Three under tiller

[Carpdaddy]

I have ran across this phrase several times and am wondering  what does one do to tiller for shooting three under. Is it making the lower limb stronger, making the shelf higher, or what?
 Thanks

[Carpdaddy]

I don't know if no one else knows the answer either or if this has been explained many times before. This is the first bow building question that I ever remember asking on here that went all day without a response. I build laminated bows (for myself) and just don't know.

[jhk1]

My understanding is that the bow should be tillered even for 3-under shooting.

On a bow tillered for split-finger shooting, the lower limb is typically stronger (resulting in positive tiller).

[Carpdaddy]

I thought that I had read that somewhere but not sure. The center of the bow being usually at the deepest part of the grip already puts the arrow shelf above center, I just was curious as to what if anything determines the difference? I have noticed on my bows that they are louder if shot three under, usually needs a little higher nock point. But is there more?

[macbow]

If when tillering you have it setup on the tree where the string and whatever hook you use pulls down where your drawing fingers will be .you watch the string as it pulls down, if it drifts to the right remove material from that limb till the string travels straight.  That will make the limbs even for your draw.

[Bowjunkie]

Yes, with the bow stable in the cradle of the tree, pull the string from exactly where you'll pull it when shooting. As the string is pulled down, the hook will be pulled toward the stronger limb. Weaken it until the hook pulls straight down without drifting to either side. I have a line drawn on the wall behind the tree to mimic how the hook should travel with limbs balanced relative to my holds. Do this without preconceived notions about what the tiller measurements should be, or what anyone else says they think they should be.

[Carpdaddy]

Thanks  guys for the input. Is it the same on a fiberglass backed bow as with wood?

[Bowjunkie]

Yes.

[macbow]

Thanks for jumping in Bowjunkie,
I was struggling trying to type on my phone.

On the fibreglass bows, I would suggest doing the tillering tree before shaping your handle. Just schetch in where you think the shelf will ne and pull from where your fingers will,be.

One you get it the way you want it cut in the shelf and shape the handle. You will have a well balanced bow.

[Carpdaddy]

I have always put the deepest part of the grip in center, I like it too balance on a finger, makes carrying nicer. I am not building one now, I usually do that after season for the next season. But I have been playing around with three under shooting more lately and just wondered if there was anything I needed to do to the bow or if this was something done during the building. I'm just an amateur bowyer that builds a few for myself and trying to learn more. Thanks for the help.

[Roy from Pa]

Here is a bow being tillered for three under. Notice the trees pull rope coming straight down the left black line on the wall. The left line is for three under tillering and the right line is for split finger tillering. Those two black lines represent where the middle finger of your drawing hand will be on the bow string when shooting the bow. The pull rope following the line indicates the limbs are timed, hence bending in sync. As Bowjunkie mentioned above, don't even worry about positive or negative tiller measurement's. Just tiller the bow so the pull rope follows the line. A bow that is limb timed is a smooth, quiet, accurate shooting bow with zero hand shock.

 

[Carpdaddy]

Thanks for the education guys and the visual Roy. Now I'm thinking about the wall where my tillering tree was with the lines on the wall now covered with shelves and a bow rack above them; hum. I only build one too three per year and thought I needed the space.

[Wolftrail]

Originally posted by macbow:
If when filleting you have it setup on the tree where the string and whatever hook you use pulls down where your drawing fingers will be .you watch the string as it pulls down, if it drifts to the right remove material from that limb till the string travels straight.  That will make the limbs even for your draw.

Good one about tillering. Gotta look at the video link that Roy posted.

[macbow]

Bowjunkie and Roy have it nailed..
I do mine that way after following their threads.

[Bowjunkie]

Good for you Mac.

Keep an eye out. I plan to do some research, testing, and hopefully a pictorial on the 'science' behind tillering in the near future. There's just too much conflicting info/opinions put forth. The thing is, I'm disuaded from using this site for it because posting pics is a pain... especially if ya need a bunch of them. We'll see though. Maybe I'll go another route and then just post a link.

[Roy from Pa]

Photobucket is easier once ya figure it out..  

I'll have to stop over and learn ya...

[Bowjunkie]

Yeah, maybe. Been using that for many years bud. The changes they made a couple years ago stress my computer out... and even this new computer just a couple months old... too many ads on the free version I'm guessing. I used it today, the first time I did it on my cell phone. It threw pop up ads and then locked up. So I got on my computer, opened it, it locked up... I rebooted and then it locked up again. After that, it seemed 'ok'... relatively speaking. That's the kind of CRAP I don't want to go through when I'm trying to post a thread/pictorial. Don't understand why this site can't let us post pics straight from our device like all other sites do...

[Carpdaddy]

I do appreciate the light you guys have shed on this subject, the video was icing on the cake.

Originally posted by Bowjunkie:
Yes, with the bow stable in the cradle of the tree, pull the string from exactly where you'll pull it when shooting. As the string is pulled down, the hook will be pulled toward the stronger limb. Weaken it until the hook pulls straight down without drifting to either side. I have a line drawn on the wall behind the tree to mimic how the hook should travel with limbs balanced relative to my holds. Do this without preconceived notions about what the tiller measurements should be, or what anyone else says they think they should be.

When you say stable do you mean the riser sitting on a flat surface vs a rounded one that sits in the throat or your grip??? Does it make a big difference???  This method makes a lot of sense... Is there a whole thread on this???

Originally posted by Bowjunkie:
Good for you Mac.

Keep an eye out. I plan to do some research, testing, and hopefully a pictorial on the 'science' behind tillering in the near future. There's just too much conflicting info/opinions put forth. The thing is, I'm disuaded from using this site for it because posting pics is a pain... especially if ya need a bunch of them. We'll see though. Maybe I'll go another route and then just post a link.