Overbuilt?

[simk]

Hi All
For testing a new wood I quickly rushed an elbish bow - round belly. It's currently pulling 49# @ 28" and its 65" ntn.
Scale says it's 525 gramms, but according to Gardners mass theory it should rather be close to 400 gramms.
What's wrong? Overbuilt, too long? Should I pike it? How much?
As it's my first elbish bow, tiller critisism also welcome....I know, it's a little stiff towards right outer...and after handle area...?
Cheers 

[Del the cat]

Just my opinion.
It's fine maybe a hint stiff in the outer on the right limb (or is that the lower limb).
Some use the mass theory... some (like me) have never used it.
Like any tool, it has it's uses, but I'd never adjust the tiller of a bow I was happy with, because of its mass.... unless maybe I'd used the technique extensively and had 100% faith in it.
It's a mathematical model, a mix of theory and empirical to give a useful guide ... I wouldn't consider it gospel.
There is no disrespect for it at all, just my preference. A bit like a tillering gizmo, a great tool for helping newer bowyers get their eye in, probably a great time saver too especially on board bows, but not something I use and probably not relevant to all bows.
Del

[simk]

Thanks Del! Very helpful...
As a slave of the mass theory I just tought, the same bow piked and retillered to 49#@28", and - lets say 420 gramms - would throw an arrow farther and faster than it does now  wouldn't it? if not breaking 

[Hamish]

You"re testing a new wood (what wood is it by the way?)so no need to push it too far.

Was it taking much set? If it was I wouldn't pike it.

[simk]

it still keeps 1" reflex of 2" glued in. bellywood is fir (picea abies), sig of .7 🤣 pushing it to the limits 🤣

[Selfbowman]

My bows nearly always comes in a bit heavy. A lot depends on what you have in the handle and my wide pyramid bows never hit the mass theory. All though it is a very good tool during design and build.
Arvin

[simk]

I'm glad to hear that also your bows come in a bit heavy regarding Badgers theory, Arvin - can't be so bad then 
Sure with stiff handled bows there's always that uncertainty about the mass in the handle...but with the elb design, where every inch is working, it should be very exact. This bow just feels heavy in the hand...what made me start thinking and putting it on the scale. I'd be really interested on how heavy a well performing elb with 50# should be...?
As the wood does not show any signs of stress I'll probably pike it a little and work it down to 450gramms. Cheers

[Del the cat]

At 65" ntn, I'd say its ok. taking an inch off each end wouldn't hurt too much tho' 
To give some context... the flight bow I made last year 48# @27" boo backed Yew was 64" long and a whisker under 7/8" wide at the grip.
It weights 340grams, so maybe that does imply you are a tad overbuilt... remember mine is a boo backed flight bow and rather extreme, with limited stability and durability.

I'd suggest you shouldn't go below 64" as an ELB is working pretty hard at that length would arguably no longer be an ELB were it much shorter.
If you want to shed weight, maybe lose some width.
Personally I'd leave well alone.
Del

[backtowood B2W]

Always on the hunt for the limit ...
I would do as Del suggested leave it alone, or maybe skinny the tips some more.
Interresting bow? - wood, whats the combo?
Good luck!!

[simk]

Del:

64" long and a whisker under 7/8" wide at the grip and 340grams

is impressive. how thick at the grip? mine is not finished. I'll do fps, then pike a little and reduce width and shoot it again. very curious. thanks for input!
b2w: with this one it's more about the legend of compression pine. its ash-backed. apart of the high mass I'm impressed so far 

[willie]

Nice bow. nothing wrong with that bend.

with this one it's more about the legend of compression pine. its ash-backed. apart of the high mass I'm impressed so far

Hi Simk,

tell us more about your compression "pine". I have used compression spruce, and it is an unusual wood. I once made a very similar maple backed larch bellied flatish elb that surprised me. the larch was from a board, and I have no idea if it was compression wood. (I have assumed it was not), while the spruce in a different bow was selected specifically for its compression wood content. Both woods acted in similar ways that is hard to describe. I think conifers  exhibit some qualities that differ from hardwoods in compression. They seem to be able to recover from temporary set better. Could be that compression wood is a bit heavier than other woods for the draw weight, so I would expect the mass principle would need some correction for the materiel.
I would not cut the bow to pike it, but would try to clamp or lash down the string to a shorter draw to see where set starts to kick in harder. Resting the bow unstrung might show more recovery than you would normally expect from other woods.
Here is a pic of a Russian traditional bow that apparently can recover from an extended full draw. Please let me know if you do not want it in your thread.

[simk]

this really is a wicked constructrion willie  what the heck is that??? a prehistoric shooting machine 
there's lots of myths and rumours around this compression stuff, eg that its reflexing when getting more moisture. as spruce (thanks for clarification) is the most common tree here, there was a natural interest on my side.
bow is laid out with belly towards lower branchside. wood smells good from pitch. pitch pockets are a bad thing you can occur.
the storm had brought down a big tree 200meters above my home. couldnt resist to harvest a few very thick branches. cut some slats from the lower half.
I have tried thin ringed construction larch before. it chrysaled. they dont like compression wood in the construction wood because its warping all the time.. i' impressed its really working on a round belly. and also how well its holding the profile. and I first time myself checked specific weight of a wood: .7 is far away from of normal spruce...definitly its different wood.

[willie]

what the heck is that??? a prehistoric shooting machine 

not sure how long ago it was invented, but it has been documented here.

https://vk.com/doc85016760_187383081

Do you have any russian friends that can help with the translation? Google worked some, but I tried to parse the specific language describing the tree it came from with little luck. It appears (near the pics at the end of the article), that the spruce selected by the bowyer was a leaning tree, but not as extreme as some that I have found here. I have tried compressionwood that came from more extreme examples, but not like the pic in the pdf.

I see that you are using a branch. How long has the wood been drying?

I have tried thin ringed construction larch before. it chrysaled

I have found some very thin ringed larch, but the thin rings came from the outer rings of a very mature tree and had a high early wood ratio and was not very dense. I did find some better larch from another board. More than twice as stiff, actually.

http://www.primitivearcher.com/smf/index.php/topic,61908.msg868115.html#msg868115

[Del the cat]

Mine has a little bit of Ash added on the belly at the grip for comfort.
At the grip it is 27mm deep x 22.7mm wide
Just beyond the built up belly it is  20.2mm deep x 22.3mm wide
mid limb 16.2 deep x 20.4 wide
Del

[bownarra]

Cool bow! Very interesting stuff.
Your bow could do with either more bend mid to outer right limb or less bend inner to mid depending on how you look at it