Too circular??

[k-hat]

Need your tiller opinions boys.  This is elm, 60" ntn, parallel (1.75) for 1/2 length then tapers to 1/2" nocks.  Got'r stretched out to 29" here, but only going to 28" (security blanket).  Is it too circular for an eliptical tiller?  Shadow makes it look like a hinge out of the left fade, just a trick of the light (my good camera's on the fritz, so no flash).  Here it is:



Thanks for lookin

[k-hat]

btw, those are two offset elipses, one for each limb.

[blackhawk]

There's two ways to look at this.

One is for proper bend to match your front profile. And yes it is too circular.

But,the other way is you are asking a straight 60" stiff handle piece of wood to be drawn to 29",so to get there you must ask the area out of the fades to bend more than it should technically.

So,basically your fine IMO

[k-hat]

I was bouncing around the same thoughts blackhawk.  I  went and looked at half-eye's 56" stiff handles and the tiller on those looks real similar (still can't believe he got 56" of wood to bend that well with a stiff handle!).  I think i'll put some arrows through her and see how she feels.  If I'm not happy with it, I'll loosen up the mid/outer thirds a touch.

Thanks again.

[half eye]

k-hat,
     Dont know that there is a "correct" tiller shape. But all of my bows I try real hard to get them circular and symetrical to each other (with or without stiff tips). It makes for a smooth draw and hard shootin bow.
     Both the 54" and the 56" are going to Lesken 2011 from the site so maybe he can tell you his opinion on the performance impressions. He allready has the 54" and will get the 56" today.
      I like the way your tiller looks, only difference is that mine would not have the tips you do. Mine would be thin rectangles with small pin knocks.
rich

[coaster500]

If your look at it this way it looks good to me ... 

[Dean Marlow]

I really like the way that is bending. I bet it will be a shooting machine. Dean

[k-hat]

Thanks half-eye, I really liked the way those two for Kenny turned out, unbelievable!  I like pin nocks as well for my personal bows (though stringing a heavy bow with pin nocks can herniate a guy!), but this is going to someone else and i'm adding stringing grooves above the nocks to make it a little easier and keep him from torquing the limbs.  A also used the overlays on this one to build up the slightly flipped tips to help with string angle/stack.

Thanks Dean, I hope she is.  She oughta finish out at 50#, n the recip plans on sticking pigs with her

Thanks again guys for the input.  I'll post when she's a fully finished bow or toothpicks

[Del the cat]

Right... Quick answer..
No!
Long answer (and I opologise to start with 'cos I'm going to be contentious here goes.  . )

1. This 'The front profile determines the propper bend' is just nonsense!
Literally "non-sense" unless the bow is of uniform thickness e.g made from a dead flat board with no thickness taper.
And anyhow, even then, how do you correllate front profile to tiller shape?
If you cut a simple tapered limb say 2" wide tapered down to nothing at the tip from thin sheet material (e.g Triangular profile) it will give a curved tiller shape ... not a triangular one so where is this mythical correlation??
I just don't get it... maybe I'm thick... or maybe it's like the Emperors new clothes?

Thickness taper and unbraced shape are far more significant in determining the full draw tiller.
There I've said it now...I expect to be struck by lightning now!

2. You have matched each limb to an elipse ... so how can it be too circular? It's not at all circular.

3. It's great! Stop worrying!

Del (scampers away to hide in secret cat nest)

[k-hat]

I'm just doin what i've been told Del, I'm only a year and 1/2 in to this!  But I hear ya, no need to scamper away.  i think i understand the rational, but i ain't got time to type my thoughts right now, it's date nite  

Maybe somebody who can elaborate will chime in while I'm out

[toomanyknots]

I would think that it is as elliptical as you can get short of making it a bend in the handle bow, right? You would have to stiffen the fades to make the mid limbs work more in order to get a more circular tiller shape, wouldn't you?

[SLIMBOB]

Looks good k-hat.  As to your question of too circular???  This is one of the things I love about stick bows and those that build 'em.  There is no law that says front view profile dictates tiller shape.  However, front view profile in my opinion does tell us what the tiller shape should be to get the best performance.  It's all about mass and movement of the limbs.  If your limbs are tapered, a circular tiller works BEST because you are moving less massive mid limbs a greater distance and they are easier to move than heavy mid limbs.  With parallel limbs and circular tiller, you are simply asking the bow to throw more mass forward than on tapered limbs.  This comes at the expense of arrow speed.  Additionally, tip deflection near the handle becomes a concern.  The heavier the draw weight, the more circular the tiller because you have more stored energy to propel the limbs forward.  The same is true for a longer draw length.  All this having been said, it is not raw arrow speed alone that we are after.  If it were, we would all be shooting wheelies with carbon darts.  I turned off that road years ago.  Still, we all aim for certain qualities with the bows we make, and efficiency in design has it's place.  Do you like your bow?  Does it release softly?  Accurate?  Those are the questions that REALLY matter.  Nice work!

[Fred Arnold]

I don't often give advice because I haven't the experience or knowledge to benefit. But if I had that bow I'd shoot it. I think you did a fine job with the tillering. Should you find that you are less than happy with the results I may be willing to trade you for some fresh cut staves.
I have elm, walnut, and mulberry.

[k-hat]

Thanks Slimbob, I'll have to think on that awhile but that makes sense.  My explanation would have been from a more mechanical perspective (change in thickness w/parallel limbs vs change in width for pyramid), but I like yours better

I guess what i was looking for was experience as far as the repercussions of having the tiller the way it is, so i could adjust if before i shoot it in.  I plan to put those arras through tomorrow n see how she does.

Thanks for the offer Fred, but my boss has been waiting awhile for this one, so one way or another, she's going to him!  Now, we might could work something out on another, i'm always in the market for staves!!

[Del the cat]

I've taken the liberty of trying to fit an actual circle to it.
I found that a slightly flattened one (e.g an elipse) does fit best, the centre of a real circle would be at the point of the string where it is pulled.
You can see the centre line of the elipse is above that.
I still think the tiller is gorgeous and not 'too' circular.
Del