Limb Timing

[adb]

What do you mean by 'harmonize' the limbs?

[PatM]

 Harmonize ="timing".
 DWS. I don't like pistol grips on a selfbow so that's not an option.
 

[bow101]

Good topic, but like some of you say if it looks good and feels good to shoot then call it a day and start another one.  I just like to build. 
I did this photo just for something to do, my bow is on the left, Bubby on the right.  Both bows are an r/d design.  I rushed the final stage and cut in a small shelf on the stronger limb (top), at any rate it looked like the stiffer one on the tiller stick. The photo is not the best but it looks like the top limb is longer.  Rather than over tiller the bow and loose weight I let it be and having a slightly more negative tiller seemed ok. It feels good and shoots fine.
And yes Bubbys is the better tiller.......

[Tuomo]

Please, see this video:

http://www.youtube.com/watch?v=8pYVmrWzTP8

Very unbalanced bow, and 1500 grains weight in upper limb. As you can see, limbs are "timed", of course, but the bow is rotating in my hand. Same is happening if you cut the string but more pronounced.

There is videos where the weight is in lower limb and with no weight.

[Del the cat]

BUT!!!... IF we get to full draw and cut the string....
THEN and only then can one limb race ahed and get home first... but without the string... it's not a bow!

That's one thing that boggles me, is how utterly crazy the string seems to go when I fire the bow from frame to frame. It seems to go nuts, and I shoot either low stretch linen or fast flight.

That could well be an artefact of the camera. See the last of the possible causes 'Rolling shutter' in this link.
http://en.wikipedia.org/wiki/Digital_artifact
You need a propper high speed camera to view it properly.
You will see lots of stills taken from video with loose S shaped wobbly strings and limbs that look out of kilter.
The camera certainly does lie!
There is some string vibration, but it more like a guitar sting than a length of wet spaghettii (other types of pasta are also available...  )
Del

[Dances with squirrels]

By the way, the Yumis are almost a completely different animal. Their unstrung profile tells me to be VERY careful about using them to compare against my own bows. Watching them in action, I've noticed that like 'our bows', they are not all tillered to suit every archer. For various archers, some bows stood straight at full draw, while others tipped forward a great deal. Some were dead in the hand at the shot, and some pitched back and forth wildly. It doesn't seem all Yumis are tillered equally well, so I'm mindful of that when studying them.

[Del the cat]

That's failed logic, Del. As you define it, they may be balanced IF the archer does NOTHING to alter the imbalance with his bow hand, but your balance requisite doesn't take into account the effects..... one of them being the positional relationship of the nock point to the shelf.

We always draw to the same anchor point, but with one limb's relative strength greater than the other, there are consequences... which I explained above, and you partially explained in your last post... i.e. the stronger limb won't flex as much as the weaker one... so the weaker one 'gives' to the stronger, giving away nock position relative to the shelf as it does so.

Again, since we always come to the same anchor, any unbalanced bow, especially your 50/20 bow, can/could be seen as the bow tilting in the hand at full draw, which I've seen on every bowmaking site I've visted. The more the limbs are out of balance, the farther the bow will try to tilt in the hand, and the farther the nock of the arrow will deviate from perpendicular travel relative to the shelf. There are also consequences to THIS, upon release.... arrow porpoising, handshock, inefficiency, unbalanced draw, etc.

The hand is supposed to merely support the bow not grip it.
A bow does naturally pivot as it is drawn because it is (generally) not entirely symmetrical.
Why would an archer fight the natural balance of the bow???
That's why modern target recurve archers (with their girly bows ) have wrist straps and support the bow loosely. Even with their bows the nocking point is above the grip so the draw isn't symmetrical.
Anyhow we are in danger of arguing about how many angels can dance on the head of a pin.
I'll hold off on the naughty step and pie until I hear something more convincing
Del

[Dances with squirrels]

"The hand is supposed to merely support the bow not grip it."

I 'grip' my bow light/relaxed. If things are designed and balanced well for the archer, gripping a bow, even stearnly, needn't have disasterous effects. If it's designed and balanced poorly, minimal human contact sure couldn't hurt on some... though there are still issues not being addressed...  and adjusting the grip, by say, affecting a high or low pressure point, might help to a certain degree on others. 

"A bow does naturally pivot as it is drawn because it is (generally) not entirely symmetrical."

Some bows will try to pivot, and they'll be prone to try to pivot more the farther the static/geographical center and string fulcrums are seperated by design, and more-so in the early part of the draw. The farther we draw, the more relative limb balance can overcome the initial fulcrum seperation, and we can then tiller/time the limbs to largely balance at full draw(dynamic balance) so that pivotting and nock point deviation from perpendicular to the shelf is minimalized. Still, the best drawing and shooting bows I've made and used were designed and timed to suit the shooting style of the archer so that there is no, or practically no pivot or pressure shifts from beginning to end.

For instance, an asymmetrical bow shot three under can have the static balance, dynamic balance, bow hand and string hand fulcrums all at the same spot, requiring no shifts during the draw and loose.

"Why would an archer fight the natural balance of the bow???"

I don't know, but many do. Heck, due to design and tiller, some bows REQUIRE a fight. Guess they ARE like women :^)

A better question might be... Why not design and tiller the bow to balance perfectly and be inherently tuned to the archer?
 
"That's why modern target recurve archers (with their girly bows  ) have wrist straps and support the bow loosely. Even with their bows the nocking point is above the grip so the draw isn't symmetrical."

You're right, it generally isn't. But it COULD be with the asymmetrical/three under thing I mentioned above.

I think they do it more for minimizing human error factor anyhow, no?

[Marc St Louis]

I've been reading your posts DWS and I see that you make a lot of assumptions.  Perhaps you could post some pictures of your bows, perhaps at different draw lengths, to assist you in what it is you are trying to say.  Come to think of it, I don't think I have ever seen you post one of your bows so I would certainly like to see one.

[Bogaman]

To all timing advocates. How would you time this puppy? ;^)

[Pappy]

I always love when this comes up,I get to fill up on popcorn.
 Pappy

[Bogaman]

Easy on the salt Pappy. You know it causes hyper-tension. Next thing you know we'll be getting into tension issues;^)

[Marc St Louis]

Nice bow

[Dances with squirrels]

Bogaman, I'd love to time that thing. I'd do it just like I do any other bow.

Marc, I don't remember the last time I posted pictures here. I have plans to do an indepth article/tutorial on tillering/timing of the various popular designs, and have the bows glued up that I'll use, but I need to postpone it temporarily now because I sold my house and am in the process of packing. I'm now finishing the last bow I may make for a while. I'll try to post some pics of a bow or two soon.

[Buckeye Guy]

That is defiantly an out doors bow !