometry is not the same???? and leads to the same question about limb footings) Since coming back to the sport I have always had that nagging doubt as to why as archers not bowyers we are allowed to change ILF bow geometry (I can see it from a marketing point of view though). May be controversially (have read how it's done by many others - but this is me and my bow I am talking about) I also put the geometry and stability higher on my list than winding in or out to get the arrow spine better matched, again because I make sure I get the right spine in the first place and from my whitehart days know that if I have the right spine I can make necessary minor adjustments without having to adjust limb bolts.

[BorderBows]

Messing with the geometry is a pain. So is the left to right adjustment.
Either way we are going to do our best to make a riser that takes either ILF or our "BGB" (term coin'd by a archer we are talking to) "Bloody Great Bolt" design of our Black Douglas.
But Either way the archer gets the choice.
The question has to be how close to the rules do you go in setting up tiller based on the fact that tiller changes, based on what the BH and preload is. And to what effect does this have on your preformance.
If None, then why have the complication, and the extra chance of it coming loose, One of my older posts says, why use new methods to solve a age old problem when all they do is complicate things. For example. Moving your arrow rest hight as part of tuning. Why not just use your nocking point?

[BorderBows]

Originally Posted by Yorker

Tiller I have nothing to do with. I just left it at factory setting. Was going to set it neutral but I was told you need tiller, so I didn't.

The technique someone mentioned though is you draw and you see if the sight risers or falls, then you can apparently adjust tiller to keep it steady so you end up on the centre of the target at fulldraw.

Changing your point of push would also do the same???

Pushing high into the throat would push the top limb forward, vs pushing more with the the heal of your hand on the bottom of the grip, push the bottom limb out more. Again not kicking the bow out of geometry to compensate for a possible bad hand position???

[geoffretired]

I have never understood tiller causing a bow to want to tilt up or down at full draw. What I can understand, is that if the top limb was much weaker than the bottom one(by design) as you draw, the top limb will bend more easily and so bend more. That will cause the bow to tilt forwards at the top, or tilt down. Once you are at full draw all the bending is finished so all the tilting should be over too, yes? By winding down one limb, it won't alter the relative stiffness of one limb to the other, so the top one will still bend more etc etc.
What is it that I'm missing?

[BorderBows]

Originally Posted by geoffretired

I have never understood tiller causing a bow to want to tilt up or down at full draw. What I can understand, is that if the top limb was much weaker than the bottom one(by design) as you draw, the top limb will bend more easily and so bend more. That will cause the bow to tilt forwards at the top, or tilt down. Once you are at full draw all the bending is finished so all the tilting should be over too, yes? By winding down one limb, it won't alter the relative stiffness of one limb to the other, so the top one will still bend more etc etc.
What is it that I'm missing?

Again, your hand pressure point can do this kind of adjustment?
The reason for the heavier weight on the bottom limb is to make up for the grip being below and arrow above centre.
The issue im questioning, is the 4mm of average tiller measured at what bow setting. I'll try to explain (i'll need beer after this one)
4mm of tiller at 8" BH is going to get a load more at full draw. If there is a 4mm difference showing at 8" what is it going to be at 28"
If a drag race car is 2 seconds faster at 1/4 mile whats the difference of the two cars at 1/2 mile. it should be 4 seconds give or take a bit?

The tiller changes you make as you change the setting of your bow means that you have hobbled the race to show the same 2 seconds difference even if the race is now over 1/2 mile...
Does that make sence?

we are in discussion that you should set your tiller at base setting. and then keep that setting relationship equal. For example Set up the tiller in the bow, adjust weight accordingly by doing equal adjustments in the limb bolts.this thought would be to not re-adjust the tiller to get back to 4mm. The reason for this is that the 4mm is the string wrap speed compensation to avoid limb flap, round the recurves which shows at full draw with no sight movement as discribed.
This setting should be the same. Though if your brace height is cut short from good tune with a hight BH, then the recurves would not have wraped at the same pace to each other giving wobble.
The other thought is that the tiller should be set up for the Brace height and preload, that the archer feels if right. This again is full of questions.

