Tiller Check - 1st time Holmgaard

[Parnell]

Heya,

Just getting back to this bow after being away for a couple of weeks in the Smokies.  First time I've done a Holmgaard design.  How is the tiller?  Bottom limb a little stiff in first half?  Thanks for thoughts.

Parnell

[attachment deleted by admin]

[Jesse]

I never made one but I've seen them tillered a lot of different ways and I'm not sure which is correct That one looks like its bending real nice. Great job

[adb]

Can you show us more pics?

[Little John]

Looks to be bending real good. what are the specs and how does she shoot.  More pictures.     Kenneth

[Del the cat]

I'd agree the lower limb looks slightly stiff.
I've seen pics of some bows here where, at full draw, the grip becomes quite angled instead of remaining vertical, (usually the lower end being pulled towards the archer. (Which is what yours is doing, slightly)
I'm loathe to criticise unless asked....
I wonder if maybe this can be caused by the centre of the bow being supported too rigidly when tillering and not being allowed to pivot... When I'm tillering I often support the bow on a sliver of old arrow shaft at the point where the hand will take the weight.
Dunno what you guys think of this theory?
Del

[radius]

specs man specs

how long is the bending portion of the limb, compared to the total length of the bow? 

[radius]

the tiller almost looks like conventional full limb tiller.  I thought that you gotta get the sucker bending right out of the handle, so that the overall tiller shape is kind of like a lemon...but then again, i've been getting too much set on my holmies, so wtf do i know?

how's it shoot?

[Parnell]

What's happenin Radius?  Specs - 66" long, levers are 8 inches to beginning of fade.  Handle is 6".  So, that means the limbs are 22" long and 1 3/8 wide.  It's hickory.  Bow is currently pulling 60 @ 27. 

So 2/3 of bow is bending limb.  1.5 inch set currently.  Heat treated belly several times during tiller. 

Shoots the best of any bow I've made as of yet.  Snappier than other designs so far, noticeably so.

You thinkin I should get it bending more out of handle?

[radius]

well, brother, i'm not sure...i've built four holmies by now, and the best one (in terms of set) was osage backed with hickory, glued into 3" of reflex.  See the one i have posted lately?  It bends like crazy out of the handle, and shoots fast, but shows lots of string follow...i'm reluctant to heat treat it, because of the many knots....

it's tricky with stave bows full of knots, but you get a cool vibe going with the wood, and each one is unique...

if that was my stave (yours, i mean), and it had no knots, i would heat temper it in to reflex (or at least straight) and then rasp away at the fades until it showed a good bend instantly out of the handle.

Did you read Tillering the Holmegaard Bow, by Dennis LaVarenne?  It's online...let's see if i can find a link for ya...

http://www.fiarc.org/public/Forum/Data/jeval/2005102714414_Tillering%20the%20Holmegaard%20Bow-2.pdf

there it is

[Parnell]

Cool - I'll read through.  Thanks for the input.

[Parnell]

Hmmm.  I see that what I've got is following a more traditional ellipse than the ideal tiller for the Holmegaard.  I guessed at lever length.  I suppose this would have followed suit to the design, more so, if levers were 12-14"?  Most of the flex looks to be in the first half of the limb.  I won't be trying to change this bow, now.  I really like how it's shooting.  I have one more piece of this hickory board.  I'll revise the design and try again after finishing up this one.
 

[radius]

cool, Parnell.  You really saw the difference in the tiller shape, eh?  The paper i sent you the link to is missing a holmie full draw pic, i think, but you can see how it's supposed to go.  Also, adb's buildalong shows how. 

The holmie i just built is damn short, but i got it drawing 50# @ 27", paying a LOT more attention to the fades/dips than usual, rasping there continuously, it seemed.  It shows a fair amount of set, and has a pretty pronounced prop twist, but i love it.  And just today i met a guy who wants a short bow to use while riding horseback in the kootenays. 

Between us, let's see if we can find a ratio that works, LEVER:BENDING LIMB...then it won't be so much a matter of "how long is the lever, and what's left for a bender?" but ... "the entire limb is this long, so that means this much lever and this much bend."

[Parnell]

Right.  I like the idea, your on.

You think, though, that lever height has to play into the ratio?  The longer the lever, the greater it's height will need to be? 

[radius]

i don't quite follow you on "height" of the lever...you mean, distance from string, thickness, what? 

I measured my shortbow yesterday, to check.  It is 57" total length.  The bending section of the limbs are about 14", plus the fades, plus 4" handle.

So...

each limb, all the way to the tip, is 26.5" long.  The bending part plus the fades = 16 inches.  that leaves 10.5 " for the lever.  so, 8:5 is the ratio for this one.  But...it shows lots of set.

[Parnell]

I'm wondering what the thickness needs to be.  I'm wondering; the longer the lever the greater the thickness would need to be.  Guess it would depend on other things, also, like wood type and lever width.  I guess I'll think about this later I'm stickin to what you're saying for now, try to just keep it simple.