What in effect we are saying is that in the 1/4 mile race we have made the faster car run a longer race, by 2 seconds worth. this should mean that they cross the line equally. But if you stop that race half way, then the faster car has not had time to catch up...

We see tiller as a best guess at getting the two recurves to wrap at the same speed based on the off balance grip and arrow positions. Its just how do you use it based on the adjustment given to you.
What gives best groups?

[geoffretired]

Thanks for that BorderBows. I see what you mean about the race and stopping it short.
I know very little about this, so if I sound as if I am disagreeing with you, please accept that I am only expressing my lack of understanding.
When a bow is drawn, the draw force is not along a centre line as it would be on a crossbow. The draw force is slightly upwards, am I right? That would cause the bottom limb to bend more as the force is moving further away from the bottom limb. On release, that set up would mean the top limb has a shorter journey and will get back first. By having a slightly weaker top limb, it can be slowed down so it returns a little later than last time. But, as it is now weaker, it bends further so it will have further to travel than when equally stiff. So by changing Brace Height or draw length you alter the length of the "RACE" and change the winner.
If someone shoots a longer draw length, would things be helped by a higher bracing height?

[geoffretired]

Originally Posted by Yorker

If the arrows are still hitting the target in a good group, does it really matter what the bow is doing to get them there?

Hi Yorker, that is a valid point. I agree with what you are saying.
Looked at from a different point of view, though, when things go wrong it's good to know what should be going on. Especially if there is a chance that what is wrong can be recognised and corrected.

[BorderBows]

Geoffretired:
Tiller is to try and get the race to end at the same time. keep in mind that the lights dont go to green at the same speed... due to the grip, Nocking point and arrow rest are not in the middle of this race.
In theory the longer the race the easier it is to see the time differences. Low brace height and long draws will help this setup, this is a simple explanation...
The idea of drag racing is a bit rough mind.

Your looking to get a knocking point path that travels downwards. but this is a curve, steeper at first, leveling out. The lower the brace height, the longer the nocking point has to level out, as long as the tune is not out.

but in short yes, the top limb is weaker as the arrow is above centre... The nocking point, if placed on the top serving, would travel upwards as the limb moved forwards. The closer to centre the less this effect happens. So if you make the bottom stronger it pulls the string downwards first... giving the downwards path that is in any bow, bar compounds. considering your NP is above centre. Thats the theory anyhow...




yorker:

if that archer is having trouble, he/she should be looking at a riser where the grip/ arrow shelf is in a better location form them? For example. why restrict the horsepower by de-tuning the car to make the race fair? Why not get the best out of the car as the car was designed, rather than comfort if its performance your after?
The bow does have a optimum. your the most flexibal part of all this equipment and your nuts dont come loose with vibration
remove the complications as there is less to worry about.
We have seen archers change there left to right hand to suit a eye dominance and gain better scores even after many years of shooting.
I tried to start a sticky thread about riser stats so that we could find riser info. For example, some risers have the middle of the throat of the grip in the geometric centre. Some have the geometric centre 1/4" above this and some up to 1/2" lower. Not all these shoot in the same pressure point. This depends on the riser designer and not the limbs.

[hollowpoint]

Originally Posted by geoffretired

I have never understood tiller causing a bow to want to tilt up or down at full draw. What I can understand, is that if the top limb was much weaker than the bottom one(by design) as you draw, the top limb will bend more easily and so bend more. That will cause the bow to tilt forwards at the top, or tilt down. Once you are at full draw all the bending is finished so all the tilting should be over too, yes? By winding down one limb, it won't alter the relative stiffness of one limb to the other, so the top one will still bend more etc etc.
What is it that I'm missing?

geoffretired, could u explain a little bit more about tillering from park's video?
YouTube - World's Best Recurve Archer: Park Sung Hyun
i don't know if park had an extreme tiller setting on her bow? but that video clearly showed her bow had tilled up quite a lot!
will you guys' bow tilt like that at full draw?

[maxwell9699]

Have a look at "The Heretic Archer" pages 47/48 by Vittorio and Michelle Frangilli. The advise is set to zero tiller. From Michelle's results it appears to work.